Top 20 NRS Pubs 20 NRS Pubsen-usMon, 10 Dec 2018 22:20:47 +0000Citizen science and tree health assessment How useful are the data? ash borer (Agrilus planipennis) has killed millions of trees in the United States. Community managers face treatment or removal decisions for all publicly owned ash (Fraxinus spp.) trees. These decisions are based on the overall condition of each tree. In this study the U.S. Forest Servicetrained a Boy Scout troop in Oconomowoc Wisconsin U.S. in a tree health assessment protocol that used rubrics designed to measure physiological stress symptoms. The city provided tree inventory data which included the location of 316 cityowned ash trees. After a twohour training session the Scouts and adult leaders assessed all ash trees in August 2015. A tree health expert reassessed 20 of the trees. The protocol measured diameter at breast height and included a suite of tree stress assessment variables. Researchers used a fiveclass system for defoliation leaf discoloration and overall vigor. Finetwig dieback was estimated in 5 classes. Digital photographs were taken and automatically processed so as to measure percent crown transparency. Expertvolunteer agreement for diameter at breast height was within 2.5 cm 92 of the time defoliation discoloration and vigor were within two classes 100 93 and 92 of the time respectively. Crown dieback estimates were within 10 of each other 76 of the time and transparency estimates were within 15 of each other 76 of the time. Researchers calculated an overall stress index value and ranked the trees from lowest to highest stress. The volunteer generated data enabled Oconomowoc to make sciencebased management decisions for its infested ash trees.Tue, 04 Dec 2018 08:46:03 +0000Comparing the stockchange and gainloss approaches for estimating forest carbon emissions for the aboveground biomass pool approaches to greenhouse gas (GHG) inventories are common namely the stockchange approach and the gainloss approach. With the stockchange approach mean annual emissions are estimated as the ratio of the difference in stock estimates at two points in time and the number of intervening years. The stockchange approach is fairly easy to implement for countries with wellestablished forest sampling programs. However countries without established forest sampling programs more commonly use the gainloss approach. With this approach emissions are estimated as the product of the areas of classes of land use change characterized as activity data and the responses of carbon stocks for those classes characterized as emission factors. Regardless of the approach the Intergovernmental Panel on Climate Change (IPCC) good practice guidelines specify that GHG inventories produce neither over nor underestimates and reduce uncertainties to the degree possible. For a study area in southeastern Norway the objectives of the study were to compare the stockchange and gainloss approaches with respect to estimates of carbon emissions for the aboveground biomass pool and to illustrate statistically rigorous methods for complying with the two IPCC good practice guidelines for both approaches. The primary conclusions were that the two approaches produced comparable estimates of mean annual emissions but that the stockchange approach produced considerably smaller estimates of uncertainty.Mon, 26 Nov 2018 12:28:10 +0000Evaluating Adaptive Management Options for Black Ash Forests in the Face of Emerald Ash Borer Invasion arrival and spread of emerald ash borer (EAB) across the western Great Lakes region has shifted considerable focus towards developing silvicultural strategies that minimize the impacts of this invasive insect on the structure and functioning of black ash (Fraxinus nigra) wetlands. Early experience with clearcutting in these forests highlighted the risks of losing ash to EAB from these ecosystems with stands often retrogressing to marshlike conditions with limited tree cover. Given these experiences and an urgency for increasing resilience to EAB research efforts began in northcentral Minnesota in 2009 followed by additional studies and trials in Michigan and Wisconsin to evaluate the potential for using regeneration harvests in conjunction with planting of replacement species to sustain forested wetland habitats after EAB infestations. Along with these more formal experiments a number of field trials and demonstrations have been employed by managers across the region to determine effective ways for reducing the vulnerability of black ash forest types to EAB. This paper reviews the results from these recent experiences with managing black ash for resilience to EAB and describes the insights gained on the ecological functioning of these forests and the unique foundational role played by black ash.Wed, 28 Nov 2018 07:36:54 +0000Forested versus herbaceous wetlands Can management mitigate ecohydrologic regime shifts from invasive emerald ash borer? selforganize