Ashoka Trust for Research in Ecology and the Environment ATREE

Bangalore, India

Ashoka Trust for Research in Ecology and the Environment ATREE

Bangalore, India

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Sundaram B.,Ashoka Trust for Research in Ecology and the Environment ATREE | Sundaram B.,National Center for Biological science | Hiremath A.J.,Ashoka Trust for Research in Ecology and the Environment ATREE
Biological Invasions | Year: 2012

The effects of invasive species on community structure remain under-investigated due to the lack of long-term data. Our objectives were to examine the correlation between Lantana camara L. invasion and native species abundance, distribution, diversity, and population structure, across different forest types in a heterogeneous landscape. We examined changes in native vegetation and L. camara between 1997 and 2008. We used existing vegetation data from 134 plots spread across the 540 km 2 landscape from 1997 and re-censused these plots in 2008. We then examined the change in species richness, Shannon's diversity, evenness, and population structure of native species from 1997 to 2008. We also examined the relationship between L. camara density and species richness, diversity, evenness, and population structure. The presence and abundance of L. camara increased dramatically from 1997 to 2008. L. camara occurred in 81% of plots by 2008, compared with only 41% of plots in 1997. Similarly, the mean density of L. camara increased almost fourfold from 1997 to 2008. This was accompanied by a change in native community structure. Species richness, diversity and evenness declined significantly in some forest types, and at the landscape scale. There were also changes in the population structure of native tree species, with reductions in the density of tree saplings, possibly due to competition with L. camara. We demonstrate the pervasive threat posed by L. camara to native vegetation at the scale of individual forest types, and at the larger landscape scale, in our study area. These changes have long-term consequences for forest structure and composition. © 2011 Springer Science+Business Media B.V.


He K.S.,Murray State University | Rocchini D.,Research and Innovation Center | Neteler M.,Research and Innovation Center | Nagendra H.,Indiana University | Nagendra H.,Ashoka Trust for Research in Ecology and the Environment ATREE
Diversity and Distributions | Year: 2011

Aim We aim to report what hyperspectral remote sensing can offer for invasion ecologists and review recent progress made in plant invasion research using hyperspectral remote sensing. Location United States. Methods We review the utility of hyperspectral remote sensing for detecting, mapping and predicting the spatial spread of invasive species. We cover a range of topics including the trade-off between spatial and spectral resolutions and classification accuracy, the benefits of using time series to incorporate phenology in mapping species distribution, the potential of biochemical and physiological properties in hyperspectral spectral reflectance for tracking ecosystem changes caused by invasions, and the capacity of hyperspectral data as a valuable input for quantitative models developed for assessing the future spread of invasive species. Results Hyperspectral remote sensing holds great promise for invasion research. Spectral information provided by hyperspectral sensors can detect invaders at the species level across a range of community and ecosystem types. Furthermore, hyperspectral data can be used to assess habitat suitability and model the future spread of invasive species, thus providing timely information for invasion risk analysis. Main conclusions Our review suggests that hyperspectral remote sensing can effectively provide a baseline of invasive species distributions for future monitoring and control efforts. Furthermore, information on the spatial distribution of invasive species can help land managers to make long-term constructive conservation plans for protecting and maintaining natural ecosystems. © 2011 Blackwell Publishing Ltd.


Nagendra H.,Ashoka Trust for Research in Ecology and the Environment Atree | Nagendra H.,Indiana University | Rocchini D.,University of Siena | Ghate R.,Institute for Research and Development
Biological Conservation | Year: 2010

Parks represent spatially and socially heterogeneous conservation units, yet are often assessed and managed using spatially homogeneous approaches. This paper represents an effort to focus on the larger social-ecological landscapes within which protected areas are embedded, to understand why conservation succeeds and fails in different parts of the landscape. In a wildlife sanctuary in the central plains of India (Tadoba Andhari Tiger Reserve), we address: (i) how people living within and immediately outside a park differentially impact its resources and (ii) how the park differentially impacts communities living within. Using forest plots, satellite imagery and interviews, we evaluate park conservation by assessing plant diversity, land cover change, forest fragmentation, and attitudes of local communities towards conservation. We find that interior villages have a negative impact on regeneration, but there is a decline in tree species diversity, and increased forest cover change and fragmentation at the park periphery. Interior villages suffer greatly from crop and livestock depredations by wildlife and consider park rules to be unfairly devised. Yet, they affirm the importance of the park for conservation, and are willing to work with park authorities for stricter protection. Park authorities largely focus on resettlement of interior villages, when they should also pay attention to protecting the peripheral areas of the park from severe degradation by surrounding villages. In summary, we find that different parts of the park landscape face different conservation challenges. Taking into account spatial variations in the factors influencing conservation can greatly benefit the management of protected areas. © Elsevier Ltd.


