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Understanding vegetation recovery after fire is critical for predicting vegetation-mediated ecological dynamics in future climates. However, information characterizing vegetation recovery patterns after fire and their determinants over large geographical extents is limited. This study uses Moderate Resolution Imaging Spectroradiometer (MODIS) leaf area index (LAI) and albedo to characterize patterns of post-fire biophysical dynamics across the western United States (US) and further examines the influence of topo-climatic variables on the recovery of LAI and albedo at two different time horizons, 10 and 20 years post-fire, using a random forest model. Recovery patterns were derived for all wildfires that occurred between 1986 and 2017 across seven forest types and 21 level III ecoregions of the western US. We found differences in the characteristic trajectories of post-fire vegetation recovery across forest types and eco-climatic settings. In some forest types, LAI had recovered to only 60 %–70 % of the pre-fire levels by 25 years after the fire, while it recovered to 120 %–150 % of the pre-fire levels in other forest types, with higher absolute post-fire changes observed in forest types and ecoregions that had a higher initial pre-fire LAI. Our random forest results showed very little influence of fire severity on the recovery of both summer LAI and albedo at both post-fire time horizons. Post-fire vegetation recovery was most strongly controlled by elevation, with faster rates of recovery at lower elevations. Similarly, annual precipitation and average summer temperature had significant impacts on the post-fire recovery of vegetation. Full recovery was seldom observed when annual precipitation was less than 500 mm and average summer temperature was above the optimal range, i.e., 15–20 °C. Climate influences, particularly annual precipitation, were a major driver of post-fire summer albedo change through its impact on ecological succession. This study provides quantitative measures of primary controls that could be used to improve the modeling of ecosystem dynamics post-fire. [ABSTRACT FROM AUTHOR]

Understanding vegetation recovery after fire is critical for predicting vegetation-mediated ecological dynamics in future climates. However, information characterizing vegetation recovery patterns after fire and their determinants are lacking over large geographical extents. This study uses Moderate Resolution Imaging Spectroradiometer (MODIS) leaf area index (LAI) and albedo to characterize patterns of post-fire biophysical dynamics across the western United States (US) and further examines the influence of topo-climatic variables on the recovery of LAI and albedo at two different time intervals, 10 and 20 years post-fire, using a random forest model. Recovery patterns were derived for all wildfires that occurred between 1986 and 2017 across seven forest types and 21 level III ecoregions of the western US. We found differences in characteristic trajectories of post-fire vegetation recovery across forest types and ecoclimatic settings. LAI in some forest types recovered only 60 %–70 % by 25 years after fire while it recovered 120 % to 150 % of the pre-fire levels in other forest types, with higher absolute post-fire changes in forest types and ecoregions that had a higher initial pre-fire LAI. Our random forest results showed very little influence of fire severity on the recovery of both summer LAI and albedo at both post-fire time intervals. Post-fire vegetation recovery was most strongly controlled by elevation, with faster rates of recovery in lower elevations. Similarly, annual precipitation and average summer temperature had significant impacts on the post-fire recovery of vegetation. Full recovery was seldom observed when annual precipitation was less than 500 mm and average summer temperature was above the optimal range i.e., 15–20 °C. Climate influences, particularly annual precipitation, was a major driver of post-fire summer albedo change through its impact on ecological succession. This study provides quantitative measure of primary controls that could be used to improve the modelling of ecosystem dynamics post-fire. [ABSTRACT FROM AUTHOR]

The U.S. Geological Survey’s Land Change Monitoring, Assessment, and Projection (LCMAP) initiative is a new end-to-end capability to continuously track and characterize changes in land cover, use, and condition to better support research and applications relevant to resource management and environmental change. Among the LCMAP product suite are annual land cover maps that will be available to the public. This paper describes an approach to optimize the selection of training and auxiliary data for deriving the thematic land cover maps based on all available clear observations from Landsats 4–8. Training data were selected from map products of the U.S. Geological Survey’s Land Cover Trends project. The Random Forest classifier was applied for different classification scenarios based on the Continuous Change Detection and Classification (CCDC) algorithm. We found that extracting training data proportionally to the occurrence of land cover classes was superior to an equal distribution of training data per class, and suggest using a total of 20,000 training pixels to classify an area about the size of a Landsat scene. The problem of unbalanced training data was alleviated by extracting a minimum of 600 training pixels and a maximum of 8000 training pixels per class. We additionally explored removing outliers contained within the training data based on their spectral and spatial criteria, but observed no significant improvement in classification results. We also tested the importance of different types of auxiliary data that were available for the conterminous United States, including: (a) five variables used by the National Land Cover Database, (b) three variables from the cloud screening “Function of mask” (Fmask) statistics, and (c) two variables from the change detection results of CCDC. We found that auxiliary variables such as a Digital Elevation Model and its derivatives (aspect, position index, and slope), potential wetland index, water probability, snow probability, and cloud probability improved the accuracy of land cover classification. Compared to the original strategy of the CCDC algorithm (500 pixels per class), the use of the optimal strategy improved the classification accuracies substantially (15-percentage point increase in overall accuracy and 4-percentage point increase in minimum accuracy). [ABSTRACT FROM AUTHOR]

