• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 20
  • Tagged with
  • 22
  • 22
  • 7
  • 7
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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.
21

A fluvial geomorphological study of river rehabilitation in the Kouga region, Eastern Cape

Pietersen, Adrian January 2009 (has links)
The Kouga Riparian Rehabilitation Project (KRRP) is seen as a pilot rehabilitation project in the Kouga region that is heavily invaded with Acacia mearnsii along the riparian zones of many mountain streams. Clearing of these black wattles and re-planting of indigenous vegetation are imperative to rehabilitation efforts. In this context, two invaded catchments were identified - the Baviaans and the Heuningnes. The aim of this research is to characterise the effects that the woody alien invasive Acacia mearnsii has had on the river channel morphology of the Baviaans and Heuningnes Rivers. A desktop and initial field analysis of the relevant study area catchments was completed. This was followed by a comparison of the channel morphology of the various study channel reaches using fixed channel transects. Ecological resource quality objectives (RQOs) for river rehabilitation from a fluvial geomorphological viewpoint were then established. A long-term monitoring protocol to assess whether or not these RQOs will be achieved was recommended. Follow-up channel transects were measured post wattle clearance in the Baviaans and short-term (<2yrs) changes in channel form were described. Differences in terms of the effect of Acacia mearnsii on channel form were then interpreted by direct comparison and through statistical analysis. Results indicate a number of significant differences between those channels impacted by black wattle infestation and those channels seen as unimpacted and natural. Short-term changes (<2yrs) that occurred within the study period post Baviaans wattle clearance were shown to be minimal for channel form as well as for bed material. The lack of any clear relationship or explanation between channel form and other channel controls suggests vegetation as the primary control. Vegetation, specifically the invasive alien vegetation, is the key controlling variable acting on channel form in the two study catchments.
22

Riparian Wetland Response to Livestock Exclusion in the Lower Columbia River Basin

Holmen, Sarah Ann 01 January 2011 (has links)
The purpose of this study was to examine the characteristics of riparian plant communities along a succession gradient of livestock exclusion in the Lower Columbia River Basin (LCRB). Livestock exclusion is an example of a passive restoration practice throughout the region. However, few studies have focused on the effects of livestock or livestock exclusion on riparian wetland ecosystems in this area. Two passive restoration sites, 3 and 13 years since livestock exclusion, and a control site with a continued livestock grazing presence were examined. It was hypothesized that native plant species richness would be lower in the excluded wetlands than in the grazed wetland due to the competitive exclusion from an increase in non-native plant dominance in the absence of grazing. Data were collected along six (45-60m) randomly distributed transects which were aligned perpendicular to the wetland shoreline of each site, providing a total of 18 transects with an accumulative length of approximately 990 meters. Vegetation cover data were collected for 10 cm intervals along these transects using the line intercept method during low water periods in August and September of 2009. The Kruskal-Wallis one-way nonparametric analysis of variance by ranks and the Mann-Whitney U test were used to detect significant (p

Page generated in 0.1275 seconds