Spatial–Temporal Variation of ANPP and Rain-Use Efficiency Along a Precipitation Gradient on Changtang Plateau, Tibet

Guangshuai Zhao,Min Liu,Ning Zong,Jingsheng Wang,Jianshuang Wu,Xianzhou Zhang,Peili Shi

doi:10.3390/rs11030325

Abstract

Aboveground net primary productivity (ANPP) and rain-use efficiency (RUE) are important indicators in assessing the response of ecosystems to climate change. In this paper, the Changtang Plateau in the Tibetan Autonomous Region was selected as the study area to analyze the spatial and temporal changes of ANPP and RUE in grassland communities and their response to climate change. The results showed the following:(1) The spatial pattern of ANPP was closely related to rainfall on the Changtang Plateau. The average ANPP over the past 15 years increased gradually from the arid west to the humid east. A consistent pattern was exhibited in different grassland types and climate zones. (2) The RUE was higher at the east and west edges of the Changtang Plateau, especially in the arid west, but was lower in the center. From the perspective of different climatic zones, the average RUE in the southern Tibetan semiarid climate zone and the Ngari arid climate zone was significantly higher than that in other climate zones. However, the average RUE in different grassland types only varied from 0.07 to 0.09 g·m−2·mm−1. The spatial variation in RUE was more distinct in different climatic zones than in different grassland types. (3) Climate change influenced the interannual variation of ANPP and RUE, but the response of ANPP to rainfall showed a significant lag. The interannual change in RUE was negatively correlated with changes in precipitation. (4) In general, a greater area showed a significant increase rather than a decrease in ANPP on the Changtang Plateau, which meant that the grassland condition is improving. The temporal variation patterns of ANPP and RUE in different climate zones were consistent with the overall patterns on the Changtang Plateau, while the variation was not significant in different grassland types.

Highlights

Aboveground net primary productivity (ANPP) is one of the key ecological properties of ecosystems, and it is closely related to precipitation in grassland ecosystems, both globally and regionally [1,2,3]
The spatial patterns of ANPP along the precipitation gradient on the Changtang Plateau were deeply impacted by precipitation levels
The self-limitation of the vegetation and biogeochemical limitations impacted the spatial patterns of rain-use efficiency (RUE), which were higher at either ends of the Changtang Plateau, especially in the arid west, while lower in the center

Summary

Introduction

Aboveground net primary productivity (ANPP) is one of the key ecological properties of ecosystems, and it is closely related to precipitation in grassland ecosystems, both globally and regionally [1,2,3]. ANPP has a strong positive correlation with mean annual precipitation (MAP). Over spatial precipitation gradient [4,5,6]. There are some disputes over the relationship between annual variation in ANPP and precipitation despite agreement on the overall findings of spatial patterns. Some researchers consider that the annual variation of ANPP is influenced by soil humidity as well as precipitation [7,10]. The other studies have shown that the annual variation of ANPP is not related to changing precipitation [2,9]. It may not possible to interpret the variation of ANPP on the basis of precipitation because variations in precipitation are on a much larger scale than changes in ANPP overall [11,12]

Methods

Results

Discussion

Conclusion