through reciprocal controls between vegetation and hydrology but external disturbance may disrupt these feedbacks with consequent changes to ecosystem state. Imminent and widespread emerald ash borer (EAB) infestation throughout North American forested wetlands has raised concern over possible ecosystem state shifts (i.e. wetter more herbaceous systems) and loss of forest function calling for informed landscapescale management strategies. In response we employed a largescale manipulative study to assess the ecohydrologic response of black ash wetlands to three alternative EAB management strategies 1) a donothing approach (i.e. simulated EAB infestation via tree girdling) 2) a preemptive complete harvesting approach (i.e. clearcut) and 3) an overstory replacement approach via group selection. We analyzed six years of daily water table and evapotranspiration (ET) dynamics in six blocks comprising black ash wetlands (controls) and management strategy treatments to quantify potential for hydrologic change and subsequent recovery. In both the donothing approach and complete harvesting approach we found persistent changes in hydrologic regime defined by shallower water tables and lower ET rates coupled with increased herbaceous vegetation growth indicating ecosystem state shifts driven by vegetationwater table interactions. The donothing approach showed the least hydrologic recovery after five years which we attribute to reduction in overstory transpiration as well as greater shade (via standing dead trees) that reduces open water evaporation and herbaceous layer transpiration compared to complete harvesting. We found no evidence of ecohydrologic disturbance in the overstory replacement approach highlighting its potential as a management strategy to preserve forested wetland habitat if periodically executed over time before EAB infestation. Although the scale of potential disturbance is daunting our findings provide a baseline assessment for forest managers to develop preemptive mitigation strategies to address the threat of EAB to ecological functions in black ash wetlands.Wed, 28 Nov 2018 07:47:55 +0000Four new species of Morchella from the Americas and molecular phylogenetic studies of true morels (Morchella) in North America the Dominican Republic Venezuela Ecuador and Peru led to the discovery of four undescribed species of Morchella. Two new species in the Elata clade one from the Dominican Republic initially distinguished by the informal designation Mel18 and a newly discovered sister species from northern Arizona are now recognized. Mel18 is described as a novel phylogenetically distinct species M. hispaniolensis. Its sister species from Arizona is described as M. kaibabensis also recovered as an endophyte of Rocky Mountain juniper. Two additional species in the Esculenta clade M. peruviana discovered in Peru and M. gracilis (previously reported as Mes14) from the Dominican Republic Venezuela and Ecuador are described as new. We also demonstrate that scanning electron microscopy (SEM) imaging of ascospores using rehydrationdehydration critical point drying preparation techniques provides for enhanced resolution of spore wall surfaces thereby increasing the number of morphological traits available to assess differences among otherwise closely related species.Fri, 07 Dec 2018 07:03:10 +0000Interspecific competition limits the realized niche of Fraxinus nigra along a waterlogging gradient studies of wetland forests have inferred that competition from upland tree species confines waterloggingtolerant tree species to hydric environments. Little is known however about competition effects on individualtree growth along stress gradients in wetland forests. We investigated tree growth and competition in mixedspecies stands representing a waterlogging stress gradient in Fraxinus nigra Marsh. (black ash) forests in Minnesota USA. Using competition indices we examined how F. nigra basal area increment (BAI) responded to competition along the gradient and whether competition was sizeasymmetric (as for light) or sizesymmetric (as for soil resources). We modeled spatial distributions of F. nigra and associated tree species to assess how variation in species mixtures influenced competition. We found that although F. nigra BAI did not significantly differ with variations in site moisture the importance of competition decreased as waterlogging stress increased. Competition across the gradient was primarily sizeasymmetric (for light). Variation in species mixtures along the gradient was an important influence on competition. Some segregation of tree species occurred at all but the most upland site where waterlogging stress was lowest and evidence of competition was greatest confirming that competition from upland tree species confines F. nigra and potentially other waterloggingtolerant species to hydric environments.Wed, 28 Nov 2018 09:27:39 +0000Is Indonesian peatland loss a cautionary tale for