Decline of Atlantic white-cedar (Chamaecyparis thyoides), an uncommon, wetland tree of the eastern coastal United States, may be due in part to successional change in which cedar is replaced by more shade-tolerant tree species. The purpose of this study was to assess population structure and natural regeneration of cedar, project future changes in stand composition, and suggest appropriate management. The research was conducted at Brown Mill Pond, an ecological reserve in Rye, New Hampshire. Age and size structure of tree species were used to infer successional trends in five plant communities: (1) mixed conifer, (2) cedar I, (3) cedar II, (4) cedar-red maple, and (5) pond edge. Depth to water table was measured over two field seasons. Differences in species composition and stand structure were associated with variations in water table depth. In all communities except the pond edge and small (< 0.2 ha) patch cuts, cedar was even-aged (> 90 years old) and recruitment was lacking. In three communities over the next 100 years, abundance of arboreal associates will likely increase while cedar will decline. In a previously unreported successional sequence, eastern hemlock (Tsuga canadensis) and red spruce (Picea rubens) will likely become dominant in the mixed conifer community, which had the lowest water table. In areas with an intermediate water table, such as the cedar-red maple community, red maple (Acer rubrum) will achieve co-dominance with cedar. While cedar will likely decline in the absence of disturbance, it is unlikely that cedar will be completely replaced by arboreal associates at Brown Mill Pond as cedar establishment was evident along the pond edge and in small patch cuts.

Despite extensive use, few studies have thoroughly tested competency of the Florist Quality Index (FQI) to assess vegetation quality by comparing it with alternative statistics and with independent measures in large data sets. We compared the efficacy of species richness and floristic quality indices in detecting temporal change and fire effects on quality within and among tallgrass prairie remnants. We calculated species richness at small (1/4-m² plot) and large (total sample) scales, as well from a Species Richness Index (SRI) that integrates these measures. These statistics were compared with FQI, which assesses quality by integrating species richness with estimates of species conservatism (C values) to undisturbed natural vegetation. We made within-site comparisons of temporal change in dry-mesic and mesic prairie vegetation following 22 years of fire exclusion and then after five years of fire management. The among-site comparisons used 33 prairies that were graded as A or B quality and sampled in 1976 by the Illinois Natural Areas Inventory (INAI). We resampled these sites in 2001 and analyzed vegetation change in relation to their fire-management histories.

Within-site comparisons found that significant declines in average plot species richness corresponded to independent measures that documented deterioration of vegetation composition and structure. In contrast, lack of significant change in average C values failed to detect these changes. We found that species richness was greatest in mesic habitats, while C values were biased toward higher values assigned to dry prairie species. Among sites, those ranked as grade A by the INAI had greater species richness than grade B sites. Temporal changes in species richness in these sites were also positively correlated with fire frequency, which in turn was negatively correlated with a shift in vegetation structure toward increasing woody vegetation and loss of grasses. Average C values did not differ significantly between the INAI A and B quality grades, nor were they correlated with fire frequency; however, they were negatively correlated with increasing woody dominance. These results indicate that, for tallgrass prairie, measures of species richness can be very sensitive indicators of vegetation change, and can help gauge differences in vegetation quality within vegetation types. In contrast, indexing floristic quality is inconsistent and problematic due to bias and lack of precision in assigning conservatism scores as well as instability in the FQI formula and potential for circular reasoning in validating its effectiveness.

Iris hexagona is a perennial freshwater species indigenous to Louisiana wetlands. Coastal iris populations that are exposed to saline conditions often suffer heavy floral browsing. This paper is the first to photographically document florivory by white-tailed deer (Odocoileus virginianus Zimmerman), which consume iris flowers and immature seed capsules. Severe florivory can prevent sexual reproduction in plants and eliminate habitat for floral arthropods. In this three-year study, we monitored environmental salinity, assessed natural levels of florivory, and established deer exclosures to test the effects of florivory on arthropod abundance and diversity. In two out of three years, florivory rates were positively correlated with the level of salinity at individual I. hexagona populations. In all three years, florivory in the brackish marsh was an order of magnitude greater than florivory in intermediate and freshwater sites. In 2003, the number and diversity of arthropods was significantly greater on unbrowsed (caged) than browsed (open) irises. In October 2002, Hurricane Lili struck our main study site, causing extensive damage to the landscape and heavy deer mortality. Despite this, floral browsing was high (88%) in spring 2003, and arthropod numbers and diversity declined significantly. Our results suggest that salinity may facilitate floral browsing, which can have direct effects on plant fitness and indirect consequences for arthropod communities in wetland plant populations.

