Emissions of methane were measured by a static chamber technique at 9 sites on 5 wetlands in the Eastern Temperate Wetland Region, north of Montreal. Mean daily methane fluxes measured from May to October ranged from 0.18 to 1071 mg/m$ sp2$/d, and estimated annual flux ranged from 0.02 to 186 g/m$ sp2$/y. Laboratory incubations of peat samples showed potential anaerobic methane production rates which ranged from 0.00 to 9.12 $ mu$g/g/d, and potential aerobic consumption rates from 0.55 to 3.75 $ mu$g/g/d. Seasonal methane emission patterns are related to water table level and CH$ sb4$ production and consumption potentials in the peat profile. Episodic fluxes were found to be important at several sites, contributing a significant portion of the total emissions. / Analysis of spectral reflectance data from 20 sites on 2 subarctic fens was carried out to address the issue of scaling up CH$ sb4$ emissions using satellite imagery. Hummocks, lawns and pools were found to be spectrally distinct enough to be differentiated by band 5 of Landsat MSS and band 3 of Landsat TM sensors. The averaging of spectral information in mixed pixels proved unlikely to be able to distinguish between wet lawn and string and pool communities. Such weaknesses can be overcome with the use of higher resolution data.

Das »Sächsische Informationssystem für Moore und organische Nassstandorte« (SIMON) bündelt Informationen zur Lage, Ausdehnung, Ausstattung und Gefährdung von Mooren. Landesweit vorliegende Karten zu biotischen und abiotischen Daten wurden zu Moorkomplexkarten verschmolzen. Auf dieser Grundlage konnten in Sachsen für 20 Moore Steckbriefe u. a. mit Angaben zu Fläche, FFH-Lebensraumtyp, Torfmächtigkeit, Landnutzung, ökologischem Zustand und aktuellem Schutzstatus erstellt werden. Die Gesamtfläche an Moorböden, oberflächennahen Torfvorkommen und moortypischen Biotopen beträgt in Sachsen 46.800 Hektar.

Das »Sächsische Informationssystem für Moore und organische Nassstandorte« (SIMON) bündelt Informationen zur Lage, Ausdehnung, Ausstattung und Gefährdung von Mooren. Landesweit vorliegende Karten zu biotischen und abiotischen Daten wurden zu Moorkomplexkarten verschmolzen. Auf dieser Grundlage konnten in Sachsen für 20 Moore Steckbriefe u. a. mit Angaben zu Fläche, FFH-Lebensraumtyp, Torfmächtigkeit, Landnutzung, ökologischem Zustand und aktuellem Schutzstatus erstellt werden. Die Gesamtfläche an Moorböden, oberflächennahen Torfvorkommen und moortypischen Biotopen beträgt in Sachsen 46.800 Hektar.

No description available.

No description available.

No description available.

