Of forests and farms
Conserving wildlife in forests and plantations in the landscape
As large nature reserves occupy only a fraction of the earth’s land surface, conservation biologists are increasingly looking into the role of private lands, habitat fragments, and plantations in the surrounding landscapes for conservation.
Conservation in the countryside
Protected areas established for wildlife conservation in the Western Ghats often contain other land-uses within, around, or adjoining their borders. This includes agriculture, home gardens, plantations such as tea and coffee, timber and fuelwood plantations such as Eucalyptus and many others. Along with these land uses there are often many habitat remnants, including forests, grasslands, rocky outcrops, and swamps, besides rivers and streams. To assess the value of these surrounding landscapes for conservation one needs to better understand their role in the persistence of wild species and populations.
Since 2000, we have studied various land uses, such as tea, coffee, cardamom and other plantations in the Anamalai hills landscape, focusing on various species such as rainforest plants, spiders, birds, bats, and otters. Different groups vary in their response to land-use alteration, but there are some broad patterns.
Plantations tend to be poorer in relation to rainforest in rainforest in diversity of wild species, particularly endemic species. Plantations that retain shade of native tree species, such as rustic cardamom or shade coffee, have higher species richness and abundance of rainforest species.
More isolated plantation and fragment sites tend to support fewer rainforest and more open-forest species. To the extent that native shade or rainforest attributes are maintained or restored in plantations, they can further enhance conservation values.
- Journal Article2015Does mixed-species flocking influence how birds respond to a gradient of land-use intensity?Proceedings of the Royal Society B 282: 20151118.Download
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Conservation biology is increasingly concerned with preserving interactions among species such as mutualisms in landscapes facing anthropogenic change. We investigated how one kind of mutualism, mixed-species bird flocks, influences the way in which birds respond to different habitat types of varying land-use intensity. We use data from a well-replicated, large-scale study in Sri Lanka and the Western Ghats of India, in which flocks were observed inside forest reserves, in ‘buffer zones' of degraded forest or timber plantations, and in areas of intensive agriculture. We find flocks affected the responses of birds in three ways: (i) species with high propensity to flock were more sensitive to land use; (ii) different flock types, dominated by different flock leaders, varied in their sensitivity to land use and because following species have distinct preferences for leaders, this can have a cascading effect on followers' habitat selection; and (iii) those forest-interior species that remain outside of forests were found more inside flocks than would be expected by chance, as they may use flocks more in suboptimal habitat. We conclude that designing policies to protect flocks and their leading species may be an effective way to conserve multiple bird species in mixed forest and agricultural landscapes.
PDF also available here: http://dx.doi.org/10.1098/rspb.2015.1118
- Dataset2015Data from: Does mixed-species flocking influence how birds respond to a gradient of land-use intensity? Proceedings of the Royal Society BDryad Data Repository doi: 10.5061/dryad.vk070
Available here: http://dx.doi.org/10.5061/dryad.vk070
- Journal Article2015Landscape scale habitat suitability modelling of bats in the Western Ghats of India:Bats like something in their teaBiological Conservation 191: 529-536.Download
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To conserve biodiversity it is imperative that we understand how different species respond to land use change, and determine the scales at which habitat changes affect species' persistence. We used habitat suitability models (HSMs) at spatial scales from 100–4000 m to address these concerns for bats in the Western Ghats of India, a biodiversity hotspot of global importance where the habitat requirements of bats are poorly understood. We used acoustic and capture data to build fine scale HSMs for ten species (Hesperoptenus tickelli, Miniopterus fuliginosus, Miniopterus pusillus, Myotis horsfieldii, Pipistrellus ceylonicus, Megaderma spasma, Hipposideros pomona, Rhinolophus beddomei, Rhinolophus indorouxii and Rhinolophus lepidus) in a tea-dominated landscape. Small (100–500 m) scale habitat variables (e.g. percentage tea plantation cover) and distances to habitat features (e.g. distance to water) were the strongest predictors of bat occurrence, likely due to their high mobility, which enables them to exploit even small or isolated foraging areas. Most species showed a positive response to coffee plantations grown under native shade and to forest fragments, but a negative response to more heavily modified tea plantations. Two species were never recorded in tea plantations. This is the first study of bats in tea planta- tions globally, and the first ecological Old World bat study to combine acoustic and capture data. Our results suggest that although bats respond negatively to tea plantations, tea-dominated landscapes that also contain forest fragments and shade coffee can nevertheless support many bat species.
