Do experimental pH increases alter the structure and function of a lowland tropical stream?

Disturbances can alter the structure and function of ecosystems. In stream ecosystems, changes in discharge and physicochemistry at short, intermediate, and long recurrence intervals can affect food webs and ecosystem processes. In this paper, we compare pH regimes in streams at La Selva Biological Station, Costa Rica, where episodic acidification frequency across the stream network varies widely due to buffering from inputs of bicarbonate-rich inter-basin groundwater. To examine the effects of acidification on ecosystem structure and function, we experimentally increased the buffering capacity of a headwater stream reach, and compared it to an unbuffered upstream reach. We compared these reaches to a naturally buffered and unbuffered reaches of a second headwater stream. We quantified ecosystem structural (macroinvertebrate assemblages on leaf litter and coarse woody debris), and functional responses (leaf litter and coarse woody debris decomposition rates, and growth rates of a focal ...干扰作用可改变生态系统的结构与功能。在溪流生态系统中，径流量与物理化学性质在短、中、长重现周期下的变化，均会影响食物网与生态系统过程。本研究针对哥斯达黎加拉塞尔瓦生物站（La Selva Biological Station）的溪流展开pH状况（pH regime）对比分析：该区域溪流网络的突发性酸化频率差异悬殊，其成因是富碳酸氢盐跨流域地下水输入所带来的缓冲效应。为探究酸化对生态系统结构与功能的影响，本研究通过实验手段提升了一处源头溪流河段的缓冲能力，并将其与未施加缓冲处理的上游河段进行对照；同时还将上述河段与第二条源头溪流的天然缓冲河段及未缓冲河段进行了对比。本研究量化了生态系统的结构响应（叶片凋落物与粗木质残体上的大型无脊椎动物群落组成）与功能响应（叶片凋落物及粗木质残体的分解速率，以及目标类群的生长速率……）