Nagendra H.,Ashoka Trust for Research in Ecology and the Environment ATREE | Nagendra H.,Indiana University | Ostrom E.,Indiana University
Ecology and Society | Year: 2011

Ecologists and practitioners have conventionally used forest plots or transects for monitoring changes in attributes of forest condition over time. However, given the difficulty in collecting such data, conservation practitioners frequently rely on the judgment of foresters and forest users for evaluating changes. These methods are rarely compared. We use a dataset of 53 forests in five countries to compare assessments of forest change from forest plots, and forester and user evaluations of changes in forest density. We find that user assessments of changes in tree density are strongly and significantly related to assessments of change derived from statistical analyses of randomly distributed forest plots. User assessments of change in density at the shrub/sapling level also relate to assessments derived from statistical evaluations of vegetation plots, but this relationship is not as strong and only weakly significant. Evaluations of change by professional foresters are much more difficult to acquire, and less reliable, as foresters are often not familiar with changes in specific local areas. Forester evaluations can instead better provide valid singletime comparisons of a forest with other areas in a similar ecological zone. Thus, in forests where local forest users are present, their evaluations can be used to provide reliable assessments of changes in tree density in the areas they access. However, assessments of spatially heterogeneous patterns of human disturbance and regeneration at the shrub/sapling level are likely to require supplemental vegetation analysis. © 2011 by the author(s).


Nagendra H.,Ashoka Trust for Research in Ecology and the Environment ATREE | Nagendra H.,Indiana University | Gopal D.,Ashoka Trust for Research in Ecology and the Environment ATREE
Urban Ecosystems | Year: 2011

Urban parks constitute critical biodiversity hotspots in crowded, concrete-dominated city environments. Despite the importance, they remain little researched. This paper assesses the biodiversity and distribution of trees in urban parks in the southern Indian city of Bangalore. 127 plots were used to survey tree distribution in parks across the city. The distribution is largely dominated by a few common species. The proportion of exotic species was very high, with 77% of trees belonging to introduced species. Park history had an impact on distribution. Old parks had fewer but larger trees, and greater species diversity compared to recently established parks. Old parks also differed in species composition, having a greater proportion of large canopy trees compared to young parks. Examination of size distributions revealed that large canopied species were gradually being phased out, and replaced by narrow and medium sized tree species which are easier to maintain, but which may not provide the same environmental and ecological benefits. Greater attention requires to be paid to the selection of trees in cities, not just with a view to easy maintenance as is currently the case, but to select an appropriate mix of trees that supports biodiversity and maximizes environmental and ecosystem services. © 2010 Springer Science+Business Media, LLC.


D'Souza R.,Ashoka Trust for Research in Ecology and the Environment ATREE | Nagendra H.,Ashoka Trust for Research in Ecology and the Environment ATREE | Nagendra H.,Indiana University
Environmental Management | Year: 2011

The city of Bangalore in southern India is rapidly expanding, resulting in major transformations in land use, wetland management, and the distribution of green spaces. This paper examines how transformations in land use and governance consequent to urbanization can change people's perceptions of and interactions with an urban ecological commons, using the case study of the Agara lake in the south Indian city of Bangalore. In less than four decades, the landscape surrounding the lake has altered from a fundamentally agricultural area, dependent on the lake for irrigation and drinking water, to a densely urbanized area where the lake is used predominantly for recreation. A change in governance from community management to state management has sidelined the fishers, fodder collectors and agricultural users who traditionally maintained this lake. The governmental agencies that are supposed to maintain the lake are unable to do so due to a complex governance structure, with overlapping jurisdictions, compounded by an ongoing litigation. Over the past decades, the lake has largely transitioned into an urban green space primarily used for recreation and nature watching. This case study provides us with a broader understanding of how changes in governance consequent to urbanization and city expansion can impact interactions between people and ecological commons in a rapidly growing Indian city. © 2011 Springer Science+Business Media, LLC.


Nagendra H.,Ashoka Trust for Research in Ecology and the Environment ATREE | Nagendra H.,Indiana University | Gopal D.,Ashoka Trust for Research in Ecology and the Environment ATREE
Urban Forestry and Urban Greening | Year: 2010

Once renowned as India's "garden city", the fast growing southern Indian city of Bangalore is rapidly losing tree cover in public spaces including on roads. This study aims to study the distribution of street trees in Bangalore, to assess differences in tree density, size and species composition across roads of different widths, and to investigate changes in planting practices over time. A spatially stratified approach was used for sampling with 152 transects of 200 m length distributed across wide roads (with a width of 24 m or greater), medium sized roads (12-24 m) and narrow roads (less than 12 m). We find the density of street trees in Bangalore to be lower than many other Asian cities. Species diversity is high, with the most dominant species accounting for less than 10% of the overall population. Narrow roads, usually in congested residential neighborhoods, have fewer trees, smaller sized tree species, and a lower species diversity compared to wide roads. Since wide roads are being felled of trees across the city for road widening, this implies that Bangalore's street tree population is being selectively denuded of its largest trees. Older trees have a more diverse distribution with several large sized species, while young trees come from a less diverse species set, largely dominated by small statured species with narrow canopies, which have a lower capacity to absorb atmospheric pollutants, mitigate urban heat island effects, stabilize soil, prevent ground water runoff, and sequester carbon. This has serious implications for the city's environmental and ecological health. These results highlight the need to protect large street trees on wide roads from tree felling, and to select an appropriate and diverse mix of large and small sized tree species for new planting. © 2009 Elsevier GmbH. All rights reserved.


