Papers by Geetha Ramaswami
Large-scale and long-term understanding of the phenology of widespread tree species is lacking in... more Large-scale and long-term understanding of the phenology of widespread tree species is lacking in the tropics, and particularly in the Indian subcontinent. In the absence of baseline information, the impacts of climate on tree phenology, and thus on trophic interactions downstream of tree phenology, are also poorly understood. Citizen scientists can help bridge this gap by contributing simple, technology-based information over large spatial scales and over the long term. In this study, we describe an India-wide citizen science initiative called SeasonWatch, with preliminary insights into contributor behaviour and species phenology. Over a period of 8 years, between 2011 and 2019, cumulative contributor numbers have increased every year, although consistent contribution remains constant and low. The phenological patterns in the 4 most-observed species (Jackfruit Artocarpus heterophyllus Lam., Mango Mangifera indica L., Tamarind Tamarindus indica L., and Indian Laburnum Cassia fistula...
Current Science
Mutualistic associations between frugivorous vertebrates and fleshy-fruited plants result in seed... more Mutualistic associations between frugivorous vertebrates and fleshy-fruited plants result in seed dispersal, a vital ecological process affecting plant populations and communities. Invasive fleshy-fruited plants can easily integrate into existing mutualistic networks if generalist frugivorous species start consuming invasive fruit. Additionally, the presence of a copiously fruiting invasive plant in the neighbourhood of fruiting native plants could affect the fruit removal from such plants by either reducing (competitive interaction), increasing (facilitative interaction) or not affecting (no interaction) visits by frugivorous vertebrates. In this study, we explore the effects of the presence of a fruiting invasive shrub Lantana camara L. in the neighbourhood of fruiting native species Erythroxylum monogynum Roxb. and Flueggea leucopyrus Willd. on the visit and fruit removal rate by avian frugivores in a semi-arid bird preserve in southern India. We conducted plant watches within fruiting patches of 30 m radius and observed the identity, numbers and fruit-handling behaviour by avian frugivores on focal native plants. We found that, on average, for the same fruit crop size, E. monogynum received more visits and more fruit removal than F. leucopyrus irrespective of the presence of fruiting neighbours. Focal tree fruit crop size was a better predictor of frugivore behaviour than the fruit crop size of neighbouring plants (both native and invasive) and was positively associated with frugivore visit rate and fruit removal from focal plants. We infer that there is little evidence for facilitation or competition by invasive neighbours for the dispersal services of vertebrate mutualists at the spatial and temporal scale examined in this study. Longer-term, larger-scale data are required to assess the changing impacts of invasive plants on native plant-frugivore interactions.
Biotropica, 2016
In the past century, our understanding of the processes driving plant invasion and its consequenc... more In the past century, our understanding of the processes driving plant invasion and its consequences for natural and anthropogenic systems has increased considerably. However, the management of invasive plants remains a challenge despite ever more resources being allocated to their removal. Often invasive plants targeted for 'eradication' are well-established, have multiple modes of reproduction, long-term seed banks, and strong associations with native and non-native mutualists that ensure dispersal and facilitate spread. The pantropical weed, Lantana camara (Lantana), is one of the most invasive woody plants globally. We illustrate that, for Lantana, eradication is an unrealistic management goal given the short-term removal approaches, irrespective of the effectiveness of removal methods. We assessed the role of dispersal by avian frugivores in the recolonization of managed areas by Lantana in the seasonally dry, tropical forests of northern and southern India. We estimated the distribution of Lantana, its dispersal potential and the proximity between managed areas and source populations. We found that Lantana was dispersed by many generalist frugivorous birds and that most managed areas were well within the median dispersal distance from source plants facilitating rapid recolonization of managed areas. We conclude that given the difficulty of eradicating long-established invasive plants, management practices should entail long-term monitoring and control in priority areas for as long as Lantana occurs in the landscape.
