Search

Plant species composition, dominance, richness, and diversity were measured across a 15-year chronosequence of created wetland sites in Virginia, USA. Using an age-class categorization (1-2 years, 3-5 years, 6-10 years, or 11-15 years), all classes had a predominance of herbaceous species with perennial life history strategy, and perennials contributed 68.6 % to the overall dominance measure (importance value; IV) averaged across all sites. There was no significant difference in species richness or diversity among age classes. Analysis of Similarity (ANOSIM) indicated that herbaceous species composition was similar between the youngest and oldest age classes, but not the intermediate classes. For woody shrubs and saplings, planted species were more prevalent in the youngest age classes, and volunteer species predominated in the oldest age classes. These results suggest that perennial herbaceous species are important in early plant development on created wetland sites, and may be influential in observed patterns of species composition over time. In the context of plant development in newly created wetlands, dominance shifts from planted to volunteer woody species suggest that planting early successional species, or species with reproductive strategies attuned to created wetland site management, may favor survivorship and recruitment of other species over time. [ABSTRACT FROM AUTHOR]

Conservation Reserve Program (CRP) fields may provide good habitat for nesting and brood-rearing ring-necked pheasants ( Phasianus colchicus) during early stages of succession. But, the success of hens in early successional CRP, relative to late successional CRP and other grassland habitats, has yet to be evaluated. The reproductive period is especially critical for populations of pheasants, and CRP's benefits to hens and chicks may decrease as fields age because of loss of vegetative diversity, decrease in vegetation density, and accumulation of residual litter. During 2005-2006, we evaluated spatial and temporal variation in nest and brood survival for radio-marked hen pheasants in areas of northeastern Nebraska where portions of CRP fields had been recently disced and interseeded (DICRP) with legumes. Nests in DICRP tended to have a higher daily survival rate (0.984; 95% CI: 0.957-0.994) than nests in grasslands (including CRP) that were unmanaged (0.951; 95% CI: 0.941-0.972). The probability of 23-day nest success was 0.696 (95% CI: 0.631-0.762) for DICRP and 0.314 (95% CI: 0.240-0.389) for unmanaged grasslands. Daily brood survival rates varied by habitat type, brood age, and date of hatch. The probability of a brood surviving to day 21 was 0.710 (95% CI: 0.610-0.856). Brood survival rates increased with time spent in DICRP and as the brood aged. Survival decreased as broods spent more time in cropland and peaked seasonally with broods that hatched on 15 June. Brood survival probability, to 21 days, would be reduced to 0.36 (95% CI: 0.100-0.701) if broods in our sample had not used DICRP. We combined nest and brood survival in a productivity model that suggested 2,000 hens, in a landscape with no DICRP, would produce 1,826 chicks, whereas the same hens in a landscape of 100% DICRP would produce 5,398 chicks. Production of first-year roosters more than doubled when hens nested in DICRP. Without DICRP, population growth rates of pheasant populations usually declined; with DICRP, populations stabilized with at annual survival rates of 0.3 or greater. The positive response of nest and brood survival to discing and interseeding CRP provides further evidence that CRP fields must be managed to optimize wildlife benefits. © 2012 The Wildlife Society. [ABSTRACT FROM AUTHOR]

The Conservation Reserve Program (CRP) is an extensive land use in the United States, which restores cultivated land to perennial vegetation through seeding. Low precipitation and high potential evapotranspiration are major limitations to the establishment and growth of seeded species in semiarid regions. We tested the rate of development of plant functional types across a chronosequence of restored fields using a model of plant succession. We also determined how the seeding of non-native (introduced) relative to native perennial grasses influenced plant community recovery. In contrast to the native shortgrass steppe (SGS), recently seeded CRP fields had high cover of annuals, forbs, C3, and introduced species. The seed mix determined which perennial grasses dominated the plant community within 18 years, but slow establishment prolonged early seral stages, allowed for the spread of colonizing perennial grasses, and limited recovery to less than half the canopy cover of undisturbed shortrass steppe. Species density declined in restored fields as seeded perennial grass cover increased and was lower in CRP fields seeded with introduced compared to native perennial grasses. Plant community composition transitioned to C4 and native species, even if fields were not seeded with these species, and was modified by shifts in the amount and seasonality of precipitation. Thus, in semiarid CRP fields, we found that the potential for recovery depended on time since CRP enrollment, seed mix, and climatic variability. Full recovery, based on similarity to vegetation cover and composition of undisturbed SGS, requires greater than 20 years. [ABSTRACT FROM AUTHOR]

