Restoring rainforest remnants: experiences from the Anamalai hills

We stood in a small wood surrounded by young rainforest trees where, fifteen years ago, there was only grass. One tree, a Trichilia connaroides about 30 cm in diameter and over 10 m tall, held loose clusters of bright red fruits. This was one of the first trees to fruit among the 268 saplings of 27 tree species planted here in July 2002 at one of our earliest rainforest restoration sites. The Trichilia now stood among other trees, larger, fast-growing Macaranga peltata, Elaeocarpus tuberculatus, and Semecarpus travancorica, and pole-like slow-growing trees such as Cullenia exarillata, Mesua ferrea, and Ormosia travancorica.

Where we used to see birds of open country, such as mynas or wagtails, feeding on the grassy expanse, we now watched forest birds: a pair of Indian scimitar-babblers foraging in the understorey, a white-cheeked barbet, and a pair of Malabar grey hornbills winging between tree branches above. The restoration site was an extension of the five-hectare Stanmore rainforest fragment, around which stood a eucalyptus fuelwood plantation and large expanses of monoculture tea plantations. The plantations sprawl over the Valparai plateau here in the Anamalai Hills of the Western Ghats, a mountain chain along India’s west coast recognised as a biological diversity hotspot. The 220-square-kilometer plateau, undulating between 900 m and 1400 m elevation, had been clothed in the dense tropical wet evergreen forest until the late 19th century when the first plantations were established during the British colonial period. The plateau is now home to over 70,000 people who live in the estates and small towns such as Valparai.

Today, Stanmore is one of about 45 rainforest remnants on the plateau. The rainforests remain as fragments embedded within private plantations of tea, coffee, eucalyptus, and cardamom, edged by reservoirs, roads, and human settlements, or occur as degraded remnants adjoining larger forest tracts in the surrounding protected reserves. The Anamalai Tiger Reserve in Tamil Nadu state with the Parambikulam Tiger Reserve and a clutch of reserved forests in Kerala state together form a tract of more than 3000 square kilometres of forests around the Valparai plateau. No spot on the plateau is over 7 km away from these larger forest tracts. And each of the rainforest remnants, small and large, are valuable for conservation, as we were to discover.

Shredded canopies
Each of the native forest remnants—anywhere between one and 300 hectares in size—retains a tantalising trace of rainforest plants and animals that managed to survive a century of fragmentation and disturbance. Entering a remnant from a shaded coffee or cardamom plantation entails passing through a relatively ‘soft’ edge, or when entering from a highway or tea estate an abrupt, ‘hard’ edge. Once inside the remnant, tall trees reach up into the canopy, creating many small openings that stream sunlight into the dense and tangled understorey.

Whereas a single hectare of undisturbed rainforest would hold around 80 tree species, up to a third of which are endemic to the Western Ghats, the disturbed remnant may retain about half that diversity. On rainforest trees, looped with climbers that increase in abundance in degraded forests, troops of Nilgiri langurs forage on leaves in the canopy. In a few larger remnants, the rare and endemic lion-tailed macaque may be seen sedately questing for juicy bites. A suite of forest birds—from babblers and flycatchers to nuthatches and hornbills—adds life and music to these remnants, but the community also includes a wide variety of birds of disturbed and open habitats, such as common tailorbirds and red-whiskered bulbuls.

Each remnant carries vegetation legacies of former land use. Some survive on rocky, shallow soils remain as narrow windbreaks or boundary strips. Roads, trails, and past tree fellings that shredded the tree canopy brought invasions of Lantana camara, Chromolaena odorata, and Mikania micrantha weeds. In some patches, introduced ground cover such as Sphagneticola trilobata and shrubs like Montanoa bipinnatifida proliferate. Where forest understorey had been cleared and planted with coffee, cardamom, or vanilla, a few forest plants now regenerate amidst remnants of crops, particularly Robusta coffee (Coffea canephora) that has invaded into fragments. Where native trees were supplanted with shade trees such as the Australian silver oak (Grevillea robusta), and Eucalyptus, or the African musizi (Maesopsis eminii), the sites contain a mostly non-native tree canopy.