Plant Ecology, 2017
Dispersal is an important ecological process that affects plant population structure and communit... more Dispersal is an important ecological process that affects plant population structure and community composition. Invasive plants with fleshy fruits rapidly form associations with native and invasive dispersers, and may affect existing native plant-disperser associations. We asked whether frugivore visitation rate and fruit removal was associated with plant characteristics in a community of fleshy-fruited plants and whether an invasive plant receives more visitation and greater fruit removal than native plants in a semi-arid habitat of Andhra Pradesh, India. Tree-watches were undertaken at individuals of nine native and one invasive shrub species to assess the identity, number and fruit removal by avian frugivores. Network analyses and generalised linear mixed-effects models were used to understand species and community-level patterns. All plants received most number of visits from abundant, generalist avian frugivores. Number of frugivore visits and time spent by frugivores at individual plants was positively associated with fruit crop size, while fruit removal was positively associated with number of frugivore visits and their mean foraging time at individual plants. The invasive shrub, Lantana camara L. (Lantana), had lower average frugivore visit rate than the community of fleshy-fruited plants and received similar average frugivore visits but greater average per-hour fruit removal than two other concurrently fruiting native species. Based on the results of our study, we infer that there is little evidence of competition between native plants and Lantana for the dispersal services of native frugivores and that more data are required to assess the nature of these interactions over the long term. We speculate that plant associations with generalist frugivores may increase the functional redundancy of this frugivory network, buffering it against loss of participating species.
In the past century, our understanding of the processes driving plant invasion and its consequenc... more In the past century, our understanding of the processes driving plant invasion and its consequences for natural and anthropogenic systems has increased considerably. However, the management of invasive plants remains a challenge despite ever more resources being allocated to their removal. Often invasive plants targeted for 'eradication' are well-established, have multiple modes of reproduction, long-term seed banks, and strong associations with native and non-native mutualists that ensure dispersal and facilitate spread. The pantropical weed, Lantana camara (Lantana), is one of the most invasive woody plants globally. We illustrate that, for Lantana, eradication is an unrealistic management goal given the short-term removal approaches, irrespective of the effectiveness of removal methods. We assessed the role of dispersal by avian frugivores in the recolonization of managed areas by Lantana in the seasonally dry, tropical forests of northern and southern India. We estimated the distribution of Lantana, its dispersal potential and the proximity between managed areas and source populations. We found that Lantana was dispersed by many generalist frugivorous birds and that most managed areas were well within the median dispersal distance from source plants facilitating rapid recolonization of managed areas. We conclude that given the difficulty of eradicating long-established invasive plants, management practices should entail long-term monitoring and control in priority areas for as long as Lantana occurs in the landscape.
SUMMARY Seasonally dry tropical forests (SDTFs), a varied and extensive ecosystem type in the tro... more SUMMARY Seasonally dry tropical forests (SDTFs), a varied and extensive ecosystem type in the tropics, are characteristically adapted to seasonal water stress in zones of low rainfall. Land-use change, resource extraction, alien invasives, changes to the atmosphere, and changing fire and climatic regimes may have serious implications for the continued persistence of SDTFs. This paper assesses the extent to which SDTFs may be resilient in the face of these threats, considering their dynamics, community-level characteristics, and functional traits of constituent species. There is evidence that some SDTF biodiversity-and structure-related properties are resistant to low-to moderate-intensity disturbances and have the potential to recover after severe, even chronic, disturbances, at timescales in the order of decades. Although global SDTFs are, on average, not necessarily more resilient than moist tropical forests (MTFs), they may be more resilient to particular disturbances such as fires and drought. SDTFs are vulnerable to regime shifts and there is considerable uncertainty about their future under a changing climate and its interactions with other anthropogenic effects. les forêts