Quantifying forest structure is important for sustainable forest management, as it relates to a wide variety of ecosystem processes and services. Lidar data have proven particularly useful for measuring or estimating a suite of forest structural attributes such as canopy height, basal area, and LAI. However, the potential of this technology to characterize forest succession remains largely untested. The objective of this study was to evaluate the use of lidar data for characterizing forest successional stages across a structurally diverse, mixed-species forest in Northern Idaho. We used a variety of lidar-derived metrics in conjunction with an algorithmic modeling procedure (Random Forests) to classify six stages of three-dimensional forest development and achieved an overall accuracy>95%. The algorithmic model presented herein developed ecologically meaningful classifications based upon lidar metrics quantifying mean vegetation height and canopy cover, among others. This study highlights the utility of lidar data for accurately classifying forest succession in complex, mixed coniferous forests; but further research should be conducted to classify forest successional stages across different forests types. The techniques presented herein can be easily applied to other areas. Furthermore, the final classification map represents a significant advancement for forest succession modeling and wildlife habitat assessment. [Copyright &y& Elsevier]

Abstract: We examined the relationship between landform types and riparian forest structure and succession in second-growth stands along mid order streams in the Cascade Mountains, Washington, USA. We sampled tree, sapling, seedling, and shrub characteristics across a range of fluvial geomorphic surfaces, which were classified into four landform classes, including low floodplain, high floodplain, terrace and hillslope. Landform classification was based on topographic characteristics, position relative to the stream channel, and estimated flood frequency. Statistical analyses using generalized estimating equations (GEE) showed that landform exerted a strong influence on the distribution and abundance of conifer and deciduous species and of different tree life stages. The floodplain landforms were characterized by initial disturbance from timber harvest, and ongoing fluvial disturbance, which favored the establishment of deciduous communities dominated by red alder (Alnus rubra) and maintenance of early successional riparian stands. In contrast, the terrace and hillslope landforms were also subject to timber harvest as the stand initiating agent but were unaffected by fluvial disturbance. However, based on differences in species distribution, we infer that forest structure on these two landforms differed from one another as a result of differences in soil moisture levels. Terraces and hillslopes were found to have high conifer tree abundance, but frequency of younger conifers was higher on hillslopes. Deciduous tree reproduction was very low on terraces and hillslopes. Our results also suggest that conifer recruitment in these second-growth riparian forests may be more successful on soil substrates than on coarse woody debris. We propose that the interplay between the disturbance regime (including type, frequency and intensity) and soil moisture conditions played an important role in influencing the course of riparian succession, present stand structure, and future successional trajectories and these were the primary mechanisms driving vegetation differences among landforms. [Copyright &y& Elsevier]

Many programs are in place to protect and restore low-order streams and riparian zones. However, information on riparian zone forests is sparse for many biogeographical regions, especially compositional and structural data that would provide useful targets for restoration. This study provides quantitative data on riparian zone composition and forest structure from three physiographic provinces of eastern United States. Data from 219 low-order (first- to fourth-order) forested reaches were arranged by three basal area (BA) categories meant to represent successional categories and variations in forest structure. Detrended correspondence analysis (DCA) was used to illustrate differences among successional categories and physiographic provinces. The DCA ordination separated stands into four physiographic subregions, based on the species composition of late-successional stands. Many early to mid-successional stands (<30 m2/ha) were similar in composition to late-successional reference stands (BA ≥ 30 m2/ha) in the same physiographic subregion. In such sites, natural successional processes would likely be sufficient to restore the compositional and structural attributes inherent in late-successional stands if provided long-term protection. Other sites with dissimilar compositions may have been recovering from more intensive types of alterations, such as mechanized land clearing. In such sites, restoration to historic compositions could benefit functionally by planting oaks ( Quercus spp. L.) and other heavy mast species. [ABSTRACT FROM AUTHOR]

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]

Quantification of the downed woody materials that comprise forest fuels has gained importance in Caribbean forest ecosystems due to the increasing incidence and severity of wildfires on island ecosystems. Because large-scale assessments of forest fuels have rarely been conducted for these ecosystems, forest fuels were assessed at 121 US Department of Agriculture forest service inventory plots on Puerto Rico, Vieques, and the US Virgin Islands. Results indicated that fuel loadings averaged 24.05 Mg ha-1 in 2004-2006. Forest litter decreased from wetter to drier forest life zones. These island forests showed a paucity of coarse woody fuels (CWD) (2.91 Mg ha-1) and relatively greater quantities of smaller-sized fine woody fuels (FWD) (10.18 Mg ha-1 for FWD and 10.82 Mg ha-1 for duff/litter) when compared to continental tropical forests. Between 2001 and 2006, CWD fuel loads decreased, while fine fuels and litter increased, such that total fuel loads remained constant on a subset of plots on Puerto Rico. This trend indicates that continued decomposition of CWD deposited by the last severe hurricane is balanced by increasing inputs of FWD from recovering and maturing secondary forests. Forest disturbance cycles and successional development must be taken into account by agencies charged with fire protection and risk assessment. [ABSTRACT FROM AUTHOR]

