The type of regional dynamics of a species can provide information on how to manage the species, and may be the only way that some rare species may persist in a given region. A metapopulation is a type of regional dynamic in which local extinction is counterbalanced by recruitment from nearby patches. Metapopulation studies were originally conducted on animals, but have been adapted to plants, and are generally restricted to single-season studies. Plant species may persist as a metapopulation in patchy habitats, such as in forest openings. Forest openings (commonly called barrens, hill prairies, or glades) are habitats found on ridgetops which are characterized by having thin or nutrient-poor soil, high sunlight exposure, and relatively low soil moisture when compared to nearby forest habitats. Forest openings commonly contain plant species more frequently found in prairies, and are often maintained by natural fires that prevents woody species encroachment. In the absence of natural fires due to human management and suppression, woody species have invaded some forest openings, dividing them into a series of patches. To determine whether it is possible for each species to persist as a metapopulation in forest openings, five studies were carried out at each of three sites within the Shawnee National Forest in southern Illinois: a plant survey and ordination using environmental variables, the use of incidence function models to determine which of the species had the potential to form a metapopulation, a metacommunity study to examine overall patterns at each site, a seed bank study, and a seed dispersal study. Forest openings were found to be separate habitats from the surrounding forest based upon canopy openness. Approximately 30% of the species fit the metapopulation model, and the metacommunities at each of the sites exhibited a Clementsian pattern, characterized by groups of co-occurring species that replace each other over the region due to turnover between the groups of species. Species that fit the metapopulation model tended to have seeds that emerge more frequently from the seed bank if annuals and less frequently in the seed bank than species not fitting the metapopulation model (non-metapopulation species) if longer-lived. Species fitting the metapopulation model dispersed equal numbers of seeds as non-metapopulation species at short (5m) and medium (10m) distances, and in some cases dispersed more seeds to longer distances than non-metapopulation species. These studies show that forest openings can be treated as islands of suitable habitat for some species, and that numerous (~30%) species (such as Scleria pauciflora, Stylosanthes biflora, and Manfreda virginica) may assume a metapopulation dynamic in any given year. Many species may have incidence patterns consistent with those of a metapopulation in multiple years; however, the exact habitat patches in which species occur in any given year may change from year to year. Species in forest openings tend to co-occur in groups (a Clementsian pattern), which means that management plans should consider the entire community rather than a single species.

