Grassland Productivity Response to Climate Change in the Hulunbuir Steppes of China

Abstract

As global climate change deeply affects terrestrial ecosystem carbon cycle, it is necessary to understand how grasslands respond to climate change. In this study, we examined the role of climate change on net primary productivity (NPP) from 1961 to 2010 in the Hulunbuir grasslands of China, using a calibrated process-based biogeochemistry model. The results indicated that: Temperature experienced a rise trend from 1961; summer and autumn precipitation showed a rise trend before the 1990s and decline trend after the 1990s. Winter and spring precipitation showed an ascending trend. Simulated NPP had a high inter-annual variability during the study period, ranging from 139 g Cm−2 to 348 g Cm−2. The annual mean NPP was significant and positive in correlation with the annual variation of precipitation, and the trend was first raised then fell with the turn point at the 1990s. Temperature had a 20–30 d lag in summer, but none in spring and autumn; precipitation had a 10–20 d lag in summer. The climate lag effect analysis confirmed that temperature had a positive effect on NPP in spring and a negative effect in summer.

Climate Warming Consistently Reduces Grassland Ecosystem Productivity

“…Climate data were acquired for 65 meteorological stations distributed across the study region (Figure 1) from the database of China's meteorological science data‐sharing service (http://data.cma.cn/). Considering the lagging response of grassland productivity to climate change (Zhang et al., 2019), we selected mean climate data of 1974–1983 (represent for the 1980) and 2004–2013 (represent for the 2010), including mean annual growing season precipitation, sunshine duration, air temperature, soil temperature at a depth of 0–20 cm, solar radiation, and cumulative daily mean temperature exceeding 5°C (AccT) (Wang et al., 2012a). The climate variables were first compiled from daily climate raster surfaces interpolated using ANUSPLIN 4.37 (Hutchinson, 2004) and then extracted for each site in ArcGIS 10.2 (ESRI, Redlands, CA, USA).…”

Soil Nitrogen Dynamics in a Managed Temperate Grassland Under Changed Climatic Conditions

“…We also observed a change of the intra-annual variability of N_PU after the translocation to a drier and warmer site. Zhang et al [18] showed for a grassland in China that an increase in temperature led to a decrease in ANPP, and thus to a lower N_PU during summer. The temperature-induced earlier start of the growing period allows a higher ANPP in spring, which follows the observation of Zhang et al [18] that higher T air at the beginning of the year has a positive effect on ANPP.…”

“…Zhang et al [18] showed for a grassland in China that an increase in temperature led to a decrease in ANPP, and thus to a lower N_PU during summer. The temperature-induced earlier start of the growing period allows a higher ANPP in spring, which follows the observation of Zhang et al [18] that higher T air at the beginning of the year has a positive effect on ANPP. With rising T air , we should therefore observe an increase in the intra-annual variation of N_PU, with a higher N_PU in spring, when water is non-limiting in this period, compared to a lower N_PU in summer because of water-limited conditions and heat stress.…”

“…Moreover, the solubility of N 2 O in the soil solution decreases with increasing T air , which is also leading to higher gaseous N 2 O emissions [17]. On the other hand, a higher T air can cause a higher N_PU if it does not lead to water or heat stress [18]. Higher N_PU in response to an increasing T air controls soil solution chemistry [19], lowers the concentration of soil dissolved inorganic nitrogen (DIN), N_Dr [20], and gaseous emissions [21,22].…”

Winter Precipitations of Northern Part of Farming-Pastoral Zone and Hulunbuir Grassland

“…The research region, called Region hereafter, is defined by the rectangle limitation comprising northern part of the farming-pastoral ecotone and Hulunbuir Grass-land, because both of the mentioned areas are economically relied on winter precipitations for crops growth, pasturage and tourism business. Up to date, many research are focused on the environment changes of such grassland ecosystem due to natural impact factors such as climate change, precipitation, grazing, fire and drought [1] [2] [3] [4] [5]. The present research focuses on precipitation factor on the forest-grassland transition zone.…”