Peru? A twocountry comparison of the magnitude and causes of tropical peatland degradation and Peru harbor some of the largest lowland tropical peatland areas. Indonesian peatlands are subject to much greater anthropogenic activity than Perus including drainage logging agricultural conversion and burning resulting in high greenhouse gas and particulate emissions. To derive insights from the Indonesian experience we explored patterns of impact in the two countries and compared their predisposing factors. Impacts differ greatly among Indonesian regions and the Peruvian Amazon in the following order Sumatra gt Kalimantan gt Papua gt Peru. All impacts except fire are positively related to population density. Factors enhancing Indonesian peatlands susceptibility to disturbance include peat doming that facilitates drainage coastal location high local population road access government policies permitting peatland use lack of enforcement of protections and dry seasons that favor extensive burning. The main factors that could reduce peatland degradation in Peru compared with Indonesia are geographic isolation from coastal population centers more compact peatland geomorphology lower population and road density more peatlands in protected areas different land tenure policies and different climatic drivers of fire whereas factors that could enhance peatland degradation include oil and gas development road expansion in peatland areas and an absence of government policies explicitly protecting peatlands. We conclude that current peatland integrity in Peru arises from a confluence of factors that has slowed development with no absolute barriers protecting Peruvian peatlands from a similar fate to Indonesias. If the goal is to maintain the integrity of Peruvian peatlands government policies recognizing unique peatland functions and sensitivities will be necessary.Thu, 29 Nov 2018 13:52:13 +0000iTree Global tools to assess tree benefits and risks to improve forest management ( is a suite of freelyavailable software tools designed to assess the benefits and values derived from trees and forests. Originally released in 2006 and designed to work in the United States these tools have expanded globally among professional and nonprofessional users (e.g. universities citizens schools land managers foresters) in more than 130 countries. iTree was developed through a collaborative publicprivate partnership and is designed to engage people in assessing and valuing their forest resources understanding forest risk and developing sustainable forest management plans to improve environmental quality and human health. These tools can be scaled to assess individual trees or entire forests in both urban and rural areas.Thu, 06 Dec 2018 06:58:39 +0000Nitrogen oligotrophication in northern hardwood forests much research over the past 30 years has focused on the deleterious effects of excess N on forests and associated aquatic ecosystems recent declines in atmospheric N deposition and unexplained declines in N export from these ecosystems have raised new concerns about N oligotrophication limitations of forest productivity and the capacity for forests to respond dynamically to disturbance and environmental change. Here we show multiple data streams from longterm ecological research at the Hubbard Brook Experimental Forest in New Hampshire USA suggesting that N oligotrophication in forest soils is driven by increased carbon flow from the atmosphere through soils that stimulates microbial immobilization of N and decreases available N for plants. Decreased available N in soils can result in increased N resorption by trees which reduces litterfall N input to soils further limiting available N supply and leading to further declines in soil N availability. Moreover N oligotrophication has been likely exacerbated by changes in climate that increase the length of the growing season and decrease production of available N by mineralization during both winter and spring. These results suggest a need to reevaluate the nature and extent of N cycling in temperate forests and assess how changing conditions will influence forest ecosystem response to multiple dynamic stresses of global environmental change.Mon, 26 Nov 2018 10:30:33 +0000Pollen flow and paternity in an isolated and nonisolated black walnut (Juglans nigra L.) timber seed orchard pollination of black walnut (Juglans nigra L.) is not practical and timber breeders have historically utilized only openpollinated halfsib families. An alternate approach called breeding without breeding consists of genotyping openpollinated progeny using DNA markers to identify paternal parents and then constructing fullsib families. In 2014 we used 12 SSR markers to genotype 884 openpollinated halfsib progeny harvested from two clonal orchards containing 206 trees comprised of 52 elite timber selections. Seed was harvested in 2011 from each of two ramets of 23 clones one upwind and one downwind