tropicales à sècheresse saisonnière (SDTFs), un type d'écosystème étendu et varié dans les tropiques, sont adaptées de manière caractéristique au stress dû au manque d'eau dans les zones de faible précipitations. les changements d'utilisation des terres, l'extraction des ressources, les espèces étrangères envahissantes, les changements atmosphériques et les régimes climatiques et des feux changeants pourraient avoir des implications sérieuses sur une continuation de la persistance des SDTFs. Ce papier évalue jusqu'où les SDTFs peuvent être résistan-tes face à ces menaces, en considérant leurs dynamiques, leurs caractéristiques au niveau communautaire, et les traits de fonctionnement des espèces les constituant. Des preuves émergent qu'une partie de la biodiversité et des propriétés liées à la structure des SDTFs est résistante aux dérangements faibles à modérés et que celles-ci détiennent un potentiel de rétablissement après des désordres sévères, et même chroniques, dans une échelle de temps, ordonnée par décennies. Bien que les SDTFs globales ne soient généralement pas nécessairement plus résistantes que les forêts tropicales humides (MTFs), elles pourraient faire preuve d'une plus grande résistance face à certains sinistres tels que le feu et la sècheresse. les SDTFs sont vulnérables aux changements de régime, et une question considérable demeure quant à leur futur dans un climat changeant et ses interactions avec d'autres effets anthropogéniques. El bosque seco tropical (BST) es un tipo de ecosistema variado y extenso de los trópicos que se adapta característicamente al estrés hídrico estacional en zonas de baja precipitación. los cambios de uso del suelo, la extracción de recursos, las especies exóticas invasoras, los cambios en la atmósfera, y los cambios en los regímenes de incendios y del clima pueden tener graves consecuencias para la persistencia continuada del BST. Este artículo evalúa el grado de resiliencia que puede alcanzar el BST frente a estas amenazas, teniendo en cuenta su dinámica, sus
Journal of Biosciences, 2014
Streams are periodically disturbed due to flooding, act as edges between habitats and also facili... more Streams are periodically disturbed due to flooding, act as edges between habitats and also facilitate the dispersal of
propagules, thus being potentially more vulnerable to invasions than adjoining regions. We used a landscape-wide
transect-based sampling strategy and a mixed effects modelling approach to understand the effects of distance from
stream, a rainfall gradient, light availability and fire history on the distribution of the invasive shrub Lantana camara
L.(lantana) in the tropical dry forests of Mudumalai in southern India. The area occupied by lantana thickets and
lantana stem abundance were both found to be highest closest to streams across this landscape with a rainfall gradient.
There was no advantage in terms of increased abundance or area occupied by lantana when it grew closer to streams in
drier areas as compared to moister areas. On an average, the area covered by lantana increased with increasing annual
rainfall. Areas that experienced greater number of fires during 1989–2010 had lower lantana stem abundance
irrespective of distance from streams. In this landscape, total light availability did not affect lantana abundance.
Understanding the spatially variable environmental factors in a heterogeneous landscape influencing the distribution
of lantana would aid in making informed management decisions at this scale.
Indian Forester, 2014
Since its introduction in India 200 years ago, Lantana camara (Lantana) has become established... more Since its introduction in India 200 years ago, Lantana camara (Lantana) has become established and naturalised across
a wide range of habitats. In Indian protected areas, lantana has been predominately managed using a range of
mechanical removal approaches, costing up to ` 6000 per hectare. However, managed sites are rapidly recolonized by
lantana and management programmes rarely achieve their goal of lantana eradication. In present study, we quantified
recolonisation of lantana at sites that were either managed only once or for two consecutive years in Rajaji National
Park, Uttarakhand. Rapid recolonisation and recruitment is occuring from seed dispersal from surrounding lantana
populations, soil seed banks and vegetative regeneration. To manage lantana effectively we need to consider these
ecological processes. An alternate management programme is recommended for long-established invasive plants such
as lantana, that focuses on (a) prioritizing critical habitats that require management of invasive species (b) long-term
monitoring and management scaled to timeframes of ecological processes, i.e., lantana dispersal and soil seed banks,
and (c) phased enlargement of managed sites such that over time, high-priority habitats can be isolated from dispersal
originating from surrounding lantana source populations.
