Canopy

Forest canopies are incredibly complex self-maintaining biological structures. Conditions above and within the canopy can differ vastly, often resulting in a vertical gradient of microclimate conditions. Canopy epiphytic plants have to deal with climatic variability on much more variable scales compared to many other plant groups. The difficulty of sensor installation and their high cost can explain why it has been ignored in many studies on canopy epiphytes. Direct measurements of microenvironmental conditions are the only accurate way to assess specific intra-canopy environmental conditions, as there is also still a lack of methodologically and financially viable alternatives to allow the collection of this type of data. This study aims to make recommendations for the direct use of microclimate measurements in epiphyte research and to summarize key discussion points concerning the number and placement of sensors required for different types of epiphyte studies. In addition, we presented high-resolution field data from the United Kingdom, where we employed over 56 microclimate sensors, to demonstrate the spatial and temporal variability of radiation, temperature, and relative humidity (RH) in a tree canopy. Our data demonstrated that sensor height in the tree and leaf-set were the most important factors determining microclimate variability in the canopy. For the first time, we have made recommendations regarding the placement and number of sensors required in studies that specifically require the use of microclimate sensors in epiphyte studies in forest canopies.

The diversity and niche specificity of hemi-epiphytic figs in a lowland dipterocarp forest in Sarawak were investigated in 1998. Twenty-seven fig species (264 individuals, c. 120 ha) colonized a diversity of host taxa (35 families), but densities were very low and only 1.77% of trees > 30 cm d.b.h. were occupied. There were no significant associations with host taxa or host-bark roughness but among 11 common species ( ≥ 9 individuals) the distributions of all other parameters (host-d.b.h., height and position of colonization, crown illumination, soil-texture and slope-angle) were significantly different, and we identified five fig guilds. The guilds corresponded to canopy strata, and appeared to reflect the establishment microsite requirements of different species. A fundamental trade-off within the hemiepiphytic habit was revealed: Species colonizing larger hosts were rarer, because of lower host densities and more specific microsite requirements, but had better light environments and attained a larger maximum size. The single strangler species appeared to escape many of these constraints, and an important source of mortality caused by hosttoppling, indicating the advantages of this strategy. Thus, the hemi-epiphytic figs in this community have come to fill a remarkable diversity of niches, despite low levels of competition, through the exigencies of a complex environment.

Aim: Shaded coffee plantations constitute an important refuge for biodiversity. Despite the fact that epiphytic plants form a significant component of these agroecosystems, their removal from the shade trees is commonplace in Latin America. To what extent does the epiphyte community recover from this severe disturbance? Location: Shaded coffee agroecosystem in Veracruz, Mexico (19128 0 03 00 N, 96155 0 58 00 W; 1200 m asl). Methods: We assessed the diversity, biomass and recolonization patterns of vascular epiphytes in shade trees, 8-9 yr after complete epiphyte removal (E À), and in control 'non-removal' sites (E 1). In order to evaluate the effects of prior epiphyte removal, all vascular epiphytes were completely removed from 10 trees per treatment (E À and E 1); all epiphyte species collected were identified and dry biomass measured. Results: Eight to nine years after removal, epiphyte biomass in the E À shade trees was 35% of that found in the control sites. A total of 55 epiphyte species, belonging to 12 families, were registered; 40 in E À , and 48 in E 1. Six species belonging to Bromeliaceae, Orchidaceae, Cactaceae and Araceae accounted for 75% of the biomass in E 1 while six species of bromeliads accounted for 76% of the biomass in E À. Some bromeliads proliferated following disturbance; however, ferns showed lower recovery. Conclusions: Epiphyte community recovery, in terms of biomass and diversity, is considerably higher in the coffee plantation than has been previously reported for other tropical ecosystems. Epiphyte recolonization patterns reflected both the abundance of species in the surrounding matrix and certain species-specific traits. For such agroecosytems to function as effective reservoirs of epiphyte diversity, epiphyte stripping should be avoided.

Abstract A lack of reliable observations for canopy science research is being partly overcome by the gradual use of lidar remote sensing. This study aims to improve lidar-based canopy characterization with airborne laser scanners through the combined use of lidar ...

Growing agricultural crops under Millettia ferruginea (Hochst.) Baker, a tree that is endemic to Ethiopia, is an age-old practice in the country, but the beneficial effects of the tree on crops have not been scientifically quantified. To achieve this, four isolated and ...

A seguito di una convenzione avviata nel 2018 tra il Dipartimento di Architettura dell’Università di Palermo e l’Istituto Autonomo Case Popolari, il Gruppo di Ricerca LabCity Architecture del Dipartimento guidato da Renzo Lecardane, ha sviluppato un progetto di ‘ricerca-azione’ incentrato sul mercato storico di Ballarò.
Obiettivo del progetto lo sviluppo di forme di collaborazione con il mondo accademico per la sistemazione di Piazza del Carmine – al centro del mercato – e in particolare sui materiali da utilizzare per la progettazione architettonica di un edificio destinato a mercato coperto, evidenziandone durabilità, facilità di montaggio/smontaggio e sostenibilità.

The combined PROSPECT leaf optical properties model and SAIL canopy bidirectional reflectance model, also referred to as PROSAIL, has been used for about sixteen years to study plant canopy spectral and directional reflectance in the solar domain. PROSAIL has also been used to develop new methods for retrieval of vegetation biophysical properties. It links the spectral variation of canopy reflectance, which is mainly related to leaf biochemical contents, with its directional variation, which is primarily related to canopy architecture and soil/vegetation contrast. This link is key to simultaneous estimation of canopy biophysical/structural variables for applications in agriculture, plant physiology, or ecology, at different scales. PROSAIL has become one of the most popular radiative transfer tools due to its ease of use, general robustness, and consistent validation by lab/field/space experiments over the years. However, PROSPECT and SAIL are still evolving: they have undergone recent improvements both at the leaf and the plant levels. This paper provides an extensive review of the PROSAIL developments in the context of canopy biophysics and radiative transfer modeling.

