Sammy L. King

The Role of the Wetland Reserve Program in Conservation Efforts in the Mississippi River Alluvial Valley

Abstract The Mississippi River Alluvial Valley includes the floodplain of the Mississippi River from Cairo, Illinois, USA, to the Gulf of Mexico. Originally this region supported about 10 million ha of bottomland hardwood forests, but only about 2.8 million ha remain today. Furthermore, most of the remaining bottomland forest is highly fragmented with altered hydrologic processes. During the 1990s landscape-scale conservation planning efforts were initiated for migratory birds and the threatened Louisiana black bear (Ursus americanus luteolus). These plans call for large-scale reforestation and restoration efforts in the region, particularly on private lands. In 1990 the Food, Agriculture, Conservation and Trade Act authorized the Wetlands Reserve Program (WRP). The WRP is a voluntary program administered by the United States Department of Agriculture that provides eligible landowners with financial incentives to restore wetlands and retire marginal farmlands from agricultural production. As of 30 September 2005, over 275,700 ha have been enrolled in the program in the Mississippi River Alluvial Valley, with the greatest concentration in Louisiana, Arkansas, and Mississippi, USA. Hydrologic restoration is common on most sites, with open-water wetlands, such as moist-soil units and sloughs, constituting up to 30% of a given tract. Over 33,200 ha of open-water wetlands have been created, potentially providing over 115,000,000 duck-use days. Twenty-three of 87 forest-bird conservation areas have met or exceed core habitat goals for migratory songbirds and another 24 have met minimum area requirements. The WRP played an integral role in the fulfillment of these goals. Although some landscape goals have been attained, the young age of the program and forest stands, and the lack of monitoring, has limited evaluations of the programs impact on wildlife populations.

The ecology, restoration, and management of southeastern floodplain ecosystems: A synthesis

Floodplain ecosystems of the southeastern United States provide numerous services to society, but hydrologic and geomorphic alterations, agricultural practices, water quality and availability, and urban development continue to challenge restorationists and managers at multiple spatial and temporal scales. These challenges are further exacerbated by tremendous uncertainty regarding climate and land use patterns and natural variability in these systems. The symposium from which the papers in 2009 ensued was organized to provide a critical evaluation of current natural resource restoration and management practices to support the sustainability of floodplain ecosystem functions in the southeastern United States. In this paper we synthesize these concepts and evaluate restoration and conservation techniques in light of our understanding of these ecosystems. We also discuss current and future challenges and attempt to identify new approaches that may facilitate the long-term sustainability of southeastern floodplain systems. We conclude that integration of disciplines and approaches is necessary to meet the floodplain conservation challenges of the coming century. Integration will not only include purposeful dialogue between interdisciplinary natural resource professionals, but it also is necessary to sincerely engage the public about goals, objectives, and desirable outcomes of floodplain ecosystem restoration.

Effects of Landscape Features on Waterbird Use of Rice Fields

Abstract. Literature is reviewed to determine the effects of landscape features on waterbird use of fields in regions where rice (Oryza sativa) is grown. Rice-growing landscapes often consist of diverse land uses and land cover, including rice fields, irrigation ditches, other agricultural fields, grasslands, forests and natural wetlands. Numerous studies indicate that local management practices, such as water depth and timing of flooding and drawdown, can strongly influence waterbird use of a given rice field. However, the effects of size and distribution of rice fields and associated habitats at a landscape scale have received less attention. Even fewer studies have focused on local and landscape effects simultaneously. Habitat connectivity, area of rice, distance to natural wetlands, and presence and distance to unsuitable habitat can be important parameters influencing bird use of rice fields. However, responses to a given landscape vary with landscape structure, scale of analysis, among taxa and within taxa among seasons. A lack of multi-scale studies, particularly those extending beyond simple presence and abundance of a given species, and a lack of direct tests comparing the relative importance of landscape features with in-field management activities limits understanding of the importance of landscape in these systems and hampers waterbird conservation and management.