PLOS ONE, Oct 2013
Invasive species, local plant communities and invaded ecosystems change over space and time. Quan... more Invasive species, local plant communities and invaded ecosystems change over space and time. Quantifying this change
may lead to a better understanding of the ecology and the effective management of invasive species. We used data on
density of the highly invasive shrub Lantana camara (lantana) for the period 1990–2008 from a 50 ha permanent plot in a
seasonally dry tropical forest of Mudumalai in southern India. We used a cumulative link mixed-effects regression approach
to model the transition of lantana from one qualitative density state to another as a function of biotic factors such as
indicators of competition from local species (lantana itself, perennial grasses, invasive Chromolaena odorata, the native
shrub Helicteres isora and basal area of native trees) and abiotic factors such as fire frequency, inter-annual variability of
rainfall and relative soil moisture. The density of lantana increased substantially during the study period. Lantana density
was negatively associated with the density of H. isora, positively associated with basal area of native trees, but not affected
by the presence of grasses or other invasive species. In the absence of fire, lantana density increased with increasing rainfall.
When fires occurred, transitions to higher densities occurred at low rainfall values. In drier regions, lantana changed from
low to high density as rainfall increased while in wetter regions of the plot, lantana persisted in the dense category
irrespective of rainfall. Lantana seems to effectively utilize resources distributed in space and time to its advantage, thus
outcompeting local species and maintaining a population that is not yet self-limiting. High-risk areas and years could
potentially be identified based on inferences from this study for facilitating management of lantana in tropical dry forests.
Plant Ecology, 2013
Native species’ response to the presence of
invasive species is context specific. This response
... more Native species’ response to the presence of
invasive species is context specific. This response
cannot be studied in isolation from the prevailing
environmental stresses in invaded habitats such as
seasonal drought.We investigated the combined effects
of an invasive shrub Lantana camara L. (lantana),
seasonal rainfall and species’ microsite preferences on
the growth and survival of 1,105 naturally established
seedlings of native trees and shrubs in a seasonally dry
tropical forest. Individuals were followed from April
2008 to February 2010, and growth and survival
measured in relation to lantana density, seasonality of
rainfall and species characteristics in a 50-ha permanent
forest plot located in Mudumalai, southern India. We
used a mixed effects modelling approach to examine
seedling growth and generalized linear models to
examine seedling survival. The overall relative height
growth rate of established seedlings was found to be
very low irrespective of the presence or absence of dense
lantana. 22-month growth rate of dry forest species was
lower under dense lantana while moist forest species
were not affected by the presence of lantana thickets.
4-month growth rates of all species increased with
increasing inter-census rainfall.Community resultsmay
be influenced by responses of the most abundant
species, Catunaregam spinosa, whose growth rates
were always lower under dense lantana. Overall
seedling survival was high, increased with increasing
rainfall and was higher for species with dry forest
preference than for species with moist forest preference.
The high survival rates of naturally established seed-
lings combined with their basal sprouting ability in this
forest could enable the persistence of woody species in
the face of invasive species.
Journal of Tropical Ecology, Jan 1, 2011
Lantana camara, a shrub of Central and South American origin, has become invasive across dry fore... more Lantana camara, a shrub of Central and South American origin, has become invasive across dry forests
worldwide. The effect of the thicket-forming habit of L. camara as a dispersal and recruitment barrier in a community
of native woody seedlings was examined in a 50-ha permanent plot located in the seasonally dry forest of Mudumalai,
southern India. Sixty 100-m2 plots were enumerated for native woody seedlings between 10–100 cm in height. Of
these, 30 plots had no L. camara thickets, while the other 30 had dense thickets. The frequency of occurrence and
abundance of seedlings were modelled as a function of dispersal mode (mammal, bird or mechanical) and affinities
to forest habitats (dry forest, moist forest or ubiquitous) as well as presence or absence of dense L. camara thickets.
