London, Nov 30 (ANI): Plants in the Tibetan Plateau have started to bloom later in spring, making the growing season shorter, due to climate change.
This change could threaten the livelihood of the thousands of nomads who survive by raising cattle on the plateau, reports Nature.
Jianchu Xu, lead author of the study, said he expected that plants on the plateau would follow the same pattern of early flowering seen elsewhere.
For instance, in many regions, climate change has advanced the timing of spring events, such as flowering or the unfolding of leaves.
But the new findings have "contradicted the linear link" that is often seen between warming temperatures and an earlier start to the growing season, said Xu.
The group used satellite data to identify the start, end and length of the growing season for the meadow and steppe vegetation of the Tibetan Plateau between 1982 and 2006, and linked it to temperature change.
The study showed an initial advance in the timing of the growing season or its 'phenology' for both the meadow and steppe for the first 15 years. But from 2000 until 2006 that trend was reversed. The net effect was a shortening of the growing season by about one month for steppe plants and three weeks for meadow vegetation.
Plants that have evolved in cold-weather climates become dormant in the winter to avoid frost damage. But the warmer winters on the plateau are delaying spring growth, said authors, because plants are not meeting their chilling requirements - a minimum period of time that plants must experience cold before they break winter dormancy.
"The change in the growing season may mean there is less grassland biomass available for grazing.
"They will have to come up with local adaptive strategies to make sure the animals have enough grazing land," said Xu.
The study appeared in the Proceedings of the National Academy of Sciences1. (ANI)