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Photosynthetic, morphological, and growth responses to light environment can be useful measurements to determine favorable habitat conditions for the conservation of endangered species. For Lindera melissifolia (Walt.) Blume, we compared morphological and photosynthetic responses under natural and controlled light regimes, and growth under three light treatments: 100%, 42%, and 19% full sunlight. Typical sun--shade morphological responses to decreasing light levels included decreased stomatal density, increased specific leaf area, and increased leaf area ratio. Photosynthetic capacity (3-6 [micro]mol C[O.sub.2] . [m.sup.-2] . [s.sup.-1]) was consistent with other shade-tolerant species. Light-saturated rates of photosynthesis of experimental plants increased with increasing light up to 42% sunlight, but declined at 100% sunlight. The 100% light treatment also resulted in lower plant biomass, primarily from a reduction in root biomass. Results indicate that canopy conditions at levels below 40% sunlight are optimal for plant growth and should be considered in management and reintroduction efforts for this species. Key words: endangered species; Lauraceae; Lindera melissifolia; morphological plasticity; optimal habitat; photosynthetic light response; pondberry; shade tolerance.

Geographically isolated wetlands (GIWs) are common features of the Dougherty Plain physiographic region in southwestern Georgia. Due to lack of protection at the state and federal levels, these wetlands are threatened by intensive agricultural and silvicultural land uses common in the region. Recently, the ecological condition of such GIWs was assessed for the southeastern United States using the Landscape Development Intensity Index (LDI), a practical assessment tool that relies on remotely sensed land use and land cover (LULC) data surrounding isolated wetlands to rapidly predict wetland condition. However, no assessments have been attempted for GIWs in the Dougherty Plain specifically. Our goal was to develop a framework to guide and refine remote assessment of wetland condition within this agriculturally intense region of the southeastern USA. In this study, we characterized human disturbances associated with isolated wetlands in the Dougherty Plain, and paired the rapid assessment of GIWs using LDI with an intensive assessment of wetland plant communities. Specifically, we: (1) examined how macrophyte assemblages and vegetation metrics vary across a human disturbance gradient in the Dougherty Plain; (2) compared multiple condition assessment outcomes using variations of the LDI method that differed in spatial extent and resolution of LULC categories; and (3) determined the predicted condition of GIWs in the Dougherty Plain as indexed by LDI and compared with region-wide assessments of GIWs of the southeastern USA. Generally, the relationship between wetland plant communities and surrounding land use supported the assumptions of the LDI index in that wetlands surrounded by agricultural land use classes featured distinct plant communities relative to those surrounded by forested land use classes. Our results indicated that finer spatial resolution of LULC data improved the predictive ability of LDI. However, based on incongruence between wetland vegetation composition and LDI scores in some forested landscapes, this study identified limitations of the LDI assessment method, particularly when applied in regions in which prescribed fire is an important ecological driver of vegetation and habitat. Thus, we conclude that LDI may be biased toward an overestimation of reference condition GIWs, even though the habitat may be functionally degraded by the absence of natural processes such as fire. Regardless, relative to the assessment of the entire southeastern US, a greater proportion of total GIWs of the Dougherty Plain were identified as impaired due to the intensity of irrigated agricultural land use. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fires reduced germination and increased mortality of buried legume seeds. [•] Manipulation of fine fuel loads did not affect germination or mortality. [•] Burning pine cones reduced germination and survival more than fine fuels alone. [•] We present a conceptual model of burning pine cone effects on the soil seed bank. [Copyright &y& Elsevier]

Abstract: Restoring the fire-maintained longleaf pine (Pinus palustris Mill.) ecosystem in the southeastern United States has become a regional conservation priority in recent years and development of cost-effective approaches to restoration is a major objective. An improved understanding of the potential role of persistent seed banks in the longleaf pine ecosystem and reliance on the seed bank for restoration efforts could contribute to reduced costs associated with restoration. We used a buried seed bag method to determine seed banking potential of species within three common families (Poaceae, Fabaceae, and Asteraceae) and a rare, endangered member of the Orobanchaceae family native to the longleaf pine ecosystem. Seeds were exhumed 1, 2, 4, and 8years after burial and tested for viability. Species within the Fabaceae showed the greatest potential for forming long-term persistent seed banks with seed viability 50% or greater after 8years of burial. Some species in the Poaceae, Asteraceae, and Orobanchaceae form transient or short-term persistent seeds banks. The ability of some species to form short- or long-term persistent seed banks may in some cases make it possible to rely on the seed bank for native species re-introductions on sites scheduled for restoration. [Copyright &y& Elsevier]

Abstract: Globally, there is a growing awareness that geographically isolated wetlands contribute to important landscape functions and ecological services. One of their most important functions is providing habitat to a diverse fauna and flora adapted to variable wet and dry environments. We focus on analysis of similarities among three distinct taxa, vascular plants, aquatic beetles, and amphibians, in isolated wetlands in the southeastern coastal plain of Georgia. Although species richness for these three taxa is quite high in isolated wetlands at a regional scale, we found a low degree of congruence in species richness and species composition among taxa. This finding demonstrates that none of these groups could be used as a surrogate for the overall biodiversity of these wetlands represented by the three taxa. We identified environmental factors influencing the complex patterns of species richness and distribution for the three groups that indicate biotic and abiotic processes operate at different scales for each taxonomic group and for individual species. Our study illustrates the importance of considering structural diversity, hydrologic variation, and landscape position as key elements to understanding overall diversity represented by the three taxa in isolated wetlands and in developing assessment tools of wetland condition. [Copyright &y& Elsevier]

