India is home to 650 endemic tree species found nowhere else in the world, 8% of the world’s biodiversity and three biodiversity hotspots. The majority of this unique flora and fauna can be found in India’s forests.
These forests provide vital services, such as carbon absorption, preserving nutrients, and providing timber or fuelwood. These services are being lost, but deforestation is also affecting the environment. Climate of IndiaAs well as places Further afield.
Commodity-driven deforestation, which is the most common cause for forest loss in the Tropics, is the main culprit. A growing number of studies are proving that there are other causes. ResearchEvidence has shown that climate change is having an impact on the survival and composition tropical forests.
It has been difficult to see how global warming is affecting the forests of India. There are some exciting possibilities, ResearchWhile there is increasing evidence about the impacts of climate change on forest distribution, little information is available on how it currently affects forests.
India Many studiesAlthough many have documented forest loss in the early 2000s and have done extensive assessments since then, very few have done so on a large scale. And the primary data source – the Forest Survey of India – lacks information on the location of deforestation and total forest loss.
Our study was published in Global Change BiologyWe take a step to close these gaps by mapping the country’s forest loss and climate change between 2001-2018.
We find that forest destruction has increased significantly over the past century, with most of the increase occurring in the north east. We also show that climate change is playing an important role in India’s forest loss – but it will likely remain secondary to other factors in the near future.
Forest loss research: updating knowledge
Our first task was to map India’s forest cover and forest loss. We used a global forest database to map forest cover and loss across India due to the absence of open-access national data on forest change. Database.
Below are maps showing forest cover in 2000 (left), and forest loss between 2001-2018 (right). These maps are divided by district. The darker shading indicates areas that have greater forest cover (green in the left-hand chart) and areas that have experienced loss (purple, right-hand chart).
We found that there is still an extensive amount of forest loss occurring in India, totalling 20,472 square kilometres (km2) of loss between 2001 and 2018, accounting for more than 7% of India’s forest cover.
Certain areas of the country support higher levels of forest cover than others – likely due to a combination of environmental and topographic conditions, human pressures and accessibility. Subsequently, these high forest cover areas also tended to be the areas where there were the highest forest losses – as there was more forest to be lost.
We identified three areas of high forest loss that you can see on the right-handmap as collections of purple districts. The Western Ghats are located parallel to the Indian Peninsula’s western coast. The north-east regions, the easternmost part of India, are biodiversity hotspots. They also harbour endemic bird species. The Eastern Central Region is a critical habitat. elephant populationsHarbours 13% of India’sFlowering plant species
Climate change mapping in areas of forest loss
Two metrics were needed to measure climate change. The first was a change over time, known as a “temporal trend”, and we calculated the change in rainfall in mm per year and the change in temperature in degrees celsius per year.
However, the impact of a warming world is not limited to changes over time. We also need to consider the surrounding conditions – for example, there are some instances where an increase in temperature could cause an organism to die out, but other instances that can be avoidable by species movement.
The survival chances could be affected by the proximity to cooler areas. These nuances cannot be measured by our typical temporal trends, so instead we use a metric called “climate velocity”.
These maps show the two types of metric. They include temporal trends in rainfall (top left) and temperature, and climate velocities (bottom left) and temperatures (bottom right) for 2001-18. Darker colours indicate a greater change – warmer/wetter (orange) and cooler/drier (purple) – over time or speed of velocity.
The maps highlight that India’s central areas are getting wetter, and that the majority of the country is getting warmer. Some areas are experiencing high climate velocities. This means that species in these areas may need to travel as much as 20 km per year to maintain the current conditions. In addition, many eastern and southern areas of the country are experiencing drying conditions that could potentially lead to drought – a key risk factor for tropical trees.
What does this all mean for forests?
These maps show how areas with high forest coverage are seeing many different trends in climate. Most are getting warmer and drier, but some – such as the north-east – are getting cooler.
We noticed that many seasons had opposing trends as we were mapping India’s climate. We quickly realized that the high degree of variation between seasons was essential if we were to understand the effects of climate change on forests.
The maps below show some variation in the rainfall changes between the seasons. It is evident that the trend of increasing rainfall in the monsoon season, top-right, strongly differs from the other seasons.
We developed statistical models to assess the correlation between climate change and forest loss in India. These models revealed that forest loss was most common in areas with lower rainfall and higher rainfall volumes. This is not surprising given the vulnerability of tropical forests. Drought.
Relationships with temperature are more complicated and it was not the areas with the fastest increasing temperatures where there was the greatest forest destruction. Instead it was the areas with the slowest increases – and cooling in some seasons.
We need more information to understand why these trends were found. However, it could be related the unusual cooling patch that was first documented by a Study Nature2018 coincides with a high area of forest loss.
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This is concerning because we don’t fully understand how tropical tree might react to cooling, and because all projections indicate that there will be warming in the future.
We also found that all three of the key hotpots for forest loss show high climate velocities – in the top 10% of values – at some point during the year, and thus may be more at risk due to the speed of climate change.
The trend for rapid drying and warming in the northern Western Ghats region was particularly alarming, which is a very bad combination for tropical trees. This area is important for fauna and flora, and contains seven protected areas. It also has high levels of human exploitation, encroachment, and could pose a double threat to forests.
Our results highlight the complexity of climate changes occurring in India’s forests. However, what we have found is that some of the areas of highest forest cover – which are vital for India’s biodiversity – are experiencing concerning speeds of climate change, and a general drying trend. This could threaten their long-term survival, as well as the continued presence of the species – and human populations – that rely on them.
Future knowledge gaps to be closed
It is important that you note that it may not be possible for tree cover to move 20km per annum to keep up to specific rainfall conditions. This is an average district. There may be other areas that are more suitable or can serve as refuges. Some species may also be able adapt to changes in temperature and rainfall.
These maps of climate velocity provide valuable insight into which species are most at risk.
This information can be used to plan conservation to ensure protected areas are in the best places to protect vulnerable locations as well as provide refuge in more climate-friendly locations. This information can also be used to create corridors between high velocity and low velocity places, which facilitates species movement. These findings have positive implications for conservation, as well as continuing the rapid warming caused by climate change.
This research demonstrates that Indian forests and biodiversity need to be conserved.
India is currently creating a new National Forest Policy. This policy will replace the one that was created in 1988. This is a crucial moment for policies to take into account the multiple threats facing forests in India. Adaptable management strategies built from up-to-date research is even more important as the country’s forests face unprecedented threats on multiple fronts.
It may be a cliché, but with knowledge comes power. Knowing which areas are more vulnerable to climate change or where species are most likely to experience rapid changes in climate can help us protect these areas and find refuges for species. Once we have identified these areas, we can create solutions to support species adaptation or build corridors that allow species to move with climate change.
Haughan, A. E. et al. (2022) Determining the role of climate change in India’s past forest loss, Global Change Biology, doi:10.1111/gcb.16161.
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