The interaction among species can be influenced by neutral processes, in which more abundant spec... more The interaction among species can be influenced by neutral processes, in which more abundant species have high effect on the structure of interaction, or can be influenced by trait matching. Despite both variables (abundance and species traits) influencing the interaction of species in mutualistic networks, few studies showed their importance in antagonistic networks. Here, we posed the question: what are the main predictors of the liana–tree interactions: species abundance, biological traits or both? In a savanna woodland fragment in southeastern Brazil, we sampled lianas and trees in 1 ha, where we recorded the abundance, maximum height and bark roughness of tree species, as well as abundance, maximum diameter and climbing system of liana species. For each species, we calculated their contribution to nestedness (n i), which is a measure of network structure, and performed simple linear regressions between n i and abundance and species traits. Abundant species contribute more to n i than rare species, indicating that neutral processes affect interactions between lianas and trees, probably because lianas are opportunistic and climb trees in their neighbourhood. The only trait related to n i was tree height, which can indicate that light availability can have a considerable role on network structure between both growth forms. Therefore, the importance of species abundance and tree height can be related to opportunism of lianas on climbing the most suitable tree in their neighbourhood.
Patterns of plant use in human populations are context-specific and influenced by many different ... more Patterns of plant use in human populations are context-specific and influenced by many different ecological and social factors like plant diversity and availability, and gender, age, and household structure. The aim of this study is to evaluate current levels of knowledge and use of native plant species in different sociocultural groups living in the same ecological area. We examine the association between an individual's species knowledge and use and (1) species availability and (2) individual age, gender, and group pertinence. Data were collected through interviews with three different groups living in the municipality of Açu, Rio Grande do Norte (n = 233): an urban community, a local community of fishers, and a traditional community of self-identified indigenous people (Caboclos de Açu). The results show no correlation between knowledge/use and resource availability. Elders know and use more species than younger interviewees. Men know more species than women, but there is no difference between the number of species used by men and women. Group pertinence was related to both current levels of species knowledge and use: the urban community had less knowledge of the flora than the local and traditional communities. Regarding species uses, the traditional community uses more plants than the local community, and informants in the urban community use the least. Our results dovetail recent anthropological research suggesting that, despite other important cultural changes, the Caboclos de Açu continue to maintain at least part of their traditional knowledge system, probably because they depend on the use of plant resources for their livelihood. Overall, our results highlight the predominance of culture above the environment in driving plant use and knowledge. Os padrões de uso de plantas em populações humanas são contexto-específicos, sendo influenciados por diferentes fatores sociais e ecológicos tais como a diversidade e disponibilidade das espécies vegetais, gênero, idade e estrutura do agregado familiar. O objetivo desse estudo é avaliar os níveis atuais de conhecimento e uso de plantas em diferentes grupos socioculturais vivendo na mesma área ecológica. Nós examinamos a associação entre o conhecimento individual e (1) disponibilidade das espécies e (2) idade, gênero e grupo social. Os dados foram coletados através de entrevistas com três grupos moradores do município de Açu, no estado do Rio Grande do Norte (n = 233): uma comunidade urbana, uma comunidade local de pescadores
Rocky outcrops are distinctive formations in arid and semiarid zones, characterized by the presen... more Rocky outcrops are distinctive formations in arid and semiarid zones, characterized by the presence of plant species with functional traits related to water deficit and high temperature tolerance. These areas are also characterized by high habitat heterogeneity. We tested three hypotheses related to organization of moss communities in rocky outcrops: 1) trait convergence related to habitat filtering; 2) trait divergence related to habitat heterogeneity; and 3) random pattern of traits related to dispersal limitation. We developed null models to test trait convergence and divergence and related these patterns to habitat filtering and heterogeneity, respectively. Additionally, we also tested for different plant strategies to cope with harsh environments and we related the size of moss' spore to the number of rocky outcrops the species occupy. In spite of the convergence in some traits, this pattern was not related to annual precipitation and temperature seasonality. Moreover, the random trait organization on some outcrops was not related to dispersal limitations of the bryophytes’ species. Each community, on the other hand, had different functional compositions, indicating that mosses species have different trait arrangements to cope with environmental constraint, blurring the detection of ecological drivers of community assembly in bryophytes from rocky outcrops.
Questions: We test the hypothesis that soil water availability operates as an
ecological filter o... more Questions: We test the hypothesis that soil water availability operates as an ecological filter on water economy plant traits, particularly in savanna stands, with consequences for species distribution and the functional profile of plant assemblages across a savanna–forest mosaic. Location: A savanna–forest mosaic, northeastern Atlantic forest, Para ıba state, Brazil. Methods: We sampled all trees and shrubs in 11 forest and 12 savanna plots in the same climatic region. Soil water storage capacity was measured, as well as the following traits: specific leaf area (SLA), internode mass fraction (IMF), max- imum height (Hmax), wood density (WD), presence of trichomes (LT) and pres- ence of abiotic seed dispersal (DD). Differences in trait values and water soil content between forest and savanna plots were assessed using Wilcoxon tests. Standardized effect size of functional richness and functional dispersion (SESF- Ric and SESFDis, respectively) were compared between forest and savanna plots with Wilcoxon tests, and the relationships between both functional indices of each trait and soil water content assessed using simple linear regression. We also used null models to test for habitat filtering in each plot, considering species assemblage (SESFRic) and abundance (SESFDis). Results: Vegetation types differed in terms of soil water availability, with savanna soils having, on average, half the content of forest soils. Compared to forest, savanna plants had heavier internodes (30% increment), lower SLA (about 42% lower) and more plants with trichomes, but plants were much smaller across savanna assemblages. Savanna assemblages also exhibited a higher probability of trait convergence (i.e. reduced functional diversity) than forest assemblages in terms of SLA and maximum height, but savannas were less prone to trait convergence in terms of leaf trichomes, considering species abun- dance. Considering both vegetation types, a variable proportion of assemblages exhibited significant values of either FRic or FDis, but soil water availability did not correlate with functional diversity measures. Conclusions: Habitat filtering not related to soil water availability favours the occurrence of conservative resource-use plants across savanna stands, reinforc- ing the notion that filtering is able to act as an assembly force by affecting the abundance/frequency of particular traits, thus contributing to the occurrence of spatially organized mosaics of vegetation.
Caatinga vegetation continues to be converted into mosaics of secondary forest stands, but the af... more Caatinga vegetation continues to be converted into mosaics of secondary forest stands, but the affect of this process on biodiversity has not yet been examined. We used 35 regenerating and old-growth stands of Caatinga to examine the recovery of plant assemblages subsequent to slash-and-burn agriculture and cattle ranching/pasture in northeastern Brazil. Plant assemblages were contrasted in terms of community structure (stem density/basal area/species richness/diversity), functional (leaf habit/reproductive traits) and taxonomic composition. Soil attributes were also examined to infer potential drivers for cross-habitat differences. As expected, plant assemblages clearly differed across a large set of community-level attributes, including all trait categories relative to leaf habit and reproduction (pollination syndrome/floral color, size, type). Overall, old-growth forest stands supported distinct and more diverse assemblages at the plot and habitat level; e.g., long-lived tree species were almost exclusively found in old-growth forest stands. For most attributes, plant assemblages subsequent to pasture exhibited intermediate values between those exhibited by old-growth forest and those of agriculture-related stands. Surprisingly, soils exhibited similar fertility-related scores across habitats. Our results indicate that: (1) sprouting/resprouting represents an important mechanism of forest regeneration; (2) assemblage-level attributes suggest recovery at distinct rates; (3) forest regen-eration implies community-level changes in both vegetative and reproductive functional attributes, including directional changes; (4) Caatinga is not able to completely recover in a period of 15-yr following land abandonment; and (5) historical land use affects recovery rates and successional pathways/taxonomic trajectories. Seasonally dry tropical forests may intrinsically cover a wide range of patterns relative to successional model, recovery rates and successional pathways. Abstract in Portuguese is available with online material.