Freshwater turtles are among the most threatened groups of taxa globally, and the bog turtle, Glyptemys muhlenbergii is among the most imperiled in North America. In Virginia, USA, bog turtles are restricted to occupying Appalachian Mountain fens. Fens are naturally small and fragmented wetlands characterized by elevated water tables and an open canopy. Although there is a strong need to document and monitor populations of bog turtles, efforts to do so are often limited by the low detection of the species. The first objective of this thesis was to assess proposed methodologies for locating populations of turtles on the landscape. My first chapter assessed a previously-developed habitat distribution model for bog turtles using an occupancy modeling approach. I conducted 216 surveys of 49 discretely predicted patches of habitat, recording conditions such as weather, size of wetland and time of year, hypothesized to affect detection during each survey. In addition, I assessed factors including stream entrenchment, grazing presence and surrounding impervious surfaces for each surveyed patch to identify data sources that could improve future models or better assess sites. I found that sites with larger total wetland area had higher detection per survey, possibly due to larger sites having higher densities of turtles (among other explanations), and that sites with higher amounts of impervious surfaces within their drainage were less likely to be occupied. In addition to the bog turtle, several plant species also occur in mountain fens. These species usually have a locally rare distribution or are disjuncts from a more northern latitude. Because of these traits, a high diversity of specialist plants may be indicative of a fen with a robust hydrology that has historically been less disturbed. Past site quality analyses have proposed using indicator diversity to assess sites, but no study has found if these species to tend to co-occur. My second chapter examines this hypothesis. I first chose a list of plant species that would most likely have habitat requirements similar to those of turtles. Then, at 12 sites, 6 with turtles and 6 without, I conducted a complete floral inventory. I first tested community-wide differences between the floral communities of these sites and found no difference, but when I narrowed my analysis to examining occurrence patterns of plant species determined a priori to be fen specialists and Glyptemys muhlenbergii, a pattern of co-occurrence was found. This lends support to the idea that indicator plants could be used as a tool to better evaluate sites that may have bog turtles. My last chapter investigated movement of bog turtles in a landscape impacted by anthropogenic development. Movement of turtles between adjacent sites is critical to maintaining genetic diversity and maintaining metapopulation integrity. Despite this importance, records of long distances movements among wetlands are scarce in the literature, likely due to the lack of long-term studies for areas with multiple adjacent sites. In Virginia, mark recapture monitoring has been done intermittently in a cluster of sites for over 32 years. To determine the prevalence of movement among sites for bog turtles, I examined the dataset for all instances of turtles found at sites different from their last capture. I calculated the straight-line distance for each recorded movement. I also examined the sex of the turtle to test whether sex influences movement the frequency and distance of movements. For a subset of movements, I calculated least-cost pathways to identify possible barriers to movement using a previously published resistance model. I found 21 instances where a turtle was caught at a different site than its last capture over 32 years of monitoring. Neither sex was more likely to move farther than the other. Although the study's observed rate of movement may appear low, it is likely an underestimate when detection and asymmetric sampling are taken into account. The least cost pathways analysis suggested that roads or driveways were likely crossed for a significant portion of movement events. Finally, to examine how movement may be affecting the current distribution of bog turtles, I described a method to test whether adjacency to known populations influences the probability of a new site being occupied by turtles. I prove the utility of the method by applying it to a map of bog turtle occurrences collected over this study and show that it can account for habitat differences and barriers to movement between sites as well. In spite of plausibility of the method, limitations in how occurrence data are currently collected prevent its immediate application. Together, this thesis will help managers not only find and assess wetlands on the landscape, it will also provide information about the network of connected patches on the landscape. Knowing where bog turtles are and what wetlands or sub-populations are potentially connected will allowed for a more directed and informed regional management strategy. / Master of Science / Freshwater turtles are facing population declines worldwide, and the bog turtle Glyptemys muhlenbergii is among the most imperiled in North America. Bog turtles occupy naturally small, specialized wetlands called Appalachian Mountain fens. The prevalence of fens on the landscape has declined over recent decades due to agricultural practices. Although there is a strong need to document and monitor bog turtle populations due to their threatened status, bog turtles are difficult to find due to their small size and ability to burrow completely into substrate. Thus, considerable effort must be expended to find populations and track their status. The first overall objective of this thesis was to assess methods for locating populations of bog turtles. My first chapter tests a habitat distribution model that uses publicly available landscape data such as topopgraphy and land cover to predict areas likely to contain turtles. To do this, I systematically surveyed 49 predicted sites multiple times each over 2 years. Simultaneously, I recorded variables such as the time of year, size of the wetland and the weather to determine whether any factor significantly explained the ability to find turtles on any given survey. In addition, I was able to record several variables relating to wetland quality and isolation that were not in the initial model. I found that larger wetlands were easier to search than smaller wetlands, possibly due to larger sites having more turtles, and that wetlands near more impermeable surfaces (such as roads and buildings) were less likely to have bog turtles. As another potential method to find bog turtles and assess sites, we tested the use of 'pristine indicator' plants as a metric for potential wetlands. Mountain fens have specific attributes, such as high groundwater influence and exposure to a large amount of sunlight. Several species, including the bog turtle, are specialized to these factors and are rarely found in the surrounding landscape. Because a distinct community exists for mountain fens in this region, sites with a higher diversity of fen specialist plants may be indicative of a higher quality site which can support more specialists, including the bog turtle. My second chapter tests this hypothesis. I first chose a list of species that would most likely have habitat requirements similar to those of bog turtles. Then, at 12 sites I documented every plant species I encountered within the wetland. I compared the plant community as a whole between bog turtle-occupied and unoccupied sites and found no significant difference between the two. When I narrowed my analysis to focus on plants I previously identified as sharing habitat requirements with the bog turtle, I found a strong pattern of their co-occurrence with bog turtles. This lends support to the idea that these 'pristine indicator' plants could be used as a tool to better evaluate sites that may have bog turtles. My last chapter investigates movement of bog turtles in a landscape impacted by human development. Movement of turtles between adjacent wetlands is critical to maintaining long term regional viability of the species, as it lets turtles colonize new sites and exchange genes. Despite the importance of these movements, records of turtles moving long distances between two wetlands is scarce in the literature, likely due to the lack of long-term studies for areas with multiple adjacent wetlands. One method of recording movements is by marking turtles with a unique ID and recording where it was encountered as wetlands are surveyed on the landscape. In Virginia, this procedure has been conducted at multiple sites over 32 years. To understand the prevalence of movement between sites for this species, I examined this dataset and examined all instances of a turtle being found at a site different from its last capture. I recorded the straight-line distance moved for each recorded movement as well as the sex of the turtle, to test if either sex was more or less likely to undertake these movements. Then, for a subset of movements, I calculated least-cost pathways, a metric that accounts for landscape features and plots the easiest route for turtles to move. This way, I could evaluate the prevalence of barriers to movement, such as roads or development, on the landscape. I found 21 documented movements among sites over 32 years of monitoring. Neither sex was more likely to move further than the other. Compared to studies looking at other freshwater turtles, the observed rate of movement appeared low, but this was likely an underestimate due to the difficulty of capturing specific individuals. I also found evidence of significant barriers to movement in 13 out of 17 evaluated least-costs paths, usually roads or driveways. Finally, to examine how movement affects bog turtle distribution, I describe a methodology of testing if adjacency to known populations influences the probability of a new site being occupied by turtles. I demonstrate the plausibility of the method by applying it to a map of occurrences collected over this study and show that it can account for habitat differences and barriers to movement between sites as well. However, limitations in my sampling scheme limit conclusions from my dataset. Together, these findings will help future managers find where turtles are and which sites may be connected. These results will help managers make more informed decisions for managing bog turtles at a statewide level.

