Estimation of pasture productivity in Mongolian grasslands: field survey and model simulation

Abstract

The Mongolian economy depends critically on products of range-fed livestock. Pasture is the major food source for livestock grazing, and its productivity is strongly affected by climatic variability. Direct measurement of pasture productivity is time-consuming and difficult, especially in remote areas of a large country like Mongolia with sparse spatial distribution of pasture monitoring. Therefore, modeling is a valuable tool to simulate pasture productivity. In this study, we used a remote sensing-based production efficiency model, that is, the Carnegie Ames Stanford Approach (CASA) model, to estimate pasture productivity in three main vegetation zones of Mongolia; desert steppe, steppe and forest steppe. The present study aimed to explore climatic and grazing effects on grassland productivity in Mongolian grasslands during 2005-2007, using ground-based measurements and simulation model outputs.The ground measurements showed that grazing caused a significant decrease in measured aboveground phytomass and plant height. Simulation results demonstrated that the highest net primary productivity (NPP) of 83.2 gC/m 2 and the lowest NPP of 12.6 gC/m 2 over the growing season (April-September) occurred at Darkhan (steppe) and Mandalgovi (desert steppe), respectively. Moreover, the comparison of temperature and water stresses on pasture productivity indicated that water stress was stronger downregulator of NPP, verifying that drought is the major concern of pasture production. Based on the comparison between the measurements and simulation, the ratio of aboveground NPP to belowground NPP in the Mongolian perennial grasslands was estimated as 1:1.5.

Synergistic effects of climate change and grazing on net primary production of Mongolian grasslands

“…, Bat‐Oyun et al. ) in Mongolia, there have been no reports of over‐compensatory or compensatory growth response. This is primarily because these studies do not include the feedback of livestock to the soil properties and plant growth or simulate grazing as a disturbance.…”

“…In arid and semiarid grasslands, there has been no consistent evidence of grazing induced compensatory or over-compensatory effects on grassland ANPP. While numerous studies were conducted on the effect of grazing on ANPP , Bat-Oyun et al 2010 in Mongolia, there have been no reports of overcompensatory or compensatory growth response. This is primarily because these studies do not include the feedback of livestock to the soil properties and plant growth or simulate grazing as a disturbance.…”

Analyzing NPP Response of Different Rangeland Types to Climatic Parameters over Mongolia

“…Numerous ecosystem models, such as the TEM model [39,40], Century model [41], Carnegie-Ames-Stanford-Approach (CASA) model [42], Biome-BGC model [43], BIOME3 model [44], Boreal Ecosystem Productivity Simulator (BEPS), MOD-Sim-Cycle model [45] and GLO-PEM model [46], have been developed over the last two decades to estimate NPP over different parts of the world. Among them, the CASA model has already been used in Mongolia to calculate NPP [47][48][49], while the BEPS model has been verified for one year over the East Asia region including Mongolia [50]. However, it has not been used in the national level NPP calculation in Mongolia.…”

Determinants of Caragana microphylla density distribution in the Mongolian steppe

“…Given the similar aridity conditions (Table 1), less frequent fires in the central steppes may be partly explained by less standing biomass (i.e., fuel) in such regions (Jargalsaikhan 2012;, which can be further linked to more grazing (Fig. 1d) and/or shorter growing seasons (Bat-Oyun et al 2010) in the central regions than the eastern steppes. However, we inferred that the short growing season was more influential than less frequent fires in the central steppes, because overgrazing is generally localized, but central regions had very few or no fires between 2000 and 2011.…”