Vegetation, soil, and flooding relationships in a blackwater floodplain forest

Hydroperiod is considered the primary determinant of plant species distribution in temperate floodplain forests, but most studies have focused on alluvial (sediment-laden) river systems. Few studies have evaluated plant community relationships in blackwater river systems of the South Atlantic Coastal Plain of North America. In this study, we characterzied the soils, hydroperiod, and vegetation communities and evaluated relationships between the physical and chemical environment and plant community structure on the floodplain of the Coosawhatchie River, a blackwater river in South Carolina, USA. The soils were similar to previous descriptions of blackwater floodplain soils but had greater soil N and P availability, substantially greater clay content, and lower soil silt content than was previously reported for other blackwater river floodplains. Results of a cluster analysis showed there were five forest communities on the site, and both short-term (4 years) and long-term (50 years) flooding records documented a flooding gradient: water tupelo community > swamp tupelo > laurel oak = overcup oak > mixed oak. The long-term hydrologic record showed that the floodplain has flooded less frequently from 1994 to present than in previous decades. Detrended correspondence analysis of environmental and relative basal area values showed that 27% of the variation in overstory community structure could be explained by the first two axes; however, fitting the species distributions to the DCA axes using Gaussian regression explained 67% of the variation. Axes were correlated with elevation (flooding intensity) and soil characteristics related to rooting volume and cation nutrient availability. Our study suggests that flooding is the major factor affecting community structure, but soil characteristics also may be factors in community structure in blackwater systems.

THE EFFECTS OF FLOODING AND SEDIMENTATION ON SEED GERMINATION OF TWO BOTTOMLAND HARDWOOD TREE SPECIES

Flooding and sedimentation are two of the dominant disturbances that influence tree species composition and succession in floodplain forests. The importance of these disturbances may be most notable during the germination and establishment phases of plant succession. Channelization of most alluvial systems in the southeastern United States has caused dramatic and systematic alterations to both hydrologic and sedimentation processes of floodplain systems. We determined the influence of these altered abiotic processes on the germination and growth of two common floodplain tree species: swamp chestnut oak (Quercus michauxii Nutt.) and overcup oak (Q. lyrata Walt.). Flood durations of 0 days, 15 days, and 30 days prior to germination was a factor in germination, but the effect varied by species. For instance, overcup oak, which has a higher tolerance to flooding than swamp chestnut oak, had higher germination rates in the flooded treatments (15-day -x = 78% and 30-day -x = 85%) compared to the non-flooded treatment (-x = 54%). In contrast, germination rates of swamp chestnut oak were negatively affected by the 30-day flood treatment. Sediment deposition rates of 2 cm of top soil, 2 cm of sand, and 8 cm of sand also affected germination, but were secondary to flood duration. The main effect of the sediment treatment in this experiment was a reduction in above-ground height of seedlings. Our study provides evidence for the importance of both flooding and sedimentation in determining tree species composition in floodplain systems, and that tolerance levels to such Stressors vary by species.

Plant succession and greentree reservoir management: implications for management and restoration of bottomland hardwood wetlands

Bottomland hardwood forests are distributed along rivers and streams throughout the central and eastern United States, with the greatest concentration in the Southeast. Past and projected losses of bottomland hardwoods and degradation of remaining stands suggest that habitat management and/or restoration strategies that target multiple species and multiple uses will be necessary to maintain, enhance, and restore flora and fauna within bottomland hardwood wetlands. A greentree reservoir is a current management strategy that entails manipulating water regimes to provide habitat for wintering waterfowl. We conducted a literature review and synthesis to determine the potential impacts of greentree reservoir management on plant succession within bottomland hardwood wetlands. Greentree reservoirs can impact vegetation establishment through several processes. Despite shortcomings of greentree reservoirs, designs similar to them could be very beneficial in restoring bottomland hardwood plant and animal communities from degraded forests provided water-level control and maintenance are substantially improved. Emulation of natural hydrologic regimes, including natural variability, could produce diverse bottomland hardwood plant communities and provide habitat for a variety of wildlife species.

Effects of flooding regimes on two impounded bottomland hardwood stands

The relationships between flooding regimes, stand structure, regeneration, and tree stress and mortality were evaluated within two overcup oak (Quercus lyrata) — willow oak (Quercus phellos) greentree reservoirs, one impoundment with levees and one without levees. Record rainfall resulted in extensive growing-season flooding in both impoundments; however, the levee system and the topographic relief of the impoundment with levees impeded drainage of surface water and prolonged growing-season flooding. Limited regeneration of all species except overcup oak was observed in both impoundments. In the impoundment with levees, the total number of overcup oak seedlings at peak establishment and overcup oak seedling mortality were related to flooding regimes. In the impoundment without levees, establishment densities were not related to any of the measured environmental variables. Stress and mortality were significantly higher in trees in larger diameter classes, and stress generally increased with flooding. these results suggest that the decision to create GTRs within a stand of naturally flooded bottomland hardwoods should be thoroughly and cautiously reviewed.