Thesis (doctoral)--Universiteit van Amsterdam, 1985. / Five charts in back cover pocket. Text in English, with foreword and summary in Dutch. Includes bibliographical references (p. 147-152).

The objective of this study is to assess current distributional patterns of species within a community, while taking into account species' evolutionary histories, as reflected in their phylogenetic relationships. The hypothesis is that closely related species segregate along environmental gradients, either due to historic evolutionary divergence of their niches, or to ecological processes presently occurring within a community. Distribution along environmental gradients was compared to phylogenetic structure of the 27 sedge species (Cyperaceae) growing in the subarctic fen communities of Schefferville, northern Quebec. Field data suggest that within these fens, sedges mostly differentiate along gradients of rooting depth and pH. Species growing in similar (micro)habitats often belong to different taxonomic sedge clades, and species belonging to the same clade usually differentiate on at least one environmental gradient. Further comparison of natural distribution to responses under greenhouse experimental conditions for four selected Carex species suggests that the two relatives in section Limosae differ in their tolerance ranges to environmental conditions due to past evolutionary events, while the two members of section Paniceae differentiate along environmental gradients in nature due to ongoing ecological processes.

Decomposition and MeHg concentration were measured for Sphagnum fuscum, Sphagnum angustifolium and Chamaedaphne calyculata in a poor fen in the low boreal forest zone of the Canadian Shield. Litter bags were transplanted reciprocally into hummocks, hollows and lawns and retrieved after 1, 2, 3,11 and 15 months. / Mass losses follow the trend: Chamaedaphne calyculata >> S. angustifolium > S. fuscum. Between species differences were far more significant than differences between locations or depths, indicating that litter quality is the major control on decomposition. / McHg concentrations generally increased during decomposition, particularly near the water table: for C. calyculata up to 13000%, for the two Sphagnum mosses up to 500%, suggesting that decomposition stimulates mercury methylation or McHg scavenging. / The discovery of a high McHg substance on C. calyculata leaf surfaces (25 ng g-1) suggests that much plant MeHg data may by skewed by the presence of a biologically active 'film'.