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Understanding the factors affecting species distribution and at what scale a species respond to these factors is a major challenge in conservation biology. I studied the distribution and abundance of a monophagous shield bug Canthophorus impressus at three spatial scales: host plants, patches and circular landscapes (area ca. 3 km2), to determine the relative importance of the different spatial scales and how habitat quality, amount and spatial configuration affect the distribution of C. impressus. Influence of habitat characteristics on occurrence and abundance of the bug was analysed with separate generalised linear mixed models. The data show that effects of habitat quality and amount dominate over configuration in determining the distribution of C. impressus. The bug prefers large host plants in warm conditions on a plant scale and abundant host plants in a landscape scale, whereas patch scale was not important for the distribution of the bug. Management should aim to preserve sites with abundant host plants and promote large host plants with low to moderate grazing. To secure sufficient number of host plants in the landscape, high densities of suitable habitat such as semi-natural grasslands should be preserved. This study suggests that analyses of multiple spatial scales are crucial for identifying appropriate actions for successful conservation of species living in fragmented habitats.

Timber harvesting results in patches of regenerating forest that are substantially different from surrounding unharvested stands, and provides an opportunity to investigate the effect of habitat change on forest fauna. In this thesis I used timber harvesting as an experimental treatment to investigate the effect of a changed resource base on the home range and resource selection of the swamp wallaby, Wallabia bicolor. I recorded habitat attributes at unharvested control, recently harvested (<12 months old), 5 year old and 10 year old sites. Initially, harvesting removed almost all above-ground plant biomass, although the nitrogen and water content of grass on recently harvested sites was relatively high. Five years after harvesting, sites were dominated by densely regenerating 1-3 m tall Eucalyptus seedlings. Relative to unharvested sites, there was substantial lateral cover and values of a forage quality index were high. In contrast, 10 year old sites supported dense, closed stands of 3-6 m tall eucalypt regeneration, had a moderate amount of lateral cover and had low values of the forage quality index. (For complete abstract open document)

Naturally-functioning riparian ecosystems provide important habitat for wildlife and serve as corridors for individuals to move from one area of suitable habitat to the next. Site-level quality and landscape-level connectivity of wildlife habitat are of critical importance to myriad species across the landscape in southern Illinois. However, multi-scale analyses of habitat suitability and connectivity of riparian corridors are rare in the literature. The first objective of this study evaluated microhabitat quality at 4 streams (3 treatments, 1 control) restored 30 years ago following strip mining for coal in Perry County, Illinois. Microhabitat differences were very minor among restored and control stream sites. Of the 41 variables measured, 14 differed among sites, 4 of which were uncorrelated: canopy cover, overstory hard mast, bare ground, and herbaceous ground cover; thus, restored riparian buffers were comparable to unmined sites, indicating that restoration efforts were successful. The second objective assessed broad-scale habitat connectivity of stream corridors across the Coastal Plain, Shawnee Hills, and Southern Till Plain Natural Divisions in southern Illinois. Landscape metrics were measured from 3,157 ha of riparian buffers utilizing the 31 longest stream segments across these study sites. Of the 39 variables measured, 17 differed among sites, 3 of which were uncorrelated: mean patch size of forested area, area-weighted mean shape index of wetland patches, and the mean nearest neighbor distance between wetland patches. The Shawnee Hills division had the largest mean patch size of forests, Coastal Plain wetlands had the most connectivity via mean nearest neighbor metrics, and Southern Till Plain wetlands were the most fragmented via their area-weighted mean shape indices. These findings can be useful to land managers when preserving or restoring riparian wildlife habitat in southern Illinois and throughout the Midwest.