Plant genotypes have different mechanisms in developing root morphology in order to increase absorption and use of nutrient to all part of plants. The objective of this research was to evaluate root morphology, plant canopy, yield and yield components of some maize varieties under nutrient deficient condition.

ABSTRACT: We estimated the diversity and abundance of ants and nymphalid butterflies on the ground and in the canopy; and of plants in six different forest sites in Venezuela. Statistical analysis using eight different diversity indices for each species group revealed large variations among them. Ground ants appeared to be the most reliable bioindicators, even when only the five most common species are sampled. Results showed in addition that ground ant diversity is correlated to that of canopy ants and that vegetational diversity is linked to butterfly diversity but not to that of canopy ants. Ant species diversity in the canopy was always less than that of the ground. We conclude that no simple index or taxon describes completely complex ecosystems, thus, biodiversity assessments require tools still to be developed.

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The aim of this study was to investigate the effect of waterlogging on morphological and physiological traits of sorghum (Sorghum bicolor L. Moench) cultivars. Four sorghum cultivars, cv. Wray, Keller, Bailey (sweet cultivar) and cv. SP1 (forage cultivar) at five expanded leaf stage were subjected to 20 days of waterlogging and drained pots were kept as the control. Twenty days of waterlogging did not cause a significant difference in shoot and root biomass among cultivars. Flooding reduced leaf area (69%), plant height (30%) and youngest leaf expansion rate of all cultivars but severely reduced in SP1 (35-80%). Flooding promoted leaf senescence of all cultivars and biomass allocation to shoot (increase in shoot/root) in Wray, Keller and Bailey, but increased biomass partitioning to root in SP1. The initiation of new nodal root was noted in SP1, whereas the ability to maintain root surface area by increase in longest root length and nodal root development near soil surface was found in Wray. Photosynthetic rate, stomatal conductance and transpiration rate were severely reduced under waterlogging conditions of sweet cultivars (65-78%), but enhanced over the control in forage cultivar (56%). The ability to conserve root surface area, allocate more biomass to shoot during waterlogging and develop root near soil surface may support new growth in Wray, whereas the ability to maintain leaf gas exchange parameters in SP1 was due to the active nodal root growth. Nevertheless, there was no relationship between photosynthetic rate and shoot growth of sorghum under anaerobic conditions.

Forest thinning and prescribed fires are practices used by managers to address concerns over ecosystem degradation and severe wildland fire potential in dry forests. There is some debate, however, about treatment effectiveness in meeting management objectives as well as their ecological consequences. The purpose of this study was to assess changes to forest stand structure following thinning and prescribed fire treatments, alone and combined, in the eastern Cascade Mountains of Washington State. Treatments were applied to 12 management units, with each treatment combination replicated three times (including untreated controls). Thinning modified forest structure by reducing overall tree density by >60% and canopy bulk density by 50%, and increased canopy base height by $4 m, thereby reducing susceptibility to crown fire. The prescribed fire treatment, conversely, did not appreciably reduce tree density or canopy fuel loading, but was effective at increasing the density of standing dead trees, particularly when combined with thinning (37 snags/ha increase). Prescribed fire effects were more pronounced when used in combination with thinning. Thinning was more reliable for altering stand structure, but spring burning was lower in intensity and coverage than desired and may have led to results that downplay the efficacy of fire to meet forest restoration goals.

on water thickness. The relationship between WI and the canopy RWC signifi-Infrared Imaging Spectrometer over Point Dume (Los cantly improved when only data from plots with green Angeles County, CA, USA) were used to assess the ability vegetation cover Ͼ70% were considered (r 2 ϭ0.88, pϽ of hyperspectral reflectance data to estimate canopy Rel-0.001). All the indices studied had an important strucative Water Content (RWC) at the landscape level. The tural component (as indicated by the strong correlation study was performed on 23 vegetation stands comprised with NDVI), yet only the indices WI and NDWI addiof three characteristic chaparral plant communities, with tionally responded to water content. These results indicontrasting phenological stages and canopy cover. Sevcate that the WI and NDWI are sensitive to variations eral estimates of water content based on the near-infrain canopy relative water content at the landscape scale. red (NIR; reflectance indices and water thickness derived ©Elsevier Science Inc., 2000 from reflectance and radiance data) and shortwave infrared (SWIR) water absorption bands were compared to measurements of vegetation structure and water content INTRODUCTION made on the ground. The Water Index (WI) and Normalized Difference Water Index (NDWI), reflectance indices