Furthermore, frequency of occurrence and abundance of individual species were also compared between thickets and
no L. camara.At the community level, L. camara density, dispersalmode and foresthabitat affinities of species determined
both frequency of occurrence and abundance of seedlings,with the abundance of dry-forestmammal-dispersed species
and ubiquitous mechanically dispersed species being significantly lower under L. camara thickets. Phyllanthus emblica
and Kydia calycina were found to be significantly less abundant under L. camara, whereas most other species were
not affected by the presence of thickets. It was inferred that, by affecting the establishment of native tree seedlings,
L. camara thickets could eventually alter the community composition of such forests.
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Papers by Geetha Ramaswami
propagules, thus being potentially more vulnerable to invasions than adjoining regions. We used a landscape-wide
transect-based sampling strategy and a mixed effects modelling approach to understand the effects of distance from
stream, a rainfall gradient, light availability and fire history on the distribution of the invasive shrub Lantana camara
L.(lantana) in the tropical dry forests of Mudumalai in southern India. The area occupied by lantana thickets and
lantana stem abundance were both found to be highest closest to streams across this landscape with a rainfall gradient.
There was no advantage in terms of increased abundance or area occupied by lantana when it grew closer to streams in
drier areas as compared to moister areas. On an average, the area covered by lantana increased with increasing annual
rainfall. Areas that experienced greater number of fires during 1989–2010 had lower lantana stem abundance
irrespective of distance from streams. In this landscape, total light availability did not affect lantana abundance.
Understanding the spatially variable environmental factors in a heterogeneous landscape influencing the distribution
of lantana would aid in making informed management decisions at this scale.
a wide range of habitats. In Indian protected areas, lantana has been predominately managed using a range of
mechanical removal approaches, costing up to ` 6000 per hectare. However, managed sites are rapidly recolonized by
lantana and management programmes rarely achieve their goal of lantana eradication. In present study, we quantified
recolonisation of lantana at sites that were either managed only once or for two consecutive years in Rajaji National
Park, Uttarakhand. Rapid recolonisation and recruitment is occuring from seed dispersal from surrounding lantana
populations, soil seed banks and vegetative regeneration. To manage lantana effectively we need to consider these
ecological processes. An alternate management programme is recommended for long-established invasive plants such
as lantana, that focuses on (a) prioritizing critical habitats that require management of invasive species (b) long-term
monitoring and management scaled to timeframes of ecological processes, i.e., lantana dispersal and soil seed banks,
and (c) phased enlargement of managed sites such that over time, high-priority habitats can be isolated from dispersal
originating from surrounding lantana source populations.
may lead to a better understanding of the ecology and the effective management of invasive species. We used data on
density of the highly invasive shrub Lantana camara (lantana) for the period 1990–2008 from a 50 ha permanent plot in a
seasonally dry tropical forest of Mudumalai in southern India. We used a cumulative link mixed-effects regression approach
to model the transition of lantana from one qualitative density state to another as a function of biotic factors such as
indicators of competition from local species (lantana itself, perennial grasses, invasive Chromolaena odorata, the native
shrub Helicteres isora and basal area of native trees) and abiotic factors such as fire frequency, inter-annual variability of
rainfall and relative soil moisture. The density of lantana increased substantially during the study period. Lantana density
was negatively associated with the density of H. isora, positively associated with basal area of native trees, but not affected
by the presence of grasses or other invasive species. In the absence of fire, lantana density increased with increasing rainfall.
When fires occurred, transitions to higher densities occurred at low rainfall values. In drier regions, lantana changed from
low to high density as rainfall increased while in wetter regions of the plot, lantana persisted in the dense category
irrespective of rainfall. Lantana seems to effectively utilize resources distributed in space and time to its advantage, thus
outcompeting local species and maintaining a population that is not yet self-limiting. High-risk areas and years could
potentially be identified based on inferences from this study for facilitating management of lantana in tropical dry forests.
invasive species is context specific. This response
cannot be studied in isolation from the prevailing
environmental stresses in invaded habitats such as
seasonal drought.We investigated the combined effects
of an invasive shrub Lantana camara L. (lantana),
seasonal rainfall and species’ microsite preferences on
the growth and survival of 1,105 naturally established
seedlings of native trees and shrubs in a seasonally dry
tropical forest. Individuals were followed from April
2008 to February 2010, and growth and survival
measured in relation to lantana density, seasonality of
rainfall and species characteristics in a 50-ha permanent
forest plot located in Mudumalai, southern India. We
used a mixed effects modelling approach to examine
seedling growth and generalized linear models to
examine seedling survival. The overall relative height
growth rate of established seedlings was found to be
very low irrespective of the presence or absence of dense
lantana. 22-month growth rate of dry forest species was
lower under dense lantana while moist forest species
were not affected by the presence of lantana thickets.