Ecological communities often transition from phylogenetic and functional clustering to overdispersion over succession as judged by space-for-time substitution studies. Such a pattern has been generally attributed to the increase in competitive exclusion of closely related species with similar traits through time, although colonisation and extinction have rarely been examined. Using 44 years of uninterrupted old-field succession in New Jersey, USA, we confirmed that phylogenetic and functional clustering decreased as succession unfolded, but the transition was largely driven by colonisation. Early colonists were closely related and functionally similar to residents, while later colonists became less similar to the species present. Extirpated species were generally more distantly related to residents than by chance, or exhibited random phylogenetic/functional patterns, and their relatedness to residents was not associated with time. These results provide direct evidence that the colonisation of distant relatives, rather than extinction of close relatives, drives phylogenetic and functional overdispersion over succession. [ABSTRACT FROM AUTHOR]

Abstract: Long-term (24-year) research regarding harvesting in bottomland hardwoods was conducted to determine the effects of different timber harvests on a water tupelo (Nyssa aquatica L.)-baldcypress (Taxodiumdistichum L. Rich.) swamp. The study is located in the Mobile-Tensaw River Delta in southern Alabama. Disturbance treatments were clearcut followed by: (1) helicopter extraction (HELI), (2) skidder simulation of ground-based extraction (SKID), and (3) complete removal of coppice and seedbank regeneration with glyphosate herbicide (GLYPH). An adjacent portion of the original forest stand provided a reference condition (REF). The overall project goal was to determine long-term treatment effects on aboveground and belowground biomass accumulation patterns in the regenerating stands. Previous studies on this site at stand ages 7 and 16years indicated that SKID treatment areas had the largest aboveground biomass accumulations while HELI treatments had greater species diversity. Twenty-four years after disturbance, results followed the same pattern with SKID treatments having more above- and belowground biomass accumulation (242.6Mgha−1) while HELI treatments had less biomass (173.6Mgha−1). GLYPH treatments are recovering (86.8Mgha−1) and are progressing through an herbaceous–shrub–scrub–pioneer tree succession pattern. SKID and HELI treatments appear to be progressing towards original stand species and biomass accumulation. The resiliency of the site following disturbance appears to be due to soil physical properties, sediment accumulations, and vegetation adaptations to flooded conditions. [Copyright &y& Elsevier]

Abstract: Although secondary succession in commercial pine plantations offers opportunities to manage for biodiversity, questions remain regarding effects of stand establishment intensity on biodiversity. Therefore, we examined 9years of post-harvest plant succession in loblolly pine plantations established under a range of intensive management regimes in Mississippi, USA, including combinations of mechanical site preparation, chemical site preparation, and herbaceous weed control. We evaluated plant community structure using coverage of eight growth forms, and community composition using species-level coverage. Stands established without chemical site preparation retained more post-harvest woody and vine species and had less variable species turnover than chemically prepared stands. Chemically prepared stands provided opportunity for greater expression of early succession herbaceous and subshrub communities. Broadcast herbaceous weed control reduced expression of the early succession community relative to banded applications, but a single broadcast application did not prevent strong re-emergence of that community the following year. Conversely, multiple broadcast applications of herbaceous weed control reduced expression of early succession species beyond the year of final treatment, possibly through inhibiting establishment until favorable conditions were past, rather than by directly favoring woody dominance. Plant community structure converged as crown closure approached, and structural differences were largely insignificant by year 5. However, small differences in composition that may affect biodiversity were retained and may last until midrotation harvest and subsequent treatment. Greater diversity of plant communities in stands with chemical site preparation may benefit biodiversity in establishing plantations if not inhibited by broadcast herbaceous weed control. Resources committed to broadcast weed control may be more usefully diverted to midrotation management that improves biodiversity after thinning. These results can be used to target management of early succession species at stand and landscape scales. Given the known effects of this limited array of treatments on biodiversity, additional establishment regimes should be monitored to provide information critical to meeting stand- and landscape-level biodiversity goals. [Copyright &y& Elsevier]