Logging can significantly change the structure of rainforest communities. To better understand how logging drives this change, butterflies and environmental variables were assessed within both unlogged and logged forest in Indonesian Borneo. In the whole dataset, we found local environmental variables and geographic distance combined captured 53.1% of the variation in butterfly community composition; 29.6% was associated with measured local environmental variables, 13.6% with geographic distance between sites, and 9.9% with covariation between geographic distance and environmental variables. The primary axis of variation in butterfly community composition represented a disturbance gradient from unlogged to logged forest. Subsequent axes represented gradients influenced by variables such as canopy cover and total tree density. There were significant associations between environmental variables and geographic range and larval host plant use of species. Specifically, butterflies using trees as larval host plants and those with distributions limited to Borneo were more likely to be present in unlogged forest. By contrast, species that tended to be more abundant in logged forest were those with widespread distributions and those using lianas and grasses as larval host plants. The results of this study highlight the importance of environmental variables and disturbance, e.g., selective logging, in structuring rainforest community diversity. Moreover, they confirm how species traits, such as larval food use and geographic distributions can determine patterns of species abundance following environmental change.Der Holzeinschlag kann die Struktur von Lebensgemeinschaften in Regenwäldern signifikant verändern. Um besser zu verstehen, wie der Holzeinschlag diese Veränderungen vorantreibt, wurden die Schmetterlinge und die Umweltvariablen in Wäldern mit und ohne Holzeinschlag im indonesischen Borneo erfasst. Im gesamten Datenset fanden wir, dass Umweltvariablen in Kombination mit geographischer Distanz 53.1% der Variation in der Zusammensetzung der Schmetterlingsgemeinschaften abdeckte: 29.6% war mit den gemessenen lokalen Umweltvariablien assoziiert, 13.6% mit der geographischen Distanz zwischen den Standorten und 9.9% mit der Kovariation zwischen geographischer Distanz und Umweltvariablen. Die primäre Achse der Variation in der Zusammensetzung der Schmetterlingsgemeinschaften repräsentierte einen Störungsgradienten von ungenutzten zu abgeholzten Wäldern. Die folgenden Achsen repräsentierten Gradienten, die von Variablen wie Kronendeckung und Gesamtbaumdichte beeinflusst waren. Es gab signifikante Assoziationen zwischen den Umweltvariablen, den geographischen Verbreitungen und der Wirtspflanzennutzung durch die Raupen der Arten. Insbesondere waren Schmetterlinge, die Bäume als Wirtspflanzen nutzen, und diejenigen, deren Verbreitung auf Borneo beschränkt war, mit größerer Wahrscheinlichkeit in ungenutzten Waldbereichen zu finden. Im Unterschied dazu waren Arten, die in eingeschlagenen Wäldern häufiger waren, solche, die Lianen und Gräser als Wirtspflanzen für die Raupen nutzen. Die Ergebnisse dieser Untersuchung betonen die Wichtigkeit der Umweltvariablen und der Störung, z. B. durch selektivem Holzeinschlag, für die Strukturierung der Diversität von Regenwaldgemeinschaften. Zusätzlich bestätigen sie, wie Arteigenschaften, wie die Nahrungsnutzung von Raupen und die geographische Verbreitung, die Muster bestimmen mit denen Artenabundanzen auf Umweltveränderungen reagieren.

RESUMO -Avaliaram-se as características estruturais do capim-tanzânia pastejado por ovinos sob lotação rotativa com quatro níveis de suplementação concentrada (NS) (0,0; 0,6; 1,2 e 1,8% PV), em delineamento de parcelas subdivididas, em que as parcelas foram os níveis de suplementação e os ciclos de pastejo (CP), as subparcelas, com quatro repetições. Estimaram-se as produções de massa seca de forragem total (MSFT), forragem morta (MSFM), forragem verde (MSFV), lâmina foliar verde (MSLV) e colmo verde (MSCV), a altura (ALT) e o número de folhas/perfilho (F/P); as relações folha/colmo (F/C) e material vivo/morto (MV/MM) no pré e pós-pastejo; a densidade populacional de perfilhos (DPP); e o índice de área foliar (IAFres). Não foram observados efeitos dos NS e nem dos ciclos para as variáveis F/P, MSFM, MSFV, MV/MM, MSLV e MSCV. Para a variável ALT, observaram-se diferenças do ciclo 4 em relação aos demais. A MSFT foi afetada pelos NS, de modo que o pasto com ovinos sob suplementação a 0,6% PV foi semelhante aos dos NS de 0,0 e 1,8% PV, porém foi superior ao do NS de 1,2% PV. Foi observado efeito dos NS sobre a MSFTres e MSFMres no nível de 0,6% PV, sendo superior ao do nível de 1,2% PV, porém semelhante aos demais. Para MSFVres observou-se efeito quadrático dos NS, porém não houve efeito dos CP. Para a relação MV/MMres, não foram observadas diferenças entre NS e nem entre CP. Observou-se efeito quadrático dos NS sobre a MSLVres, o IAFres e a MSCVres. Houve aumento linear na F/C com o aumento do NS. Quanto à DPP, não foi observada diferença entre NS. Os níveis crescentes de suplementação não comprometeram o vigor da rebrotação da pastagem, em razão da manutenção dos componentes da biomassa dentro de níveis aceitáveis.

This research integrates the agricultural study of trees with the sciences of representation, in order to describe the architectural form of an olive tree and to show a scientific visualization of the relationship between morphology and light interception in the canopy. The representation of plant architecture, manipulated with pruning operation for agricultural purposes of light optimization, describes the action of sunlight in the tree, testing the potential of digital design toolsespecially generative modelling. Through the design of a specific algorithm, the tree is interpreted like a fragmented photovoltaic panel, analysed using 14,000 control points corresponding to the leaves. The possibility to select these classes of elements becomes the instrument to explain the canopy structure, finding categories that describe and simulate the annual radiance and illuminance. The developed modelling process and its purely theoretical significance constitute the basis for a variety of applications in data analysis and comparison between different models, evaluations, theories, and operations.

Some practitioners within the green industry have lauded the application of sugar-containing products to the soil around trees as a method to improve plant health. A research study was initiated to evaluate the effects of exogenous applications of glucose and starch on the growth and vitality of healthy live oaks (Quercus virginiana P. Miller). Glucose, starch, or a 50:50 mixture of both carbohydrates were applied as soil drenches around 60 young live oaks growing at a field nursery. Carbohydrates were dissolved in water and applied at concentrations of 0, 40, 80, and 120 g L À1 within 0.5 m from the trunk. Solutions were applied using 10 L per application every four months during an 18-month period. Trunk diameter, root and canopy growth, and carbohydrate content of twigs and roots were measured every four months, and net photosynthetic rate, chlorophyll fluorescence, and soil respiration were measured every six months. Tissue samples from twigs and roots were collected after 16 months to measure carbon isotope composition (d 13 C) as an indicator of carbohydrate uptake. Chlorophyll fluorescence varied throughout the experiment but did not demonstrate a clear trend. Higher carbohydrate applications did influence the concentration of glucose in twigs although the results did not clearly indicate that this effect was caused by an uptake of glucose from roots. d 13 C signatures did not provide any evidence about potential carbohydrate uptake. Even though there was a significant increase in soil respiration after being treated with starch, no significant increase in growth or vitality was detected on healthy live oaks.