Relative Nest Density, Nest Success, and Site Occupancy of King Rails in Southwestern Louisiana Rice Fields

Abstract King Rail (Rallus elegans) populations are listed as threatened or endangered in 13 states. One remaining area of relative abundance is the rice-growing region of southwestern Louisiana. Rice fields are flooded for much of the year and support thick emergent vegetation, potentially providing high-quality habitat for King Rails. The objectives of this study were to determine: 1) relative nest density of King Rails in rice; 2) which local and landscape factors influence relative nest densities; 3) nest survival of King Rails in rice fields; 4) effectiveness of callback surveys in indicating King Rail breeding activity; and 5) site occupancy of King Rails in rice fields. In the summers of 2004 and 2005, King Rail surveys and nest searches were conducted in Cameron, Jefferson Davis, Vermilion, and Acadia Parishes in southwestern Louisiana. In 2004, 42 fields were searched for nests and 30 of those were surveyed with callback survey techniques. In 2005, 40 fields were searched and 60 were surveyed. A total of 77 King Rail nests was found, and relative nest density was between 3.4 and 4.8 nests/km2. The highest nest densities were in fields with a high proportion of irrigation canals around the perimeters and a low proportion of trees. Nest survival was ∼50% in both years. Most survey responses were detected in June, and survey detections were correlated with nest abundance. Site occupancy was estimated as 0.35 ± 0.11 in 2004 (no estimates for 2005) from callback surveys and between 0.4 (2004) and 0.5 (2005) from nest searches. Callback surveys were an effective technique for monitoring King Rails in this region. Given high nest survival rates and apparently stable nest densities, rice fields appear to provide high-quality habitat for King Rails in southwestern Louisiana.

EFFECTS OF CANOPY GAPS AND FLOODING ON HOMOPTERANS IN A BOTTOMLAND HARDWOOD FOREST

Canopy disturbance is a major factor affecting forest structure and composition and, as a result of habitat alterations, can influence insect communities. We initiated a field study to quantify the effects of canopy disturbance on aerial insect abundance and distribution within a bottomland hardwood forest along the Cache River, Arkansas, USA. We used passive flight-intercept traps to sample insects in canopy gap and forest interior habitats from May to July in 1996, 1997, and 1998. The hydrologic conditions of our study site varied among years: 1996 was relatively dry, 1997 incurred a long-duration flood, and 1998 was moderately wet. Of the 34,000+ Homopterans collected, many groups were distributed in a non-uniform manner among years and between habitats. Total Homopterans, two families of Homopterans, and six morphospecies were more abundant in canopy gaps than interior forest. Many Homopteran taxa were least abundant in 1997 following almost six months of flooding. Alternatively, relatively large Homopteran abundances were associated with the dry conditions of 1996 and the moderately wet conditions of 1998. Differences in Homopteran abundance among years and habitats may be related to differences in vegetation density. Canopy gaps supported more vegetation cover than the interior forest in all but the first sampling interval. In addition, similar to Homopteran abundance, vegetation density was lower in 1997 than in 1998. These results demonstrate that natural disturbance and flooding contribute to Homopteran abundance and distribution patterns in bottomland hardwood forests of the south central United States.

LEAST BITTERN DISTRIBUTION AMONG STRUCTURALLY DIFFERENT VEGETATION TYPES IN MANAGED WETLANDS OF NORTHWEST TENNESSEE, USA

We conducted Least Bittern (Ixobrychus exilis) surveys on Reelfoot Lake and nearby Black Bayou Waterfowl Refuge, in northwest Tennessee, USA during May–June 2003 to determine the distribution of Least Bitterns among structurally different vegetation types, including giant cutgrass (Zizaniopsis miliacea), swamp loosestrife (Decodon verticillatus), and woody vegetation. Least Bitterns were historically abundant on Reelfoot Lake when giant cutgrass once occupied 1,000 ha, but water-level stabilization resulted in 93% of the emergent zone now being dominated by swamp loosestrife interspersed with trees and saplings, including baldcypress (Taxodium distichum) and maple (Acer spp.). Least Bitterns were detected 49 times. Sites with Least Bitterns had greater percent giant cutgrass coverage, less woody vegetation coverage, and fewer tall trees than sites where Least Bitterns were not detected; however, Least Bittern presence was positively related with only giant cutgrass coverage and was unrelated to woody vegetation coverage or tall tree density. Density of Least Bitterns was greater on Black Bayou (0.45/ha) than Reelfoot Lake (0.11/ha). The lower density of Least Bitterns on Reelfoot Lake is partially attributed to the shift in the dominant emergent species from a grass to a shrub. In the absence of vegetation management, Least Bitterns will continue to decline on Reelfoot Lake as many swamp loosestrife marshes convert to forests.