During European settlement, the vast majority of grasslands in Illinois were converted for agricultural purposes. Some of the remaining natural areas in southern Illinois include natural xeric forest openings (i.e., barrens, glades, outcrops), that have transitional community compositions representative of previously extensive grasslands and adjacent hardwood forests. Previous research in these forest openings show that the communities are largely driven by edaphic conditions and vary spatially across southern Illinois. While most of these communities are currently protected and established as nature preserves, threats to these natural xeric forest openings continue to persist, such as climate change and exotic invasion. These threats are capable of altering taxonomic, phylogenetic, and functional diversity and community composition. The overall goals of this research were to 1) determine metapopulations and metacommunity structure in a local group of sandstone outcrop communities (a subset of natural xeric forest opening communities), 2) expand resolution to a regional scale to include natural xeric forest openings with several substrates to investigate changes in taxonomic, phylogenetic, and functional diversity and community composition since surveys conducted in 1988, and 3) include spatial analyses to characterize autocorrelation structure of diversity and environmental variables and biological turnover of natural xeric forest openings at a global scale. Sandstone outcrop communities at Jackson Hollow in Pope County, Illinois had several metapopulation species based on Hanski’s incidence functional model. These metapopulation species were more often members of the Asteraceae and Poaceae than members of other plant families, and were often exotic in origin with short-lived lifecycles. These metapopulation species were also neither dominant species or singletons within sandstone patches. Based on the Elements of Metacommunity (EMS) Framework, positive coherence, species turnover, and boundary clumping indicate that these sandstone outcrop communities are predictable communities where species replace one each other regularly as groups of species and respond similarly to environmental gradients. Furthermore, diversity metrics were all positively correlated with each other, but not with patch characteristics. In addition, total species and metapopulation species were positively associated with phylogenetic and functional diversity, but metapopulation species were positively associated with non-standardized phylogenetic and functional indices. When looking at several natural xeric forest openings across southern Illinois and comparing them based on substrate types and between surveys in 1988 and 2019, taxonomic, phylogenetic, and functional compositions were distinct based on substrates, but were stable and resilient across surveys. Sandstone and shale communities were the most similar based on composition, followed by limestone communities compared to sandstone and shale communities, and then loess communities being the most dissimilar from all other communities. Environmental variables that best explained differences in community composition were canopy cover, soil acidity, photosynthetically active radiation, and soil depth. Diversity variables that best explained differences in community composition were phylogenetic nearest taxon index, Faith’s phylogenetic diversity, and dominant species richness. Ninety-four different species were either significant indicators for specific substrates, or 2019 surveys. While no cases of phylogenetic signal were observed based on functional traits, substrate types, or surveys, three cases of functional signal based on dominant communities were observed in sandstone communities in 2019, shale communities in 2019, and overall shale communities across 1988 and 2019 surveys. When applying spatial analyses to these natural xeric forest openings to understand autocorrelation structure and biological turnover, soil depth was the only environmental variable that exhibited significant spatial autocorrelation, as previous glacial events caused loess hill prairies in the northwestern extent of this study to have deeper soil due to Quaternary loess deposition. However, several diversity metrics exhibited spatial structure based on 1988 and 2019 surveys (1988: dominant species richness, Pielou’s evenness, Shannon-Weiner diversity, Faith’s phylogenetic diversity, and distance-based functional diversity; 2019: dominant species richness, Pielou’s evenness, Shannon-Weiner diversity, Faith’s phylogenetic diversity, and phylogenetic nearest taxon index). In addition, climate variables daily mean temperature and total annual precipitation exhibited spatial structure. Most variables were spatially clustered at local site scales and spatially dispersed at larger scales and spatially over-dispersed at a regional scale. Generalized dissimilarity models constructed based on elevation, soil, and climate variables showed that models based on both functional composition and 2019 surveys best explained biological turnover compared to taxonomic and phylogenetic and 1988 models. Several variables included in models differed based on aspects of biological turnover or surveys, but temperature annual range and soil bulk density variables were common across all models. However, differences between total deviance explained and null deviances show that geographic distance between natural xeric forest openings was overwhelmingly the most influential variable contributing to biological turnover. Given these observations, natural xeric forest openings at local scales persist as distinct habitat patches amidst a landscape that largely constitutes an inhospitable matrix to colonizing species, yet certain species are able to migrate between patches. The resulting community assembly of individual patches is determined by both colonizing species and environmental gradients across the landscape. Despite simultaneous threats to diversity and composition in natural xeric forest openings at a regional scale, substrate continues to drive community assembly, in that certain species are characteristic indicators of these substrates. Furthermore, the most recent surveys in sandstone and shale communities exhibited functional signals. However, these natural xeric forest openings are spatially structured based on soil depth due to glacial history, certain metrics of diversity, and climate variables. Along with these occurrences of spatial autocorrelations, different aspects of biological turnover are best predicated by geographic distance as well as unique combinations of climate and soil variables between different aspects of diversity and surveys.

In 1982, several rectangular openings were cut in a 100 year old sub-alpine Norway spruce forest stand to initiate regeneration at the Lusiwald site at Davos, Switzerland. The openings on the steep, north-facing slope created rapid changes to the environment of the border trees. Growth reactions of these border trees were compared and analysed with reference trees from the adjacent closed canopy stand in 1997. The radial growth pattern of the two data sets differed within the 14-year period since the openings were cut; the border trees showed growth releases. The growth reaction at the stem base was larger than at breast height. Changes in wind exposure may have influenced border trees to adapt their root systems. Sub-alpine Norway spruce stands aged around 100 years, which are usually considered slow-growing on a north aspect, still seem capable of reacting to greater resource availability such as sudden light changes.

From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / Profiles of snowpack build-up in openings in forest overstories have been widely observed; however, a quantitative characterization of such a snowpack profile would aid in developing empirical guidelines for improving water yields from snowpacks. A technique is outlined that illustrates (a) evaluating snowpack profiles in and adjacent to individual forest openings in terms of increase or decrease in water equivalent, and (b) defining trade-offs between the estimated increase or decrease in snowpack water equivalent and the forest resource removed. Snowpack water equivalent during peak seasonal accumulation was measured in and adjacent to a clearcut strip in a ponderosa pine stand in north-central Arizona. A 4-degree polynomial, which defines the snowpack profile in terms of deposition, redistribution, and ablation characteristics, was empirically selected to describe snowpack water equivalent data points. An increase of 60 percent in snowpack water equivalent was realized by removing 46 percent of the ponderosa pine in the zone of influence, using a strip equal to one and one-half the height of the adjacent overstory.