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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Linking decision support systems for ducks with relative abundance of other grassland bird species

Skinner, Susan Patricia 29 April 2004
Decision support systems (DSS) that integrate long-term duck population and land use data are currently being used to develop conservation programs on the Canadian prairies. However, understanding inter-relationships between ducks and other grassland bird species would greatly enhance program planning and delivery among various bird conservation initiatives. Therefore, to achieve these goals, grassland bird species richness and relative abundance were compared between areas of low, moderate and high predicted waterfowl breeding densities (strata) in the southern Missouri Coteau, Saskatchewan. Roadside point counts were conducted during spring 2001 and 2002, and habitats were delineated within 400 m radius of each point. More birds of more species were encountered in the high density waterfowl stratum when compared with low but species that tended to co-occur with ducks were primarily wetland-associated. Overall, duck and other grassland bird species richness and abundance were moderately correlated (0.69 > r > 0.37, all Ps < 0.05); strong positive correlations between priority species of conservation concern and northern pintails were not found. No difference in mean number of priority grassland species occurred among strata, but differences were found for both number of species and total birds detected among routes within strata. High duck density stratum was more heterogeneous, consisting of greater areas of forage, shrub, wetlands, and open water bodies whereas low stratum contained larger, more uniformly-shaped habitat patches and greater proportion of cropland. Ordination analyses revealed that most priority species occurred in grassland-dominated sites with lower shrub area and wetland density whereas most wetland-associated species, including ducks and 2 priority species (Wilsons phalarope and marbled godwit) inhabited cultivated areas with higher wetland density. Ducks and priority species generally did not co-occur at the stop-level in highly heterogeneous landscapes but suitable habitats for both groups may exist in near proximity. In homogeneous landscapes, ducks and other wetland-associated common species were less abundant because of limited number of suitable wetlands. To achieve these dual goals, conservation efforts should be focused in areas containing wetlands adjacent to contiguous tracts of native pasture.
2

Linking decision support systems for ducks with relative abundance of other grassland bird species

Skinner, Susan Patricia 29 April 2004 (has links)
Decision support systems (DSS) that integrate long-term duck population and land use data are currently being used to develop conservation programs on the Canadian prairies. However, understanding inter-relationships between ducks and other grassland bird species would greatly enhance program planning and delivery among various bird conservation initiatives. Therefore, to achieve these goals, grassland bird species richness and relative abundance were compared between areas of low, moderate and high predicted waterfowl breeding densities (strata) in the southern Missouri Coteau, Saskatchewan. Roadside point counts were conducted during spring 2001 and 2002, and habitats were delineated within 400 m radius of each point. More birds of more species were encountered in the high density waterfowl stratum when compared with low but species that tended to co-occur with ducks were primarily wetland-associated. Overall, duck and other grassland bird species richness and abundance were moderately correlated (0.69 > r > 0.37, all Ps < 0.05); strong positive correlations between priority species of conservation concern and northern pintails were not found. No difference in mean number of priority grassland species occurred among strata, but differences were found for both number of species and total birds detected among routes within strata. High duck density stratum was more heterogeneous, consisting of greater areas of forage, shrub, wetlands, and open water bodies whereas low stratum contained larger, more uniformly-shaped habitat patches and greater proportion of cropland. Ordination analyses revealed that most priority species occurred in grassland-dominated sites with lower shrub area and wetland density whereas most wetland-associated species, including ducks and 2 priority species (Wilsons phalarope and marbled godwit) inhabited cultivated areas with higher wetland density. Ducks and priority species generally did not co-occur at the stop-level in highly heterogeneous landscapes but suitable habitats for both groups may exist in near proximity. In homogeneous landscapes, ducks and other wetland-associated common species were less abundant because of limited number of suitable wetlands. To achieve these dual goals, conservation efforts should be focused in areas containing wetlands adjacent to contiguous tracts of native pasture.
3

Differences in plant trait distribution in semi-natural grassland habitats of Sweden

Vepsäläinen, Viivi January 2020 (has links)
Habitat type has been suggested to be a major factor contributing to differencesin plant trait distribution of grassland habitats. Land use changes in agricultural landscapes have affected the available habitats and the dispersal ability of plants, which may effect plant trait diversity of agricultural landscapes. Little is also known about the effects of landscape openness on plant trait diversity. This study analysed differences in plant traits between different semi-natural grassland habitats in agricultural landscapes in four different regions in Sweden: Skåne, Södermanland, Gävleborg, and Norrbotten. The following research questions were used: (1) How does landscape openness (the amount of open andarable land found in a landscape) affect plant trait values collected from a new database in semi-natural grassland habitats in agricultural landscapes? (2) How does the type of habitat affect plant trait values in semi-natural grassland habitats in agricultural landscapes? (3) How does geographical location in Sweden affect plant trait values in semi-natural grassland habitats in agricultural landscapes? Overall 12 landscapes in each region were surveyed for plant data using 20 sample plots in each landscape. Trait values for biodiversity relevance, nectar production, nitrogen, phosphorus, grazing/mowing, soil disturbance, longevity, pollinator dependence, and seed dispenser were assigned for each plant species based on an external database, and average trait values were calculated for each of the studied traits in each sample. Kruskal-Wallis test andANOVA were performed on average trait values to identify differences between each habitat types and regions. Besides the effect of habitat type, the effect of openness in the landscape on the chosen traits was analysed with Spearman’s and Pearson’s correlations. The results revealed differences between habitat types in almost all studied traits: grazed habitats had plants with higher biodiversity relevance but lower nectar production. Differences were also found between the southern and northern regions. More open landscapes had plants with higher biodiversity relevance as well as higher tolerance for both nitrogen and phosphorus. Less open landscapes had higher tolerance for grazing/mowing and higher nectar production. The results of this study therefore support earlier findings of the importance of habitat in plant trait distribution of grassland habitats.

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