^{© PRASENJEET YADAV}

Vidushi Pant

Since it first gained popularity in the early 1990s, the term “landscape connectivity” has gradually made its way into the lexicon of wildlife conservationists and policymakers alike. In simple terms, landscape connectivity measures how well different areas in a landscape are connected to each other. It has mostly been studied for its role in facilitating the movement of iconic animals such as grizzly bears, jaguars, tigers, and elephants, as they move around in search of mates, food, and other resources. The passageways—or areas with high landscape connectivity—used by animals are more popularly known as “wildlife corridors”. Some famous corridors include the trans-boundary Yellowstone–Yukon Corridor that traverses across the United States and Canada, Serengeti-Mara Corridor that spans across Tanzania and Kenya, and the Kanha–Pench Corridor in Central India.

However, wildlife corridors are not just highways for animals. These corridors influence various biotic and abiotic flows between two or more habitats, affecting everything from seed dispersal to water movement and even the spread of wildfires and diseases in some cases. These flows on the land surface, below ground and through the atmosphere, can have consequences that ripple beyond the wilderness and contribute to human well-being and in some cases hazards as well. Take, for instance, their potential role in safeguarding the water resources in a region. As wildlife corridors often include large swathes of natural or semi-natural habitats (such as forests, grasslands, and agriculture-forest mosaic), they can play a crucial role in safeguarding the water resources in watersheds, shielding them from sedimentation, contamination, and flood risks and also contribute to rainfall in neighboring regions through recycling of transpired water from vegetation.

Given this potential association between wildlife corridors and water resources, it is only fitting to inquire whether this relationship has received comprehensive attention in the existing body of literature.

A recent study by scientists from India and the United States reviewed the degree to which the hydrologic function of wildlife corridors has been assessed in literature and conservation practice. The authors assessed the literature on connectivity using a bibliometric analysis, which is a quantitative research method used to evaluate and analyze scholarly literature to identify the trends in studies. They analyzed 3600+ research papers published between 1990 and 2023 and reported that only limited studies on landscape connectivity have addressed hydrology (with only 15 studies in 2022). About 50% of the publications that address wildlife or biodiversity along with hydrology or watersheds were published after 2015, highlighting the early stage of this thematic research area. Further studies are warranted to reveal how landscape connectivity for wildlife corridors can affect watershed protection in different landscapes.

Central Indian Highlands: A Case in Point

To underpin the synergy between wildlife corridors and hydrology, the authors also included a case study of the Central Indian Highlands. These highlands comprise a series of different hill ranges and plateaus, and are a part of the larger Deccan Plateau, spanning across Madhya Pradesh and parts of Maharashtra and Chattisgarh. They boast a diverse landscape, featuring dense forests, rolling hills, deep valleys, and numerous rivers and streams. This region also supports a rich biodiversity and has been a focal point for tiger conservation in India and houses several famous protected areas such as Kanha National Park and Pench, Melghat, and Satpura tiger reserves, among others.

Notably, the headwaters for several major rivers, including the Narmada, Tapti, Wainganga, and Pench rivers lie in these highlands. These rivers are vital for providing water resources to downstream areas, which have been home to indigenous communities and tribal populations for centuries. However, a previous study has reported that about 74% of the area of the Central Indian Highlands experienced water stress for a minimum of four months every year between 2004 and 2012. Water security in this region—as with several areas in India—has been recognized as a critical issue by policymakers, civil society organizations, academics, and researchers.

To understand the importance of wildlife corridors for rivers, the authors of the study overlaid topographic data and stream networks over the known wildlife corridors and their surrounding areas in Central India Highlands. They compared the forest cover, terrain ruggedness, and the number of headwater and small streams within the corridor areas as compared to the surrounding regions. They found that wildlife corridors in the region are three times more forested than surrounding areas. The significance of corridors in the region, therefore, becomes evident as forests play a pivotal role in reducing soil erosion, slowing surface runoff, and enhancing infiltration. Wildlife corridor areas were also twice as rugged as the surrounding areas. The ruggedness of an area refers to the degree of roughness or unevenness in the physical terrain of a region, typically characterized by the presence of steep slopes, cliffs, ridges, valleys, and other irregular landforms. Note that terrain ruggedness is important as it can ensure hydrological connectivity, maintain water quality, and reduce soil erosion, among other things.

The researchers further assessed the proportion of wildlife corridor areas that overlap with the catchment areas of five largest dams in the study area. These dams include Bansagar, Bargi, Gosekhurd, Tawa, and Pench Totaladah. They found that about 50% of the total area of all wildlife corridors in the region overlap with the catchment areas of these dams. This high proportion of overlap highlights the importance of maintaining these forested corridors for ensuring water quality and flow, both of which can have direct consequences for communities living downstream.

This interplay between wildlife corridors and water security underscores the need for adopting a more holistic approach to landscape management as wildlife corridors have the potential to serve multiple objectives, benefiting both wildlife and vulnerable human populations. Further, more detailed studies that identify this synergy between corridors and hydrology in different landscapes can provide additional rationale for policymakers to manage and conserve these corridors.

Some Key Terms

Watershed	A watershed, also known as a drainage basin or catchment area, is a geographical area of land defined by natural topographic boundaries such as ridges, hills, and mountains. It is a region where all precipitation and surface water drains into a common outlet, such as a river, stream, lake, or ocean.
Headwater and small streams	Headwaters refer to the source or starting point of a river or stream. They are typically found in high-elevation areas, such as mountains or hills, where water from precipitation (rain or snow) begins to flow downhill. Headwaters are often characterized by small, narrow channels and can be ephemeral, meaning they may only have water during and immediately after rain or snowmelt events, but sometimes are perennial. Despite their small size, headwaters are vital because they feed into larger rivers, and their quality can significantly influence downstream water quality.
Catchment area of a dam	The catchment area of a dam, often referred to as the reservoir’s catchment or drainage basin, is the geographical area from which a dam collects water from upstream through precipitation, runoff, and tributary rivers or streams. This catchment area serves as the source of water for the reservoir created by the dam.

This article is based on the following study:
DeFries, R., Parashar, S., Neelakantan, A., Clark, B. and Krishnaswamy, J., 2023. Landscape Connectivity For Wildlife and Water: The State of the Literature. Current Landscape Ecology Reports, pp.1-10.https://doi.org/10.1007/s40823-023-00091-0