The Importance of Patch Forests

 

The WWCT’s Patch Forest Project explores the impact of deforestation and forest fragmentation on Sri Lankan wildlife.  In Sri Lanka, up to 60% of the primary rainforest has been destroyed over the past 80 years, due to current and historic land use practices.  These include the export of timber during the colonial period, to make way for cash crops such as rubber, coconut, and tea; increased agricultural production that fuels a plantation-dominated industry; the large-scale irrigation of the dry zone for agricultural use; and the overall population increase, which has led to a demand for expanded slash-and-burn cultivation, for large-scale vegetable plantations, and for agricultural lands.  The consequences of which, have been the deforestation of the land and the continuing fragmentation of the landscape, creating patched forests.

 

Forest fragmentation can have adverse effects on species richness and population size.  The diversification of land use creates a mosaic landscape, with increased isolation of wildlife and potentially hostile habitat in-between.  Unlike natural landscapes, man-made forest patches are modified to form harsh edges unsuitable for wildlife.  In addition, forest isolation can subdivide populations thereby reducing species interactions and creating a loss in genetic diversity, which is vital for species survival. 

 

Research into patch forests is essential as it allows us to understand the importance of the remaining forest cover for wildlife diversity and movement.  Tracking species presence and movement patterns helps us to understand the ways in which the local wildlife is adapting to these human-induced changes and the effects any hostile areas can have on species population by limiting genetic diversity.  The Patch Forest Project is not only an opportunity for the WWCT to carry out this vital research, but also an opportunity to educate the landowners of small patch forests so they, too, can better understand the role their land could be playing in the larger system and to improve the overall habitat for wildlife. 

 

Ongoing work

 

The key research goal of the WWCT is to document the presence, distribution, and land use of Sri Lanka’s endangered apex predator - the leopard. Additionally, the island's 3 other cats - the fishing cat, the jungle cat, and the rusty-spotted cat are also being assessed. Our work is establishing that small patch forests are playing a key role for these wildcats, especially the wide-ranging leopard, as dispersal routes and refuges between larger protected forest landscapes.

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Previous studies have highlighted the importance of small patch forests and corridors for all local species.  An island residence means that local wildlife has little opportunity to move when faced with change and adversity.  Instead, animals are forced to adapt, and research is showing that patch forest cover is vital for this process to take place.  Although overall biodiversity has not been overtly affected, individual species classes show low rates of diversity in some patch forest areas.  Leopards have been recorded residing and breeding within forest areas as small as 5km2 in addition to fishing cats, rusty spotted cats, and various mammalian prey species.   With little contiguous cover remaining, it is proving essential that patches of forest be protected to increase patch connectivity and size and allow for the dispersal and breeding and long-term persistence of wildlife species.  

 

The WWCT has been conducting research on Central Highland patch forests such as the Dunumadalawa Forest, Kandy; Agra Arboretum, Agrapatana; Duckwari patch forest, Matale and Dunkeld Estate, Dick Oya. Dry zone patch forests in the Gal Oya complex, Dehigaha Ela and Pidurangala, Sigiriya are now being researched as well. For a detailed account of each study site, please see the links below.