Resilience and resistance of ecosystem functional response to a precipitation pulse in a semi‐arid grassland
Resilience and resistance of ecosystem functional response to a precipitation pulse in a semi‐arid grassland
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DOI：
10.1111/j.1365-2745.2005.01060.x
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发表时间：
2006-01
影响因子：
5.5
通讯作者：
D. Potts;T. Huxman;B. Enquist;J. Weltzin;David G. Williams
中科院分区：
文献类型：
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作者：
D. Potts;T. Huxman;B. Enquist;J. Weltzin;David G. Williams
1. 在水分受限的生态系统中，离散的降水事件引发了短暂但重要的生物活动阶段。地上和地下生物群落对降水的不同反应可能会限制生态系统层面的生物地球化学转化。
2. 我们在2002年6月和2003年期间，以植物生理和生态系统气体交换测量作为主成分分析（PCA）中的状态变量，对39毫米灌溉事件（降水脉冲）引起的整个生态系统响应的短期动态进行了量化。实验地块由在半干旱草原的两种不同地貌表面单一种植的本地（扭黄茅）或非本地（雷曼画眉草）丛生禾草组成。
3. 在15天内，处理在状态变量空间中遵循相似的非线性轨迹，测量时段形成不同的集群；PCA轴1和轴2共同解释了2002年和2003年期间80.7%的变异。
4. 在这两年中，丛生禾草物种与土壤类型相互作用，使得在细质地粘土地貌表面种植非本地丛生禾草物种的地块中，生态系统功能抗性降低。
5. 由于光合作用、呼吸作用和蒸散作用对降水的独立反应而出现的系统层面的滞后现象，表明了存在替代功能状态的可能性。
6. 量化一个季节内生态系统对单个降水事件的替代功能状态的频率和持续时间，将有助于深入了解物种、土壤和气候对生态系统碳和水循环的控制。
1 In water‐limited ecosystems, discrete precipitation events trigger brief but important episodes of biological activity. Differential responses of above‐ and below‐ground biota to precipitation may constrain biogeochemical transformations at the ecosystem scale. 2 We quantified short‐term dynamics of whole ecosystem response to 39 mm irrigation events (precipitation pulses) during June 2002 and 2003 using plant physiological and ecosystem gas‐exchange measurements as state variables in a principal components analysis (PCA). Experimental plots consisted of either native (Heteropogon contortus L.) or non‐native (Eragrostis lehmanniana Nees) bunchgrasses planted in monoculture on two distinct geomorphic surfaces in a semi‐arid grassland. 3 For 15 days, treatments followed similar, non‐linear trajectories through state variable space with measurement periods forming distinct clusters; PCA axes 1 and 2 combined to explain 80.7% of the variation during both 2002 and 2003. 4 During both years, bunchgrass species interacted with soil type such that there was a reduction in ecosystem functional resistance in plots planted with the non‐native bunchgrass species on the fine‐textured clay geomorphic surface. 5 System‐level hysteresis, emerging as a result of independent responses of photosynthesis, respiration and evapotranspiration to precipitation, indicated the potential for alternative functional states. 6 Quantifying the frequency and duration of ecosystem alternative functional states in response to individual precipitation events within a season will provide insights into the controls of species, soils and climate on ecosystem carbon and water cycles.