In China, air temperature has increased by 0.27 °C per decade from 1961 to 2003 with accelerating trends after 1990. However, few studies have examined corresponding trends in soil temperature. Comparing temperature trends under forest canopies with those more commonly measured in open lands should improve understanding of warming in forested areas.

Dr. ZHANG Yiping and his team of Xishuangbanna Tropical Botanical Garden have studied climate change in Ailaoshan Station for Subtropical Forest Ecosystem Studies (ASSFE, 24°32′N, 101°01′E and 2480 m asl.) for many years. They utilized temperature observations in open land (1983–2010) and under forest canopy (1986–2010) and measured short-term radiation components simultaneously. Their study was aimed at seeking a further understanding on climate trends in Ailaoshan subtropical mountain forest, SW China.

They addressed the following three questions: 1) What are the microclimatic differences between open land and under forest canopy? 2) What is the pattern of air/soil temperature trends both in open land and under forest canopy? 3) When does soil temperature respond differently than air temperature in open land?

Their study showed that limited energy reached the ground under the forest canopy. Airand soil temperatures at all depths have increased more in winter than in other seasons. It also revealed that an increasing trend of 0.36 °C/decade in air temperature, which is double the previously reported trends in their regional temperatures. Stronger winter warming in their study suggested an enhanced aridity in winter. Increased temperature and sunshine hours could strengthen evaporative water demand.

The researchers suggested that the impact of changes in temperature and aridity on the ecological and biological perspective of mountain forests need to be addressed.

The study entitled "Observed air/soil temperature trends in open land and understory of a subtropical mountain forest, SW China” has been published online in International Journal of Climatology, DOI: 10.1002/joc.3494.