Plants are much more dynamic than we usually expect them to be. This dynamic behaviour is of paramount importance for their performance under natural conditions, when resources are distributed heterogeneously in space and time. However, plants are not only the cue ball of their physical and chemical environment. Endogenous rhythms and networks controlling photosynthesis and growth buffer plant processes from external fluctuations. This review highlights recent evidence of the importance of dynamic temporal and spatial organization of photosynthesis and of growth in leaves and roots. These central processes for plant performance differ strongly in their dependence on environmental impact and endogenous properties, respectively. Growth involves a wealth of processes ranging from the supply of resources from external and internal sources to the growth processes themselves. In contrast, photosynthesis can only take place when light and CO 2 are present and thus clearly requires 'input from the environment'. Nevertheless, growth and photosynthesis are connected to each other via mechanisms that are still not fully understood. Recent advances in imaging technology have provided new insights into the dynamics of plant-environment interactions. Such processes do not only play a crucial role in understanding stress response of plants under extreme environmental conditions. Dynamics of plants under modest growth conditions rise from endogenous mechanisms as well as exogenous impact too. It is thus an important task for future research to identify how dynamic external conditions interact with plant-internal signalling networks to optimize plant behaviour in real time and to understand how plants have adapted to characteristic spatial and temporal properties of the resources from their environment, on which they depend on. Time lapse analysis of root elongation rates of rice and sorghum during the day and night.

The review sums up research conducted at CIAT within a multidiscipline effort revolving around a strategy for developing improved technologies to increase and sustain cassava productivity, as well as conserving natural resources in the various eco-edaphic zones where the crop is grown, with emphasis on stressful environments. Field research has elucidated several physiological plant mechanisms underlying potentially high productivity under favourable hot-humid environments in the tropics. Most notable is cassava inherent high capacity to assimilate carbon in near optimum environments that correlates with both biological productivity and root yield across a wide range of germplasm grown in diverse environments. Cassava leaves possess elevated activities of the C 4 phosphoenolpyruvate carboxylase (PEPC) that also correlate with leaf net photosynthetic rate (P N ) in field-grown plants, indicating the importance of selection for high P N . Under certain conditions such leaves exhibit an interesting photosynthetic C 3 -C 4 intermediate behaviour which may have important implications in future selection efforts. In addition to leaf P N , yield is correlated with seasonal mean leaf area index (i.e. leaf area duration, LAD). Under prolonged water shortages in seasonally dry and semiarid zones, the crop, once established, tolerates stress and produces reasonably well compared to other food crops (e.g. in semiarid environments with less than 700 mm of annual rain, improved cultivars can yield over 3 t ha −1 oven-dried storage roots). The underlying mechanisms for such tolerance include stomatal sensitivity to atmospheric and edaphic water deficits, coupled with deep rooting capacities that prevent severe leaf dehydration, i.e. stress avoidance mechanisms, and reduced leaf canopy with reasonable photosynthesis over the leaf life span. Another stress-mitigating plant trait is the capacity to recover from stress, once water is available, by forming new leaves with even higher P N , compared to those in nonstressed crops. Under extended stress, reductions are larger in shoot biomass than in storage root, resulting in higher harvest indices. Cassava conserves water by slowly depleting available water from deep soil layers, leading to higher seasonal crop water-use and nutrient-use efficiencies. In dry environments LAD and resistance to pests and diseases are critical for sustainable yields. In semiarid zones the crop survives but requires a second wet cycle to achieve high yields and high dry matter contents in storage roots. Selection and breeding for early bulking and for medium/short-stemmed cultivars is advantageous under semiarid conditions. When grown in cooler zones such as in tropical high altitudes and in low-land sub-tropics, leaf P N is greatly reduced and growth is slower. Thus, the crop requires longer period for a reasonable productivity. There is a need to select and breed for more cold-tolerant genotypes. Selection of parental materials for tolerance to water stress and infertile soils has resulted in breeding improved germplasm adapted to both favourable and stressful environments.

Competitive advantages possessed by invasive species encourage aggressive growth that ultimately results in loss of native species diversity and richness. Eurasian watermilfoil, Myriophyllum spicatum L., is a non-native invasive macrophyte that has altered native species composition on several trophic levels. In this study, we examined changes in the nitrogen and phosphorus porewater content within sediments underlying areas dominated by M. spicatum and adjacent sediments supporting native macrophytes. Total dissolved phosphorus (TDP) concentrations were significantly greater early in the growing season in porewater underlying an M. spicatum canopy and declined more rapidly early in the growing season under areas dominated by M. spicatum than under native macrophytes. Rapid, early season uptake of TDP may provide a competitive advantage for M. spicatum . Throughout the growing season, total dissolved nitrogen (TDN) concentrations were on average 2 to 3 times greater in porewater fro...

