Relationships Between Hydrology and Soils Describe Vegetation Patterns in Seasonally Flooded Tree Islands of the Southern Everglades, Florida

Abstract

Tree island ecosystems are important and distinct features of Florida Everglades wetlands. We described the inter-relationships among abiotic factors describing seasonally flooded tree islands and characterized plant-soil relationships in tree islands occurring in a relatively unimpacted area of the Everglades. We used Principal Components Analysis (PCA) to reduce our multi-factor dataset, quantified forest structure and vegetation nutrient dynamics, and related these vegetation parameters to PCA summary variables using linear regression analyses. We found that, of the 21 abiotic parameters used to characterize the ecosystem structure of seasonally flooded tree islands, 13 parameters were significantly correlated with four principal components, and they described 78% of the variance among the study islands. Most variation was described by factors related to soil oxidation and hydrology, exemplifying the sensitivity of tree island structure to hydrologic conditions. PCA summary variables describing tree island structure were related to variability in Chrysobalanus icaco (L.) canopy cover, Ilex cassine (L.) and Salix caroliniana (Michx.) canopy cover, Myrica cerifera (L.) plot frequency, litter turnover, % phosphorus resorption of co-dominant species, and nitrogen nutrient-use efficiency. This study supported findings that vegetation characteristics can be sensitive indicators of variability in tree island ecosystem structure. This study produced valuable, information which was used to recommend ecological targets (i.e. restoration performance measures) for seasonally flooded tree islands in more impacted regions of the Everglades landscape.

Litter decomposition promotes differential feedbacks in an oligotrophic southern Everglades wetland

“…Flow rate also described positive relationships with P and N concentrations and final mass P, and negative relationships with C:N molar ratio and absolute mass C (Table 3). Notably, flow rates measured in the marsh varied from 0.87 to 1.23 cm s -1 , 0.63 to 0.82 cm s -1 , and 0.62 to 0.72 cm s -1 in Flow, Wall and No Flow treatments, respectively (Troxler Gann and Childers 2006).…”

“…The post-levee increase in freshwater flow to the C-111 Basin provides a unique opportunity to investigate the effects of hydrologic restoration. We investigated the effects of this increase in freshwater input by selecting tree islands in two different locations relative to the C-111 canal (Troxler Gann and Childers 2006). Six islands were located directly downstream of this canal (i.e., islands with increased freshwater flow) and three islands were in an area west of the canal that had minimal influence of the levee removal (we refer to the latter three islands as ''No Flow'' islands; Fig.…”

“…1b). See Troxler Gann and Childers (2006) for details of our experimental design and other sampling.…”

“…From a larger dataset of environmental parameters collected in association with this study, and published elsewhere, we removed auto-correlated hydrologic parameters using Pearson correlation coefficients (Troxler Gann and Childers 2006). Hydroperiod, average water level, wet season water level, water flow rate, annual TP, TN and TOC loads were thus used to determine which of these factors had the greatest influence on leaf litter decomposition.…”

“…Hydroperiod, average water level, wet season water level, water flow rate, annual TP, TN and TOC loads were thus used to determine which of these factors had the greatest influence on leaf litter decomposition. See Troxler Gann and Childers (2006) for details of these data.…”