Background: Biogeographic patterns of species invasions hold important clues to solving the recalcitrant 'who', 'where', and 'why' questions of invasion biology, but the few existing studies make no attempt to distinguish alien floras (all non-native occurrences) from invasive floras (rapidly spreading species of significant management concern), nor have invasion biologists asked whether particular habitats are consistently invaded by species from particular regions. Methodology/Principal Findings: Here I describe the native floristic provenances of the 2629 alien plant taxa of the Eastern Deciduous Forest of the Eastern U.S. (EUS), and contrast these to the subset of 449 taxa that EUS management agencies have labeled 'invasive'. Although EUS alien plants come from all global floristic regions, nearly half (45%) have native ranges that include central and northern Europe or the Mediterranean (39%). In contrast, EUS invasive species are most likely to come from East Asia (29%), a pattern that is magnified when the invasive pool is restricted to species that are native to a single floristic region (25% from East Asia, compared to only 11% from northern/central Europe and 2% from the Mediterranean). Moreover, East Asian invaders are mostly woody (56%, compared to just 23% of the total alien flora) and are significantly more likely to invade intact forests and riparian areas than European species, which dominate managed or disturbed ecosystems. Conclusions/Significance: These patterns suggest that the often-invoked 'imperialist dogma' view of global invasions equating invasion events with the spread of European colonialism is at best a restricted framework for invasion in disturbed ecosystems. This view must be superseded by a biogeographic invasion theory that is explicitly habitat-specific and can explain why particular world biotas tend to dominate particular environments. [ABSTRACT FROM AUTHOR]

The once widespread Longleaf pine ( Pinus palustris)–dominated ecosystems of the southeastern coastal plain of the United States have been greatly reduced in extent, and many of the remaining stands are being degraded by hardwood invasion due to fire suppression. The first step toward pine savanna restoration is often hardwood removal, a costly process due to their large volumes and low market values. Despite these problems, by marketing a wide range of hard- and softwood products, the costs of 13 restoration projects in northern Florida were substantially reduced. Ten different products were sold to 19 different buyers. Fuel chips represented 71–100% of all biomass removed (8.2–81.1 Mg/ha). Although landowners were charged modest amounts for removing biomass harvested as fuel chips, other marketed products yielded revenues. Overall, four projects earned net profits of $29–$383/ha, and four projects generated sufficient revenue to pay 17–99% of the cost of hardwood removal as fuel chips. A carbon accounting of a second set of projects demonstrated that carbon harvested as fuel chips far exceeded that consumed in harvest and transport, yielding net carbon offsets of 451–1,320 Mg C/project (3.3–13.9 Mg C/ha). Using fuel consumption results of this second set of projects, carbon offsets for the 13 restoration projects were estimated as 89–1,524 Mg (3.8–37.9 Mg C/ha). Restorationists should monitor traditional forest product markets as well as developing carbon markets for price fluctuations that could provide significant revenues to restoration projects. [ABSTRACT FROM AUTHOR]

The article comments on the paper "Plant Species Invasions Along the Latitudinal Gradient in the United States," by Curtis H. Flather, Thomas J. Stohlgren, Catherine Jarnevich, David Barnett, and John Kartesz. The authors assert that the study made by Stohlgren and colleagues has two major deficiencies in which the researchers's data set of county richness values underestimates true county richness and the richness values were incorrectly transformed to report for variation in survey area. They argue the conclusions of the researchers which include the absence of relationship between native plant richness and latitude at the country level and the strongest single predictor of exotic species richness is native species richness.

Measures the above-ground biomass production and species composition in a grassland ecosystem in Texas. Effect of atmospheric carbon dioxide concentration; Tissue nitrogen concentration; Community succession.

A relict population of eastern white pine (Pinus strobus L.) occurs at White Pine Hollow State Preserve in northeastern Iowa, USA. White pine was not self-replacing in our study plots here, and without disturbances that alter the successional trend the species will eventually disappear from the flat to rolling uplands where most pines currently occur. Some natural pine reproduction occurs on steep slopes. Live tree density was 967 trees ha[sup -1], and mean basal area was 34 m² ha[sup -1]. Basal area was significantly greater on plots with white pine. Without recruitment of pine into the overstory, these plots will experience declines in basal area. The diameter distribution of all live trees had a negative exponential shape. However, the distributions for white pine, white oak (Quercus alba L.), and northern red oak (Quercus rubra L.) were unimodal, with no or few trees in the smaller size classes. Compared to a previous study at White Pine Hollow, there has been a dramatic decrease in the density of white pine and white oak trees, and an increase in sugar maple (Acer saccharum Marsh.). Mean density of standing dead trees was 95 trees ha[sup -1] with basal area 4 m² ha[sup -1]. Overall, the number of standing dead trees by diameter class was 10% that of live trees, but this relationship did not hold true for individual species. For white pine and the oaks, the ratio of dead to live trees was much greater than the average for all species combined. The mean volume of downed wood was 66 m³ ha[sup -1]. [ABSTRACT FROM AUTHOR]