Logging can significantly change the structure of rainforest communities. To better understand how logging drives this change, butterflies and environmental variables were assessed within both unlogged and logged forest in Indonesian Borneo. In the whole dataset, we found local environmental variables and geographic distance combined captured 53.1% of the variation in butterfly community composition; 29.6% was associated with measured local environmental variables, 13.6% with geographic distance between sites, and 9.9% with covariation between geographic distance and environmental variables. The primary axis of variation in butterfly community composition represented a disturbance gradient from unlogged to logged forest. Subsequent axes represented gradients influenced by variables such as canopy cover and total tree density. There were significant associations between environmental variables and geographic range and larval host plant use of species. Specifically, butterflies using trees as larval host plants and those with distributions limited to Borneo were more likely to be present in unlogged forest. By contrast, species that tended to be more abundant in logged forest were those with widespread distributions and those using lianas and grasses as larval host plants. The results of this study highlight the importance of environmental variables and disturbance, e.g., selective logging, in structuring rainforest community diversity. Moreover, they confirm how species traits, such as larval food use and geographic distributions can determine patterns of species abundance following environmental change.Der Holzeinschlag kann die Struktur von Lebensgemeinschaften in Regenwäldern signifikant verändern. Um besser zu verstehen, wie der Holzeinschlag diese Veränderungen vorantreibt, wurden die Schmetterlinge und die Umweltvariablen in Wäldern mit und ohne Holzeinschlag im indonesischen Borneo erfasst. Im gesamten Datenset fanden wir, dass Umweltvariablen in Kombination mit geographischer Distanz 53.1% der Variation in der Zusammensetzung der Schmetterlingsgemeinschaften abdeckte: 29.6% war mit den gemessenen lokalen Umweltvariablien assoziiert, 13.6% mit der geographischen Distanz zwischen den Standorten und 9.9% mit der Kovariation zwischen geographischer Distanz und Umweltvariablen. Die primäre Achse der Variation in der Zusammensetzung der Schmetterlingsgemeinschaften repräsentierte einen Störungsgradienten von ungenutzten zu abgeholzten Wäldern. Die folgenden Achsen repräsentierten Gradienten, die von Variablen wie Kronendeckung und Gesamtbaumdichte beeinflusst waren. Es gab signifikante Assoziationen zwischen den Umweltvariablen, den geographischen Verbreitungen und der Wirtspflanzennutzung durch die Raupen der Arten. Insbesondere waren Schmetterlinge, die Bäume als Wirtspflanzen nutzen, und diejenigen, deren Verbreitung auf Borneo beschränkt war, mit größerer Wahrscheinlichkeit in ungenutzten Waldbereichen zu finden. Im Unterschied dazu waren Arten, die in eingeschlagenen Wäldern häufiger waren, solche, die Lianen und Gräser als Wirtspflanzen für die Raupen nutzen. Die Ergebnisse dieser Untersuchung betonen die Wichtigkeit der Umweltvariablen und der Störung, z. B. durch selektivem Holzeinschlag, für die Strukturierung der Diversität von Regenwaldgemeinschaften. Zusätzlich bestätigen sie, wie Arteigenschaften, wie die Nahrungsnutzung von Raupen und die geographische Verbreitung, die Muster bestimmen mit denen Artenabundanzen auf Umweltveränderungen reagieren.

1. This account presents information on all aspects of the biology of Gunnera tinctoria (Molina) Mirb. (G. chilensis Lam.; G. scabra Ruix & Pav.; G. pilosa Kunth) that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation. 2. Gunnera tinctoria is a gynomonoecious, clonal, perennial herb that is naturalized in parts of Britain, becoming invasive in parts of Ireland and, more recently, Scotland. It occurs where winter temperatures are mild, and precipitation and humidity are high. Gunnera tinctoria is native to South America, predominantly in the Andean region of Chile and Colombia, and probably in parts of Argentina, ranging from sea level to c. 2000 m a.s.l. 3. Typical habitats in Britain and Ireland include stream and river banks, lake and pond margins, coastal cliffs, as well as disturbed areas, such as roadsides, quarries and ditches. In its native range it occurs predominantly on the banks of rivers and streams, on coastal cliffs and within canopy gaps or at the margins of temperate-humid rain forests. 4. Gunnera tinctoria occurs on a variety of substrates, mainly on alluvial or colluvial soils derived from volcanic material or on thin gley soils of marine origin. In Ireland, it occurs naturally on soils with a pH ranging from 4.6 to 6.2 and has been cultivated in soils with a pH up to 7. Soil moisture content and soil organic matter vary greatly, although it rarely colonizes highly organic soils such as peat. It is susceptible to even mild water deficits at all stages of development, and its seedlings are also sensitive to waterlogged conditions. 5. Gunnera tinctoria produces large numbers of seeds and also spreads clonally, by a horizontal rhizome system. It is wind pollinated, although insect pollination has been reported in New Zealand. Seeds are likely to be predominantly water and/or bird dispersed. In its invasive range, it can form a large and persistent soil seed bank. Recruitment from seeds seems to be important for its initial establishment, while vegetative propagation is the main means of expansion, leading to dense clonal stands. Long-distance seed dispersal seems to be central to the colonization of new areas, although the transport of vegetative propagules may also be important. 6. Gunnera tinctoria is a strong competitor in its invasive range, particularly in wet, humid environments. Its competitive ability arises from its large stature, the persistence of its seeds and rhizomes and a capacity for fixing nitrogen through a unique intracellular symbiosis with cyanobacteria (Nostoc) that may be particularly important for supporting the rapid growth of established plants early in the spring.

