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Vol. 18 No. 1 - January 2012

Impact of Climate Change on Mountain Ecosystems of India:
Special Reference to the Eastern Himalayas.

 by: Soumit K. Behera*

India ranks 10th in the list of most forested nations in the world with 76.87 million ha of forest and tree cover. Like other forests of the world, our forests also provide critical ecosystem goods and services. However, the significant role of forests in carbon storage and sequestration has increased their importance manifold and brought them to the centre-stage of climate change mitigation strategies. India’s forest and tree cover accounts for about23.4% of the total geographical area of the country. Over the past decades, national policies of India aimed at conservation and sustainable management of forests have transformed India’s forests into a net sink of CO2.

Why should India be concerned about climate change?

Indians should be concerned about climate change since this phenomenon might have substantial adverse impacts on them. Not all possible consequences of climate change are yet fully understood, but the three main ‘categories’ of impacts are those on agriculture, sea level rise leading to submergence of coastal areas, as well as increased frequency of extreme events. Each of these pose serious threats to India. However, these are long term issues. The overriding immediate concern for India should be the fast pace at which negotiations are taking place on the climate front. India’s main energy resource is coal. With the threat of climate change, India is called upon to change its energy strategy based on coal, its most abundant resource, and to use other energy sources (e.g. oil, gas, renewable and nuclear energy) instead, which may turn out to be expensive.

Mountain biodiversity and climate change

Mountains are amongst the most vulnerable and hazardous environments in the world: they also harbour rich repositories of biodiversity. Some of the world’s most threatened and endemic species are found in mountain areas. Mountains have been recognised as important ecosystems by the Convention on Biological Diversity (CBD) and its special programme on ‘mountain biodiversity’ which aims to reduce the loss of biological diversity in the mountains at global, regional, and national levels. There are enormous impediments to this because of various drivers of global change, including climate change (Nogues-Bravo et al. 2007). In the context of climate change, mountains could suffer wide-ranging environmental and socio-economic impacts, for example on the hydrological cycle, and this in turn would alter the distribution, seasonality, and amount of precipitation and result in changes in river runoff, ultimately affecting not only mountain watersheds but also the lowlands below (Beniston 2003). There is an evident inter-connectedness between climate change and biodiversity, not just in the impacts of climate change on biodiversity but also in concomitant changes occurring in the carbon and water cycles. The Millennium Ecosystem Assessment (MEA) identified climate change as one of the major drivers having adverse affects on biodiversity and associated goods and services (MEA 2005). Studies on climate change in mountain areas are incomplete and scattered (IPCC 2007, Nogues-Bravo et al. 2007),although certain studies from the Hindu Kush- Himalayas (Shrestha et al. 1999) do indicate that climate change has an undesirable impact on Himalayan biodiversity and its services.

The Eastern Himalayas

The Eastern Himalayas (EH hereafter) are counted in the ‘crisis ecoregions’; ‘biodiversity hotspots’; ‘endemic bird areas’; ‘mega diversity countries’; and ‘global 200 ecoregions’ (Brooks et al. 2006).. As yet, there are no concrete studies assessing the magnitude of future warming and its impact on biological resources in the EH, although considerable efforts have been undertaken to conserve the region’s unique biodiversity. Three bio geographical realms meet in the EH Region; namely, the Indo-Malayan, Palaearctic, and Sino-Japanese, and it contains parts of three of 34 global biodiversity hotspots, accounting for 39% of the Himalayan hotspot, 8% of the Indo-Burma hotspot, and 13% of the Mountains of Southwest China hotspot. The complex topography and extreme altitudinal gradients from less than 300 m (tropical lowlands) to more than 8,000 m (high mountains) have led to a variety of vegetation patterns.

Climate-Change Scenario, Threats, Vulnerabilities and Potential Impacts on Biodiversity Climate-change trends and projections

The Himalayan region, including the Tibetan Plateau, has shown consistent warming trends during the past 100 years (Yao et al. 2006). Current knowledge of the climatic characteristics of the EH region, however, is limited by both paucity of observation and the insufficient theoretical attention given to the complex interaction of spatial scales in weather and climate phenomena in mountain areas. The analysis of spatial distribution of annual and seasonal temperature trends (Shrestha and Devkota 2010) shows that annual mean temperature is increasing at the rate of 0.01°C/yr or more. Though warming in the winter is much greater and more widespread in area, the warming trend has been greatest during the post-monsoon season and at high elevations. An analysis shows progressively greater warming rates with increasing elevation.

 The past trend and change projections suggest that temperatures will continue to rise and rainfall patterns will become more variable, with both localised increases and decreases. The figures for the EH region do not present a drastic deviation from the IPCC outcomes for South Asia; they reinforce the scientific basis for the contention that the EH region is undergoing a warming trend (Shrestha and Devkota 2010).

The analysis of the region suggests the following:

  • The Eastern Himalayas are experiencing widespread warming and the rate is generally greater than 0.01°C per year.

  • Using usual seasonal dichotomies, the highest rates of warming are in winter and the lowest, or even cooling, are in summer.

  • There is progressively more warming with elevation, with areas higher than 4,000 m experiencing the greatest warming rates.

Threats to and vulnerability of biodiversity

Assessing the consequences of climate change in the EH region is indeed a big challenge mainly due to limited data availability, uncertainties associated with the climate scenarios, and the existence of non-linear feedbacks between impacts. Nevertheless, through various review and consultative processes we have focused on some thematic indicators such as land-use and land-cover change, critical habitats and eco regions, bioclimatic zones and phenology, agro-biodiversity, and threatened and endemic species that throw light on the potential impacts and vulnerabilities of biological diversity due to climate change.