In spatially structured populations, distributional dynamics are driven by the quantity, connectivity and quality of habitat. Because these drivers are rarely measured directly and simultaneously at relevant scales, information on their relative importance remains unclear. I assessed the influence of both direct and indirect measures of local habitat quality, and of landscape habitat amount and connectivity on long-term territory occupancy dynamics of non-migratory pygmy owls. Direct measures of local habitat quality based on territory-specific reproductive output had greater effects on distribution than landscape factors, but only when spatio-temporal fluxes in performance linked to environmental stochasticity and intraspecific competition were considered. When habitat quality was measured indirectly based on habitat structure, however, landscape factors had greater effects. Although all landscape factors were important, measures of landscape connectivity that were uncorrelated with habitat amount and based on attributes of matrix structure and habitat configuration that influence dispersal movements had greater effects than habitat effective area (amount weighted by quality). Moreover, the influence of connectivity (but not habitat effective area) depended on local habitat quality. Such results suggest the relative importance of local habitat quality in driving distribution has been underestimated and that conservation strategies should vary spatially depending on both local and landscape contexts.

The violet copper (Lycaena helle) is one of the most endangered butterflies in Europe, with a population pattern of steady decline despite consevation efforts. The main threat to the species is believed to be habitat fragmentation and loss due to changes in land use practices. In order to direct conservation efforts toward the areas where they make the most difference, we need to better understand the ecological needs of the species, on both local and meta population levels. Since habitat quality is a crucial factor for succesful reproduction, increased knowledge of the species’ habitat requirements is of utmost importance. In this study, I investigated whether there is a correlation between the share of hatched eggs and leaf size and shape of the host plant Bistorta vivipara, which vary greatly depending on the level of solar exposure. In the summer of 2022, I searched for eggs and larvae of L. helle on leaves of B. vivipara on three rich fens situated in the municipality of Ånge, Västernorrland County. All leaves with eggs and/or larvae were photographed next to a ruler in order to measure length and width, and the total number of eggs as well as the number of hatched eggs were documented. I then divided the leaves into four classes based on the length/width ratio. Chi-square tests were conducted on the share of hatched eggs per leaf class and locality. The results showed a tendency for a larger share of hatched eggs than expected in leaf class 2, and a smaller share of hatched eggs than expected in leaf class 3, but the results were non-significant. Similarly, the results showed a tendency of a larger share of hatched eggs than expected on locality 2, and slightly smaller shares of hatched eggs on localities 1 and 3, but these too were non-significant. In conclusion, more studies are needed in order to better understand how we can conserve this threatened species.