Presents a study that examine Eversgerd Post Oak Flatwoods in Illinois to determine its woody composition and structure. Background on post oak flatwoods; Methodology; Effects of fire suppression on canopy closure and plant succession.

Provides information on a study which evaluated the effects of plant succession on habitat use and fruit resources availability for autumn migratory and resident songbirds of abandoned farm fields in central New Jersey. Study area and methods; Results; Discussion.

Examines how rates and mechanisms of succession vary spatially and temporally in xeric, subalpine forests in Colorado. Reconstruction of 300 years of succession; Species abundance; Basal areas; Measures of ecological similarity.

Explores the plant succession on pumice at Mount Saint Helens, Washington. Methods; Results; Discussion.

Examines the colonization and inhibition abilities of species in a successional grassland in California. Prediction of population and community change; Successional change in undistributed sites; Dependence of species differences in colonizing ability on the different densities of seed rain.

Examines the species interactions in a successional grassland in California. Species distributions; Seed rain and seedling recruitment; Estimation of seed bank contribution to recruitment using seed exclosures.

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.

Explores local variation in rate of plant succession by computing three contrasting measures of change for ten New Jersey old fields through the first 18 years after abandonment. Euclidean distance in ordination space; Turnover analysis; Regression analysis of species loss from the initial cohort.

Reports on temporal patterns of species composition and diversity following grass-to-forest succession from a long-term experiment in the Coweeta Basin, western North Carolina. Documentation on how species richness and diversity recover from severe large-scale disturbance; Human disturbance in the area; Abundance of early successional woody species.

Several plant communities in the Southwest have been drastically altered within a century by the rapid spread of a small number of woody species. The habitats principally affected have been the plateaus and plains at intermediate elevations, which formerly supported grassland and have now been invaded on a massive scale by mesquite and other native shrubs, and the stream courses, which have been extensively occupied by tamarisk, an alien species from Eurasia. Historical evidence and field observation suggest that these invasions have resulted of commercial livestock ranching led to increased seed dispersal, overgrazing, and the suppression of grass fires, the combined effects of which favored the invasion of grassland by woody plants. Short-term climatic fluctuations towards greater aridity have tended to accentuate rather than to initiate the processes of invasion. The spread of tamarisk is owing mainly to changes in stream regime resulting from the creation of reservoirs. The history of recent plant invasion in the Southwest illustrates how man may unintentionally bring about rapid and profound ecological changes in dry areas by the introduction of new systems of land use.

The article focuses on the study results of the process of change in plant ecosystem of the brush-prairie using the quadrat method in north-western Minnesota. The brush-prairie has germinated on the wet flats left on the niche of the glacial Lake Agassiz, resulting to the hydrarch of successions. Several brush of the region composes of Corylus americana or Prunus virginiana as principal species, Populus balsamifera and Pojmlus tremuloides consocies with Salix discolor are also mentioned. The grassland and woodland are cited as two different lines which increase successions associated with the hydrophytic habitats in drying up.

The article features the Ecologically Based Invasive-Plant Management (EBIPM) decision-making model for the restoration of a healthy mix of vegetation in Western rangelands. Developed by the team of Agricultural Research Service (ARS) scientists led by Roger Sheley, it says, EBIPM was based on the approach that proposed general plant succession causes including species availability, species performance and site availability. It also notes the Rangeland Health Assessment protocol.

Presents an abstract of the study `Mycorrhizae of Mt. St. Helens: a study of symbiotic influence on primary succession,' by Sharol L. Lindenstein and presented during the 1995 Annual Meeting of the Botanical Society of America.

Presents an abstract of the study `The interaction of seed dispersal and microsite quality in early primary succession on Mount St. Helens,' by David M. Wood and presented during the 1995 Annual Meeting of the Botanical Society of America.

Presents an abstract of the study `The role of allogenic and autogenic processes in dunes succession at Miller, Indiana,' by Thomas L. Poulson and presented during the 1995 Annual Meeting of the Botanical Society of America.

Presents an abstract of the study `Caprice and predictability during early primary succession on Mount St. Helens,' by Roger del Moral and presented in the 1995 Annual Meeting of the Botanical Society of America.