Land-use and land-cover changes

Changes in land cover (biophysical attributes of the earth’s surface) and land use (human purpose or intent applied to these attributes) are among the most important drivers of climate change as they relate to carbon sequestration and nitrogen deposition (Lal 2004; Foley et al. 2005). Land-use and land-cover changes contribute to local and regional climate changes (Chase et al. 1999) and global climate warming (Penner et al. 1994; Houghton et al. 1999); and they have a direct impact on biodiversity (Chapin et al. 2000), influencing the reduction in species’ diversity (Franco et al. 2006). However, there is little documentation on changes over time (Khan et al. 1997). Land-use change from forest to other usages in the EH has been quite conspicuous in the last few decades, causing depletion of natural resources in the Himalayas (Singh and Singh 1992). Shankar Raman (2001) revealed that the North Eastern states of India lost 378 sq.km. of forest due to human-induced activities between 1989 and 1991; 488 sq.km. between 1991 and 1993; and 175 sq.km. between 1993 and 1995. Other information from the North Eastern Indian states from 1991-2005 shows an increase in forest cover in Assam, Meghalaya and Tripura and either mixed or decreasing trends elsewhere. The gross forest cover of these seven states increased by 1,250 sq.km. (0.7%) in total between 1991 and 2001, and 19 sq.km. (0.01%) between 2003 and 2005.

An analysis made of overall land cover in the 1970s and 2000s, based on six broad categories, using satellite images revealed that land-cover types in the EH changed significantly over 25 years between the1970s and 2000s The data revealed a substantial increase of 17,394 sq.km. (40.4%) of shrub land, which accounts for 3.3% of the total area of the EH. Forest cover decreased by 9,314 sq.km (3.4% of the same class and 1.8% of the whole EH) and grassland decreased by 3,261 sq.km (8.2%), accounting for 0.6% of the EH. Cultivated area changed by only 594 sq.km. (0.5% of the same class and 0.1% of the EH). The area of denuded and uncultivated land increased by 1,369 sq.km (6.1%), accounting for 0.3% of the EH. No significant change took place in water bodies which show a decrease of 10 sq.km. Snow cover decreased by 6,756 sq.km. (24.6% of the same class and 1.3% of the EH).

Vulnerable habitats and eco-regions

The EH region is known for diverse habitats and eco-regions that are subject to a high level of human-induced threats (Myers et al. 2000; CEPF 2005; 2007). Conservationists from across the globe have realized that the prevailing climate change trend and projections could mean that there will be substantial changes in critical habitats and the species therein because of the limited scope for expansion as the habitats outside protected areas are subject to intense fragmentation (Pounds et al. 1999; Wilson et al. 2007). Among the 25 eco-regions, 17 protected area complexes, and 41 candidate priority areas in the EH are many which are extremely important for biodiversity conservation (WWF and ICIMOD 2001). Among the eco-regions, Eastern Himalayan broadleaved forests, Brahmaputra Valley semi-evergreen forests, and Himalayan subtropical pine forests have the greatest conservation values because of the number of mammals, birds, and plants found in them (WWF and ICIMOD 2001).

Bioclimatic zones and phenology

Although there is no strict compartmentalization of vegetation along altitudinal gradients in the EH region, elevation has important implications for its ecology, evolution, physiology, and conservation and is highly relevant to species’ composition and phenology patterns (Chettri et al. 2001; Carpenter 2005). As a result of microclimatic variations, most organisms found in the EH are confined to specific habitats such as highland pastures, forests, and so on. This is a special risk factor for highland species that are sensitive to climate change (Pounds et al. 1999) and more likely to be at risk of extinction. Globally, there is evidence of the shift of species towards the north in latitude (Hickling et al. 2006) or higher elevations (Wilson et al. 2007), especially for species in the transition zone between subalpine and alpine which are more vulnerable to climate change as they have limited scope for movement. Analyses for the EH are few and limited to certain pockets of areas (Carpenter 2005). Observations have been made about the change in events related to plant and animal phenology and also to shifting of tree lines and encroachment of woody vegetation into alpine meadows. Phenological changes, such as early budding or flowering and ripening of fruits in plants, and hibernation, migration, and breeding in animals, could have adverse impacts on pollination patterns. Consequently, this may have an impact on the population of pollinators, leading to changes in ecosystem productivity and species’ composition in high-altitude habitats (Thuiller et al. 2008).

Recommendations and Future Strategies

While acknowledging the significant diversity of biological resources in the EH and the existence of a fair understanding of the important drivers of change, it is recognized that concerted efforts to monitor and research the impacts of climate change on biodiversity in the EH region are essential. An enabling policy environment is essential to support and strengthen community efforts to cope with change. Documentation and assessments indicate the need for policy dialogue focusing on areas identified. A clear concern was the multiplicity of policy actors governing natural resource management and livelihood support and the need for convergence of different (often conflicting) policies under one forum for ease of implementation. There is a critical role for scientific institutions in regard to policy formulation concerning natural resource management, livelihood support, and climate change. Policy makers require authentic data inputs and, more often than not, these are not available or not in a comprehensible form. Scientific institutions need to fill this gap so that policy making can be based on scientific findings.

*Scientist, CSIR-National Botanical Research Institute, Lucknow (India), <[email protected]>

This article has been reproduced from the archives of EnviroNews - Newsletter of ISEB India.

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