Wildfires have major effects on forest dynamics, succession and the carbon cycle in the boreal biome. They are a significant source of carbon emissions, and current observed changes in wildfire regimes due to changes in climate could affect the balance of the boreal carbon pool. A better understanding of postwildfire vegetation dynamics in boreal forests will help predict the future role of boreal forests as a carbon sink or source. Time series of Normalized Difference Vegetation Index (NDVI) and Normalized Difference Shortwave Infrared Index (NDSWIR) derived from Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the Terra satellite were used to investigate whether characteristic temporal patterns exist for stands of different ages in the Siberian boreal forests and whether their postwildfire dynamics are influenced by variables such as prewildfire vegetation cover. Two types of forests, evergreen needle-leaf (ENF) and deciduous needle-leaf (DNF), were studied by analysing a sample of 78 burned forest areas. In order to study a longer time frame, a chronosequence of burned areas of different ages was built by coupling information on location and age provided by a forest burned area database (from 1992 to 2003) to MODIS NDVI and NDSWIR time series acquired from 2001 to 2005. For each of the burned areas, an adjacent unburned control plot representing the same forest type was selected, with the aim of separating the interannual variations caused by climate from changes in NDVI and NDSWIR behaviour due to a wildfire. The results suggest that it takes more than 13 years for the temporal NDVI and NDSWIR signal to recover fully after wildfire. NDSWIR, which is associated to canopy moisture, needs a longer recovery period than NDVI, which is associated to vegetation greenness. The results also suggest that variability observed in postwildfire NDVI and NDSWIR can be explained partially by the dominant forest type: while 13 years after a fire NDVI and NDSWIR are similar for ENF and DNF, the initial impact appears to be greater on the NDVI and NDSWIR of ENF, suggesting a faster recovery by ENF.

Keywords: leaf conductance / leaf water potential / drought sensitivity / mixed forest / xylem sap flux Abstract • Five temperate broad-leaved tree species were compared with respect to their water consumption strategies under ample and restricted water supply. We measured synchronously leaf conductance (g L ) in the sun canopy, xylem sap flux (J s ) and leaf water potential (predawn, Ψ pd and noon, Ψ noon ) in adult trees in a mixed stand and related them to the fluctuations in vapor pressure deficit (D) and soil moisture.

La redécouverte de la valeur culturel du projet et de la nouvelle esthétique de la temporalité sont deux enjeux parmi ces émergents dans la ville en temps de crise en Italie qui se mesurent à travers de processus d'implication active des habitants, des associations et des acteurs institutionnels.
La recherche a proposé des explorations concrètes de transformation de la rue en espace public à travers une prospective interdisciplinaire des pratiques et des interlocutions participatives. C’est dans ce cadre que la recherche s’intéresse au valeur culturel et matériel de l’espace urbain en tant que projection des relations sociales vers une nouvelle esthétique de la temporalité qui vise à renverser le regard des espaces en attente à travers des projets temporaires pour des expériences permanentes.
Une cartographie des MicroMacro espaces du Marché Ballarò, au centre-ville de Palerme, montre des nouveaux imaginaires dans plusieurs lieux marginaux, dégradés et oubliés à travers des projets-actions inattendus et à fort contenu social. Progressivement renforcées par des démarches de recherche-action, cet approche développé par le Groupe de Recherche LabCity Architecture (D’ARCH-UniPA) dans le cadre de Manifesta 12 Palermo 2018, a reçu un écho favorable auprès des associations, marchants et habitants à l’occasion de présentations publiques et d’exposition internationales.

In a one-year-survey in Panama we examined the influence of a tree crown's epiphyte assemblage on its ant fauna. Ants were collected with various types of insect traps in 25 crowns of Annona glabra trees. The study trees were assigned to three different categories according to their epiphyte load, and to an epiphyte-free control group. We collected 22,335 specimens of 91 morphospecies, 32 genera and six subfamilies. By far the most abundant species was Solenopsis zeteki, a minute Myrmicinae, which was found in each of the 25 study trees. Many other species were also rather common and widely distributed throughout the study area. Only six species were singletons. Measures of αand β-diversity, species abundance and species composition were not affected by the epiphyte load of a tree. We also made direct in situ observations of ants on 34 additional Annona glabra trees with and without epiphytes. Workers were attracted with tuna and sugar baits, and interspecific interactions and nesting sites were recorded. In total, 40 species of ants were found, all of which had also been collected in the traps. Almost half of the colonies (48%) used dead wood as nesting substrate, while 29% nested in epiphytes. Consistent with the results of the trap survey, the epiphyte load of the study trees had no influence on ant species richness and composition, but a significant correlation between ant abundance and epiphyte load was detectable. In both data sets, the lack of associations between ant species indicated that the ant assemblages were not structured in a mosaic-like fashion. We conclude that epiphytes do hardly influence the composition of ant assemblages in the studied tree crowns, probably because arboreal ants are highly opportunistic with respect to their host plants.

Plant responses to the projected future levels of CO 2 were first characterized in short-term experiments lasting days to weeks. However, longer term acclimation responses to elevated CO 2 were subsequently discovered to be very important in determining plant and ecosystem function. Free-Air CO 2 Enrichment (FACE) experiments are the culmination of efforts to assess the impact of elevated CO 2 on plants over multiple seasons and, in the case of crops, over their entire lifetime. FACE has been used to expose vegetation to elevated concentrations of atmospheric CO 2 under completely open-air conditions for nearly two decades. This review describes some of the lessons learned from the long-term investment in these experiments. First, elevated CO 2 stimulates photosynthetic carbon gain and net primary production over the long term despite down-regulation of Rubisco activity. Second, elevated CO 2 improves nitrogen use efficiency and, third, decreases water use at both the leaf and canopy scale. Fourth, elevated CO 2 stimulates dark respiration via a transcriptional reprogramming of metabolism. Fifth, elevated CO 2 does not directly stimulate C 4 photosynthesis, but can indirectly stimulate carbon gain in times and places of drought. Finally, the stimulation of yield by elevated CO 2 in crop species is much smaller than expected. While many of these lessons have been most clearly demonstrated in crop systems, all of the lessons have important implications for natural systems.