1. Large rivers in the central United States experience a variety of ecological interactions. Both short- and long-term temporal changes affect both fish and zooplankton communities in rivers. Variation in diel patterns of predation could affect differences of behavior in prey. Long term temporal changes across seasons can lead to different areas of rivers providing growth or costing energy. Spatial changes also affect habitat quality and behaviors of the aquatic organisms within large rivers. Spatial variation can be dynamic and occur between longitudinally connected habitats or vary through different sections of the reach and can also change seasonally. 2. Invasive species have major economic and ecological impacts. In aquatic ecosystems, plankton are the base of the food web and a planktivore invader can cause major ecological disruptions. The Wabash River is a large free flowing river with a variable hydrology, which causes dramatic changes in habitat availability through time. Therefore, habitat usage, quality, and availability may differ for native and invasive species through time. The objectives of this study were to assess how habitat quality changes in a large, flashy, free-flowing river over time, and to compare the quantity and overlap of quality macrohabitat for invasive and native fish. Growth rate potential (GRP) was used to quantify habitat quality for Silver Carp (Hypophthalmichthys molitrix; invasive) and Gizzard Shad (Dorosoma cepedianum; native). To calculate GRP, bioenergetic models were used with monthly observations of food abundance (zooplankton, phytoplankton, and detritus), water temperature, dissolved oxygen, and water velocity of various habitat types from the Wabash River’s confluence with the Ohio River upstream to Terre Haute, Indiana, approximately 215 river miles. Negative GRP for both Silver Carp and Gizzard Shad occurred during spring and most of summer. However, in the fall, the majority of the river had a positive GRP for both species. Reduced flows and increases in food abundance were the cause for the switch from negative to positive GRP. There was a high degree of spatial overlap in positive GRP areas between Silver Carp and Gizzard Shad, suggesting that there is a high degree of competition. Acoustically tagged Silver Carp selected for areas predicted to have a positive GRP from the model presented in the study. This model showed that regulation of flows in hydrologically altered systems could potentially lower the impact of Silver Carp in those systems. With Silver Carp selecting for predicted habitats, a bioenergetics model can be used to inform commercial fishers where to focus effort to maximize catch.3. Temporal changes in rivers tend to be quantified at broad seasonal scales. However, river conditions including water flow, water temperature, dissolved oxygen, and availability of zooplankton prey may change daily. In large rivers, these conditions may change in a diel fashion between backwater and main channel habitats. To assess diel changes in the Illinois River, zooplankton, paired with mobile hydroacoustic surveys for fish were sampled from three main channel and three off-channel sites in the LaGrange reach every four hours in a twenty-four-hour period at different depths between October 22 and 26, 2018. Water depth, water temperature, water velocity, and fish (planktivore and nonplanktivore) densities were quantified during each sampling time. Water temperature and water velocity differed between the two habitat types. Water temperature was higher and water velocity was lower in the off-channel. Water temperature was colder in the morning in both the main channel and off-channel. Water velocity did not change throughout the day. The majority of the zooplankton community was comprised of rotifers which were less mobile than larger taxa and did not migrate. When evaluating the more mobile, large body zooplankton, time and depth affected copepod density in off-channel environments, where the deeper depth had a higher copepod density than the shallower depth. In contrast, only time of day affected off-channel cladoceran density, where densities increased at night. Fish did not exhibit diel patterns and the off-channel habitat had a higher density. The most likely mechanism behind the diel movements of the large bodied zooplankton was predation by planktivorous fish. The present study suggests that connections to the off-channel habitats in large rivers will promote quality habitat for both zooplankton and fish.

Land use changes have been shown to have significant effects on wildlife species. Sixty three percent of the national Parks and Reserves in Kenya are located in the savannas. Because of the seasonality associated with savanna ecosystems, 75% of the wildlife species and numbers in Kenya occur in savanna nonpark areas. Therefore, conservation of wildlife in Kenya has to address the changes that are taking place in savanna areas outside parks. I studied land use changes and their effects on elephant habitat quality in Amboseli Basin, Kenya. I used visual interpretation to analyze land use changes from satellite images for 1975, 1988, and 1993. I determined that during the evaluation period, conversion of areas to agricultural land has been unidirectional. The hectarage under cultivation was 2,937, 10,950, and 24,476 for 1975, 1988, and 1993 respectively. Trend analysis seems to suggest that during the evaluation period, conversion of areas to agricultural land has followed an exponential function (R² = 0.99) in Amboseli Basin. The area under cultivation was 6.9% of the total area studied. This is small but significant considering that agricultural land was almost exclusively located in areas that form the dry season fall back areas. Such areas are important for the survival of elephants and other species during critical periods. I developed a dry season habitat suitability index (HSI) model for the African elephant based on the density of acacia trees (# of trees > 5 cm dbh/ha) and distance (km) to natural sources of water in the basin. The amount of good quality habitat (i.e., HSI > 0.6) declined from 74,666 ha in 1975 to 54,890 ha in 1988, to 23,208 ha in 1993. This is a drop of 51,890 ha (65.5%) of good quality habitat in the basin. On the other hand, low quality habitat (HSI < 0.2) increased by 272% between 1975 and 1993. The weighted HSI values in the basin showed a decline, as did the habitat units for the 3 evaluation years. The weighted HSI declined by 0.13 between 1975 and 1993, while the total habitat units (ha) declined by 40,567 ha during the 18 year period. It appears that elephant habitat quality has steadily declined in the Amboseli Basin during the period considered in this study. The use of nonpark areas by elephants leads to direct interaction and conflicts with humans. Between June 1996 and July 1997, I recorded a total of 489 elephant damage incidents while the Amboseli National Park authorities recorded 143. The damage types were crops, livestock deaths, and human deaths and injuries. The majority of the damage cases involved crop depredation. The Amboseli National Park authorities significantly under-reported the number of elephant damage incidents in the basin (P < 0.0001). / Ph. D.