Abstract: Despite assumptions that agriculture will automatically go into a mode of decline at the Rural Urban Interface (RUI), official statistics suggest that agriculture as a whole remains a strong (and in some cases a growing) industry in many U.S. RUI counties. RUI scholars have acknowledged internal family dynamics can significantly influence farm persistence and adaptation strategies, however, few studies have sought to document the specific role succession has on farm structure at the RUI. Building off rural geography models of farm organization at the RUI and succession research embedded in rural studies we analyze interviews from 33 U.S. farm families to 1) explore the relationship between farm adaptation and succession at the RUI, and 2) examine how succession is related to the different types of enterprises found at the RUI (direct marketers vs. commodity producers) and the types of growth strategies these farm families implement. We find that families who can not identify an heir either disinvest or enter a static management mode. Among farm families who can identify an heir we identify a variety of horizontal and vertical growth strategies (expanding, intensifying, and entrepreneurial stacking) designed to achieve farm reproduction goals. We discuss the theoretical and policy related implications of this research. [Copyright &y& Elsevier]

Abstract: The mixed deciduous forests of the upper Midwest, USA are approaching an ecological threshold in which early successional canopy trees are reaching maturity and beginning to senesce, giving way to a more diverse canopy of middle and late successional species. The net primary production (NPP) of these forests is generally considered past peak and in decline, but recent studies show a striking resilience in the NPP trajectories of some middle and late successional forests; yet, the mechanisms controlling such temporal changes in NPP are largely unknown. At the University of Michigan Biological Station in northern Michigan, we used a ≥9-year continuous record of wood net primary production (NPP), leaf area index (LAI), canopy composition, and stem mortality in 30 forested plots to identify the constraints on wood NPP as a mixed forest transitions from early to middle succession. Although wood NPP decreased over time in most stands, the rate of decline was attenuated when the canopy comprised a more diverse assemblage of early and middle/late successional species. The mechanism for sustained NPP in stands with more species diverse canopies was the proliferation of LAI by intact later successional tree species, even as stem mortality rates of early successional trees increased. We conclude that projections of carbon sequestration for the aging mixed forests of the upper Midwest should account for species composition shifts that affect the resilience wood NPP. [Copyright &y& Elsevier]

Abstract: Shrubland birds have become one of the most conservation-reliant avian groups in the Northeastern United States. Their contemporary distribution is restricted to regenerating commercial forests, utility rights-of-way, and other types of managed early-successional habitat. This study explored whether a highly fragmented urban pine barrens can have conservation value for shrubland birds. Specifically, we estimated the amount of core early-successional habitat available to shrubland birds in the Albany Pine Bush Preserve (East-central New York State) and quantified bird–habitat associations from systematic point count surveys. This 1255ha urban preserve contains approximately 150ha of core early-successional habitat dominated by pitch pine and scrub oaks. Eighty-two species, including 24 shrubland birds, were observed in one breeding season. Many of these birds have shown regional population declines and six are species of greatest conservation need in New York. Two shrubland species previously extirpated were common across the preserve, and on average shrubland species were similarly abundant to non-shrubland species. Several shrubland species were strongly associated with the limited early-successional habitat, and the prairie warbler is recommended as the best potential avian indicator for monitoring ecosystem health and management effectiveness in this globally rare pine barrens. Twenty years of ecosystem restoration, including prescribed fire and invasive plant management, is buffering the effects of fire suppression, habitat loss, and fragmentation on shrubland birds in this landscape. When managed appropriately, urban shrublands can provide suitable breeding habitat and may aid in the regional conservation of early-successional shrubland birds. [Copyright &y& Elsevier]

Climate change could have a devastating effect on human and environmental health. Potential effects of climate change on human health include higher rates of respiratory and heat-related illness, increased prevalence of vector-borne and waterborne diseases, food and water insecurity, and malnutrition. Persons who are elderly, sick, or poor are especially vulnerable to these potential consequences. Addressing climate change could have substantial benefits to human health. In this position paper, the American College of Physicians (ACP) recommends that physicians and the broader health care community throughout the world engage in environmentally sustainable practices that reduce carbon emissions; support efforts to mitigate and adapt to the effects of climate change; and educate the public, their colleagues, their community, and lawmakers about the health risks posed by climate change. Tackling climate change is an opportunity to dramatically improve human health and avert dire environmental outcomes, and ACP believes that physicians can play a role in achieving this goal. [ABSTRACT FROM AUTHOR]