based on prevailing wind direction from the westsouthwest. One orchard was isolated from wild black walnut and composed of forward selections while the other orchard was adjacent to a natural forest containing mature black walnut composed of backward selections. Isolation significantly increased withinorchard pollination (85) of the progeny from the isolated orchard compared to 42 from the nonisolated orchard. Neither prevailing wind direction nor seed tree position in the orchard affected paternity patterns or wild pollen contamination. Genetic diversity indices revealed that progeny from both orchards were in HardyWeinberg equilibrium with very little inbreeding and no selfing. A significant level of inbreeding was present among the forward selected parents but not the first generation (backward selected) parents. Some orchard clones failed to sire any progeny while other clones pollinated upwards of 20 of progeny.Fri, 07 Dec 2018 07:11:39 +0000Sizegrowth relationship tree spatial patterns and treetree competition influence tree growth and stand complexity in a 160year red pine chronosequence rotations have been suggested as a strategy for balancing timber production and ecological objectives. By lengthening the period of stand development extended rotations may increase tree size inequality and other elements of structural complexity thus reducing the disparity between managed and oldgrowth stands. A potential limitation of extended rotations is the tradeoff between reduced standlevel productivity and greater largetree growth that typically occurs with stand age. The mechanisms driving this tradeoff have not been fully explored. To fill this knowledge gap we investigated the sizegrowth relationship (SGR) tree spatial patterns and treetree competition along an established 160yr chronosequence of 19 singlecohort unthinned red pine (Pinus resinosa) stands in northern Minnesota USA. We analyzed SGR a standlevel metric used to estimate the relative efficiency with which different sized trees utilize available resources to assess how the relationship between tree size and growth changed over an extended period of stand development. We performed spatial analysis to examine whether tree spatial clustering a criterion of structural complexity increased with stand age. We modeled individualtree biomass increment to test whether competition along the chronosequence was sizesymmetric (access of individual trees to resources is directly proportional to size) or sizeasymmetric (larger trees suppress the growth of smaller individuals by preempting resources) and how SGR tree spatial patterns and competition together influenced individualtree growth. We found low SGR (i.e. disproportionately slow growth of larger trees compared to smaller trees) across the chronosequence a finding that contrasts with hypothesized models of SGR during stand development but is consistent with previous research on pinedominated systems. Tree spatial patterns trended towards clustering with stand age indicating higher structural complexity over time. In agreement with our SGR findings competition across the chronosequence was sizesymmetric suggesting that competition reduced individualtree growth while maintaining relative size equality. Individualtree biomass increment was strongly dependent on tree size with the growth of small trees appearing relatively less affected by competition. Differences in SGR did not translate into individualtree growth and tree spatial clustering was associated with reduced growth especially in larger trees. Our results indicate that disproportionately slow largetree growth and sizesymmetric competition throughout stand development may delay the emergence of stand structural complexity in extended rotation red pine stands. Silvicultural treatments may be required to promote stand structural complexity and increase large croptree growth.Wed, 28 Nov 2018 07:42:45 +0000The interannual variability of wind energy resources across China and its relationship to largescale circulation changes study investigates the interannual variability of wind energy resources across China and how it changes with season by applying empirical orthogonal function (EOF) analyses to gridded wind data from the Climate Forecast System Reanalysis (CFSR) from January 1979 through December 2011. The first EOF mode (EOF1) represents between 22 variance for winter and 29 for summer. Spatially the variation is largely consistent across China for summer and autumn and almost opposite between north and south for spring and winter and the strongest variation in all seasons is found over Inner Mongolia and Tibet. The second EOF mode (EOF2) represents between 13 variance for autumn and 16 for spring and is largely dominated by a sharp contrast between Inner Mongolia and Tibet for all seasons. The EOF1 appears to be linked statistically to the pacific decadal oscillation for summer and autumn and to the Pacific North