Temperature change is an important environmental variable for global change sciences since it largely affects the physiology of plants in forest ecosystems. Canopy temperature depression (CTD) - the result of the deviation of the air temperature (Ta) from the plant canopy surface temperature (Tc) - varies depending on the meteorological and environmental conditions of the forests. 

In a study published in iForest-Biogeosciences and Forestry, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) valuated the differences in CTD between a rubber plantation (RP) and a tropical rainforest (TR) in Xishuangbanna, southwestern China across the various time series of the period of 2011 to 2015. 

The researchers analyzed the diurnal, monthly, seasonal and yearly evolution of CTD in a tropical rainforest and a rubber plantation. The results showed that the mean values of air temperature (Ta) and canopy surface temperature (Tc) at the RP site were higher than those at the TR site but that the CTD value of the RP site was lower than that of the TR site in the diurnal, monthly, seasonal and yearly time series. The five-year data also showed the same result. 

The CTD at the TR site was higher than that of the RP site, which was evident from the greater differences in the Ta and Tc at the TR site than at the RP site. 

Given the differential behavior of both sites, it was important to avoid transpiration water losses when quantifying the level of drought stress. Hence, CTD appears to be one of the effective selection criteria for determining the tolerance to drought stress in these two sites. 

“This study pointed out the need to emphasize the water stress and drought effects, which would perhaps prove to be good aspects of focus in terms of future work”, said Prof. ZHANG Yiping, principal investigator of the study. 

Contact 

ZHANG Yiping Ph.D 

Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China              

E-mail: yipingzh@xtbg.ac.cn