Abstract: Welsh et al. [Welsh, H.H., Jr. Pope, K.L., Wheeler, C.A., 2008. Using multiple metrics to assess the effects of forest succession on population status: a comparative study of two terrestrial salamanders in the US Pacific Northwest. Biological Conservation 141, pp. 1149–1160] argued for the use of four metrics to monitor population status of two terrestrial amphibians, the Siskiyou Mountains (Plethodon stormi) and Del Norte (Plethodon elongatus) salamanders. We show that inherent problems exist with Welsh et al.’s application of all four of these metrics, and that their inferences about population status are likely to be uncertain as a consequence and potentially misleading to managers. Welsh et al. (2008) used data from different populations and different years to estimate detection probabilities for both P. elongatus and P. stormi, a decision which assumes that detection probabilities do not differ across sites and populations are closed. In addition, Welsh et al. (2008) present count data for both salamanders, a metric that assumes capture probability does not vary by age, gender, size, other individual characteristics, and most importantly in their application, habitat characteristics. Welsh et al. (2008) estimated survival based upon age ratios. Age ratios are known to be biased when immigration and emigration are unequal Conn et al. [Conn, P.B., Doherty, P.F., Jr. Nichols, J.D., 2005. Comparative demography of New World populations of thrushes (Turdus spp.): comment. Ecology 86, pp. 2536–2541]. In source-sink systems, immigration and emigration are expected to be unequal. Thus, the use of this estimation technique to characterize survival in source-sink systems is invalid unless it can be shown that immigration and emigration are equal, a rare occurrence in source-sink systems. The final metric used by Welsh et al. (2008) was an index of body condition, i.e., the residuals of a least squares regression of mass on the length. Several recent articles have outlined a number of potential problems with the technique and a theoretically more robust and efficient alternative has been published. Unfortunately, Welsh et al. (2008) did not provide the details (model diagnostic statistics, tests of assumptions) needed to assess whether or not their analyses of body condition may be accurate. We think that evaluation of specific hypotheses, well-designed sampling programs, and methods such as mark–recapture and ratio sampling are more likely to provide reliable inference than re-analysis of old data sets that were collected for other purposes and obsolete methods (i.e., counting individuals on single occasions) that are known to be flawed. We agree that potential forest management impacts to sensitive taxa require evaluation and monitoring, and that changes in occupancy and abundance are useful metrics for this task (while recognizing that, when feasible to collect, information about reproductive success and survival is superior). However, reliable inference about potential impacts can only be made if reliable methods are employed and if critical assumptions receive empirical evaluation. We offer several suggestions to strengthen inference about management treatments. [Copyright &y& Elsevier]

Abstract: Widespread declines of foundation species, such as many corals, kelps, and overstory trees, are of grave concern because, by definition, these species create and maintain habitat that supports other species. Nevertheless, past responses to their declines, many of which were caused by invasive species, have been late and ineffective, underscoring the need to predict changes in biodiversity and ecosystem function associated with species invasions and foundation species losses. One predictive, but under-used, approach is to compare the species and functions associated with the afflicted foundation species to its projected replacement communities. The taxa associated with the foundation species and subsequent successional stages would be expected to decline and increase, respectively. We used this approach to generate hypotheses for how arthropod diversity might change in response to extensive losses of eastern hemlock trees caused by the invasive, hemlock woolly adelgid (insect: Hemiptera, Adelgidae). Our all-strata survey of the arthropods in an eastern hemlock forest and its expected replacement climax community in the mid-Atlantic region of the United States, mixed hardwood forest, suggests that eastern hemlock losses might initiate increases in arthropod abundance, alpha diversity, and 23 arthropod taxa, might produce no change in evenness or composition of arthropod functional groups, but might trigger decreases in beta diversity and seven hemlock indicator taxa. These predictions are consistent with observed trends in arthropod responses to hemlock losses in other studies, and thus might be useful for targeting early monitoring, management, and conservation efforts. This research is exploratory, however, and tests of these predictions across larger spatial scales will be necessary to determine the generality of the findings. [Copyright &y& Elsevier]