We assessed the influence of species phylogenetic relatedness on the interaction between woody
cl... more We assessed the influence of species phylogenetic relatedness on the interaction between woody climbing plants (lianas) and their host trees (phorophytes). Considering that closely related species tend to have similar niches, we expected (1) closely related lianas to co-occur in similar phorophyte sets and (2) original lianas (phylogenetically distinct lianas with unique set of features) to occur on distinct phorophyte sets. We sampled three highly diverse forest sites in SE Brazil (a tropical rainforest, a savanna woodland and a tropical semideciduous forest), and sought for (1) a phylogenetic signal in liana climbing traits; (2) a phylogenetic signal in the lianaphorophyte interaction by testing the correlation between (a) phylogenetic distances and similarity of interacting species sets and (b) the species phylogenetic originality and the number of their interactions; and (3) a positive relationship between phylogenetic originality and the specificity of liana-phorophyte interactions. We found phylogenetic signal in climbing systems of liana species. In the semideciduous forest, we observed that closely related lianas share similar phorophyte sets, and original lianas occur on a small number of phorophyte species. However, when we evaluated the interactions of species with high originality, we found an opposing pattern in forests and savanna. In forests, the phylogenetically original liana species co-occurred more frequently with very distinct phorophyte sets; whereas in the savanna woodland, the phylogenetically original liana species co-occurred conversely with common phorophyte sets. We argued that environmental differences in forests and savannas could have mediated different tree morphological traits, such as bark characteristics, which might structure different lianaphorophyte interactions.
There is growing knowledge about and appreciation of the importance of Non-timber Forest Products... more There is growing knowledge about and appreciation of the importance of Non-timber Forest Products (NTFPs) to rural livelihoods in developing countries, and to a lesser extent, developed countries. However, there is also an assumption on the part of policy-makers that any harvesting of wild animal or plant products from the forests and other natural and modified ecosystems must be detrimental to the long-term viability of target populations and species. This book challenges this idea and shows that while examples of such negative impacts certainly exist, there are also many examples of sustainable harvesting systems for NTFPs. The chapters review and present coherent and scientifically sound information and case studies on the ecologically sustainable use of NTFPs. They also outline a general interdisciplinary approach for assessing the sustainability of NTFP harvesting systems at different scales. A wide range of case studies is included from Africa, Asia and South America, using pl...
International Journal of Biodiversity Science, Ecosystem Services & Management, 2015
Lianas can change forest dynamics, slowing down forest regeneration after a perturbation. In thes... more Lianas can change forest dynamics, slowing down forest regeneration after a perturbation. In these cases, it may be necessary to manage these woody climbers. Our aim was to simulate two management strategies: (1) focusing on abundant liana species and (2) focusing on the largest lianas, and contrast them with the random removal of lianas. We applied mathematical simulations for liana removal in three different vegetation types in southeastern Brazil: a Rainforest, a Seasonal Tropical Forest, and a Woodland Savanna. Using these samples, we performed simulations based on two liana removal procedures and compared them with random removal. We also used regression analysis with quasi-Poisson distribution to test whether larger lianas were aggressive, i.e., if they climbed into many trees. The procedure of cutting larger lianas was as effective as cutting them randomly and proved not to be a good method for liana management. Moreover, most of the lianas climbed into one or two trees, i.e., were not aggressive. Cutting the most abundant lianas proved to be a more effective method than cutting lianas randomly. This method could maintain liana richness and presumably should accelerate forest regeneration.
Background: Antagonistic interactions, such as parasitism and herbivory, are generally specialise... more Background: Antagonistic interactions, such as parasitism and herbivory, are generally specialised and have a strong phylogenetic signal for specialisation. As lianas and trees interact antagonistically, we expect to find phylogenetic signal for specialisation. Aims: We aimed to answer the following questions: (1) Is the liana-tree network specialised? (2) Is the specialisation of liana-tree network related to the abundance of both the life forms? (3) Is liana and tree specialisation related to species phylogeny? (4) Do phylogenetically related liana species occupy phylogenetically related tree species, and vice versa? Methods: For three areas in southern Brazil, we calculated the specialisation value of each liana and tree species (d') and of the entire network (H 2 ′). Binomial regression and null models were used to test the role of abundance on d' and H 2 ′, respectively. We searched for the presence of phylogenetic signal with phylogenetic independent contrasts for d'. We also compared the similarity of species sets and their interaction with phylogenetic distance between them using Mantel test. Results: All three networks had significant values of H 2 ′, but the values of d' did not have significant phylogenetic signals. Closely related lianas did not share similar host-tree assemblages and vice versa. Rare species were more specialised than abundant species, and abundance did not influence H 2 ′. Conclusions: Our study indicates that the significant H 2 ′ may be due to co-evolution in some lineages of lianas and trees. Nevertheless, the abundance of species may also play an important role in species interaction, mainly rare species.
Citação completa: Dias ADS, Sfair JC (2014) Associação entre árvores e lianas. In: VILLAGRA BLP, ... more Citação completa: Dias ADS, Sfair JC (2014) Associação entre árvores e lianas. In: VILLAGRA BLP, MELO MMRF, ROMANIUC NETO S, BARBOSA LM (eds) Diversidade e conservação de trepadeiras: contribuição para a restauração de ecossistemas brasileiros. Imprensa Oficial do Estado de São Paulo, São Paulo, pp 163–176
Tropical forests are being exposed to increasing levels of habitat loss and fragmentation, threat... more Tropical forests are being exposed to increasing levels of habitat loss and fragmentation, threatening the maintenance of global biodiversity. However, the effect that land-use change may have on the spatial dissimilarities in taxonomic and functional composition of remaining assemblages (i.e., taxonomic/functional β-diversity) remains poorly understood. Here we examined a large vegetation database from an old and severely fragmented Atlantic forest landscape to test two alternative hypotheses: (1) tree assemblages experience a taxonomic and functional homogenization (reduced β-diversity) between forest fragments and along forest edges, or alternatively (2) these edge-affected forests show increased taxonomic and functional differentiation (increased β-diversity) when compared to forest interior (reference) stands. Taxonomic and functional β-diversity were examined via novel abundance-based metrics, and considering functional traits related to plant dispersion, recruitment and growth. Overall, taxonomic β-diversity among fragments was significantly higher than among edge and reference plots. Edge plots also showed higher β-diversity than reference plots, but only when considering dominant species. In functional terms, β-diversity among reference plots was also lower than among forest fragments and among edge plots. These patterns support the “landscape-divergence hypothesis”, which postulates that variable human disturbances among forest fragments and along forest edges can lead to contrasting trajectories of vegetation changes, thus increasing the compositional and functional differentiation of tree communities in these emerging environments. Our results also show that such differentiation can preserve landscape-wide biodiversity, thus overriding negative effects of habitat fragmentation on local (α) diversity. Therefore, our findings demonstrate that forest fragments and forest edges can be more valuable for maintaining species diversity and ecosystem function in fragmented tropical landscapes than previously thought.
Mais um material (dentre muitos) introdutório ao uso do R. São as aulas de uma disciplina que oco... more Mais um material (dentre muitos) introdutório ao uso do R. São as aulas de uma disciplina que ocorreu na UFPE em 2015 cujo objetivo foi repassar fundamentos da linguagem de programação R. As aulas foram bem introdutórias, pouco aprofundadas.