Mineral sites are scarce resources of high ion concentration used heavily by the Pacific Coast subpopulation of band-tailed pigeons. Over 20% of all known mineral sites used by band-tailed pigeons in western Oregon, including all hot springs, have been abandoned. Prior investigations have not analyzed stand or landscape level habitat composition in relation to band-tailed pigeon use of mineral sites. We used logistic regression models to evaluate the influence of habitat types, identified from Gap Analysis Program (GAP) products at two spatial scales, on the odds of mineral site use in Oregon (n = 69 currently used and 20 historically used). Our results indicated that the odds of current use were negatively associated with non-forested terrestrial and private land area around mineral sites. Similarly, the odds of current mineral site use were positively associated with forested and special status (GAP stewardship codes 1 and 2) land area. The most important variable associated with the odds of mineral site use was the amount of non-forested land cover at either spatial scale. Our results demonstrate the utility of meso-scale geographic information designed for regional, coarse-filter approaches to conservation in fine-filter investigation of wildlife-habitat relationships. Adjacent landcover and ownership status explain the pattern of use for known mineral sites in western Oregon. In order for conservation and management activities for band-tailed pigeons to be successful, mineral sites need to be addressed as important and vulnerable resources. Management of band-tailed pigeons should incorporate the potential for forest management activities and land ownership patterns to influence the risk of mineral site abandonment.

We monitored populations of Canada thistle biocontrol agents Cassida rubiginosa, Ceutorhynchus litura, Larinus (= Hadroplantus) planus, Urophora cardui, Orellia (= Terellia) ruficauda, and Rhinocyllus conicus on Canada thistle (Cirsium arvense) at two national wildlife refuges in South Dakota from 1999 through 2003. C. litura, U. cardui, O. ruficauda, and R. conicus were present on both refuges. Agent populations were low except for C. litura, which was present in up to 90% of stems in some plots. C. litura infestation did not reduce thistle flowering, stem length, or over-winter survival. There was no change in thistle stem numbers over the study period and no difference in stem numbers in areas of high C. litura populations compared to areas of low C. litura populations. Our results suggest that insect biological control agents are inadequate for reduction of Canada thistle in southern South Dakota.

Approximately eight hectares of shrub swamp wetland, primarily consisting of willow (Salix caroliniana Michx.), were roller-chopped to test the efficacy of this management technique in returning the plant community to one dominated by herbaceous species. Roller-chopping caused severe disturbance to the treatment area. Few willows were left standing and a majority of trees were uprooted entirely. Three months following chopping, limited re-sprouting of willow was observed. However, by the following March, no live willows were found in the treatment area. Willow remained absent for three years post-treatment. Hydrologic conditions may have influenced willow mortality through drought-induced stress and subsequent inundation in the treatment area. In contrast, these hydrologic conditions did not appear to affect willows in the control area. Following the elimination of willow, herbaceous plant species re-colonized the treatment areas, increasing in richness and abundance. Free-floating plants became the dominant species in the newly opened areas. Gradually, free-floaters became less important while rooted emergents, such as graminoids and forbs, became more abundant. This study indicates that, under dry conditions followed by flooding, roller-chopping can be an effective method of willow control. However, utilization of heavy equipment may alter topography, compact soil, and affect drainage patterns. Therefore, managers should exercise caution when applying this technique.

Understanding historical forest condition is important as a basis for forest restoration and the development of forest management policies. White pine (Pinus strobus L.) historically has been an important commercial tree species, and significant post-settlement declines in its populations have been suggested in eastern North America since the 1600s. Logging of white pine in eastern Ontario, Canada, began in the late 1700s. We estimated the loss of white pine and changes in white pine diameter distribution in Algonquin Provincial Park by direct sampling of old stumps, censussing trees in an area that has never been harvested, assessing Crown Surveyor's records from the 1800s, using a GIS mapping technique to assess probabilistic change in pine-dominated stands, and comparing our data to other published information. Stump and tree densities since the 1800s suggested a mean reduction in the number of white pine trees of 88% from about 3 to >8 pines/ha to <1 pine/ha today in mixed and deciduous stands. GIS-based mapping predicted a maximum decline of pine-dominated stands of about 40% by area, from 539 km² that may have historically supported such forests. The diameter distribution of the current white pine trees was significantly smaller than in the historical forest (means, 44.5 cm vs. 73.4 cm, P < 0.001). Aside from early over logging, the continued low density of white pine in all forest types can be attributed in part to intense post-logging fires in the 1800s and to the past 60 years of fire suppression, which have eliminated seed sources and seedbeds. We suggest that a program using several silvicultural techniques will be necessary to restore the white pine in forest types that existed historically.