Ostrom E.,Indiana University | Nagendra H.,Indiana University | Nagendra H.,Ashoka Trust for Research in Ecology and the Environment ATREE
Environmental Economics and Policy Studies | Year: 2014

Many scholars call for the establishment of one kind of formal tenure—government ownership, privatization, or community control—as the way to solve problems associated with high levels of deforestation. This will not work without extensive and consistent monitoring of forest use. In this article, we draw on analyses of time-series remote images, on-the-ground social-ecological surveys of local stakeholders and their forests, and experimental laboratory studies to show that “protected” forests may not be protected in practice when tenure alone is deemed to be the “solution.” When users themselves consider the rules in place to be legitimate, they are frequently willing to engage themselves in monitoring and sanctioning of uses considered illegal, even when related to government-owned property. When users are genuinely engaged in decisions about rules affecting their use, the likelihood of users to follow the rules and monitor others is much greater than when an external authority simply imposes rules. Simple formulas focusing on formal ownership, particularly ones based solely on public ownership of forested lands, will not solve the problems of resource overuse. © 2007, Springer Japan.


Chetana H.C.,Ashoka Trust for Research in Ecology and the Environment ATREE | Ganesh T.,Ashoka Trust for Research in Ecology and the Environment ATREE
Journal of Tropical Ecology | Year: 2012

Abandoned plantations of coffee, tea and other commercial crops offer opportunities for understanding ecological processes in modified forest ecosystems. Unlike tree plantations tea is maintained as a shrub with a continuous dense short canopy that precludes large-frugivore activity thereby limiting dispersal of forest species to such areas. In this study we determine how location and density of Grevillea robusta a shade tree in tea plantations and proximity of plantations to forests influences seed arrival from forests into the plantations. We also estimate the importance of dispersal modes in the colonization processes. We laid 10 × 10-m plots at three distance intervals from the forest edge in three different plantation types with varying shade tree densities. Within the plots we laid four 1× 1-m subplots at the corners of the plot. We estimated species richness, abundance and categorized the seeds into dispersal modes in these plots. Grevillea robusta increased species richness of seeds by three times and abundance of seeds by 3-30 times compared with plantations without them. Higher density of G. robusta increased seed input changed species composition and altered species dominance in the plantations. Distance to forests influenced seed arrival in plantations without G. robusta trees and plots 95 m from the forest did not have any seeds in them. No such effect was seen in plantations with G. robusta trees. Seeds dispersed by birds or a combination of birds and mammals contribute 30% of the seeds reaching the plantations with G. robusta and this was not influenced by distance from the forest. In plantations without G. robusta bird dispersal is restricted to 25 m from the forest edge. In general density of shade trees has a strong influence on seed arrival which can negate the forest proximity effect and enhance natural forest colonization. © Cambridge University Press 2012.


Vailshery L.S.,Ashoka Trust for Research in Ecology and the Environment ATREE | Jaganmohan M.,Ashoka Trust for Research in Ecology and the Environment ATREE | Nagendra H.,Ashoka Trust for Research in Ecology and the Environment ATREE
Urban Forestry and Urban Greening | Year: 2013

One of the fastest growing cities in India, Bangalore is facing challenges of urban microclimate change and increasing levels of air pollution. This paper assesses the impact of street trees in mitigating these issues. At twenty locations in the city, we compare segments of roads with and without trees, assessing the relationship of environmental differences with the presence or absence of street tree cover. Street segments with trees had on average lower temperature, humidity and pollution, with afternoon ambient air temperatures lower by as much as 5.6°C, road surface temperatures lower by as much as 27.5°C, and SO2 levels reduced by as much as 65%. Suspended Particulate Matter (SPM) levels were very high on exposed roads, with 50% of the roads showing levels approaching twice the permissible limits, while 80% of the street segments with trees had SPM levels within prescribed limits. In an era of exacerbated urbanization and climate change, tropical cities such as Bangalore will have to face some of the worst impacts including air pollution and microclimatic alterations. The information generated in this study can help appropriately assess the environmental benefits provided by urban trees, providing useful inputs for urban planners. © 2013 Elsevier GmbH.

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