Canopy crane-based studies have been carried out to quantify the sets of arthropods that visit the flowers of a suite of common species of trees, palms and vines within the Cape Tribulation study area.Those Orders that increase significantly in abundance between the budding and flowering stages of inflorescences are identified, and multivariate and univariate comparisons have been made first, among coflowering plant species and second, at different seasons for the same plant species. The analysis has been repeated for both the profile of higher arthropod taxa in the samples and for the relative abundances of families of Coleoptera: one of the Orders most frequently suggested as critical in the pollination biology of Australian rainforests. In all cases significant differences are identified among species confirming that the visitor profile is a plant species-specific phenomenon. Profiles within plant species at different times also differed. At the ordinal level significant differences in visitor profiles associated with coflowering plants, were observed, variously, in Thysanoptera, Diptera, Lepidoptera, Coleoptera and Hymenoptera. Within the Coleoptera significant differences occurred in relative abundances of Scarabaeidae, Phalacridae, Latridiidae and Curculionidae. Seasonal differences in visitation to Syzygium gustavioides, Normanbya normanbyi and Calamus radicalis, reflected differences in Diptera, Lepidoptera, Homoptera, Thysanoptera, Hymenoptera and Araneida. Within the Coleoptera, the Elateridae and Curculionidae varied significantly between occasions.The various forms of flower/arthropod interaction that may be represented in these results are discussed, as are the implications for pollination.

Planting pattern affects canopy structure of crops and influences other physiological characteristics such as light interception and radiation use efficiency. In the current paper, the effects of planting patterns on the canopy structure, light interception, and photosynthetic characteristics at silking stage of two maize (Zea mays L.) cultivars (Beiyu288 and Xianyu 335) were examined in three planting patterns narrow-wide rows of (1) 30 cm + 170 cm (P1, 6.4 plants m -2 ), and (2) 40 cm+90 cm (P2, 6.4 plants m -2 ), and uniform row of 65 cm (control, i.e. CK, 6.4 plants m -2 ). The ratio of leaves perpendicular to rows was highest in P1 and the leaf orientation value in P1 was constant and slightly lower in P2 compared with that in CK. Although a decrease in the total intercepted photosynthetically active radiation (IPAR) of P1 was found in the two cultivars, more incoming PAR was detected at the middle-low canopy strata of P1. The apparent quantum yield and the net photosynthesis rate (P N ) in P1 and P2 were significantly higher than those in CK. The P N and stomatal conductance (g s ) values in P1 were significantly higher than those in CK, and the intercellular CO 2 concentration decreased with an increase in P N . These results indicated that narrow-wide row planting patterns improved the canopy structure, allowed more IPAR to reach the middle-low strata of the canopy, and enhanced the leaf photosynthetic characteristics of maize crops at silking stage compared with CK.

Insect herbivores often respond to leaf texture in making oviposition or feeding choices. This study examined the importance of leaf pubescence for an assemblage of generalist caterpillars (Lepidoptera: Limacodidae) feeding on oaks (Quercus spp.) and a variety of other tree species in eastern North America. Based on 10 yr of larval sampling on canopy and understory black and white oak (Quercus velutina and Q. alba, respectively) in the Ozark Mountains of Missouri, larval density of slug caterpillars (14 species as a group and 3 individual species) was higher on glabrous canopy leaves of Q. velutina than on highly pubescent understory leaves of that species. In contrast, there was no effect of stratum on overall density for Q. alba, which has glabrous leaves in both microenvironments. Individually, stratum effects for Q. alba were signiÞcant for Þve species, four of which were more abundant in the understory. Additional censusing of larvae on 20 tree species varying in leaf pubescence found that, as a group, slug caterpillar density was negatively correlated with leaf hair density. Finally, feeding trials conÞrmed that slug caterpillars prefer canopy over understory leaves of Q. velutina and vice versa for Q. alba leaves. When hairs were experimentally removed from one side of Q. velutina understory leaves, caterpillars preferred the side from which hairs were removed over the intact side. Together, these results indicate that leaf pubescence inßuences patterns of host plant use by these generalist herbivores, and in so doing, contributes to the structuring of local herbivore communities.

1] A multiple-layer canopy scattering model to estimate shortwave radiation distribution within a wheat canopy was derived mathematically, which incorporated processes of radiation penetration through gaps between leaves, and radiation absorption, reflection, and transmission in leaf layers. The model is able to simulate the multiple scattering processes that occur among different canopy layers and to predict the vertical distributions of upward, downward, and reflected shortwave radiation within the canopy, as well as the magnitude of subcanopy radiation that penetrates to the soil surface. One of the primary advantages of this model, in contrast to other models, is that the multiple scattering processes are represented by a set of linear simultaneous equations that can be solved in a single pass through the equations, without iteration. This achieves computational economy while still accounting for the details of multiple scattering of radiation within the canopy. Stability analyses of the model showed that the canopy, with a leaf area index within a normal field range from 0 to 7, needed to be divided into about 50 or more layers in order to converge upon its final solution. Satisfactory agreement was obtained between model results and field measurements for downward shortwave radiation impinging on the soil surface below the canopy, and upward reflected radiation above the canopy, both for daily total values and for the 20-min averages throughout the diurnal cycle.

The lack of maps depicting forest three-dimensional structure, particularly as pertaining to snags and understory shrub species distribution, is a major limitation for managing wildlife habitat in forests. Developing new techniques to remotely map snags and understory shrubs is therefore an important need. To address this, we first evaluated the use of LiDAR data for mapping the presence/absence of understory shrub species and different snag diameter classes important for birds (i.e. ≥15 cm, ≥ 25 cm and ≥ 30 cm) in a 30,000 ha mixed-conifer forest in Northern Idaho (USA). We used forest inventory plots, LiDAR-derived metrics, and the Random Forest algorithm to achieve classification accuracies of 83% for the understory shrubs and 86% to 88% for the different snag diameter classes. Second, we evaluated the use of LiDAR data for mapping wildlife habitat suitability using four avian species (one flycatcher and three woodpeckers) as case studies. For this, we integrated LiDAR-derived products of forest structure with available models of habitat suitability to derive a variety of species-habitat associations (and therefore habitat suitability patterns) across the study area. We found that the value of LiDAR resided in the ability to quantify 1) ecological variables that are known to influence the distribution of understory vegetation and snags, such as canopy cover, topography, and forest succession, and 2) direct structural metrics that indicate or suggest the presence of shrubs and snags, such as the percent of vegetation returns in the lower strata of the canopy (for the shrubs) and the vertical heterogeneity of the forest canopy (for the snags). When applied to wildlife habitat assessment, these new LiDAR-based maps refined habitat predictions in ways not previously attainable using other remote sensing technologies. This study highlights new value of LiDAR in characterizing key forest structure components important for wildlife, and warrants further applications to other forested environments and wildlife species.

