Water chemistry in Sycamore Creek, Phoenix Arizona, 2010 to 2013

The primary objective of this LTREB is to understand how long-term climate variability and change influence the structure and function of desert streams via effects on hydrologic disturbance regimes. Climate and hydrology are intimately linked in arid landscapes; for this reason, desert streams are particularly well suited for both observing and understanding the consequences of climate variability and directional change. Researchers try to (1) determine how climate variability and change over multiple years influence stream biogeomorphic structure (i.e., prevalence and persistence of wetland and gravel-bed ecosystem states) via their influence on factors that control vegetation biomass, and (2) compare interannual variability in within-year successional patterns in ecosystem processes and community structure of primary producers and consumers of two contrasting reach types (wetland and gravel-bed stream reaches). This specific dataset was collected to monitor long term changes in dissolved nutrient concentrations (N, P, C) by sampling surface water within gravel and wetland dominated reaches during base-flow. We also seek to determine amounts of nutrient input to these sites during late summer (monsoon) and winter flood events.

本长期生态生物学研究项目（Long-Term Research in Environmental Biology，LTREB）的核心研究目标，是厘清长期气候变异性与气候变化如何通过影响水文扰动格局，进而调控荒漠溪流的结构与功能。干旱景观中气候与水文紧密耦合，正因如此，荒漠溪流成为观测与解析气候变异性及方向性变化所产生影响的理想研究对象。本研究旨在完成两项核心任务：其一，通过调控植被生物量的相关驱动因子，明确多年尺度的气候变异性与气候变化如何影响溪流生物地貌结构——即湿地与砾石床生态系统状态的分布范围与存续时长；其二，对比两类具有显著差异的河段类型（湿地河段与砾石床溪流河段）的初级生产者、消费者类群的群落结构，以及生态系统过程的年内演替模式的年际变异性。本数据集通过在基流期对以砾石床和湿地为主的河段采集地表水样本，旨在监测溶解态营养盐（氮、磷、碳）浓度的长期变化。此外，本研究还将量化夏末（季风期）与冬季洪水事件期间，上述监测河段的营养盐输入量。