American pattern for spring and winter while the EOF2 seems to be connected to the Arctic Oscillation for spring and winter and to an interdecadal variability for summer and autumn. The anomalous wind fields associated with these largescale circulation patterns modify the climatological wind fields in different ways that lead to an increase or a decrease of the 80m winds in different regions of China.Wed, 28 Nov 2018 07:31:28 +0000Carbon dioxide and methane fluxes in grazed and undisturbed mountain peatlands in the Ecuadorian Andes are widespread throughout the tropical Andean pramo. Despite the large carbon stocks in these ecosystems carbon dioxide (CO2) and methane (CH4) flux data are lacking. In addition cattle grazing is widespread in the pramo and could alter gas fluxes. Therefore our objectives were to measure CO2 and CH4 fluxes with the static chamber technique in an undisturbed and in an intensively cattle grazed peatland in the mountains of Ecuador. We found that hummocks in the undisturbed site had higher net ecosystem exchange (NEE) gross primary production (GPP) ecosystem respiration (ER) and CH4 fluxes compared to lawns. In contrast microtopography at the grazed site did not predict CO2 fluxes whereas vegetation cover was correlated for all three metrics (NEE ER and GPP). At low vegetation cover NEE was positive (losing carbon). CH4 emissions in the undisturbed site were low (8.1 mg CH4 m2 d1). In contrast CH4 emissions at the grazed site were much greater (132.3 mg CH4 m2 d1). This is probably attributable to trampling and nutrient inputs from cattle. In summary the two peatlands differed greatly in CO2 and CH4 exchange rates which could be due to the variation in climate and hydrology or alternatively to intensive grazing by cattle.Mon, 10 Dec 2018 14:30:48 +0000Influence of Mature Overstory Trees on Adjacent 12Year Regeneration and the Woody Understory Aggregated Retention versus Intact Forest harvesting an approach that intentionally retains legacy features such as mature overstory trees provides options for achieving ecological objectives. At the same time retained overstory trees may compete with the nearby recovering understory for resources and much remains to be learned about potential tradeoffs with regeneration objectives particularly over extended time periods. We assessed the influence of aggregated retention (reserved mature overstory and understory patches) versus intact forest on structure and productivity (standing biomass) of the adjacent woody understory and regeneration 12 years after harvest in northern Minnesota USA. Each site was dominated by Populus tremuloides Michx. a species that regenerates prolifically via root sprouts following disturbance. Overall fewer differences than expected occurred between the effects of intact forest and aggregated retention on regeneration despite the small size (0.1 ha) of aggregates. Instead harvest status and distance from harvest edge had a greater influence on structure and standing woody biomass. Proximity to aggregates reduced large sapling biomass (all species combined) relative to open conditions but only up to 5 m into harvested areas. This suggests the tradeoff for achieving productivity objectives might be minimal if managers use retention aggregates in this region to achieve ecological objectives and meet management guidelines.Wed, 28 Nov 2018 09:33:19 +0000Influence of Repeated Prescribed Fire on Tree Growth and Mortality in Pinus resinosa Forests Northern Minnesota fire is widely used for ecological restoration and fuel reduction in firedependent ecosystems most of which are also prone to drought. Despite the importance of drought in fireadapted forests little is known about the cumulative effects of repeated prescribed burning on tree growth and related response to drought. Using dendrochronological data in red pine (Pinus resinosa Ait.)dominated forests in northern Minnesota USA we examined growth responses before and after understory prescribed fires between 1960 and 1970 to assess whether repeated burning influences growth responses of overstory trees and vulnerability of overstory tree growth to drought. We found no difference in treelevel growth vulnerability to drought expressed as growth resistance resilience and recovery between areas receiving prescribed fire treatments and untreated forests. Annual mortality rates during the period of active burning were also low (less than 2) in all treatments. These findings indicate that prescribed fire can be effectively integrated into management plans and climate change adaptation strategies for red pine forest ecosystems without significant short or longterm negative consequences for growth or mortality rates of overstory trees.Wed, 28 Nov 2018 11:16:43 +0000Interactive effects of climate change and fungal communities on woodderived carbon in forest soils wood makes up the majority of forest biomass the importance of wood contributions to stable soil