Why fragments still matter
Many research projects conducted since the 1990s confirm that these fragments matter for conservation. One survey identified the Anamalai landscape, including these rainforest remnants, as one of the most significant areas for great hornbill conservation in the Western Ghats. In other studies, field biologists recorded in a set of remnants, virtually all the mammal species found in surrounding protected rainforests, including rare endemics like Nilgiri marten and Malabar spiny dormouse. In a landscape where three species of otters occur, otter spraints and signs are scattered along most of the rivers and streams. Several large carnivores—leopard, dhole, sloth bear, and even the occasional tiger—range over the landscape, thriving on a diet largely composed of wild prey from porcupine to sambar. Small fragments cannot meet the year-round needs of large wildlife such as elephants, hornbills, and leopards, but do serve as supplementary habitats or stepping stones in the landscape.

Map of the Valparai plateau showing land use, human settlements, and rainforest remnants (in dark green). The plateau is surrounded by the Anamalai Tiger Reserve (to the north and west) and Reserved Forests in Kerala (west and south).

By night, the forests come alive with owls and frogmouths and flying squirrels, nearly twenty species of bats, and many small mammals including the endemic brown palm civet. The remnants are also home to many recently described species—such as the purple frog and the Anamalai gliding frog. Here, too, species such as the bat Barbastella leucomelas darjelingensis have been recorded for the first time in the Western Ghats, while others like the snail Corilla anax were rediscovered after decades.

The landscape matrix surrounding the remnants also matters. Fragments adjoining coffee or cardamom plantations with numerous native shade trees provide better support for rainforest species than those ringed by open tea monocultures. The diversity of species surviving in the fragmented landscape can be attributed to the rainforest remnants and to surrounding plantations that are biodiversity-friendly, besides the proximity to surrounding forests and the near-absence of hunting.

Overall, the research suggests that fragment size, habitat quality within fragments, and the permeability of the surrounding landscape all influence the persistence of rainforest species. It also points to ways forward to enhance the conservation value of the landscape. First, retain and protect the rainforest remnants that are in reasonably good shape and contain key species or populations. Second, work with plantation businesses and local communities to foster better and diverse land use in the surrounding landscape matrix. Finally, carry out the ecological restoration of the highly degraded remnants.

Bringing back rainforests
Over the last sixteen years, we have been working to put this restoration plan into action. In 2001, we began our efforts at rainforest restoration, preparing ourselves for the long haul imagining forest recovery as an inherently long-term effort. Starting with Stanmore and the nearby nineteen-hectare Injipara rainforest fragment, we slowly expanded work in other degraded remnants in the landscape by striking partnerships with the plantation companies in whose estates the remnants are embedded.
Over several years, after long dialogues with owners and senior managers, three companies (Hindustan Unilever which later became Tea Estates India Ltd, Tata Coffee Ltd, and Parry Agro Industries Ltd) came on board. Finding that rainforest protection and restoration aligned with their efforts towards sustainable agriculture, their corporate social and environment policies, or their personal interests in wildlife, these companies, and many individual managers extended support. As part of these partnerships, the three companies recognised and protected 35 rainforest remnants within their estates. Further, Tata Coffee now provides space for a rainforest nursery. In the nursery, we germinate and nurture over 160 species of trees and lianas native to the mid-elevation rainforest for use in restoration and native shade plantings.

When funds started trickling in, we began restoration of other heavily degraded sites, adding one to five hectares every year. Early each year, we survey and prepare the sites for restoration. In smaller fragments, rapid assessments of forest structure and vegetation are followed by careful weed removal across the entire site, during which we take care to retain all naturally established native plants. In larger fragments and remnants, we focus on the disturbed edges, reasoning that if these improve, forest interiors will automatically benefit. During the monsoon, 20 – 80 native species are planted in each site following a mixed native species planting protocol, tweaking the mix of species and planting density based on initial site conditions and the history of disturbance.

