Aboveground Biomass Dynamics in the Low-Mountain Dry Grasslands of the Tianshan Mountains

Abstract

Identifying the dynamics of aboveground biomass (AB) is vital for effective grassland management, yet knowledge on this phenomenon remains limited in the low-mountain dry grasslands (LMDG) of the Tianshan Mountains. In this study, systematic observations were conducted from 2014 to 2017 to determine AB dynamics in the LMDG of the Tianshan Mountains. To accomplish this, a cutting experiment, an HL20 Bowen ratio system, and TDR300 and WatchDog1400 systems were used. AB dynamics had unique characteristics, because of the influence of the unique environment of this region. AB increased rapidly in spring (April-May), and then increased slowly in summer (June-August) and autumn (September-October). Plants entered dormancy in summer (primarily August). In autumn, plants continued to grow after dormancy, except in years with low precipitation which limited plant growth. Plants generally suffered from water stress in this region. However, in spring, the limiting factor for plant growth was heat, not water. Heat might also be the limiting factor for plant growth in autumn. The results are expected to enhance the understanding of AB dynamics in the LMDG of the Tianshan Mountains, providing data to support local grassland management.