Above and belowground net primary productivity of grassland influenced by supplemental water and nitrogen in Inner Mongolia

• Published in: Plant and soil Vol. 340; no. 1-2; pp. 253 - 264
• Main Authors: Li, Jiangzhou, Lin, Shan, Taube, Friedhelm, Pan, Qingmin, Dittert, Klaus
• Format: Journal Article
• Language: English
• Published: Dordrecht Dordrecht : Springer Netherlands 01.03.2011; Springer; Springer Netherlands; Springer Nature B.V
• Subjects: Analysis; ANPP; Biomass; Biomass allocation; Biomedical and Life Sciences; BNPP; China; Climate models; dry matter partitioning; Ecology; Ecosystems; Field capacity; Global climate; Grassland soils; Grasslands; Grazing; Grazing history; Irrigation; Irrigation water; Life Sciences; Moisture content; Nitrogen; Nutrient availability; nutrient use efficiency; Pastures; Plant Physiology; Plant Sciences; Plant species; Plants; prediction; primary productivity; Rain; Rain and rainfall; Regular Article; Salsola; Salsola collina; Semiarid grasslands; Semiarid lands; semiarid zones; Soil moisture; Soil Science & Conservation; Soil sciences; Soil water; Soil water content; Species composition; Species diversity; Terrestrial ecosystems; Vegetation; Water; Water availability; Water content; Water treatment; Water use; Water use efficiency; Water/nitrogen use efficiency; China; China, People's Rep., Inner Mongolia; Species diversity; ANPP; BNPP; Water/nitrogen use efficiency; Biomass allocation; Grazing history
• DOI: 10.1007/s11104-010-0612-y
• ISSN: 0032-079X

While water availability determines grassland productivity in semiarid regions, nutrient availability is the main limiting factor under wet conditions. An experiment was conducted in 2008 at two sites in Inner Mongolia with histories of heavy grazing (HG) and moderate grazing (MG) to study the interactive effects of water and nitrogen on above- and belowground net primary productivity (ANPP and BNPP), biomass partitioning, and plant species composition. The study comprises two water treatments (no irrigation and irrigated when soil water content was below 70% of the field capacity), and two nitrogen (N) levels (0 and 100 kg N ha⁻¹). Mean values of ANPP at the peak biomass time reached 1,028 ± 95 SD g m⁻² at the HG site and 568 ± 32 SD g m⁻² at the MG site in irrigated and fertilized treatment. Nitrogen use efficiency (NUE) was significantly higher at irrigated plots compared to rain-fed plots at both HG and MG sites. Water use efficiency (WUEt) based on total water input and ANPP decreased with irrigation at the HG site. Meanwhile, N application significantly increased WUEt, WUEp (based on precipitation), and WUEi (based on irrigation water) at both sites. BNPP was significantly higher at irrigated plots compared to rain-fed plots at both HG and MG sites, and it tended to decrease with N addition. However, the fraction of belowground to total biomass (f BNPP = BNPP/(ANPP+BNPP) decreased with the addition of supplemental resources and exhibited a negative correlation with ANPP. Species diversity remained lower at the HG site compared to the MG site; it decreased with the addition of supplemental resources at the latter site. The annual Salsola collina contributed the most to the total biomass under irrigation. Based on global climate models, more frequent extreme climates are predicted in the future, which can result in changes in resource availabilities. Therefore, our research results have important implications for predicting the production and other properties of grassland ecosystems.