4-month growth rates of all species increased with
increasing inter-census rainfall.Community resultsmay
be influenced by responses of the most abundant
species, Catunaregam spinosa, whose growth rates
were always lower under dense lantana. Overall
seedling survival was high, increased with increasing
rainfall and was higher for species with dry forest
preference than for species with moist forest preference.
The high survival rates of naturally established seed-
lings combined with their basal sprouting ability in this
forest could enable the persistence of woody species in
the face of invasive species.
worldwide. The effect of the thicket-forming habit of L. camara as a dispersal and recruitment barrier in a community
of native woody seedlings was examined in a 50-ha permanent plot located in the seasonally dry forest of Mudumalai,
southern India. Sixty 100-m2 plots were enumerated for native woody seedlings between 10–100 cm in height. Of
these, 30 plots had no L. camara thickets, while the other 30 had dense thickets. The frequency of occurrence and
abundance of seedlings were modelled as a function of dispersal mode (mammal, bird or mechanical) and affinities
to forest habitats (dry forest, moist forest or ubiquitous) as well as presence or absence of dense L. camara thickets.
Furthermore, frequency of occurrence and abundance of individual species were also compared between thickets and
no L. camara.At the community level, L. camara density, dispersalmode and foresthabitat affinities of species determined
both frequency of occurrence and abundance of seedlings,with the abundance of dry-forestmammal-dispersed species
and ubiquitous mechanically dispersed species being significantly lower under L. camara thickets. Phyllanthus emblica
and Kydia calycina were found to be significantly less abundant under L. camara, whereas most other species were
not affected by the presence of thickets. It was inferred that, by affecting the establishment of native tree seedlings,
L. camara thickets could eventually alter the community composition of such forests.
propagules, thus being potentially more vulnerable to invasions than adjoining regions. We used a landscape-wide
transect-based sampling strategy and a mixed effects modelling approach to understand the effects of distance from
stream, a rainfall gradient, light availability and fire history on the distribution of the invasive shrub Lantana camara
L.(lantana) in the tropical dry forests of Mudumalai in southern India. The area occupied by lantana thickets and
lantana stem abundance were both found to be highest closest to streams across this landscape with a rainfall gradient.
There was no advantage in terms of increased abundance or area occupied by lantana when it grew closer to streams in
drier areas as compared to moister areas. On an average, the area covered by lantana increased with increasing annual
rainfall. Areas that experienced greater number of fires during 1989–2010 had lower lantana stem abundance
irrespective of distance from streams. In this landscape, total light availability did not affect lantana abundance.
Understanding the spatially variable environmental factors in a heterogeneous landscape influencing the distribution
of lantana would aid in making informed management decisions at this scale.
a wide range of habitats. In Indian protected areas, lantana has been predominately managed using a range of
mechanical removal approaches, costing up to ` 6000 per hectare. However, managed sites are rapidly recolonized by
lantana and management programmes rarely achieve their goal of lantana eradication. In present study, we quantified
recolonisation of lantana at sites that were either managed only once or for two consecutive years in Rajaji National
Park, Uttarakhand. Rapid recolonisation and recruitment is occuring from seed dispersal from surrounding lantana
populations, soil seed banks and vegetative regeneration. To manage lantana effectively we need to consider these
ecological processes. An alternate management programme is recommended for long-established invasive plants such
as lantana, that focuses on (a) prioritizing critical habitats that require management of invasive species (b) long-term
monitoring and management scaled to timeframes of ecological processes, i.e., lantana dispersal and soil seed banks,
and (c) phased enlargement of managed sites such that over time, high-priority habitats can be isolated from dispersal
originating from surrounding lantana source populations.
