CRB:Manipulation of Vertical and Horizontal Heterogeneity in a Large-Scale, Restoration Experiment

[01:21 . 05]生态系统退化通常涉及地形异质性的丧失，地形异质性是一种重要的生态系统属性，随着沉积物填满洼地、使地表变平和海拔升高而下降。在南加州，因支持濒危动植物而备受重视的沿海栖息地遭受了灾难性的沉积，随之而来的是物种分布的改变和生物多样性的降低。当试图恢复时，地形的复杂性通常被忽略，因为沉积物是由推土机挖掘出来的。垂直和水平异质性不足可能是湿地恢复到与未受干扰地点的结构和功能等效的关键制约因素。在本项目中，我们将研究增加地形异质性如何加速生态系统恢复的进程。本文的主要假设是，在湿地中加入垂直和水平格局有助于湿地结构和功能的恢复。为了验证这一假设，在蒂华纳河国家河口研究保护区（加利福尼亚州圣地亚哥县）内设计了一个完整的8公顷潮汐湿地恢复场地，以支持大规模的生态实验。这项耗资310万美元的挖掘工程已于2000年2月完成，并连接了一条主要的潮汐通道。在恢复潮汐冲刷后的22个月里，我们监测了几个特征。我们建议充分利用实验处理，研究(1)地形异质性的垂直模式，以复杂的潮汐溪流网络的形式，(2)盐沼盐植物种植密度的变化提供的水平模式，对多种响应变量和营养水平的多样性、丰度和组成的影响：地貌、藻类、维管植物、无脊椎动物和鱼类。除了测试湿地恢复的方法外，本文提出的综合工作将展示恢复实验的力量，并为地形异质性与生态系统结构（物种组成和丰度）和功能（例如生态系统）的发展之间的关系提供新的见解。（以鱼为食）。保护与恢复生物学（CRB）。

0212005ZedlerEcosystem degradation often involves the loss of topographic heterogeneity, a criticalecosystem property that declines as sediments fill in depressions, flatten surfaces andraise elevations. In southern California, coastal habitat that is highly valued for itssupport of endangered plants and animals has suffered catastrophic sedimentation,followed by altered species distributions and lowered biodiversity. When recovery isattempted, topographic complexity is typically ignored as sediments are excavated andrestoration sites contoured by bulldozer. Insufficient vertical and horizontalheterogeneity might be a key constraint on the restoration of wetlands toward structuraland functional equivalency with undisturbed sites.In this project, we will investigate how adding topographic heterogeneity mightaccelerate the progress of ecosystem restoration. The principal hypothesis is that addingvertical and horizontal pattern at to will facilitate the restoration of wetland structure andfunction. To test this hypothesis, an entire 8-ha tidal wetland restoration site within theTijuana River National Estuarine Research Reserve (San Diego County, CA) wasdesigned to support the large-scale, ecological experiment. The $3.1-million excavationwas completed in February 2000 with the connection of the site to a main tidal channel,and we have monitored several attributes over the 22 months since tidal flushing wasreinstated. We propose to take full advantage of the experimental treatments andexamine the influence of (1) a vertical pattern of topographic heterogeneity, in the formof complex tidal creek networks, and (2) a horizontal pattern furnished by varyingdensities of planted salt marsh halophytes, on the diversity, abundance and compositionof multiple response variables and trophic levels: geomorphology, algae, vascular plants,invertebrates, and fish.In addition to testing methods for recovering wetlands, the integrative work proposedherein will demonstrate the power of restoration experiments and contribute fundamentalnew insights into the relationship between topographic heterogeneity and thedevelopment of ecosystem structure (species composition and abundance) and function(e.g., foraging by fish). Conservation and Restoration Biology (CRB).