The harvesting of non-timber forest products (NTFP) can influence the pattern of resource allocat... more The harvesting of non-timber forest products (NTFP) can influence the pattern of resource allocation in plants, affecting their growth, survival, and reproduction. However, only a small number of studies have addressed the impacts of NTFP harvesting on the reproductive phenology of the exploited species. The aim of this observational study was to assess the effects of harvesting and climatic variables on the reproductive phenology of Himatanthus drasticus, a highly exploited medicinal tree from the Brazilian savanna (Cerrado). We evaluated the effects of two different debarking levels (50 and 100%) in comparison to a control (no harvesting). We performed monthly counts of the number of buds, flowers in anthesis, unripe and ripe fruits in each sampled tree (intensity index), as well as the number of trees in each phenophase (activity index), over 2 yr. We used circular statistics tools to compare the effects of each treatment on flower and fruit production and to test whether the reproductive peaks were related to climatic variables. Both the activity and intensity indexes exhibited the same patterns; flower and fruit production were lower in the control, intermediate in the 50 percent debarking group and higher in the 100 percent debarking group. To the best of our knowledge, this is the first study of NTFP to demonstrate an increase in reproductive activity after several years of harvesting. All phenophases were positively correlated with higher temperature and precipitation, as it is common in the Cerrado.
Resumo
Lianas interagem de forma negativa com as árvores, uma vez que aumentam suas taxas de mort... more Resumo Lianas interagem de forma negativa com as árvores, uma vez que aumentam suas taxas de mortalidade. Seria esperado, portanto, que árvores apresentassem possíveis caracteres que as defenderiam contra lianas. O objetivo desse estudo foi testar se os seguintes caracteres das árvores limitam sua infestação por lianas: 1) baixa altura; 2) tronco com ramificações altas (fuste alto); 3) casca lisa; 4) casca esfoliante, e 5) menor índice de iluminação da copa. O estudo foi realizado em um fragmento de Floresta Estacional Semidecídua no município de Alfenas (MG) no qual foi amostrado em 0,1 ha, todas as árvores com diâmetro na altura do peito maior do que 3 cm. Para cada árvore registrou-se os caracteres citados anteriormente, bem como foi estimada a porcentagem de cobertura de lianas na copa. Encontrou-se que quanto maior a altura e o índice de iluminação da copa, maior a sua ocupação por lianas. Essas árvores, apesar de atingirem o dossel da floresta e, portanto, adquirirem mais luz para crescimento e reprodução, estão também mais sujeitas à ocupação por lianas. Apesar disso, supõe-se que as árvores não investem em estruturas que poderiam diminuir a ocupação por lianas, provavelmente porque a competição com outras plantas da vizinhança pode ser também intensa. Palavras-chave: competição, comunidade vegetal, Floresta Estacional Semidecídua, trepadeira. Abstract Lianas (woody climbers) interact negatively with trees, increasing their mortality rates. We expect, therefore, that trees have developed supposed traits that would defend them against lianas. The aim of this paper was test if these tree traits limit their liana occupation: 1) smaller height; 2) taller free bole height; 3) smooth bark; 4) exfoliating bark, and 5) low crown illumination. This study was carried out in a fragment of a seasonal semideciduous forest in Alfenas (Minas Gerais; Southeastern Brasil). We sampled in 0.1 ha all trees with diameter at breast height larger than 3 cm. For each tree we noted the traits previously cited, as well as we estimated the percentage of liana occupation on the tree crowns. We found that, for taller trees and trees with higher crown illumination, the probability of a tree to carry lianas was higher. These trees, in spite of reaching the forest canopy, and, therefore, acquire more light for reproduction and growth, they are also more prone to liana occupation. In spite of that, we suppose that the trees do not invest on traits that could decrease the liana occupation, probably because the competition with neighbor’s plants may also be intense. Key words: competition, plant community, Semideciduous Forest, climber.
Lianas can change forest dynamics, slowing down forest regeneration after a perturbation. In thes... more Lianas can change forest dynamics, slowing down forest regeneration after a perturbation. In these cases, it may be necessary to manage these woody climbers. Our aim was to simulate two management strategies: (1) focusing on abundant liana species and (2) focusing on the largest lianas, and contrast them with the random removal of lianas. We applied mathematical simulations for liana removal in three different vegetation types in southeastern Brazil: a Rainforest, a Seasonal Tropical Forest, and a Woodland Savanna. Using these samples, we performed simulations based on two liana removal procedures and compared them with random removal. We also used regression analysis with quasi-Poisson distribution to test whether larger lianas were aggressive, i.e., if they climbed into many trees. The procedure of cutting larger lianas was as effective as cutting them randomly and proved not to be a good method for liana management. Moreover, most of the lianas climbed into one or two trees, i.e., were not aggressive. Cutting the most abundant lianas proved to be a more effective method than cutting lianas randomly. This method could maintain liana richness and presumably should accelerate forest regeneration
Background: Antagonistic interactions, such as parasitism and herbivory, are generally specialise... more Background: Antagonistic interactions, such as parasitism and herbivory, are generally specialised and have a strong phylogenetic signal for specialisation. As lianas and trees interact antagonistically, we expect to find phylogenetic signal for specialisation. Aims: We aimed to answer the following questions: (1) Is the liana–tree network specialised? (2) Is the specialisation of liana–tree network related to the abundance of both the life forms? (3) Is liana and tree specialisation related to species phylogeny? (4) Do phylogenetically related liana species occupy phylogenetically related tree species, and vice versa? Methods: For three areas in southern Brazil, we calculated the specialisation value of each liana and tree species (d') and of the entire network (H 2 ′). Binomial regression and null models were used to test the role of abundance on d' and H 2 ′, respectively. We searched for the presence of phylogenetic signal with phylogenetic independent contrasts for d'. We also compared the similarity of species sets and their interaction with phylogenetic distance between them using Mantel test. Results: All three networks had significant values of H 2 ′, but the values of d' did not have significant phylogenetic signals. Closely related lianas did not share similar host-tree assemblages and vice versa. Rare species were more specialised than abundant species, and abundance did not influence H 2 ′. Conclusions: Our study indicates that the significant H 2 ′ may be due to co-evolution in some lineages of lianas and trees. Nevertheless, the abundance of species may also play an important role in species interaction, mainly rare species
We investigated the importance of specific tree attributes: height, exfoliating bark, smooth bark... more We investigated the importance of specific tree attributes: height, exfoliating bark, smooth bark, and fast growth to determine whether single or multiple attributes were more important in liana colonization on trees. Specifically we asked: Does the presence of multiple liana-shedding attributes in trees reduce the number of lianas on a tree? We sampled the number of lianas on each tree and recorded tree attributes in three ecologically distinct sites in southeast Brazil. Data were analyzed using model selection by Akaike Information Criterion, in which the number of lianas on a tree was the response variable and tree attributes were explanatory variables. We found that a combination of two attributes in trees was sufficient to deter liana infestation, whereas only one attribute had zero probability of deterring lianas across all sites. Taller trees bear more lianas, probably because of their well-lit canopies, but tree height was always associated with other attributes: slow growth in rain forest, exfoliating bark in seasonal forest, and rough bark in savanna woodland. We conclude that the presence of two attributes is sufficient to reduce liana infestation on a tree.
Essa é a segunda versão do tutorial de análises de estatística circular em linguagem de programaç... more Essa é a segunda versão do tutorial de análises de estatística circular em linguagem de programação R. Várias análises novas foram incluídas, inclusive algumas que não estão presentes nos pacotes disponíveis. Foi incluída também uma sessão de ferramentas de construção de gráficos, que ficam muito mais elegantes do que nos softwares estatísticos disponíveis (como Oriana e Bioestat). Qualquer dúvida, entre em contato. Boas análises!
