An Unpredictable Rhythm
When we talk about 'erratic rainfall', it’s not just about more or less water over the year. It’s about a fundamental change in the monsoon's behaviour. Studies show that a warming climate is making the Indian summer monsoon more chaotic. Instead of steady,
prolonged showers, we are seeing longer dry spells punctuated by bursts of extreme, intense rainfall. In some regions, the total amount of rain might not change much, but its delivery is becoming more volatile. This shift disrupts the predictable cycle of moisture that forests have adapted to, creating a new and challenging environment for countless species.
How Forests Read the Rain
Forest ecosystems are intricately timed to the monsoon's clock. The arrival of rain triggers seed germination, flowering, and fruiting. Deciduous trees, for instance, shed their leaves during the dry season and depend on the monsoon to burst back to life. However, recent research highlights that disruptions to these rainfall patterns are affecting the very lifecycles of trees, a study known as phenology. For example, a lack of moisture and unusual temperature spikes have been observed to cause some trees, like the Semal, to alter their leaf development cycles. This temporal mismatch can have far-reaching consequences, affecting everything from pollination to the availability of food for wildlife.
A Tale of Winners and Losers
This new, unpredictable climate doesn't affect all species equally. It creates a landscape of winners and losers. Drier conditions and more variable rainfall tend to favour hardy, drought-resistant species over those that require consistent moisture. For example, a study of the Panchmarhi Biosphere Reserve in central India found that dry teak forests saw a significantly higher loss in canopy cover compared to their moist deciduous counterparts. Similarly, research in Tamil Nadu's Western Ghats warns that evergreen and moist deciduous forests could shrink, while drier thorn forests may expand by 2050. This shift could lead to a 'savanna-like' landscape in some regions, fundamentally changing the character and composition of these vital ecosystems.
The Cascade Effect on Wildlife
When the plant life in a forest changes, the effects cascade through the entire food web. Herbivores that depend on specific moisture-loving plants may struggle to find food. This, in turn, affects the predators that hunt them. The Western Ghats, a global biodiversity hotspot, is particularly vulnerable. Changes in rainfall and temperature threaten the habitats of endemic species like the Nilgiri Tahr and the Malabar Pied Hornbill. Even the smallest creatures are impacted. Altered flooding patterns in the Western Ghats, for instance, have been shown to affect the diversity of insect populations and important plant families like nutmeg. These changes ripple outwards, destabilising the entire ecosystem from the ground up.
A View from the Ground
The impacts are being observed across India. In the Himalayas, shifting precipitation patterns are altering forest structure. More intense rainfall on steeper slopes increases the risk of landslides, which can decimate forest patches. Meanwhile, a long-term analysis of forests in central India showed a loss of nearly 400 square kilometres of forest cover over five decades, driven partly by climate shifts alongside human pressures. In the biodiversity-rich northeast, a decline in southwest monsoon rainfall is creating more drought-like conditions, affecting everything from rice production to forest health. These on-the-ground changes are a clear signal that climate variability is no longer a future threat, but a present-day reality for India's forests.