1. This correlational study examines the relationship between the red imported fire ant ( Solenopsis invicta) and native ants in a longleaf pine savanna. Fire ants are frequently associated with a decline in native ants throughout the invaded range, but fire ant invasion is often coupled with habitat disturbance. Invasion of fire ants into the longleaf pine savanna provides an opportunity to examine the structure of the ant community in the absence of habitat disturbance. 2. Pitfall trapping was conducted within the longleaf pine savanna as well as across a naturally occurring soil moisture gradient, in plots that had been artificially watered. 3. Species richness did not vary as a function of fire ant density. There was an inverse relationship between native ant density and fire ant density, but this abundance pattern does not necessarily imply a causal link between fire ant invasion and native ant decline. For individual species, fire ant densities were negatively correlated with the densities of only two native ant species, including Solenopsis carolinensis, a native species that potentially limits the invasion of fire ants. Additionally, fire ants and native ants respond differently to soil moisture, with native ants favouring drier conditions than fire ants. 4. The possible exclusion of fire ants by some native ants, as well as differences in habitat preferences, provide alternative explanations for the frequently observed negative correlation between fire ants and native ants. [ABSTRACT FROM AUTHOR]

Abstract Regeneration and expansion of Aristida beyrichiana and Aristida stricta (wiregrass) populations in remaining fire-maintained Pinus palustris (longleaf pine) stands of the southeastern United States has become an objective of land managers. Although growing-season fire is required for successful wiregrass seed production, studies examining naturally occurring wiregrass seedling dynamics are few. This study investigates how seedling survivorship is affected by season of burn, seedling size, time since germination, and proximity to adult plants. Restoration at this research site was begun in 1992 with the planting of containerized longleaf pine and wiregrass seedlings. Study plots were established in November 1997 after a growing-season prescribed fire (June 1996) that resulted in successful seed production and seedling recruitment. Burn treatment plots included (1) no burn (control), (2) fire in the dormant season of the first year after germination (March 1998), (3) fire in the growing season of the first year after germination (August 1998), and (4) fire in the growing season of the second year after germination (July 1999). Seedling mortality increased with growing season burning and close proximity to planted adults. Natural seedling recruitment continued into the second year after initial seed-drop in all plots, which verifies that wiregrass seed banking occurs for a minimum of 2 years after seed drop. Where wiregrass management objectives include population expansion, seedling recruits should be allowed 1 to 2 years post-germination without growing season fire for successful establishment. [ABSTRACT FROM AUTHOR]

Abstract Restoration of the longleaf pine ecosystems of the southeastern United States has focused interest on the regeneration and establishment of Aristida sp. (wiregrass) as a means to reestablish ecological function and structure of the ecosystem. This study examined dispersal distance from planted adults and canopy cover and density effects on establishment and reproduction. In 1994 wiregrass plugs were planted in two densities (500 seedlings/100 m2 and 49 seedlings/100 m2 ) and three canopy-thinning treatments (25 m2 basal area/ha, 16 m2 basal area/ha, and 8 m2 basal area/ha) were implemented in a 20-year-old longleaf plantation in southwestern Georgia. Due to the intense site preparation and the density of pines planted, virtually no understory vegetation was present. The site was burned in June 1995, which promoted seed production of the planted wiregrass. Results indicate that the 8 m2 basal area/ha treatment results in larger plants that in turn produce a greater number of seedling recruits. No seedling recruitment occurred in control plots. Dispersal distances of up to 594 cm were recorded. Natural seedling recruitment occurred at low-density transplanting (5 plants/10 m2 ), denoting that high-density planting similar to natural density (5 plants/m2 ) is not required for successful establishment or reproduction. However, overstory thinning in dense pine plantations is required for reproduction and increases the survival of individual plants due to changes in the environmental conditions at the forest floor. [ABSTRACT FROM AUTHOR]

When wetland restoration includes re-establishing native plant taxa as an objective, an understanding of the variables driving the development of plant communities is necessary. With this in mind, we examined soil and physiographic characteristics of depressional wetlands ofthree vegetation types (cypress-gum swamps, cypress savannas, and grass-sedge marshes) located in a fire-maintained longleaf pine ecosystem in southwestern Georgia, USA. Our objective was to establish whether plant community development in these wetlands is controlled primarily by hydrogeomorphic features or by different disturbance histories. We did not identify physical features that uniquely separate the wetland vegetation types. Instead, we observed a range of topo-edaphic conditions that likely drive variations in hydrologic regimes, which in turn, are probable influences on fire regime. We propose that several long-term successional trajectories may be initiated in the prolonged absence of fire, altered hydrology, or both, which link the distinctive vegetation types. Thus, a range of vegetation types may be suitable as potential restoration goals for these depressional wetlands. We suggest that the opportunities or constraints for use of prescribed fire in the long-term management of restored wetlands and adjacent uplands should be a significant consideration in the development ofrestoration strategies targeting specific plant communities. [ABSTRACT FROM AUTHOR]