Jilin Provincial Laboratory of Grassland Farming, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
Institute of Grassland Science, Northeast Normal University, Changchun 130024, China.
Sci Total Environ. 2019 Jan 10;647:1344-1350. doi: 10.1016/j.scitotenv.2018.08.025. Epub 2018 Aug 3.
Water and nitrogen (N) availability to plants are spatially and temporally variable in arid and semi-arid grasslands. We aimed to investigate the eco-physiological responses of three bunchgrass species to water and N addition along a gradient of habitat degradation in the Inner Mongolian typical grasslands. The effects of water and N addition on aboveground and belowground growth and biomass allocation and water- and nitrogen-use efficiency (WUE and NUE) of Stipa grandis, Agropyron cristatum and Cleistogenes squarrosa from non-degraded, moderately-degraded and heavily-degraded grasslands, respectively, were compared. Stipa grandis had higher specific root length and WUE than C. squarrosa, while C. squarrosa had higher NUE than S. grandis in water- and N-limited conditions. Responses of A. cristatum were intermediate between those of S. grandis and C. squarrosa. Water and N addition did not have a significant effect on growth and biomass allocation of S. grandis, but it increased growth and leaf biomass allocation of A. cristatum and growth and stem biomass allocation of C. squarrosa. The three species differ in WUE, NUE, biomass allocation and responses to water and N addition, and these differences are adaptive to their respective habitats. The degraded grasslands can be restored by an increase in water and N availability such as is expected to occur via climatic change, but S. grandis will not benefit from the increases.
水和氮（N）在干旱半干旱草原中对植物的可利用性在空间和时间上是多变的。我们旨在研究三种丛生草种对水分和 N 添加的生态生理响应，这些响应沿内蒙古典型草原生境退化梯度变化。分别比较了非退化、中度退化和重度退化草地中水分和 N 添加对大针茅、冰草和旱雀麦地上和地下生长、生物量分配以及水分和氮利用效率（WUE 和 NUE）的影响。在水分和氮限制条件下，大针茅的比根长和 WUE 高于旱雀麦，而旱雀麦的 NUE 高于大针茅。冰草的响应介于大针茅和旱雀麦之间。水分和 N 添加对大针茅的生长和生物量分配没有显著影响，但增加了冰草的生长和叶片生物量分配，以及旱雀麦的生长和茎生物量分配。这三种植物在 WUE、NUE、生物量分配以及对水分和 N 添加的响应方面存在差异，这些差异是对其各自生境的适应性表现。退化草地的水分和 N 可利用性增加（如气候变化预期的那样）可以恢复，但大针茅不会受益于这种增加。