The interaction among species can be influenced by neutral processes, in which more abundant spec... more The interaction among species can be influenced by neutral processes, in which more abundant species have high effect on the structure of interaction, or can be influenced by trait matching. Despite both variables (abundance and species traits) influencing the interaction of species in mutualistic networks, few studies showed their importance in antagonistic networks. Here, we posed the question: what are the main predictors of the liana–tree interactions: species abundance, biological traits or both? In a savanna woodland fragment in southeastern Brazil, we sampled lianas and trees in 1 ha, where we recorded the abundance, maximum height and bark roughness of tree species, as well as abundance, maximum diameter and climbing system of liana species. For each species, we calculated their contribution to nestedness (n i), which is a measure of network structure, and performed simple linear regressions between n i and abundance and species traits. Abundant species contribute more to n i than rare species, indicating that neutral processes affect interactions between lianas and trees, probably because lianas are opportunistic and climb trees in their neighbourhood. The only trait related to n i was tree height, which can indicate that light availability can have a considerable role on network structure between both growth forms. Therefore, the importance of species abundance and tree height can be related to opportunism of lianas on climbing the most suitable tree in their neighbourhood.
Patterns of plant use in human populations are context-specific and influenced by many different ... more Patterns of plant use in human populations are context-specific and influenced by many different ecological and social factors like plant diversity and availability, and gender, age, and household structure. The aim of this study is to evaluate current levels of knowledge and use of native plant species in different sociocultural groups living in the same ecological area. We examine the association between an individual's species knowledge and use and (1) species availability and (2) individual age, gender, and group pertinence. Data were collected through interviews with three different groups living in the municipality of Açu, Rio Grande do Norte (n = 233): an urban community, a local community of fishers, and a traditional community of self-identified indigenous people (Caboclos de Açu). The results show no correlation between knowledge/use and resource availability. Elders know and use more species than younger interviewees. Men know more species than women, but there is no difference between the number of species used by men and women. Group pertinence was related to both current levels of species knowledge and use: the urban community had less knowledge of the flora than the local and traditional communities. Regarding species uses, the traditional community uses more plants than the local community, and informants in the urban community use the least. Our results dovetail recent anthropological research suggesting that, despite other important cultural changes, the Caboclos de Açu continue to maintain at least part of their traditional knowledge system, probably because they depend on the use of plant resources for their livelihood. Overall, our results highlight the predominance of culture above the environment in driving plant use and knowledge. Os padrões de uso de plantas em populações humanas são contexto-específicos, sendo influenciados por diferentes fatores sociais e ecológicos tais como a diversidade e disponibilidade das espécies vegetais, gênero, idade e estrutura do agregado familiar. O objetivo desse estudo é avaliar os níveis atuais de conhecimento e uso de plantas em diferentes grupos socioculturais vivendo na mesma área ecológica. Nós examinamos a associação entre o conhecimento individual e (1) disponibilidade das espécies e (2) idade, gênero e grupo social. Os dados foram coletados através de entrevistas com três grupos moradores do município de Açu, no estado do Rio Grande do Norte (n = 233): uma comunidade urbana, uma comunidade local de pescadores
Rocky outcrops are distinctive formations in arid and semiarid zones, characterized by the presen... more Rocky outcrops are distinctive formations in arid and semiarid zones, characterized by the presence of plant species with functional traits related to water deficit and high temperature tolerance. These areas are also characterized by high habitat heterogeneity. We tested three hypotheses related to organization of moss communities in rocky outcrops: 1) trait convergence related to habitat filtering; 2) trait divergence related to habitat heterogeneity; and 3) random pattern of traits related to dispersal limitation. We developed null models to test trait convergence and divergence and related these patterns to habitat filtering and heterogeneity, respectively. Additionally, we also tested for different plant strategies to cope with harsh environments and we related the size of moss' spore to the number of rocky outcrops the species occupy. In spite of the convergence in some traits, this pattern was not related to annual precipitation and temperature seasonality. Moreover, the random trait organization on some outcrops was not related to dispersal limitations of the bryophytes’ species. Each community, on the other hand, had different functional compositions, indicating that mosses species have different trait arrangements to cope with environmental constraint, blurring the detection of ecological drivers of community assembly in bryophytes from rocky outcrops.
Questions: We test the hypothesis that soil water availability operates as an
ecological filter o... more Questions: We test the hypothesis that soil water availability operates as an ecological filter on water economy plant traits, particularly in savanna stands, with consequences for species distribution and the functional profile of plant assemblages across a savanna–forest mosaic. Location: A savanna–forest mosaic, northeastern Atlantic forest, Para ıba state, Brazil. Methods: We sampled all trees and shrubs in 11 forest and 12 savanna plots in the same climatic region. Soil water storage capacity was measured, as well as the following traits: specific leaf area (SLA), internode mass fraction (IMF), max- imum height (Hmax), wood density (WD), presence of trichomes (LT) and pres- ence of abiotic seed dispersal (DD). Differences in trait values and water soil content between forest and savanna plots were assessed using Wilcoxon tests. Standardized effect size of functional richness and functional dispersion (SESF- Ric and SESFDis, respectively) were compared between forest and savanna plots with Wilcoxon tests, and the relationships between both functional indices of each trait and soil water content assessed using simple linear regression. We also used null models to test for habitat filtering in each plot, considering species assemblage (SESFRic) and abundance (SESFDis). Results: Vegetation types differed in terms of soil water availability, with savanna soils having, on average, half the content of forest soils. Compared to forest, savanna plants had heavier internodes (30% increment), lower SLA (about 42% lower) and more plants with trichomes, but plants were much smaller across savanna assemblages. Savanna assemblages also exhibited a higher probability of trait convergence (i.e. reduced functional diversity) than forest assemblages in terms of SLA and maximum height, but savannas were less prone to trait convergence in terms of leaf trichomes, considering species abun- dance. Considering both vegetation types, a variable proportion of assemblages exhibited significant values of either FRic or FDis, but soil water availability did not correlate with functional diversity measures. Conclusions: Habitat filtering not related to soil water availability favours the occurrence of conservative resource-use plants across savanna stands, reinforc- ing the notion that filtering is able to act as an assembly force by affecting the abundance/frequency of particular traits, thus contributing to the occurrence of spatially organized mosaics of vegetation.
Caatinga vegetation continues to be converted into mosaics of secondary forest stands, but the af... more Caatinga vegetation continues to be converted into mosaics of secondary forest stands, but the affect of this process on biodiversity has not yet been examined. We used 35 regenerating and old-growth stands of Caatinga to examine the recovery of plant assemblages subsequent to slash-and-burn agriculture and cattle ranching/pasture in northeastern Brazil. Plant assemblages were contrasted in terms of community structure (stem density/basal area/species richness/diversity), functional (leaf habit/reproductive traits) and taxonomic composition. Soil attributes were also examined to infer potential drivers for cross-habitat differences. As expected, plant assemblages clearly differed across a large set of community-level attributes, including all trait categories relative to leaf habit and reproduction (pollination syndrome/floral color, size, type). Overall, old-growth forest stands supported distinct and more diverse assemblages at the plot and habitat level; e.g., long-lived tree species were almost exclusively found in old-growth forest stands. For most attributes, plant assemblages subsequent to pasture exhibited intermediate values between those exhibited by old-growth forest and those of agriculture-related stands. Surprisingly, soils exhibited similar fertility-related scores across habitats. Our results indicate that: (1) sprouting/resprouting represents an important mechanism of forest regeneration; (2) assemblage-level attributes suggest recovery at distinct rates; (3) forest regen-eration implies community-level changes in both vegetative and reproductive functional attributes, including directional changes; (4) Caatinga is not able to completely recover in a period of 15-yr following land abandonment; and (5) historical land use affects recovery rates and successional pathways/taxonomic trajectories. Seasonally dry tropical forests may intrinsically cover a wide range of patterns relative to successional model, recovery rates and successional pathways. Abstract in Portuguese is available with online material.