A decline in biodiversity in agricultural landscapes has been reported for decades. One of the most important habitats for biodiversity in agricultural landscapes is semi-natural grasslands. To preserve species-rich semi-natural grasslands, research need to focus both on local habitat quality and on landscape composition at various scales. In the current study I examined how nectar sources, host plants and other environmental parameters affected the occurrence of adults of four burnet moth species, residents of semi-natural grasslands. Also, I investigated the effects of landscape composition at 34 spatial scales. The results in general showed positive effects of host plants cover, nectar sources abundance, dry soil, sun exposure, tall sward height, small herb and grass cover. At the landscape level all the species responded negatively to the amount of arable land and positively to the amount of forests at scales up to 10000 m. Two species were negatively affected by the amount of artificial surfaces and pasture at some scales. Though the amount of semi-natural grasslands and patch area did not affect the occurrence of the species, at the local scale semi-natural grasslands were still important for the species. Thus, my results suggest that management should be focused both on local and landscape levels. Focus should be to preserve sunny and open areas of high-quality semi-natural grasslands rich in burnet moths’ host plants and especially nectar sources that seem to be more important than host plants for adults. Semi-natural grasslands should be preferably adjacent to forests and not arable land.

Lake trout (Salvelinus namaycush) have a broad distribution across Canada’s north, yet most studies that describe reproductive habitat and behaviour have been conducted in the southern extent of their range. Northern regions are experiencing unprecedented changes from climate and industrial development, and thus there is a pressing need to understand the reproductive habitat and behaviour of this species. I examined a dozen sites around Alexie Lake, Northwest Territories, to test if physical habitat and wind exposure were important determinants of spawning site use and embryonic survival. Spawning was found to occur in ~2 m water depth, on 3–15 cm diameter clean substrate on the leading edge of shoals that ended in a rock crib rising abruptly in nearshore regions around the lake. Wind direction was predominantly from the west, although it was highly variable within and among spawning seasons. I found evidence of lake trout spawning at each site examined, which was not limited to shoals facing a predominant wind direction. High variation in embryonic survival (2–83%) from incubation trays was observed among spawning sites, demonstrating a large gradient in habitat quality exists within a given lake. However, modelled wind exposure did not predict embryonic survival, nor did physical characteristics - including shoal depth and slope, as well as cobble size and shape - that may influence interstitial water flow on spawning shoals. Using an acoustic telemetry monitoring system and novel spatial temporal clustering analysis, I was able to quantify lake trout spawning movements and behaviours over the course of an entire spawning season. Lake trout formed clusters on spawning shoals around the entire nearshore region, as well as around several islands, confirming that suitable spawning habitat is abundant in Alexie Lake. Males arrived on spawning shoals earlier than females and remained longer for a maximum of 25 consecutive days; females occupied spawning shoals for a maximum of 8 consecutive days over the course of the spawning season. Males formed over four times as many spawning clusters and visited twice as many sites than females. Spawning clusters were predominantly formed at night but were also observed during daylight hours, especially during the peak spawning season (September 9–19). I found males had higher activity rates, and spent longer periods on spawning shoals, than females, in spite of similar daily travel distances between sexes. Overall, my findings challenge the conventional role of wind as a predominant predictor of lake trout spawning site quality. I propose that the unpredictable nature of wind and abundance of suitable habitat may favour lake-wide spawning by lake trout as a bet-hedging strategy in northern lakes with limited fetch. / May 2016