may lead to a better understanding of the ecology and the effective management of invasive species. We used data on
density of the highly invasive shrub Lantana camara (lantana) for the period 1990–2008 from a 50 ha permanent plot in a
seasonally dry tropical forest of Mudumalai in southern India. We used a cumulative link mixed-effects regression approach
to model the transition of lantana from one qualitative density state to another as a function of biotic factors such as
indicators of competition from local species (lantana itself, perennial grasses, invasive Chromolaena odorata, the native
shrub Helicteres isora and basal area of native trees) and abiotic factors such as fire frequency, inter-annual variability of
rainfall and relative soil moisture. The density of lantana increased substantially during the study period. Lantana density
was negatively associated with the density of H. isora, positively associated with basal area of native trees, but not affected
by the presence of grasses or other invasive species. In the absence of fire, lantana density increased with increasing rainfall.
When fires occurred, transitions to higher densities occurred at low rainfall values. In drier regions, lantana changed from
low to high density as rainfall increased while in wetter regions of the plot, lantana persisted in the dense category
irrespective of rainfall. Lantana seems to effectively utilize resources distributed in space and time to its advantage, thus
outcompeting local species and maintaining a population that is not yet self-limiting. High-risk areas and years could
potentially be identified based on inferences from this study for facilitating management of lantana in tropical dry forests.
invasive species is context specific. This response
cannot be studied in isolation from the prevailing
environmental stresses in invaded habitats such as
seasonal drought.We investigated the combined effects
of an invasive shrub Lantana camara L. (lantana),
seasonal rainfall and species’ microsite preferences on
the growth and survival of 1,105 naturally established
seedlings of native trees and shrubs in a seasonally dry
tropical forest. Individuals were followed from April
2008 to February 2010, and growth and survival
measured in relation to lantana density, seasonality of
rainfall and species characteristics in a 50-ha permanent
forest plot located in Mudumalai, southern India. We
used a mixed effects modelling approach to examine
seedling growth and generalized linear models to
examine seedling survival. The overall relative height
growth rate of established seedlings was found to be
very low irrespective of the presence or absence of dense
lantana. 22-month growth rate of dry forest species was
lower under dense lantana while moist forest species
were not affected by the presence of lantana thickets.
4-month growth rates of all species increased with
increasing inter-census rainfall.Community resultsmay
be influenced by responses of the most abundant
species, Catunaregam spinosa, whose growth rates
were always lower under dense lantana. Overall
seedling survival was high, increased with increasing
rainfall and was higher for species with dry forest
preference than for species with moist forest preference.
The high survival rates of naturally established seed-
lings combined with their basal sprouting ability in this
forest could enable the persistence of woody species in
the face of invasive species.
worldwide. The effect of the thicket-forming habit of L. camara as a dispersal and recruitment barrier in a community
of native woody seedlings was examined in a 50-ha permanent plot located in the seasonally dry forest of Mudumalai,
southern India. Sixty 100-m2 plots were enumerated for native woody seedlings between 10–100 cm in height. Of
these, 30 plots had no L. camara thickets, while the other 30 had dense thickets. The frequency of occurrence and
abundance of seedlings were modelled as a function of dispersal mode (mammal, bird or mechanical) and affinities
to forest habitats (dry forest, moist forest or ubiquitous) as well as presence or absence of dense L. camara thickets.
Furthermore, frequency of occurrence and abundance of individual species were also compared between thickets and
no L. camara.At the community level, L. camara density, dispersalmode and foresthabitat affinities of species determined
both frequency of occurrence and abundance of seedlings,with the abundance of dry-forestmammal-dispersed species
and ubiquitous mechanically dispersed species being significantly lower under L. camara thickets. Phyllanthus emblica
and Kydia calycina were found to be significantly less abundant under L. camara, whereas most other species were
not affected by the presence of thickets. It was inferred that, by affecting the establishment of native tree seedlings,
L. camara thickets could eventually alter the community composition of such forests.