We assessed the influence of species phylogenetic relatedness on the interaction between woody
cl... more We assessed the influence of species phylogenetic relatedness on the interaction between woody climbing plants (lianas) and their host trees (phorophytes). Considering that closely related species tend to have similar niches, we expected (1) closely related lianas to co-occur in similar phorophyte sets and (2) original lianas (phylogenetically distinct lianas with unique set of features) to occur on distinct phorophyte sets. We sampled three highly diverse forest sites in SE Brazil (a tropical rainforest, a savanna woodland and a tropical semideciduous forest), and sought for (1) a phylogenetic signal in liana climbing traits; (2) a phylogenetic signal in the lianaphorophyte interaction by testing the correlation between (a) phylogenetic distances and similarity of interacting species sets and (b) the species phylogenetic originality and the number of their interactions; and (3) a positive relationship between phylogenetic originality and the specificity of liana-phorophyte interactions. We found phylogenetic signal in climbing systems of liana species. In the semideciduous forest, we observed that closely related lianas share similar phorophyte sets, and original lianas occur on a small number of phorophyte species. However, when we evaluated the interactions of species with high originality, we found an opposing pattern in forests and savanna. In forests, the phylogenetically original liana species co-occurred more frequently with very distinct phorophyte sets; whereas in the savanna woodland, the phylogenetically original liana species co-occurred conversely with common phorophyte sets. We argued that environmental differences in forests and savannas could have mediated different tree morphological traits, such as bark characteristics, which might structure different lianaphorophyte interactions.
There is growing knowledge about and appreciation of the importance of Non-timber Forest Products... more There is growing knowledge about and appreciation of the importance of Non-timber Forest Products (NTFPs) to rural livelihoods in developing countries, and to a lesser extent, developed countries. However, there is also an assumption on the part of policy-makers that any harvesting of wild animal or plant products from the forests and other natural and modified ecosystems must be detrimental to the long-term viability of target populations and species. This book challenges this idea and shows that while examples of such negative impacts certainly exist, there are also many examples of sustainable harvesting systems for NTFPs. The chapters review and present coherent and scientifically sound information and case studies on the ecologically sustainable use of NTFPs. They also outline a general interdisciplinary approach for assessing the sustainability of NTFP harvesting systems at different scales. A wide range of case studies is included from Africa, Asia and South America, using pl...
International Journal of Biodiversity Science, Ecosystem Services & Management, 2015
Lianas can change forest dynamics, slowing down forest regeneration after a perturbation. In thes... more Lianas can change forest dynamics, slowing down forest regeneration after a perturbation. In these cases, it may be necessary to manage these woody climbers. Our aim was to simulate two management strategies: (1) focusing on abundant liana species and (2) focusing on the largest lianas, and contrast them with the random removal of lianas. We applied mathematical simulations for liana removal in three different vegetation types in southeastern Brazil: a Rainforest, a Seasonal Tropical Forest, and a Woodland Savanna. Using these samples, we performed simulations based on two liana removal procedures and compared them with random removal. We also used regression analysis with quasi-Poisson distribution to test whether larger lianas were aggressive, i.e., if they climbed into many trees. The procedure of cutting larger lianas was as effective as cutting them randomly and proved not to be a good method for liana management. Moreover, most of the lianas climbed into one or two trees, i.e., were not aggressive. Cutting the most abundant lianas proved to be a more effective method than cutting lianas randomly. This method could maintain liana richness and presumably should accelerate forest regeneration.
Background: Antagonistic interactions, such as parasitism and herbivory, are generally specialise... more Background: Antagonistic interactions, such as parasitism and herbivory, are generally specialised and have a strong phylogenetic signal for specialisation. As lianas and trees interact antagonistically, we expect to find phylogenetic signal for specialisation. Aims: We aimed to answer the following questions: (1) Is the liana-tree network specialised? (2) Is the specialisation of liana-tree network related to the abundance of both the life forms? (3) Is liana and tree specialisation related to species phylogeny? (4) Do phylogenetically related liana species occupy phylogenetically related tree species, and vice versa? Methods: For three areas in southern Brazil, we calculated the specialisation value of each liana and tree species (d') and of the entire network (H 2 ′). Binomial regression and null models were used to test the role of abundance on d' and H 2 ′, respectively. We searched for the presence of phylogenetic signal with phylogenetic independent contrasts for d'. We also compared the similarity of species sets and their interaction with phylogenetic distance between them using Mantel test. Results: All three networks had significant values of H 2 ′, but the values of d' did not have significant phylogenetic signals. Closely related lianas did not share similar host-tree assemblages and vice versa. Rare species were more specialised than abundant species, and abundance did not influence H 2 ′. Conclusions: Our study indicates that the significant H 2 ′ may be due to co-evolution in some lineages of lianas and trees. Nevertheless, the abundance of species may also play an important role in species interaction, mainly rare species.
Citação completa: Dias ADS, Sfair JC (2014) Associação entre árvores e lianas. In: VILLAGRA BLP, ... more Citação completa: Dias ADS, Sfair JC (2014) Associação entre árvores e lianas. In: VILLAGRA BLP, MELO MMRF, ROMANIUC NETO S, BARBOSA LM (eds) Diversidade e conservação de trepadeiras: contribuição para a restauração de ecossistemas brasileiros. Imprensa Oficial do Estado de São Paulo, São Paulo, pp 163–176
Tropical forests are being exposed to increasing levels of habitat loss and fragmentation, threat... more Tropical forests are being exposed to increasing levels of habitat loss and fragmentation, threatening the maintenance of global biodiversity. However, the effect that land-use change may have on the spatial dissimilarities in taxonomic and functional composition of remaining assemblages (i.e., taxonomic/functional β-diversity) remains poorly understood. Here we examined a large vegetation database from an old and severely fragmented Atlantic forest landscape to test two alternative hypotheses: (1) tree assemblages experience a taxonomic and functional homogenization (reduced β-diversity) between forest fragments and along forest edges, or alternatively (2) these edge-affected forests show increased taxonomic and functional differentiation (increased β-diversity) when compared to forest interior (reference) stands. Taxonomic and functional β-diversity were examined via novel abundance-based metrics, and considering functional traits related to plant dispersion, recruitment and growth. Overall, taxonomic β-diversity among fragments was significantly higher than among edge and reference plots. Edge plots also showed higher β-diversity than reference plots, but only when considering dominant species. In functional terms, β-diversity among reference plots was also lower than among forest fragments and among edge plots. These patterns support the “landscape-divergence hypothesis”, which postulates that variable human disturbances among forest fragments and along forest edges can lead to contrasting trajectories of vegetation changes, thus increasing the compositional and functional differentiation of tree communities in these emerging environments. Our results also show that such differentiation can preserve landscape-wide biodiversity, thus overriding negative effects of habitat fragmentation on local (α) diversity. Therefore, our findings demonstrate that forest fragments and forest edges can be more valuable for maintaining species diversity and ecosystem function in fragmented tropical landscapes than previously thought.
Mais um material (dentre muitos) introdutório ao uso do R. São as aulas de uma disciplina que oco... more Mais um material (dentre muitos) introdutório ao uso do R. São as aulas de uma disciplina que ocorreu na UFPE em 2015 cujo objetivo foi repassar fundamentos da linguagem de programação R. As aulas foram bem introdutórias, pouco aprofundadas.
The harvesting of non-timber forest products (NTFP) can influence the pattern of resource allocat... more The harvesting of non-timber forest products (NTFP) can influence the pattern of resource allocation in plants, affecting their growth, survival, and reproduction. However, only a small number of studies have addressed the impacts of NTFP harvesting on the reproductive phenology of the exploited species. The aim of this observational study was to assess the effects of harvesting and climatic variables on the reproductive phenology of Himatanthus drasticus, a highly exploited medicinal tree from the Brazilian savanna (Cerrado). We evaluated the effects of two different debarking levels (50 and 100%) in comparison to a control (no harvesting). We performed monthly counts of the number of buds, flowers in anthesis, unripe and ripe fruits in each sampled tree (intensity index), as well as the number of trees in each phenophase (activity index), over 2 yr. We used circular statistics tools to compare the effects of each treatment on flower and fruit production and to test whether the reproductive peaks were related to climatic variables. Both the activity and intensity indexes exhibited the same patterns; flower and fruit production were lower in the control, intermediate in the 50 percent debarking group and higher in the 100 percent debarking group. To the best of our knowledge, this is the first study of NTFP to demonstrate an increase in reproductive activity after several years of harvesting. All phenophases were positively correlated with higher temperature and precipitation, as it is common in the Cerrado.