Abstract: In unglaciated areas of the Mississippi Valley region, the typical full loess–paleosol succession contains the Modern Soil developed in Peoria Silt, weakly developed Farmdale Geosol developed in Roxana Silt, Sangamon Geosol developed in Loveland Silt, and Yarmouth Geosol developed in Crowley''s Ridge Silt. Although a fifth loess called the Marianna Silt is reported at one area, the paleosol that separates the Crowley Ridge and Marianna Silts is not well defined. Previous thermoluminescence (TL) and optical stimulated luminescence (OSL) age chronology has suggested multiple phases of Sangamon Geosol developed in Loveland Silt, but clear morphological evidence of polygenetic Sangamon Geosol profiles have not been found. Recently, a thick loess–paleosol sequence has been studied in the middle Mississippi Valley in unglaciated southern Illinois, USA. Soil morphology and analytical results revealed five loesses and associated paleosol units. Two Sangamon Bt horizons were found separated by a thick ACtk horizon, interpreted to indicate two phases of Sangamon Geosol development. This well-preserved loess–paleosol succession provides one of the most complete mid–late Quaternary loess records in the middle Mississippi Valley to date, and is important for studying the stratigraphic framework and paleoclimate and environment changes. [Copyright &y& Elsevier]

Two-age (deferment or leave tree) harvesting is used increasingly in even-aged forest management, but long-term responses of breeding avifauna to retention of residual canopy trees have not been investigated. Breeding bird surveys completed in 1994–1996 in two-age and clearcut harvests in the central Appalachian Mountains of West Virginia, USA allowed us to document long-term changes in these stands. In 2005 and 2006, we conducted point counts in mature unharvested forest stands and in 19–26 year-old clearcut and two-age harvests from the original study and in younger clearcut and two-age stands (6–10 years old). We found differences in breeding bird metrics among these five treatments and temporal differences in the original stands. Although early-successional species are typically absent from group selection cuts, they were almost as common in young two-age stands as clearcuts, supporting two-age harvests as an alternative to clearcutting. Although older harvests had lower species richness and diversity, they were beginning to provide habitat for some species of late-successional forest songbirds that were absent or uncommon in young harvests. Overall, late-successional forest-interior species were more flexible in their use of different seral stages; several species used both age classes and harvest types in addition to mature forest, which may reflect the lack of edges in our heavily-forested landscape. Consequently, two-age management provides habitat for a diverse group of species as these stands mature and may be an ecologically sustainable alternative to clearcutting in landscapes where brown-headed cowbirds (Molothrus ater) are uncommon. [Copyright &y& Elsevier]

Vegetation plays a central role in controlling terrestrial carbon (C) exchange, but quantifying its impacts on C cycling on time scales of ecological succession is hindered by a lack of long-term observations. The net ecosystem exchange of carbon (NEE) was measured for several years in adjacent ecosystems that represent distinct phases of ecological succession in the southeastern USA. The experiment was designed to isolate the role of vegetation – apart from climate and soils – in controlling biosphere–atmosphere fluxes of CO2 and water vapor. NEE was near zero over 5 years at an early successional old-field ecosystem (OF). However, mean annual NEE was nearly equal, approximately −450 g C m−2 yr−1, at an early successional planted pine forest (PP) and a late successional hardwood forest (HW) due to the sensitivity of the former to drought and ice storm damage. We hypothesize that these observations can be explained by the relationships between gross ecosystem productivity (GEP), ecosystem respiration (RE) and canopy conductance, and long-term shifts in ecosystem physiology in response to climate to maintain near-constant ecosystem-level water-use efficiency (EWUE). Data support our hypotheses, but future research should examine if GEP and RE are causally related or merely controlled by similar drivers. At successional time scales, GEP and RE observations generally followed predictions from E. P. Odum's ‘Strategy of Ecosystem Development’, with the surprising exception that the relationship between GEP and RE resulted in large NEE at the late successional HW. A practical consequence of this research suggests that plantation forestry may confer no net benefit over the conservation of mature forests for C sequestration. [ABSTRACT FROM AUTHOR]

