James A. Reinartz

Development of vegetation in small created wetlands in southeastern Wisconsin

We examined the natural colonization by vascular plants of 11 created wetlands in southeastern Wisconsin. The wetlands studied were small depressional wetlands that were isolated from other wetland sites. Wetlands were sampled over a two-year period, providing samples of wetlands aged one to three years. The development of wetland vegetation in these 11 naturally colonized sites was compared to that in five wetlands to which we introduced 22 species of native wetland plants. We identified 142 species of vascular plants in the naturally colonized wetlands. Of these, 82 (58%) were native, obligate or facultative wetland plants. The diversity and richness of native wetland plants and the proportion of total plant cover that was comprised of native wetland species increased from one-to three-year-old wetlands. The diversity and richness of native wetland species increased with wetland age, wetland size, and with proximity to the nearest established wetland. Distance to the nearest seed source had a particularly strong effect on the number of native wetland species present. Cattail (Typha spp.) accounted for 15% of the cover of native wetland species in one-year-old wetlands; this increased to 55% in three-year-old wetlands. We predict that the naturally colonized wetlands will develop into near monocultures of cattail with a fringe of willows (Salix spp.) and cottonwood (Populus deltoides) at the wetland/upland margin. Wetlands seeded with native wetland species had much higher diversity and richness of native wetland species than unseeded wetlands after two years. Seventeen of the 22 seeded species became established in at least two wetlands after simple introduction of seed to the sites. Cattail cover after two years was lower in seeded sites, both as an absolute cover and as a proportion of native wetland plant cover. Early introduction of a diversity of wetland plants may enhance the long-term diversity of vegetation in created wetlands.

Genetic consequences of rarity in Aster Furcatus (asteraceae), a threatened, self-incompatible plant

Aster furcatus is a rare, self‐incompatible plant with fewer than 50 known populations throughout its range. We verified self‐incompatibility in A. furcatus by conducting experimental self‐ and cross‐pollinations and by examining seed set in a small population comprised of a single clonal genet. We examined variation at 22 electrophoretic loci in 23 populations of A. furcatus from across its range in Wisconsin, Illinois, Indiana, and Missouri. Except for two rare alleles found in single individuals in three populations, all loci but one of those examined were fixed for single alleles. The only variable locus (triosephosphate isomerase, TPI‐1) tended to exhibit genotype frequencies in Hardy‐Weinberg equilibrium or with a slight excess of heterozygotes. Although overall gene diversity was extremely low, TPI genotype frequencies were indicative of an outcrossing plant. We examined the subpopulation genetic structure among clonal plants within one Wisconsin population in greater detail. F statistics indicated that much of the genetic variation at the polymorphic TPI locus was due to differentiation among populations. We discuss the implications of self‐incompatibility and low levels of genetic variation for the evolution and conservation of Aster furcatus and other rare plants with similar breeding systems.

Restoring forest in wetlands dominated by reed canarygrass: The effects of pre-planting treatments on early survival of planted stock

Reed canarygrass (Phalaris arundinacea L.) is an aggressive and persistent invasive species in formerly forested wetlands of the northern United States. Heavy shading reduces the dominance of reed canarygrass, so a promising long-term approach to restoration of reed canarygrass-dominated wetlands is the establishment of woody plants that will overtop and shade the grass. The first step toward developing this long-term restoration method is to determine a combination of reed canarygrass control methods and suitable trees and shrubs to provide high early survival of the native woody plants. We tested 23 tree and shrub species in five treatments to determine: 1) the woody species that have the highest survival when planted in treated stands of reed canarygrass, and 2) the pre-planting treatments that lead to the highest rates of survival. Near-monocultures of reed canarygrass were herbicided, mowed and herbicided, herbicided and plowed, or herbicided and burned. One-to three-year-old, mostly bare-rooted trees and shrubs were hand-planted into these treatments and into untreated control plots at three sites, and over two growing seasons. Fall herbicide followed by spring plowing provided the highest survival for the majority of species planted. However, all experimental treatments (controlling reed canarygrass with a single herbicide application) provided reasonably high survival of the 10 most successful woody species. Those pre-planting treatments and study sites that developed the greatest herbaceous species diversity after treatment had the highest tree and shrub survival. The early establishment success we found using these methods is encouraging for development of a technique for restoring swamp forest in degraded reed canarygrass-dominated wetlands.

An exotic invasive shrub has greater recruitment than native shrub species within a large undisturbed wetland.

The idea that invasive species have higher recruitment and tolerate a wider range of conditions than native species requires more rigorous examination across a range of community types. We aimed to compare the recruitment and distribution patterns of adults and seedlings of an exotic invasive plant, glossy buckthorn (Frangula alnus), with four co-occurring native shrub species within a heterogeneous Wisconsin wetland. Detailed vegetation survey data were analyzed for spatial and compositional patterns of shrub distributions. In adult plant frequency and cover, buckthorn was not significantly different from the native winterberry. However, the number of glossy buckthorn seedlings exceeded by more than seven times the combined number of seedlings of the four native species. Sample units containing buckthorn adults were also much more likely to contain seedlings than for native shrubs. However, native seedlings were not more likely to occur at sites lacking adults, suggesting no greater dependence on recruitment away from adults in native species. Buckthorn, winterberry, poison sumac, and dogwood all showed preference for sites with higher tree densities and lower predominance of obligate wetland species in an ordination of 114 species. Glossy buckthorn adults and seedlings and winterberry seedlings were more widely distributed across seven community types than adults and seedlings of the other native species, suggesting broad tolerance to the conditions in different community types. High recruitment is the key factor that may allow glossy buckthorn to overcome community resistance and spread.

Effects of temperature and availability of insect prey on bat emergence from hibernation in spring

Bats at northern latitudes may hibernate for up to 8 months during winter and must subsist on stored fat over this period. Environmental influences on bat emergence from hibernation are not well understood, and the degree to which bat emergence coincides with availability of their insect prey is not known. We used electronic detectors to monitor bat activity from 2001 to 2013 at a major hibernaculum, used primarily by Myotis lucifugus, in Wisconsin. We estimated dates of entry into hibernation in fall and recorded bat activity as bats emerged in spring over this 13-year period. Temperatures outside and inside the mine and airflow at the mine entrance were measured. Night-flying insects were monitored during spring from 2008 to 2013. Bat activity in spring was most strongly associated with warmer temperatures outside of the mine and was also correlated with airflow in the mine entrance. Changes in airflow were driven by temperature differentials between the mine and outside, and could serve as a signal for outside temperatures to bats inside of the mine. Insect abundance was also positively correlated with warmer outside temperatures. However, bat activity peaked before insects started to become abundant. Over the 13 years of the study, the date at which 5% of bat activity for the season was reached ranged from 10 April to 20 April, and for 50% of bat activity for the season the range was from 28 April to 4 May. The date of 5% bat activity for the season was not correlated with the date of entry into hibernation the previous fall, mean winter temperatures inside or outside of the mine, or the degree days (base 0°C) inside or outside of the mine. Our study was conducted before white-nose syndrome was documented in Wisconsin, thus our study documents hibernation behavior of healthy bats.