Resumo
Lianas interagem de forma negativa com as árvores, uma vez que aumentam suas taxas de mort... more Resumo Lianas interagem de forma negativa com as árvores, uma vez que aumentam suas taxas de mortalidade. Seria esperado, portanto, que árvores apresentassem possíveis caracteres que as defenderiam contra lianas. O objetivo desse estudo foi testar se os seguintes caracteres das árvores limitam sua infestação por lianas: 1) baixa altura; 2) tronco com ramificações altas (fuste alto); 3) casca lisa; 4) casca esfoliante, e 5) menor índice de iluminação da copa. O estudo foi realizado em um fragmento de Floresta Estacional Semidecídua no município de Alfenas (MG) no qual foi amostrado em 0,1 ha, todas as árvores com diâmetro na altura do peito maior do que 3 cm. Para cada árvore registrou-se os caracteres citados anteriormente, bem como foi estimada a porcentagem de cobertura de lianas na copa. Encontrou-se que quanto maior a altura e o índice de iluminação da copa, maior a sua ocupação por lianas. Essas árvores, apesar de atingirem o dossel da floresta e, portanto, adquirirem mais luz para crescimento e reprodução, estão também mais sujeitas à ocupação por lianas. Apesar disso, supõe-se que as árvores não investem em estruturas que poderiam diminuir a ocupação por lianas, provavelmente porque a competição com outras plantas da vizinhança pode ser também intensa. Palavras-chave: competição, comunidade vegetal, Floresta Estacional Semidecídua, trepadeira. Abstract Lianas (woody climbers) interact negatively with trees, increasing their mortality rates. We expect, therefore, that trees have developed supposed traits that would defend them against lianas. The aim of this paper was test if these tree traits limit their liana occupation: 1) smaller height; 2) taller free bole height; 3) smooth bark; 4) exfoliating bark, and 5) low crown illumination. This study was carried out in a fragment of a seasonal semideciduous forest in Alfenas (Minas Gerais; Southeastern Brasil). We sampled in 0.1 ha all trees with diameter at breast height larger than 3 cm. For each tree we noted the traits previously cited, as well as we estimated the percentage of liana occupation on the tree crowns. We found that, for taller trees and trees with higher crown illumination, the probability of a tree to carry lianas was higher. These trees, in spite of reaching the forest canopy, and, therefore, acquire more light for reproduction and growth, they are also more prone to liana occupation. In spite of that, we suppose that the trees do not invest on traits that could decrease the liana occupation, probably because the competition with neighbor’s plants may also be intense. Key words: competition, plant community, Semideciduous Forest, climber.
Lianas can change forest dynamics, slowing down forest regeneration after a perturbation. In thes... more Lianas can change forest dynamics, slowing down forest regeneration after a perturbation. In these cases, it may be necessary to manage these woody climbers. Our aim was to simulate two management strategies: (1) focusing on abundant liana species and (2) focusing on the largest lianas, and contrast them with the random removal of lianas. We applied mathematical simulations for liana removal in three different vegetation types in southeastern Brazil: a Rainforest, a Seasonal Tropical Forest, and a Woodland Savanna. Using these samples, we performed simulations based on two liana removal procedures and compared them with random removal. We also used regression analysis with quasi-Poisson distribution to test whether larger lianas were aggressive, i.e., if they climbed into many trees. The procedure of cutting larger lianas was as effective as cutting them randomly and proved not to be a good method for liana management. Moreover, most of the lianas climbed into one or two trees, i.e., were not aggressive. Cutting the most abundant lianas proved to be a more effective method than cutting lianas randomly. This method could maintain liana richness and presumably should accelerate forest regeneration
Background: Antagonistic interactions, such as parasitism and herbivory, are generally specialise... more Background: Antagonistic interactions, such as parasitism and herbivory, are generally specialised and have a strong phylogenetic signal for specialisation. As lianas and trees interact antagonistically, we expect to find phylogenetic signal for specialisation. Aims: We aimed to answer the following questions: (1) Is the liana–tree network specialised? (2) Is the specialisation of liana–tree network related to the abundance of both the life forms? (3) Is liana and tree specialisation related to species phylogeny? (4) Do phylogenetically related liana species occupy phylogenetically related tree species, and vice versa? Methods: For three areas in southern Brazil, we calculated the specialisation value of each liana and tree species (d') and of the entire network (H 2 ′). Binomial regression and null models were used to test the role of abundance on d' and H 2 ′, respectively. We searched for the presence of phylogenetic signal with phylogenetic independent contrasts for d'. We also compared the similarity of species sets and their interaction with phylogenetic distance between them using Mantel test. Results: All three networks had significant values of H 2 ′, but the values of d' did not have significant phylogenetic signals. Closely related lianas did not share similar host-tree assemblages and vice versa. Rare species were more specialised than abundant species, and abundance did not influence H 2 ′. Conclusions: Our study indicates that the significant H 2 ′ may be due to co-evolution in some lineages of lianas and trees. Nevertheless, the abundance of species may also play an important role in species interaction, mainly rare species
We investigated the importance of specific tree attributes: height, exfoliating bark, smooth bark... more We investigated the importance of specific tree attributes: height, exfoliating bark, smooth bark, and fast growth to determine whether single or multiple attributes were more important in liana colonization on trees. Specifically we asked: Does the presence of multiple liana-shedding attributes in trees reduce the number of lianas on a tree? We sampled the number of lianas on each tree and recorded tree attributes in three ecologically distinct sites in southeast Brazil. Data were analyzed using model selection by Akaike Information Criterion, in which the number of lianas on a tree was the response variable and tree attributes were explanatory variables. We found that a combination of two attributes in trees was sufficient to deter liana infestation, whereas only one attribute had zero probability of deterring lianas across all sites. Taller trees bear more lianas, probably because of their well-lit canopies, but tree height was always associated with other attributes: slow growth in rain forest, exfoliating bark in seasonal forest, and rough bark in savanna woodland. We conclude that the presence of two attributes is sufficient to reduce liana infestation on a tree.
Essa é a segunda versão do tutorial de análises de estatística circular em linguagem de programaç... more Essa é a segunda versão do tutorial de análises de estatística circular em linguagem de programação R. Várias análises novas foram incluídas, inclusive algumas que não estão presentes nos pacotes disponíveis. Foi incluída também uma sessão de ferramentas de construção de gráficos, que ficam muito mais elegantes do que nos softwares estatísticos disponíveis (como Oriana e Bioestat). Qualquer dúvida, entre em contato. Boas análises!
É um proto-tutorial, com indicações de como calcular CWM, grupos funcionais, relações entre atrib... more É um proto-tutorial, com indicações de como calcular CWM, grupos funcionais, relações entre atributos funcionais e índices de diversidade funcional. Tudo no R
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Papers by Julia Sfair
ecological filter on water economy plant traits, particularly in savanna stands,
with consequences for species distribution and the functional profile of plant
assemblages across a savanna–forest mosaic.
Location: A savanna–forest mosaic, northeastern Atlantic forest, Para ıba state,
Brazil.
