RECOVER MAP 3.1.3.6 Landscape Pattern - Ridge, Slough, and Tree Island Mosaics 4600001726 Baseline

In the current managed Everglades system, the pre-drainage, patterned mosaic of sawgrass ridges, sloughs and tree islands has been substantially altered or reduced largely as a result of human alterations to historic ecological and hydrological processes that sustained landscape patterns. The pre-compartmentalization ridge and slough landscape was a mosaic of sloughs, elongated sawgrass ridges (50-200m wide), and tree islands. The ridges and sloughs and tree islands were elongated in the direction of the water flow, with roughly equal area of ridge and slough. Over the past decades, the ridge-slough topographic relief and spatial patterning have degraded in many areas of the Everglades. Nutrient enriched areas have become dominated by Typha with little topographic relief; areas of reduced flow have lost the elongated ridge-slough topography; and ponded areas with excessively long hydroperiods have experienced a decline in ridge prevalence and shape, and in the number of tree islands (Sklar et al. 2004, Ogden 2005).

Decoupling of soil elevations from underlying bedrock topography in areas of relatively conserved landscape pattern suggests that historic microtopography and landscape structure were self-organized by feedbacks between vegetation, hydrology, and soil elevations. Potential mechanisms for such positive feedbacks include differential peat production, sediment entrainment and deposition, transpiration-driven nutrient concentration (particularly in tree islands), and hydrologic competence (Larsen et al. 2007, Givnish et al. 2007, Ross et al. 2006, Watts et al in review). While the relative importance of and interactions between these mechanisms remains an active area of research, observations of pattern loss in response to hydrologic management, nutrient enrichment, and other disturbances points to the disruption of those feedbacks as a primary cause of landscape degradation (Sklar et al. 2004).
This monitoring project seeks to provide information necessary for the evaluation of efficacy of the Comprehensive Everglades Restoration Program (CERP), as delineated in the Water Resources Development Act (WRDA) of 2000. The work described will provide indices of system-wide applicability of performance measures related to the response of the ridge-slough mosaic, tree islands, and other landscape features of the central Everglades to the restoration of historic hydrologic conditions, with the goal of informing the adaptive management of Everglades restoration as outlined in the CERP Monitoring and Assessment Plan (RECOVER 2004).

The general goals of restoration are to stem, and possibly reverse, degradation of the ridge-slough-tree island landscape by redirecting flows now released unused to coastal waters across the surface of this landscape (USACE and SFWMD 1999). The CERP MAP, Parts 1 and 2, presented the overarching monitoring framework for guiding restoration efforts throughout the entire process (RECOVER 2004, 2006). This requires not only a comprehensive assessment of the current state of the ecosystem and assessment of restoration endpoints (targets), but also ongoing monitoring and evaluation throughout the process that will aid the implementing agencies in optimizing operational procedures and project designs. The work described below is the first step toward full implementation of the system wide landscape monitoring design that was developed with RECOVER MAP funds and provides for a multi-year monitoring program for the Greater Everglades Wetlands ecosystem.

The primary objective of this monitoring project is to begin systematic implementation of a landscape sampling design, described below, across the Greater Everglades Wetlands ecosystem. This effort will establish the current condition of the ridge and slough ecosystem and will allow scientists to detect changes/trends in the patterns and vegetation communities of these systems as a result of water management operations, restoration initiatives and episodic events such as droughts, fire and hurricanes. Our secondary objective of this project is to work with other RECOVER researchers to integrate knowledge regarding landscape patterning, soil dynamics and community structure and composition with hydrologic data provided by Everglades Depth Estimation Network (EDEN) and other sources. We will pay particular attention to how these dynamics might: 1) be affected by restoration and 2) relate to CERP hypotheses from the MAP. The resulting data will be utilized to validate existing models and establish or revise restoration targets.
This four (4) year monitoring project addresses needs identified in the Greater Everglades wetlands performance measures: 1) Wetland Landscape Patterns – Ridge-Slough Community Sustainability and 2) Wetland Landscape Patterns - Marl Prairie Cape Sable Sparrow Habitat. Our proposal specifically address the Greater Everglades Wetland Landscape and Plant Community Dynamics hypotheses: 1) ridge and slough micro-topography in relation to organic soil accretion and loss, 2) ridge and slough landscape pattern in relation to microtopography, and 3) plant community dynamics along elevation gradients as water depths and thus hydroperiods change (RECOVER 2006).
The specific objectives of the proposed work are:
1) To determine extant reference conditions for each of the performance measures described below (including variability of those measures in time and space).
2) To establish present status of landscape performance measures throughout the central Everglades, particularly in areas of historic ridge-slough landscape patterning, identify spatial and temporal trends of those performance measures, and quantify their relationships to the present hydrologic regime.
3) To detect unanticipated changes in ecosystem structure and processes that result from hydrologic management or manipulation, CERP restoration activities, or climatic variation
4) To provide data in support of scientific studies of inter-relationships among vegetation, microtopography, and hydrologic regime that may provide insight into the causes of unanticipated ecosystem responses.

Monitoring efforts will consist of three core components: (1) mapping vegetation features from aerial photographs, (2) aerial surveys for classification of tree island type, and (3) ground surveys of water depth and plant community structure (both tree island and marsh), which will be used to quantify aspects of the hydrologic regime, determine relationships between vegetation structure and water depth, quantify the distribution and spatial structure of peat elevations, and ground-truth broader-scale maps based on remote sensing and aerial surveys.