Reviving the rainforest
Ecological restoration of degraded rainforest in the Anamalai hills
Can a biologically diverse forest, once degraded or destroyed, be brought back to its original state? Relatively undisturbed forests are best left alone, rather than modified in the belief that they can be restored. Yet, forests already degraded or fragmented may be worth restoring, as in the Anamalai hills.
Fixing fragmented forests
Our restoration programme in the Western Ghats focuses on the region’s unique, biologically diverse tropical rainforests. Historically, due to human activities, these forests have been cleared, degraded, or reduced to fragments scattered like islands amidst towns and cities, dams and mines, farms and plantations. A growing body of field research, including our own, suggests that remnant rainforests cannot be conserved through protection alone. One also needs to restore degraded lands to improve habitat quality to enable the survival of threatened species that live within these forest patches and to reconnect existing patches, if possible, to enhance the entire conservation landscape.
Restoration and recovery
Since 2001, we have worked in the Valparai plateau, Anamalai hills, to ecologically restore ten rainforest fragments (1 to 100 ha in area), three sites contiguous with the Anamalai Tiger Reserve, and a perennial stream flowing through tea plantation. The sites are identified and protected in partnership with the plantation companies (Parry Agro Industries Ltd, Tata Coffee Ltd, Tea Estates India Ltd–earlier Hindustan Unilever Ltd) and the Tamil Nadu Forest Department. While the sites occupy around 300 ha, restoration plantings targeted 45 plots (50 ha) in the most degraded portions, especially fragment edges. In these sites, we have planted 26,500 saplings of over 160 native rainforest tree (and some liana) species.Early monitoring showed that an average of 61% of the planted saplings survived at the end of two years. As these sapling establish along with resurgent natural vegetation, the fragments are on the road to recovery. Visit our Rainforest Restoration Project Showcase to see more.
Native shade trees in plantations
Restoration of rainforest fragments can be complemented by efforts to improve land-use practices and increase native tree cover in surrounding plantations. A large number of native tree species hold potential for use as shade trees in plantations, but have been overlooked or rarely tried out. Using saplings from our rainforest plant nursery at Valparai, plantation companies in the Anamalai hills have planted nearly 15,000 saplings of around 60 native tree species since 2004. A number of species, planted out as shade in coffee, cardamom, tea, and vanilla plantations have established well, some even doing better than commonly used alien species such as silver oak.
- Journal Article2017Successional status, seed dispersal mode and overstorey species influence tree regeneration in tropical rain-forest fragments in Western Ghats, IndiaJournal of Tropical Ecology 33: 270-284. DOI: 10.1017/S0266467417000219
The effects of fragmentation and overstorey tree diversity on tree regeneration were assessed in tropical rain forests of the Western Ghats, India. Ninety plots were sampled for saplings (1–5 cm diameter at breast height (dbh); 5×5-m plots) and overstorey trees (>9.55 cm dbh; 20×20-m plots) within two fragments (32 ha and 18 ha) and two continuous forests. We tested the hypotheses that fragmentation and expected seed-dispersal declines (1) reduce sapling densities and species richness of all species and old-growth species, and increase recruitment of early-successional species, (2) reduce the prevalence of dispersed recruits and (3) increase influence of local overstorey on sapling densities and richness. Continuous forests and fragments had similar sapling densities and species richness overall, but density and richness of old-growth species declined by 62% and 48%, respectively, in fragments. Fragments had 39% lower densities and 24% lower richness of immigrant saplings (presumed dispersed into sites as conspecific adults were absent nearby), and immigrant densities of old-growth bird-dispersed species declined by 79%. Sapling species richness (overall and old-growth) increased with overstorey species richness in fragments, but was unrelated to overstorey richness in continuous forests. Our results show that while forest fragments retain significant sapling diversity, losses of immigrant recruits and increased overstorey influence strengthen barriers to natural regeneration of old-growth tropical rain forests.
- Journal Article2017Bats in the Ghats: Agricultural intensification reduces functional diversity and increases trait filtering in a biodiversity hotspot in IndiaBiological Conservation 210: 48-55.
The responses of bats to land-use change have been extensively studied in temperate zones and the neotropics, but little is known from the palaeotropics. Effective conservation in heavily-populated palaeotropical hotspots requires a better understanding of which bats can and cannot survive in human-modified landscapes. We used catching and acoustic transects to examine bat assemblages in the Western Ghats of India, and identify the species most sensitive to agricultural change. We quantified functional diversity and trait filtering of assemblages in forest fragments, tea and coffee plantations, and along rivers in tea plantations with and without forested corridors, compared to protected forests.
Functional diversity in forest fragments and shade-grown coffee was similar to that in protected forests, but was far lower in tea plantations. Trait filtering was also strongest in tea plantations. Forested river corridors in tea plantations mitigated much of the loss of functional diversity and the trait filtering seen on rivers in tea plantations without forested corridors. The bats most vulnerable to intensive agriculture were frugivorous, large, had short broad wings, or made constant frequency echolocation calls. The last three features are characteristic of forest animal-eating species that typically take large prey, often by gleaning.
Ongoing conservation work to restore forest fragments and retain native trees in coffee plantations should be highly beneficial for bats in this landscape. The maintenance of a mosaic landscape with sufficient patches of forest, shade-grown coffee and riparian corridors will help to maintain landscape wide functional diversity in an area dominated by tea plantations.
- Popular Article2016Rātriñcaranmār [In Malayalam: Night rangers, article on small carnivores].Koodu, October 4(5): 70-72.
- Art & Literary2016Elephant crossingOrion 35(3): 6. (May | June 2016)
- Popular Article2016Hornbills: the feathered foresters.Mudappa, D. 2016. JLR Explore, 15 May 2016.
Most of us are familiar with charismatic mammals such as tigers, elephants and apes. And there are charismatic species amongst birds too: bustards, cranes, eagles. But in the Asian and African tropics are birds that gain charisma from their large size, spectacular appearance, and extraordinary breeding habits: the hornbills.
- Popular Article2016Icons of Anamalais: Malabar Whistling ThrushPollachi Papyrus, July – September 3(3): 38-41.
Shorter, edited version of article ‘Musician of the Monsoon’ that appeared in The Hindu Sunday Magazine on 6 Sep 2009.
- 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
PDF, 1.92 MB
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.
- Popular Article2015The long road to growthThe Hindu, Op-ed Comment, 19 March 2015, Page 9.
As power lines and roads slice up forest cover, it becomes clear that a knowledge economy must tackle development with a wider perspective than that of mere short-term gains. Available from here: http://www.thehindu.com/opinion/op-ed/the-long-road-to-growth/article7008158.ece
In Tamil translation by P. Jeganathan in The Hindu Tamil and here: http://blog.ncf-india.org/2015/04/19/the-long-road-to-growth_tamil-version/
- Popular Article2015Restoring the fabricSanctuary Asia, June 2015, 35(6): 53.
- Popular Article2015Current ecological concerns in the power sector: options to avoid or minimise impactsPages 89-100 in M N Goswami and P Chaudhry (editors) An Epochal Shift in the Idea of India-Meeting aspirations? IPPAI Knowledge Report, Independent Power Producers Association of India, New Delhi.