Methods: We sampled all trees and shrubs in 11 forest and 12 savanna plots in
the same climatic region. Soil water storage capacity was measured, as well as
the following traits: specific leaf area (SLA), internode mass fraction (IMF), max-
imum height (Hmax), wood density (WD), presence of trichomes (LT) and pres-
ence of abiotic seed dispersal (DD). Differences in trait values and water soil
content between forest and savanna plots were assessed using Wilcoxon tests.
Standardized effect size of functional richness and functional dispersion (SESF-
Ric and SESFDis, respectively) were compared between forest and savanna plots
with Wilcoxon tests, and the relationships between both functional indices of
each trait and soil water content assessed using simple linear regression. We also
used null models to test for habitat filtering in each plot, considering species
assemblage (SESFRic) and abundance (SESFDis).
Results: Vegetation types differed in terms of soil water availability, with
savanna soils having, on average, half the content of forest soils. Compared to
forest, savanna plants had heavier internodes (30% increment), lower SLA
(about 42% lower) and more plants with trichomes, but plants were much
smaller across savanna assemblages. Savanna assemblages also exhibited a
higher probability of trait convergence (i.e. reduced functional diversity) than
forest assemblages in terms of SLA and maximum height, but savannas were less
prone to trait convergence in terms of leaf trichomes, considering species abun-
dance. Considering both vegetation types, a variable proportion of assemblages
exhibited significant values of either FRic or FDis, but soil water availability did
not correlate with functional diversity measures.
Conclusions: Habitat filtering not related to soil water availability favours the
occurrence of conservative resource-use plants across savanna stands, reinforc-
ing the notion that filtering is able to act as an assembly force by affecting the
abundance/frequency of particular traits, thus contributing to the occurrence of
spatially organized mosaics of vegetation.
climbing plants (lianas) and their host trees (phorophytes). Considering that closely related
species tend to have similar niches, we expected (1) closely related lianas to co-occur in similar
phorophyte sets and (2) original lianas (phylogenetically distinct lianas with unique set of
features) to occur on distinct phorophyte sets. We sampled three highly diverse forest sites in SE
Brazil (a tropical rainforest, a savanna woodland and a tropical semideciduous forest), and
sought for (1) a phylogenetic signal in liana climbing traits; (2) a phylogenetic signal in the lianaphorophyte interaction by testing the correlation between (a) phylogenetic distances and
similarity of interacting species sets and (b) the species phylogenetic originality and the number
of their interactions; and (3) a positive relationship between phylogenetic originality and the
specificity of liana-phorophyte interactions. We found phylogenetic signal in climbing systems
of liana species. In the semideciduous forest, we observed that closely related lianas share similar phorophyte sets, and original lianas occur on a small number of phorophyte species. However,
when we evaluated the interactions of species with high originality, we found an opposing
pattern in forests and savanna. In forests, the phylogenetically original liana species co-occurred
more frequently with very distinct phorophyte sets; whereas in the savanna woodland, the
phylogenetically original liana species co-occurred conversely with common phorophyte sets.
We argued that environmental differences in forests and savannas could have mediated different
tree morphological traits, such as bark characteristics, which might structure different lianaphorophyte interactions.
Lianas interagem de forma negativa com as árvores, uma vez que aumentam suas taxas de mortalidade.
Seria esperado, portanto, que árvores apresentassem possíveis caracteres que as defenderiam contra lianas.
O objetivo desse estudo foi testar se os seguintes caracteres das árvores limitam sua infestação por lianas:
1) baixa altura; 2) tronco com ramificações altas (fuste alto); 3) casca lisa; 4) casca esfoliante, e 5) menor
índice de iluminação da copa. O estudo foi realizado em um fragmento de Floresta Estacional Semidecídua
no município de Alfenas (MG) no qual foi amostrado em 0,1 ha, todas as árvores com diâmetro na altura do
peito maior do que 3 cm. Para cada árvore registrou-se os caracteres citados anteriormente, bem como foi
estimada a porcentagem de cobertura de lianas na copa. Encontrou-se que quanto maior a altura e o índice de
iluminação da copa, maior a sua ocupação por lianas. Essas árvores, apesar de atingirem o dossel da floresta
e, portanto, adquirirem mais luz para crescimento e reprodução, estão também mais sujeitas à ocupação por
lianas. Apesar disso, supõe-se que as árvores não investem em estruturas que poderiam diminuir a ocupação
por lianas, provavelmente porque a competição com outras plantas da vizinhança pode ser também intensa.
Palavras-chave: competição, comunidade vegetal, Floresta Estacional Semidecídua, trepadeira.
Abstract
Lianas (woody climbers) interact negatively with trees, increasing their mortality rates. We expect, therefore,
that trees have developed supposed traits that would defend them against lianas. The aim of this paper was
test if these tree traits limit their liana occupation: 1) smaller height; 2) taller free bole height; 3) smooth bark;
4) exfoliating bark, and 5) low crown illumination. This study was carried out in a fragment of a seasonal
semideciduous forest in Alfenas (Minas Gerais; Southeastern Brasil). We sampled in 0.1 ha all trees with
diameter at breast height larger than 3 cm. For each tree we noted the traits previously cited, as well as we
estimated the percentage of liana occupation on the tree crowns. We found that, for taller trees and trees with
higher crown illumination, the probability of a tree to carry lianas was higher. These trees, in spite of reaching
the forest canopy, and, therefore, acquire more light for reproduction and growth, they are also more prone
to liana occupation. In spite of that, we suppose that the trees do not invest on traits that could decrease the
liana occupation, probably because the competition with neighbor’s plants may also be intense.
Key words: competition, plant community, Semideciduous Forest, climber.
necessary to manage these woody climbers. Our aim was to simulate two management strategies: (1) focusing on abundant
liana species and (2) focusing on the largest lianas, and contrast them with the random removal of lianas. We applied
mathematical simulations for liana removal in three different vegetation types in southeastern Brazil: a Rainforest, a
Seasonal Tropical Forest, and a Woodland Savanna. Using these samples, we performed simulations based on two liana
removal procedures and compared them with random removal. We also used regression analysis with quasi-Poisson
distribution to test whether larger lianas were aggressive, i.e., if they climbed into many trees. The procedure of cutting
larger lianas was as effective as cutting them randomly and proved not to be a good method for liana management.
Moreover, most of the lianas climbed into one or two trees, i.e., were not aggressive. Cutting the most abundant lianas
proved to be a more effective method than cutting lianas randomly. This method could maintain liana richness and
presumably should accelerate forest regeneration
phylogenetic signal for specialisation. As lianas and trees interact antagonistically, we expect to find phylogenetic signal for
specialisation.
Aims: We aimed to answer the following questions: (1) Is the liana–tree network specialised? (2) Is the specialisation
of liana–tree network related to the abundance of both the life forms? (3) Is liana and tree specialisation related to
species phylogeny? (4) Do phylogenetically related liana species occupy phylogenetically related tree species, and
vice versa?
Methods: For three areas in southern Brazil, we calculated the specialisation value of each liana and tree species (d')
and of the entire network (H 2 ′). Binomial regression and null models were used to test the role of abundance on d'
and H 2 ′, respectively. We searched for the presence of phylogenetic signal with phylogenetic independent contrasts
for d'. We also compared the similarity of species sets and their interaction with phylogenetic distance between them
using Mantel test.
Results: All three networks had significant values of H 2 ′, but the values of d' did not have significant phylogenetic signals.
Closely related lianas did not share similar host-tree assemblages and vice versa. Rare species were more specialised than
abundant species, and abundance did not influence H 2 ′.
Conclusions: Our study indicates that the significant H 2 ′ may be due to co-evolution in some lineages of lianas and
trees. Nevertheless, the abundance of species may also play an important role in species interaction, mainly rare
species
ecological filter on water economy plant traits, particularly in savanna stands,
with consequences for species distribution and the functional profile of plant
assemblages across a savanna–forest mosaic.
Location: A savanna–forest mosaic, northeastern Atlantic forest, Para ıba state,
Brazil.