Prescribed fire in rangeland ecosystems is applied for a variety of management objectives, including enhancing productivity of forage species for domestic livestock. In the big sagebrush (Artemisia tridentata Nutt.) steppe of the western United States, fire has been a natural and prescribed disturbance, temporarily shifting vegetation from shrub-grass codominance to grass dominance. There is limited information on the impacts of grazing to community dynamics following fire in big sagebrush steppe. This study evaluated cattle grazing impacts over four growing seasons after prescribed fire on Wyoming big sagebrush (Artemisia tridentata subsp. Wyomingensis [Beetle & Young] Welsh) steppe in eastern Oregon. Treatments included no grazing on burned and unburned sagebrush steppe, two summer-grazing applications after fire, and two spring-grazing applications after fire. Treatment plots were burned in fall 2002. Grazing trials were applied from 2003 to 2005. Vegetation dynamics in the treatments were evaluated by quantifying herbaceous canopy cover, density, annual yield, and perennial grass seed yield. Seed production was greater in the ungrazed burn treatments than in all burn-grazed treatments; however, these differences did not affect community recovery after fire. Other herbaceous response variables (cover, density, composition, and annual yield), bare ground, and soil surface litter did not differ among grazed and ungrazed burn treatments. All burn treatments (grazed and ungrazed) had greater herbaceous cover, herbaceous standing crop, herbaceous annual yield, and grass seed production than the unburned treatment by the second or third year after fire. The results demonstrated that properly applied livestock grazing after low-severity, prescribed fire will not hinder the recovery of herbaceous plant communities in Wyoming big sagebrush steppe. Resumen El fuego prescrito en los ecosistemas de pastizales se aplica para una variedad de objetivos de manejo que incluyen mejorar la productividad de especies de forraje para el ganado dome´stico. En un estepa de artemisa (Artemisia tridentaza Nutt.) del oeste de los Estados Unidos, el fuego ha sido un disturbio natural y preescrito temporalmente intercambiando la vegetación de una codominancia de arbusto-grama a una dominancia de grama. Hay información limitada sobre los impactos del pastoreo en las dinámicas de la comunidad posterior al fuego en una estepa de artemisa. Este estudio evaluó los impactos del pastoreo de ganado por sobre cuatro temporadas de crecimiento después un fuego prescrito en una estepa de artemisa tridentata de Wyoming (Artemisia tridentaza subsp. Wyomingensis [Beetle & Young] Welsh) en el este de Oregón. Los tratamientos incluyeron: no pastoreo en estepa de artemisa quemada y no quemada, dos aplicaciones de pastoreo en el verano luego del fuego y dos aplicaciones de pastoreo en la primavera luego del fuego. Las parcelas de tratamientos fueron quemadas en el otoñ o del 2002. Los transectos de pastoreo se aplicaron a partir de 2003-2005. La dinámica de la vegetación en los tratamientos fue evaluada mediante la cuantificación de la cubierta del dosel herbáceo, densidad, rendimiento anual, y el rendimiento de semillas de gramas perennes. La producción de semillas fue mayor en el tratamiento quemado sin pastoreo que en todos los tratamientos quemados con pastoreo; sin embargo, estas diferencias no afectaron la recuperación de la comunidad despue´s del fuego. Otras respuestas variables de las herbáceas (cubierta, densidad, composición, y rendimiento anual), suelo desnudo y la materia orgánica en la superficie del suelo no difieren entre los tratamientos quemados pastados y no pastados. Todos los tratamientos quemados (pastado y no pastado) tuvieron mayor cobertura de herbáceas, cultivo de herbáceas permanente, rendimiento anual de herbáceas y producción de semillas de grama que el tratamiento no quemado por segundo ó tercer añ o después del fuego. Los resultados demuestran que el pastoreo de ganado propiamente aplicado despue´s de un fuego prescrito de baja intensidad no debe entorpecer con la recuperación de las comunidades de herbáceas en la estepa de artemisa tridentata de Wyoming.

Remote sensing has been used to directly detect and map invasive plants, but has not been used for forest understory invaders because they are obscured by a canopy. However, if the invasive species has a leaf phenology distinct from native forest species, then temporal opportunities exist to detect the invasive. Amur honeysuckle, an Asian shrub that invades North American forests, expands leaves earlier and retains leaves later than native woody species. This research project explored whether Landsat 5 TM and Landsat 7 ETM+ imagery could predict Amur honeysuckle cover in woodlots across Darke and Preble Counties in southwestern Ohio and Wayne County in adjacent eastern Indiana. The predictive abilities of six spectral vegetation indices and six reflectance bands were evaluated to determine the best predictor or predictors of Amur honeysuckle cover. The use of image differencing in which a January 2001 image was subtracted from a November 2005 image provided better prediction of Amur honeysuckle cover than the use of the single November 2005 image. The Normalized Difference Vegetation Index (NDVI) was the best-performing predictor variable, compared to other spectral indices, with a quadratic function providing a better fit (R 2 5 0.75) than a linear function (R 2 5 0.65). This predictive model was verified with 15 other woodlots (R 2 5 0.77). With refinement, this approach could map current and past understory invasion by Amur honeysuckle.