Herbicides are useful tools to manage undesirable plants on grasslands. However, the negative response of desirable plants is a common concern when herbicides are used to manipulate grassland plant composition. Our objective was to determine the response of the forb community in a tallgrass prairie following herbicide application to manage Rhus glabra L. (smooth sumac). Two experiments (replicated in space and time) were conducted to evaluate forb response to selected herbicides, application rates, and broadcast spray and hand-held wick application techniques. In Experiment 1, the shrub Amorpha canescens Pursh (leadplant) had the greatest frequency where 2,4-D was selectively applied with a wick and Ambrosia psilostachya DC. (western ragweed) and Solidago missouriensis Nutt. (Missouri goldenrod) were greatest where glyphosate was applied with a wick, whereas Aster ericoides L. (heath aster) frequency was greatest where no herbicide was applied. In Experiment 2, Helianthus annus L. (annual sunflower) frequency was greatest where picloram was broadcast applied. Species richness varied by treatment in Experiment 1 with the greatest species richness in the areas where picloram 2,4-D and glyphosate were applied with a wick. In Experiment 2, species richness did not differ among treatments. We determined that wick-applied herbicides were less detrimental to the forb community than broadcast spraying when managing R. glabra in a tallgrass prairie.

Managing invasive species in natural areas of high ecological value generally involves the selection of an appropriate control method that is cost effective while minimizing the secondary impacts of the control operation on the ecosystem. During the last decades, speckled alder (Alnus incana ssp. rugosa) has been invading wet sedge meadows of the Lac Saint-François National Wildlife Area (NWA), Québec, Canada. This invasion threatens the habitat of several bird and plant species considered rare at the national and provincial levels. We evaluated effectiveness and impacts of four methods for controlling alder invasion in the wetland. As a short-term control method, controlled fire appears to be ineffective in the context of the Lac Saint-François NWA, as suggested by the high survival of alders in a zone previously burnt on our study site. Double-cut of the shoots aims at killing the shrubs by depleting nutrient reserves in the roots using two successive cuts during the same growing season. This method was also shown to be ineffective: more than 80% of the treated alders resprouted vigorously the following year. Foliar application of herbicide with a rope-wick applicator to control smaller shrubs did kill all treated individuals. However, this method showed high risks of herbicide dripping and should be used with care. The most promising control method was the herbicide treatment of cut stumps. This method was efficient and cheap. It was also efficient at the end of winter, when the ground of the wetland was still frozen, which facilitated accessibility and limited damages to non-target species caused by trampling or herbicide dripping.

Pitcher plant bogs of the Little River Canyon National Preserve in northern Alabama contain the federally endangered green pitcher plant (Sarracenia oreophila (Kearney) Wherry). Multivariate analysis of the bog vegetation and environmental variables revealed three communities with unique species compositions and soil characteristics. The significant soil characteristics were percent A-horizon sand and A-horizon depth. A blackgum (Nyssa sylvatica Marsh.)-yellow-poplar (Liriodendron tulipifera L.)-azalea (Rhododendron canescens (Michx.) Sweet) type was found on sites bisected by ephemeral streams with a closed canopy. A scarlet oak (Quercus coccinea Muenchh.)-flowering dogwood (Cornus florida L.)-sweet goldenrod (Solidago speciosa Nutt. var. erecta (Pursh) MacM.) type was found on upland sites close to the canyon rim and along perennial streams sites. A smooth yellow false foxglove (Aureolaria flava (L.) Farw.)-pale-spike lobelia (Lobelia spicata Lam.)-violet lespedeza (Lespedeza violacea (L.) Pers. type was found on relatively flat sites away from the canyon rim. The results can be used to locate potential sites for restoration of green pitcher plant bogs. Survival of the bogs is threatened by encroachment of over and midstory vegetation.

Severe fragmentation as a result of the introduction and expansion of mechanized agriculture has decimated the once dominant tallgrass prairie throughout much of the mid-western and mid-southern United States. In Arkansas, the Arkansas Natural Heritage Commission is charged with managing many of the remaining remnant tallgrass prairie fragments as Natural Areas. Though managed nearly annually by prescribed burning, a number of Natural Areas in Arkansas are hayed at least once a year. Since haying removes aboveground vegetation, many essential plant nutrients contained in that vegetation are also removed and are not returned to the same soil from which they were extracted. Therefore, the objective of this study was to evaluate the effects of vegetation removal (i.e., haying) on soil physical, chemical, and biological properties of a native tallgrass prairie fragment in east-central Arkansas. The study site was the Konecny Prairie Natural Area, which contains three areas of differing durations of vegetation removal by haying. Soil bulk density and bacterial biomass concentration in the top 10 cm were highest in the prairie area where vegetation removal by haying is still being conducted, while the prairie area where vegetation removal by haying ceased in 1998 had the highest soil organic matter, but lowest Ca and Mn contents. The effects of duration of vegetation removal by haying on native soil quality were variable and, for some soil properties, unexpected. Remnant prairie fragments can provide benchmark soil data for many properties to help ascertain the effects of land use change, particularly conversion to cultivated agriculture, and can provide target values for soil properties in ecosystem restoration efforts.