carbon (C) pools is uncertain. Complex interactions among climate soil physical properties intrinsic properties of woody residues and biological processes all exert dynamic controls over the stabilization destabilization and transport of woodderived C in soils. Many studies have demonstrated the strong physical controls on decomposition rates in soils but little work has been done to relate these to changes in decomposer community composition and how this influences the fate of woodderived C in soils. Here we examine the effects of initial fungal inoculation temperature soil texture Free Air CO2 Enrichment (FACE) wood type and location of wood residue in the soil with an experiment investigating the fate of woodderived C from soils in the first two years following clearcut harvest in aspen (Populus tremuloides Michx.) forests. We applied 13Cdepleted aspen wood chips in 168 experimental plots across six sites in northern Michigan USA and tracked the depleted 13C signature through the mineral soil as DOC and from the soil surface as CO2. Wood residue location had the largest impact on soil CO2 efflux with surface wood treatments having more than twice as much woodderived soil CO2 efflux as buried wood treatments (1.20 g CO2 m2 h1 versus 0.49 g CO2 m2 h1 respectively p lt 0.001). Initial fungal decomposers had a significant effect on DOC quantity and quality with higher woodderived DOC concentrations levels of humification and tannin content for whiterot treatments compared with brownrot treatments. Buried chip treatments within opentop chambers had onethird higher woodderived soil CO2 efflux than buried chips in ambient temperature treatments (p lt 0.002). FACE wood type also influenced soil C fluxes from the decomposing wood chips. The average woodderived soil CO2 efflux and the average percentage of woodderived soil CO2 efflux were significantly greater from wood grown under elevated CO2 than wood grown under elevated CO2 O3 (p 0.002 and p 0.004 respectively). Furthermore wood grown under elevated CO2 had increased DOC aromaticity relative to wood grown in ambient conditions. Taken together these results show that woodderived C sources and the decomposers that process them are significant determinants of C fluxes from and transformations within the soil following harvest in aspen forests.Mon, 10 Dec 2018 14:38:18 +0000Biomass growth response to spatial pattern of variableretention harvesting in a northern Minnesota pine ecosystem harvesting (VRH) is an approach for sustaining complex structure in managed forests. A criticism of VRH is that ecological benefits may come at a cost of reduced growth of regeneration due to competition with residual trees. However the spatial pattern of retention i.e. dispersed or aggregated in VRH systems can be manipulated to minimize suppression of regeneration and resource limitation to regeneration might be mitigated by reduction of woody shrubs. Continued growth of the residual cohort will compensate for growth reduction of regeneration although this may differ with retention pattern. We examined aboveground wholestand biomass growth of trees in a VRH experiment in Pinus resinosa forest in Minnesota USA. Treatments included dispersed retention aggregated retention and an uncut control as well as a shrub treatment (reduced density or ambient). We addressed the following hypotheses (1) biomass growth of a cohort of planted pine seedlings will be highest with aggregated rather than dispersed retention (2) biomass growth of the planted seedlings will increase with shrub reduction and (3) biomass growth of the residual overstory will be higher with dispersed rather than aggregated retention. Aboveground biomass growth of the planted pines ranged from 0.4 kgha1yr1 in the overstorycontrolambientshrub treatment to 23 kgha1yr1 in the aggregatedretention shrubreduction treatment. The difference between the control and the retention treatments was significant (Plt 0.0001) but not between dispersed and aggregated retention (P 0.97). Thus our first hypothesis was not supported. In all treatments biomass growth was significantly higher (gt100 increase) with shrub reduction (P0.001) supporting our second hypothesis. Biomass growth of residual trees ranged from 2404 kgha1yr1 in the uncutcontrol ambientshrub treatment to 1043 kgha1yr1 in the aggregatedretentionshrubreduction treatment. Differences were significant between the control and retention treatments (P 0.003) and marginally higher with dispersed vs. aggregated retention (P 0.09) lending support to our third hypothesis. Our results suggest that managers have flexibility in application of VRH and can expect similar standlevel biomass growth of planted regeneration regardless of retention pattern but somewhat higher standlevel biomass growth of retained trees with dispersed retention.Wed, 28 Nov 2018 11:21:13 +0000Comparing predicted historical distributions of tree species using two treebased ensemble