Himalayan grasslands

We drive past slopes covered with pines, over and over again, whenever we are in the lower Himalayas or the Siwaliks below them. We hardly ever stop to walk into them. I now realize that I was brainwashed by old and false certainties. The false statements are the following: forests of Himalayan Chir pine (Pinus roxburghii) are ecologically barren. We bought into popular but false ecological lore which extends this into statements about pine forests encroaching into productive oak forests because of deadly human interventions involving fire. These assumptions are at best questionable, and at worst completely wrong.

The new understanding is that these are not forests but savannahs, grasslands which are protected by the longleaf pines. These chir pines secrete terpins which drip into the ground and by changing the chemistry of the soil make it inhospitable to some species. The grasslands are not barren. Recent biodiversity counts show that the Himalayan pine savannahs support more species of flora (mainly grasses and herbs) than oak forests. Worldwide, the biodiversity of animal life in forests is dominated by insects, and these counts are missing in Himalayan ecology. Apparently, the biodiversity of grasslands is always undercounted: for example, they are often full of ants, and someone really should count them in pine savannahs here. I have clambered up a pine covered slope once to look at griffons resting in this habitat, so I have first hand evidence that they are not barren.

Chir pines (Pinus roxburghii, also called longleaf pines) are easy to recognize. They have the distinction of having the longest needles among all pines. Although they are evergreens, they shed needles copiously in April and October-November. November is usually very wet in the hills, but April is dry. Locals and seasoned travelers told us that late April and May are known as the fire season in these parts. This year the winter was very dry, and apparently the fires started in October and have smouldered since then.

Ratnam and her co-authors, in their impressive paper on tropical grasslands, present a closely argued case that the role of fire in the management of Himalayan grasslands has been misunderstood since the 19th century. As a result, fire prevention was written into the law in the 1940s. However, worldwide, fires are an intrinsic part of savannah ecologies, and terminology like “prescribed burns” is a common part of forestry practices elsewhere. The argument is expanded on in a separate paperwhich makes the case in more detail, where they relate this understanding to the degradation of all types of grasslands in India. One consequence of this that most bird-watchers are aware of is the tragic collapse of the population of the Great Indian Bustards (Ardeotis nigriceps) in the grasslands of the Indian plains.

Chir pines are adapted to alternation of fire and shade. The seeds germinate faster in red light, which is abundant on the forest floor, after sunlight filters through the trees. The growth habits of seedlings are also fire adapted, as are the grown trees themselves. Studies of the effect of fire on the ecology of chir pine savannah have also been published. It seems that biodiversity is highest on patches which have been burnt more than once. This could be why the traditional fire management methods evolved.

I have spent a lot of time walking in oak forests, and mixed forests on these lower slopes of the Himalayas. They are full of birds and animals (including exotica like the Himalayan red giant flying squirrel, which has the distinction of having the most adjectives preceding its generic name). But I have spent almost no time in pine savannahs. It is time to restore the balance, and see for myself what animal life I can find in them.