Algal Nutrient Limitation Bioassays in Sycamore Creek, Arizona, USA (2010-2020)

The primary objective of this project 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 dataset addresses patterns of nutrient limitation by primary producers as indicated by *in situ* growth on artificial substrates.本项目的核心研究目标为阐明长期气候变异性与气候变化如何通过作用于水文扰动格局（hydrologic disturbance regimes），进而影响荒漠溪流的结构与功能。干旱景观中气候与水文联系紧密，正因如此，荒漠溪流尤其适于观测并解析气候变异性与方向性变化所带来的生态效应。研究人员拟开展两项研究：其一，明确多年尺度的气候变异性与气候变化如何通过调控植被生物量的相关影响因子，进而作用于溪流生物地貌结构（biogeomorphic structure）——即湿地与砾石床生态系统状态的占比与存续性；其二，对比两种截然不同的河段类型（湿地河段与砾石床溪流河段）的生态系统过程、初级生产者（primary producers）与消费者（consumers）群落结构的年内演替格局的年际变异性。本数据集聚焦于初级生产者的养分限制格局，该格局可通过人工基质（artificial substrates）上的原位（in situ）生长情况予以表征。