Abstract: Growth of fouling organisms on suspended fish cages is an impediment to aquaculture projects in coastal waters around the world. The present study characterized ecological succession of fouling communities on the netting of fish cages at an open ocean aquaculture site 10 km east of New Hampshire, USA in the western Gulf of Maine. Ecological succession can be defined as the process by which a community moves from a simple level of organization to a more complex community. Routine cleaning of the cages causes loss of organisms and initiation of ecological succession. Experimental panels of nylon net material were deployed at different times of the year and for different durations from September 2002 to September 2003 (eleven sets of 1-month panels, four sets of 3-month panels, two sets of 6-month panels, and one set of 1-year panels), with four replicates of each deployment. Panels were randomly arranged on a grid that was attached to a fish cage at a water depth of ∼15 m. There were substantial and significant differences in density and biomass of the total communities of most successional sequences when comparing panels deployed during May–September to those deployed during the cooler months, October–April. However, the blue mussel, Mytilus edulis, dominated in density and biomass in almost every sequence, regardless of time of initiation or duration. Other species that occurred in high numbers and/or biomass were the amphipods Caprella sp. and Jassa marmorata, the molluscs Hiatella arctica and Anomia sp., the seastar Asterias vulgaris, and the anemone Metridium senile. Juveniles and adults of some species were also present in some early (1-month) successional sequences, indicating that migration may be an important process in community development. Some of the dominant species listed above were present in all successional stages (early, intermediate and late), differing only in relative abundances in the community. The consistent dominance of M. edulis, and other differences in successional patterns compared to what has been typically observed for epifaunal communities in the region, were hypothesized to be the result of a combination of factors: a lack of predators such as seastars and fish that typically consume mussels in natural communities, excessive predation by nudibranchs on those species (e.g., Tubularia sp.) normally abundant in early successional stages, year-round availability of mussel larvae, and cage cleaning protocols that do not remove all the organisms present. The introduction of predatory fishes or seastars into or onto the cages might provide some amount of control on the growth of fouling organisms. [Copyright &y& Elsevier]

Deals with a study which attempted to reconstruct the composition and dimensions of an old-growth pine forest stand in northern Wisconsin. Methodology; Comparative data on old-growth stands in the area; Secondary succession following logging and fire.

Insight into potential mechanisms of succession following disturbance to an ecological community can be gained by considering processes that contribute to the rise (colonization, interactions with established species) and demise (differential mortality) of specific stages within the successional sequence. Most successional theories focus on the rise to dominance, assuming demise is the result of competition, but other factors can cause differential mortality among species, including physical disturbance, senescence, and consumers. In rocky intertidal communities on the coast of Washington state, USA, gaps in mussel beds exhibit a succession from predator-susceptible to predator-resistant species following disturbance, suggesting that differential consumption by mobile species may play an important role in the demise of early succession species and the eventual dominance of the mussel Mytilus californianus . Experimental manipulation of a dominant species earlier in succession, the blue mussel Mytilus trossulus , demonstrated that this species inhibits the invasion of M. californianus in the absence of predators. Experimental manipulation of predatory snails (Nucella emarginata and Nucella canaliculata ), which feed heavily on M. trossulus but not M. californianus , greatly increased the rate at which M. californianus invaded gaps. These results and those of other studies indicate that consumers frequently have important effects on the dynamics of succession in benthic marine systems, and might also play a role in other settings. [ABSTRACT FROM AUTHOR]

Reports on long-term field experiments in ecology in the United States. Description of the field experiment in long-term succession; Succession as a framework for teaching ecology; Use of the field experiment in teaching ecology.

Studies the disturbance history and successional dynamics of tree species in old-growth forests in southern West Virginia. Use of dendroecological analysis of successional dynamics; Examination of the pattern of tree recruitment in relation to disturbance events; Impact of protection of the forests during the late 20th century.

Studies the historical effects in a successional rocky intertidal community in Oregon. Mosaic patches in various stages of succession; Variations in initial conditions; Manipulation of the presence of sessile species.

Examines the mechanisms of primary succession following deglaciation at Glacier Bay, Alaska. Effect of initial nitrogen-fixing colonizers; Background on Glacier Bay; Change of environment through the first 200 years of succession; Seeds of early-successional species; Growth of naturally occurring spruce seedlings.

Studies causes and ecosystem consequences of multiple pathways of primary succession at Glacier Bay National Park, Alaska. Stand reconstructions; Trunk radial growth and basal area; Advance of cone-bearing spruce; Refugial forests; Soils; Effect of initial site conditions on early spruce invasion; Multiple pathways and their causes.

Characterizes the juvenile survivorship of ten dominant tree species in the United States of oak transition-Northern hardwood forests using species-specific mathematical models. Geographic and environmental variation in mortality; Comparison to previous characterizations of shade tolerance; Findings using the SORTIE model of forest dynamics; Juvenile mortality and forest succession.