- Book Chapter2014Restoring nature: wildlife conservation in landscapes fragmented by plantation crops in India.Pages 178-214. In Nature Without Borders (Eds. Mahesh Rangarajan, MD Madhusudan & Ghazala Shahabuddin), Orient Blackswan, New Delhi.
- Journal Article2014The response of birds and mixed-species bird flocks to human-modified landscapes in Sri Lanka and southern IndiaForest Ecology and Management 329: 384–392Download
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While there is no substitute for undisturbed forest, secondary forests and agroforests are increasingly common in tropical areas and may be critical to conservation plans. We compared the diversity and abundance of birds and the characteristics of mixed-species bird flocks in forests inside protected reserves to ‘‘buffer’’ areas, consisting of degraded forests and non-native timber plantations at reserve boundaries, and to agricultural areas. We monitored a network of 57 transects placed over an altitudinal gradient (90–2180 masl) in Sri Lanka and southern India, collecting 398 complete flock observations and 35,686 observations of birds inside and outside of flocks over two years. Flocks were rarely found in agri- cultural areas. However, the density of flocks in buffer areas was similar to that in forests, although buffer flocks were smaller in average flock size and differed significantly in composition, as measured by the proportion of species that were classified, from the literature, as forest interior or open-landscape species. While flock composition was distinct between agricultural, buffer and forest areas, the differences in the composition of flocks was not as great as the differences between the overall communities in these different habitats. Considering buffer transects alone, pine plantations retained fewer forest interior species in flocks than did forests, and small areas of agriculture and abandoned agriculture attracted open-landscape species. Though clearly not equivalent to protected forests, degraded forests and agroforests in buffer areas still hold some conservation value, with forest species found particularly in mixed-species flocks in these human-modified habitats.
- Journal Article2012Streamside amphibian communities in plantations and a rainforest fragment in the Anamalai hills, IndiaJournal of Threatened Taxa 4: 2849–2856.Download
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Stream amphibian communities, occupying a sensitive environment, are often useful indicators of effects of adjoining land uses. We compared abundance and community composition of anuran amphibians along streams in tea monoculture, shade coffee plantation, and a rainforest fragment in Old Valparai area of the Anamalai hills. Overall species density and rarefaction species richness was the highest in rainforest fragment and did not vary between the coffee and tea land uses. Densities of certain taxa, and consequently community composition, varied significantly among the land uses, being greater between rainforest fragment and tea monoculture with shade coffee being intermediate. Observed changes are probably related to streamside alteration due to land use, suggesting the need to retain shade tree cover and remnant riparian rainforest vegetation as buffers along streams.
- Journal Article2012Conservation of the Asian small-clawed otter (Aonyx cinereus) in human-modified landscapes, Western Ghats, IndiaTropical Conservation Science 5: 67-78.Download
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Conservation in human-modified landscapes is important for riparian animals as their habitats extend linearly beyond adjoining protected areas. We examined occupancy and intensity of habitat use of Asian small-clawed otters in coffee and tea plantations and an adjoining protected area in the Western Ghats. We sampled 66 stream segments of 500 m length, using spraints as an indicator of habitat use. Several variables characterising the stream and shoreline were also measured. Occupancy, corrected for detection of spraints, was >0.75 in all three land use types, indicating widespread use of the riparian ecosystem in human-modified landscapes. Intensity of habitat use, however, was much lower in tea (2.08 spraints/500 m) and coffee (2.42) plantations than in the protected area (3.86). Using GLMs we identified the abundance of potential refuges (such as boulders and fallen trees), which was greater in the protected area, as the major factor influencing intensity of habitat use. Shoreline diversity, which was lowest in the tea plantation, might also be another factor. The retention of much of the riparian vegetation and the presence of forest fragments which provide refuges have led to wide occupancy of the tea and coffee plantations although with less intensive use. Sand mining, fishing and infrequent poaching might be other reasons for the relatively low use of human-modified landscape. This study highlights the need to retain remnant forests and riparian vegetation, and to control some human activities for integrated management of species like the small-clawed otter in both protected areas and adjoining human-modified habitats.