Methods: We sampled all trees and shrubs in 11 forest and 12 savanna plots in
the same climatic region. Soil water storage capacity was measured, as well as
the following traits: specific leaf area (SLA), internode mass fraction (IMF), max-
imum height (Hmax), wood density (WD), presence of trichomes (LT) and pres-
ence of abiotic seed dispersal (DD). Differences in trait values and water soil
content between forest and savanna plots were assessed using Wilcoxon tests.
Standardized effect size of functional richness and functional dispersion (SESF-
Ric and SESFDis, respectively) were compared between forest and savanna plots
with Wilcoxon tests, and the relationships between both functional indices of
each trait and soil water content assessed using simple linear regression. We also
used null models to test for habitat filtering in each plot, considering species
assemblage (SESFRic) and abundance (SESFDis).
Results: Vegetation types differed in terms of soil water availability, with
savanna soils having, on average, half the content of forest soils. Compared to
forest, savanna plants had heavier internodes (30% increment), lower SLA
(about 42% lower) and more plants with trichomes, but plants were much
smaller across savanna assemblages. Savanna assemblages also exhibited a
higher probability of trait convergence (i.e. reduced functional diversity) than
forest assemblages in terms of SLA and maximum height, but savannas were less
prone to trait convergence in terms of leaf trichomes, considering species abun-
dance. Considering both vegetation types, a variable proportion of assemblages
exhibited significant values of either FRic or FDis, but soil water availability did
not correlate with functional diversity measures.
Conclusions: Habitat filtering not related to soil water availability favours the
occurrence of conservative resource-use plants across savanna stands, reinforc-
ing the notion that filtering is able to act as an assembly force by affecting the
abundance/frequency of particular traits, thus contributing to the occurrence of
spatially organized mosaics of vegetation.
climbing plants (lianas) and their host trees (phorophytes). Considering that closely related
species tend to have similar niches, we expected (1) closely related lianas to co-occur in similar
phorophyte sets and (2) original lianas (phylogenetically distinct lianas with unique set of
features) to occur on distinct phorophyte sets. We sampled three highly diverse forest sites in SE
Brazil (a tropical rainforest, a savanna woodland and a tropical semideciduous forest), and
sought for (1) a phylogenetic signal in liana climbing traits; (2) a phylogenetic signal in the lianaphorophyte interaction by testing the correlation between (a) phylogenetic distances and
similarity of interacting species sets and (b) the species phylogenetic originality and the number
of their interactions; and (3) a positive relationship between phylogenetic originality and the
specificity of liana-phorophyte interactions. We found phylogenetic signal in climbing systems
of liana species. In the semideciduous forest, we observed that closely related lianas share similar phorophyte sets, and original lianas occur on a small number of phorophyte species. However,
when we evaluated the interactions of species with high originality, we found an opposing
pattern in forests and savanna. In forests, the phylogenetically original liana species co-occurred
more frequently with very distinct phorophyte sets; whereas in the savanna woodland, the
phylogenetically original liana species co-occurred conversely with common phorophyte sets.
We argued that environmental differences in forests and savannas could have mediated different
tree morphological traits, such as bark characteristics, which might structure different lianaphorophyte interactions.
Lianas interagem de forma negativa com as árvores, uma vez que aumentam suas taxas de mortalidade.
Seria esperado, portanto, que árvores apresentassem possíveis caracteres que as defenderiam contra lianas.
O objetivo desse estudo foi testar se os seguintes caracteres das árvores limitam sua infestação por lianas:
1) baixa altura; 2) tronco com ramificações altas (fuste alto); 3) casca lisa; 4) casca esfoliante, e 5) menor
índice de iluminação da copa. O estudo foi realizado em um fragmento de Floresta Estacional Semidecídua
no município de Alfenas (MG) no qual foi amostrado em 0,1 ha, todas as árvores com diâmetro na altura do
peito maior do que 3 cm. Para cada árvore registrou-se os caracteres citados anteriormente, bem como foi
estimada a porcentagem de cobertura de lianas na copa. Encontrou-se que quanto maior a altura e o índice de
iluminação da copa, maior a sua ocupação por lianas. Essas árvores, apesar de atingirem o dossel da floresta
e, portanto, adquirirem mais luz para crescimento e reprodução, estão também mais sujeitas à ocupação por
lianas. Apesar disso, supõe-se que as árvores não investem em estruturas que poderiam diminuir a ocupação
por lianas, provavelmente porque a competição com outras plantas da vizinhança pode ser também intensa.
Palavras-chave: competição, comunidade vegetal, Floresta Estacional Semidecídua, trepadeira.
Abstract
Lianas (woody climbers) interact negatively with trees, increasing their mortality rates. We expect, therefore,
that trees have developed supposed traits that would defend them against lianas. The aim of this paper was
test if these tree traits limit their liana occupation: 1) smaller height; 2) taller free bole height; 3) smooth bark;
4) exfoliating bark, and 5) low crown illumination. This study was carried out in a fragment of a seasonal
semideciduous forest in Alfenas (Minas Gerais; Southeastern Brasil). We sampled in 0.1 ha all trees with
diameter at breast height larger than 3 cm. For each tree we noted the traits previously cited, as well as we
estimated the percentage of liana occupation on the tree crowns. We found that, for taller trees and trees with
higher crown illumination, the probability of a tree to carry lianas was higher. These trees, in spite of reaching
the forest canopy, and, therefore, acquire more light for reproduction and growth, they are also more prone
to liana occupation. In spite of that, we suppose that the trees do not invest on traits that could decrease the
liana occupation, probably because the competition with neighbor’s plants may also be intense.
Key words: competition, plant community, Semideciduous Forest, climber.
necessary to manage these woody climbers. Our aim was to simulate two management strategies: (1) focusing on abundant
liana species and (2) focusing on the largest lianas, and contrast them with the random removal of lianas. We applied
mathematical simulations for liana removal in three different vegetation types in southeastern Brazil: a Rainforest, a
Seasonal Tropical Forest, and a Woodland Savanna. Using these samples, we performed simulations based on two liana
removal procedures and compared them with random removal. We also used regression analysis with quasi-Poisson
distribution to test whether larger lianas were aggressive, i.e., if they climbed into many trees. The procedure of cutting
larger lianas was as effective as cutting them randomly and proved not to be a good method for liana management.
Moreover, most of the lianas climbed into one or two trees, i.e., were not aggressive. Cutting the most abundant lianas
proved to be a more effective method than cutting lianas randomly. This method could maintain liana richness and
presumably should accelerate forest regeneration
phylogenetic signal for specialisation. As lianas and trees interact antagonistically, we expect to find phylogenetic signal for
specialisation.
Aims: We aimed to answer the following questions: (1) Is the liana–tree network specialised? (2) Is the specialisation
of liana–tree network related to the abundance of both the life forms? (3) Is liana and tree specialisation related to
species phylogeny? (4) Do phylogenetically related liana species occupy phylogenetically related tree species, and
vice versa?
Methods: For three areas in southern Brazil, we calculated the specialisation value of each liana and tree species (d')
and of the entire network (H 2 ′). Binomial regression and null models were used to test the role of abundance on d'
and H 2 ′, respectively. We searched for the presence of phylogenetic signal with phylogenetic independent contrasts
for d'. We also compared the similarity of species sets and their interaction with phylogenetic distance between them
using Mantel test.
Results: All three networks had significant values of H 2 ′, but the values of d' did not have significant phylogenetic signals.
Closely related lianas did not share similar host-tree assemblages and vice versa. Rare species were more specialised than
abundant species, and abundance did not influence H 2 ′.
Conclusions: Our study indicates that the significant H 2 ′ may be due to co-evolution in some lineages of lianas and
trees. Nevertheless, the abundance of species may also play an important role in species interaction, mainly rare
species