Now, in 2017, with 40,000 saplings planted out for restoration, the effort spans 50 sites and about 60 hectares in 15 rainforest remnants that together cover over 300 hectares. Over this period, plantation companies, too, planted about 25,000 saplings of around 75 native species, sourced from our nursery, as shade in coffee, cardamom, vanilla, and even tea estates.
Each year, the area of restored rainforest increases in small increments, while more native shade trees spread their boughs within commercial plantations.

Looking back, moving ahead
Still, there are questions to ask and answer. Does a plantation of rainforest trees constitute a restored rainforest? To what extent, and after how long, does a healthy rainforest’s diversity, ecological processes, and an intricate network of interactions re-establish in restoration sites? When will rainforest bees and beetles return to pollinate the young Myristica tree’s flowers, or great hornbills arrive to eat the fruits, bringing in more seeds from distant rainforests? Will the trajectory of recovery bring restored sites closer to undisturbed rainforest or will competing weeds or insect herbivores overwhelm planted saplings to revert the site to a degraded state? Or will the saplings hold on only as long as they are being cared for?

Our recent research on forest recovery and soils in restoration sites has generated some preliminary answers. After 15 years, actively restored sites are ecologically closer to undisturbed rainforests than sites left to themselves with no restoration intervention. Restored fragments manifest recovery of forest structure, as evidenced by tree density, canopy height, and carbon storage. The number of rainforest species and the similarity of plant species mix are gradually increasing in comparison with relatively undisturbed rainforests. Soil microbes appear to be doing better in some restored sites, as shown by increases in soil nutrients and fertility. Once the growing saplings form a low canopy with other naturally-established native plants, weedy species thin out and decline in the shade.

Yet, restored sites lack key characteristics of undisturbed, mature rainforests. In the restored sites, natural plant colonisation and regeneration of typical rainforest plants, including shrubs and herbs, appears low. On the ground, leaf and other organic debris remain sparse, while up on the trees, epiphytes are still scarce.

While restored sites in isolated fragments are generally an improvement over adjoining naturally- regenerating sites that remain degraded, this is not always the case. At the edge of the surrounding extensive forest reserves, degraded sites appear to recover well through passive natural regeneration even when left alone. As some larger fragments and remnants were in reasonably good shape already, these edges need only protection from disturbance rather than any active restoration.

Landscape futures
Quantitative measures of recovery may not capture other tangible and intangible benefits and spin-offs of restoration efforts. On private lands, the recognition and protection of rainforest fragments that were previously ignored by landowners help expand conservation and restoration into wider landscapes beyond protected reserves and involve new constituencies and stakeholders. Remnants have other values, too, as watersheds and refugia for pollinators and natural predators of crop pests. While a start has been made, there is a long way to go before plantation businesses, landowners, and managers integrate ecological understanding and approaches into routine production practices.

Restoration—as a hands-on practice—also forces renewed appreciation of ecological history and the peculiarities of each restoration site. Nurturing the skills needed to work with each parcel of land and learning by doing become at least as important as grasping theoretical foundations and concepts in restoration ecology such as secondary succession or the roles of keystone or framework species. Ecological restoration melds science and praxis in relation to land.
As oases of diversity, beauty, and wonder, rainforest remnants add to the fullness of life in heavily used and transformed landscapes. For biologists like us, carry the additional joys of discovery and observing recovery of remarkable rainforests. Over a century since the rainforests were fragmented, we envision a more connected future where farms and forests, wildlife and people, science and wonder, all coexist.

Further reading
Mudappa, D., T. R. S. Raman, and M. A. Kumar. 2014. Restoring nature: wildlife conservation in landscapes fragmented by plantation crops in India. In: Nature without borders (eds. Rangarajan, M., M. D. Madhusudan, and G. Shahabuddin). Pp. 178–214. New Delhi: Orient Blackswan.

Nature Conservation Foundation. 2018. Reviving the rainforest: ecological restoration of degraded rainforest in the Anamalai hills. Accessed March 7, 2018.


This article is from issue


2018 Mar