classification methods scale spatial mapping of historical tree records over large extents is important for determining historical species distributions. We compared performance of two ensemble methods based on classification trees random forests and boosted classification for mapping continuous historical distributions of tree species. We used a combination of soil and terrain predictor variables to predict species distributions for 21 tree species or species groups from historical tree surveys in the Missouri Ozarks. Mean true positive rates and AUC values of all species combined for random forests and boosted classification at a modeling prevalence and threshold of 0.5 were similar and ranged from 0.80 to 0.84. Although prediction probabilities were correlated (mean r 0.93) predicted probabilities from random forests generated maps with more variation within subsections whereas boosted classification was better able to differentiate the restricted range of shortleaf pine. Both random forests and boosted classification performed well at predicting species distributions over large extents. Comparison of species distributions from two or more statistical methods permits selection of the most appropriate models. Because ensemble classification trees incorporate environmental predictors they should improve current methods used for mapping historical trees species distributions and increase the understanding of historical distributions of species.Wed, 28 Nov 2018 11:30:41 +0000Histosols most soils of the world comprise primarily mineral materials a small but important group of soils are formed from organic materials derived from plants or less frequently from animals. Organic soil materials contain a minimum of 1218 organic carbon depending on the particle size of the mineral component (Soil Survey Staff 2010). Generally speaking soils with at least 40 cm of the upper 80 cm that are organic materials and which do not have permafrost within 1 m of the soil surface are Histosols.Thu, 29 Nov 2018 13:41:25 +0000Soil seed bank analysis of planted and naturally revegetating thermallydisturbed riparian forests the reestablishment of a mature biotic community following a disturbance is a common goal of restoration ecology. In this study we describe the relative successional status of a recently disturbed riparian seed bank when compared with less recently disturbed and undisturbed systems and the shortterm effects of restoration on seed bank development within the recently disturbed system. The study location the U.S. Department of Energys Savannah River Site in South Carolina provides a unique opportunity to investigate the development of wetland seed banks following a severe disturbance in this case the release of elevated temperature and flow effluent from nuclear reactor operations. To assess the recovery of wetland seed banks over time we compared seed banks of naturally recovering riparian corridor and swamp delta sites of two different ages since disturbance (nine years and 30 years) with undisturbed forested corridor and swamp sites. To assess the potential effects of restoration efforts (site preparation and planting of seedlings) on seed bank development we compared seed banks of naturally recovering (unplanted) and planted riparian corridor and swamp delta sites in the more recently disturbed system. We expected total germinants and species richness to be highest in the recently disturbed sites and decline as wetland systems matured. Within recently disturbed sites we expected planted sites to have higher abundance and richness than unplanted sites. We also expected a greater abundance of woody species in the undisturbed forested sites. The number of germinants differed among the sites ranging from 748 individuals per m2 in the undisturbed swamp area to 10322 individuals per m2 in the recently disturbed planted swamp delta. When corridor and delta sites within a stream system were combined the mean number of germinants was greater in the recently disturbed system intermediate in the 30year (midsuccessional) system and lowest in the undisturbed system. Seed banks from the recently disturbed and midsuccessional sites were more similar in composition than they were to the undisturbed systems. Across all stream systems riparian corridors had greater mean species richness than swamp deltas though differences in seed bank abundances were not significant. Sedges and rushes were the predominant life forms in the recently disturbed and midsuccessional sites while undisturbed sites had a greater proportion of herbs and woody seedlings. In addition there were more germinants from planted sites than from unplanted sites. The dominance by early successional species at recently disturbed planted sites may be an unintended consequence of site preparation treatments and such potential effects should be recognized and weighed during the development of restoration plans.Thu, 29 Nov 2018 13:46:29 +0000