Jean-Philippe Puyravaud

Why Do Some Tropical Forests Have So Many Species of Trees

Understanding why there are so many kinds of tropical trees requires learning, not only how tree species coexist, but what factors drive tree speciation and what governs a tree clade’s diversification rate. Many report that hybrid sterility evolves very slowly between separated tree populations. If so, tree species rarely originate by splitting of large populations. Instead, they begin with few trees. The few studies available suggest that reproductive isolation between plant populations usually results from selection driven by lowered fitness of hybrids: speciation is usually a response to a “niche opportunity.” Using Hubbell’s neutral theory of forest dynamics as a null hypothesis, we show that if new tree species begin as small populations, species that are now common must have spread more quickly than chance allows. Therefore, most tree species have some setting in which they can increase when rare. Trees face trade-offs in suitability for different microhabitats, different-sized clearings, different soils and climates, and resistance to different pests. These trade-offs underlie the mechanisms maintaining a-diversity and species turnover. Disturbance and microhabitat specialization appear insufficient to maintain a-diversity of tropical trees, although they may maintain tree diversity north of Mexico or in northern Europe. Many studies show that where trees grow readily, tree diversity is higher and temperature and rainfall are less seasonal. The few data available suggest that pest pressure is higher, maintaining higher tree diversity, where winter is absent. Tree a-diversity is also higher in regions with more tree species, which tend to be larger, free for a longer rime from major shifts of climate, or in the tropics, where there are more opportunities for local coexistence.

The Nilgiris Biosphere Reserve: an unrealized vision for conservation

The Man and Biosphere Program of UNESCO (MAB) was a pioneer in recognizing the role of local communities in the conservation of biodiversity. Biosphere reserves of MAB were designed with a core zone with maximum protection, a buffer zone with regulated activities, and a transition zone outside the reserve proper. The transition zone is where experimental management options to promote sustainable development could be developed, and could add value to the conservation network and to regional activities. The Nilgiris Biosphere Reserve (NBR), with a core zone of 1,240 km2 and a buffer zone of 4,280 km2, was created in 1986 without a transition zone. The absence of a transition zone separates the protected areas (PAs) from each other, and the hard boundary between the PA and surrounding areas promotes human-wildlife conflict and encourages development inimical to the mandate of the Biosphere Reserve, ultimately affecting the regional economy through progressive degradation of the environment. We examine three case studies to illustrate these concerns: the implementation of the India-based Neutrino Observatory, resistance by tourist resorts against regulations for connecting elephant corridors, and whether the goals of local tourism operators meet the conservation objectives of the NBR. Landscape ecology and econometry can help design a transition zone on a sound economic basis. A better environment management is within technical and financial reach. But is it within political reach?

An ecological review of the WGEEP report (2011) and environmental management planning in India

Purpose – The Ministry of Environment and Forest, Government of India, set up the Western Ghats Ecology Expert Panel (WGEEP) in March 2010 to provide guidelines for improved management within the Western Ghats biodiversity hotspot. The WGEEPs Mandate was to identify ecologically sensitive areas (ESAs). The Panel submitted their report in 2011 but it remained unimplemented. It was not clear whether the delay was due to the unwillingness of civil society to accept ambitious environment management plans, or whether the report had shortcomings. The paper aims to discuss these issues. Design/methodology/approach – The authors undertook a critique of the WGEEP report and its Mandate, to evaluate key issues that could have prevented its implementation. Findings – The analysis indicated that the WGEEP Mandate was ill-defined and the WGEEP report identified ESAs without providing a working definition. The absence of critical review of earlier environment management failures, the delayed dialogue with civil societ...