- Journal Article2010Effects of plantations and home-gardens on tropical forest bird communities and mixed-species bird flocks in the southern Western Ghats.Journal of the Bombay Natural History Society 107: 91-108.Download
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Conservation scientists and policy makers are increasingly aware of the role countryside habitats play in supporting tropical fauna in modern landscapes. We studied the value of different land-uses by examining composition of tropical bird communities and mixed-species bird flocks in human-altered landscapes of Thattekad and the Anamalai Hills, situated in two different altitudes, in the southern Western Ghats. Sixteen line transects distributed across tropical rainforests, shade plantations of coffee and cardamom, timber monocultures of teak, tea plantations, and home-gardens were surveyed for bird flocks, vegetation structure, foliage profile, and canopy attributes. Results indicate that tea plantations were extremely altered habitats, supporting few rainforest species and were devoid of mixed-species bird flocks. Teak monocultures had high species density but were less conducive for rainforest species that require a well developed and structurally more complex habitat. While bird species richness varied little across land-uses, there was significant variation in community composition, with some sensitive bird species absent from all altered habitats. Coffee plantations with surviving rainforest fragments and cardamom plantations with more native shade trees that mimicked a forest habitat supported more rainforest bird species both in communities and flocks. Maintenance of these shade plantations and restoration of forest fragments is recommended, while their conversion into a poor, more open habitat (tea, teak) is strongly discouraged for bird conservation in fragmented landscapes.
- Journal Article2006Effects of habitat structure and adjacent habitats on birds in tropical rainforest fragments and shaded plantations in the Western Ghats.Biodiversity and Conservation 15: 1577-1607.Download
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As large nature reserves occupy only a fraction of the earth’s land surface, conservation biologists are critically examining the role of private lands, habitat fragments, and plantations for conservation. This study in a biodiversity hotspot and endemic bird area, the Western Ghats mountains of India, examined the effects of habitat structure, floristics, and adjacent habitats on bird communities in shade-coffee and cardamom plantations and tropical rainforest fragments. Habitat and birds were sampled in 13 sites: six fragments (three relatively isolated and three with canopy connectivity with adjoining shade-coffee plantations and forests), six plantations differing in canopy tree species composition (five coffee and one cardamom), and one undisturbed primary rainforest control site in the Anamalai hills. Around 3300 detections of 6000 individual birds belonging to 106 species were obtained. The coffee plantations were poorer than rainforest in rainforest bird species, particularly endemic species, but the rustic cardamom plantation with diverse, native rainforest shade trees, had bird species richness and abundance comparable to primary rainforest. Plantations and fragments that adjoined habitats providing greater tree canopy connectivity supported more rainforest and fewer open-forest bird species and individuals than sites that lacked such connectivity. These effects were mediated by strong positive effects of vegetation structure, particularly woody plant variables, cane, and bamboo, on bird community structure. Bird community composition was however positively correlated only to floristic (tree species) composition of sites. The maintenance or restoration of habitat structure and (shade) tree species composition in shade-coffee and cardamom plantations and rainforest fragments can aid in rainforest bird conservation in the regional landscape.
- Report2004Effects of landscape matrix and plantations on birds in tropical rainforest fragments of the Western Ghats, India.NCF Technical Report No. 9. Nature Conservation Foundation, Mysore.Download
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As large nature reserves occupy only a fraction of the earth’s land surface, conservation biologists are critically examining the role of private lands, habitat fragments, and plantations for conservation. This study in a global biodiversity hotspot and endemic bird area, the Western Ghats mountain range of India, examined the effects of connectivity of rainforest fragments with shade-coffee plantations and the influence of habitat structure and floristics on tropical rainforest bird communities. Systematic sampling for habitat and birds was carried out in 13 sites, including six fragments (three relatively isolated and three with canopy continuity with adjoining shade-coffee plantations and forests), six plantations differing in canopy tree species composition (five coffee and one cardamom), and one control site containing a large relatively undisturbed primary rainforest in the Valparai plateau of the Anamalai hills. Around 3300 detections of about 6000 individual birds belonging to 106 species were obtained. The plantations were depauperate in relation to rainforest in rainforest bird species, particularly endemic species, but one site (cardamom plantation) with an entirely native canopy of tall rainforest trees, had species richness and bird abundance values comparable to that of primary rainforest. Plantation and fragment sites that were less isolated (more canopy continuity in surrounding landscape) tended to support greater number of rainforest and lesser number of open-forest bird species and individuals than more isolated sites. Rainforest bird richness and abundance were positively related to the vegetation component representing densities of woody plants, canes, lianas, and bamboos. Bird community composition was however related only to floristic (tree species) composition of sites. The results indicate that the maintenance or restoration of such attributes in plantations and fragments can aid in bird conservation in the region. The potential of rainforest fragments and shade-coffee and cardamom plantations for bird conservation outside wildlife protected areas is emphasised.