Effects of N and water supply on water use-efficiency of a semiarid grassland in Inner Mongolia
Effects of N and water supply on water use-efficiency of a semiarid grassland in Inner Mongolia
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DOI：
10.1007/s11104-009-0128-5
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发表时间：
2010-03-01
期刊：
影响因子：
4.9
通讯作者：
Lin, Shan
中科院分区：
文献类型：
--
作者：
Brueck, Holger;Erdle, Klaus;Lin, Shan
半干旱草地的生产力主要受季节性降雨量的限制，在潮湿条件下，越来越受到养分有效性的限制。采用2因子试验，研究了水氮互作对草地生产力及水分利用相关参数的影响。试验设2个水分水平（灌水量：158 mm;灌溉量：839（N 0）和972（N1）mm）和施氮量（0或180 kg N ha（-1））。芸香由ANPP和累积供水量计算。根据气象资料和叶面积动态计算裸土蒸发量（E），并利用HYDRUS-1D估算渗漏量（D）和蒸腾量（T）。计算水分利用效率（WUE，ANPP /（T + D））和蒸腾效率（TE，ANPP / T）。资源可利用性对半干旱草地水分利用效率有显著影响。芸香，WUE和TE都下降灌溉相比，灌溉条件下，显着增加与N肥的应用在两个水平的供水。虽然灌溉对水利用效率参数的影响相应地反映在稳定的碳同位素签名，氮供应导致显着减少负三角洲C-13-值下灌溉，但不灌溉条件。可以得出结论，在资源可用性的空间或时间梯度有显着的影响，半干旱草地的水分利用效率。高供水量下水分利用效率的降低与TE的差异有关，而与非生产性水分损失的相对增加无关。碳同位素分辨率与WUE和TE高度相关，但对芸香的预测能力较差。
Productivity of semiarid grasslands is primarily limited by seasonal rainfall amount and becomes increasingly limited by nutrient availability under wet conditions. Interactive effects of water and N availability on grassland productivity and parameters related to water use were studied on a grassland site in Inner Mongolia, China, in a 2-factorial experiment with two levels of water (rainfed: 158 mm; irrigated: 839 (N0) and 972 (N1) mm) and N supply (0 or 180 kg N ha(-1)). RUE was calculated from ANPP and cumulative water supply. Bare soil evaporation (E) was calculated from climatic data and leaf area dynamics, and percolation (D) and transpiration (T) were estimated with HYDRUS-1D. Water-use efficiency (WUE, ANPP / (T + D)) and transpiration efficiency (TE, ANPP / T) were calculated. Resource availability had pronounced effects on the water-use efficiency of semiarid grassland. RUE, WUE, and TE all decreased under irrigated compared to rainfed conditions and were significantly increased with N fertilizer application at both levels of water supply. While the irrigation effect on parameters of water-use efficiency were accordingly reflected in stable carbon isotope signatures, N supply resulted in significantly less negative delta C-13-values under rainfed but not irrigated conditions. It is concluded, that spatial or temporal gradients in resource availability have pronounced effects on the water-use efficiency of semiarid grassland. The decrease of water use-efficiency under high water supply was related to differences in TE and not to a relative increase of unproductive water loss. Carbon isotope discrimination was highly correlated with WUE and TE, but can be a poor predictor of RUE.