https://commons.ufh.ac.za/vital/access/manager/Index en-us 5 https://commons.ufh.ac.za/vital/access/manager/Repository/vital:36580 Wed 13 Mar 2024 09:30:27 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:8468 Wed 12 May 2021 23:59:26 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:29053 Wed 12 May 2021 23:37:27 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:36483 Wed 12 May 2021 23:23:16 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:39713 Wed 12 May 2021 23:21:49 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:16154 Wed 12 May 2021 23:20:19 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:9793 Wed 12 May 2021 23:18:43 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:33920 Wed 12 May 2021 23:03:58 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:9955 Wed 12 May 2021 22:59:34 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:9482 Wed 12 May 2021 22:57:59 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:20437 Wed 12 May 2021 22:56:10 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:39482 Wed 12 May 2021 22:33:26 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:8160 Wed 12 May 2021 21:03:46 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:21125 Wed 12 May 2021 20:57:33 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:39408 Wed 12 May 2021 20:27:28 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:32058 Wed 12 May 2021 20:26:28 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:16128 Wed 12 May 2021 20:19:09 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:32585 Wed 12 May 2021 20:18:08 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:10062 Wed 12 May 2021 20:12:28 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:38335 Wed 12 May 2021 20:07:20 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:8530 Wed 12 May 2021 20:07:00 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:29479 Wed 12 May 2021 19:46:14 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:33385 Wed 12 May 2021 19:31:26 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:28477 Wed 12 May 2021 19:31:26 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:10727 Wed 12 May 2021 19:20:42 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:34126 Wed 12 May 2021 19:08:39 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:16132 Wed 12 May 2021 18:16:10 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:38189 Wed 12 May 2021 18:05:20 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:28902 Wed 12 May 2021 17:54:31 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:33029 10 and TPI between -1 and 1. Landslides are less pronounced on slope zones where slope gradient is <15˚ and >45˚, profile curvature <0, TWI <8 and >18, SPI <10 and TPI >1. Deep soil profiles ranging between 2.5 and 7 meters are a major characteristic of the study area. Soils are characterized by clay pans at a depth ranging between 0.75 and 3 meters within the profiles. The study area is dominated by clay texture, except for the uppermost surface horizons, which are loamy sand. All surface horizons analysed had the percentage of sand, silt and clay ranging from 33 to 55%, 22 to 40% and 10 to 30% respectively. In the deeper horizons, sand was observed to reduce drastically to less than 23%, while clay increased to greater than 50%. The clay content is very high in the deeper horizons exceeding 35%. By implication, such soils with a very high clay content and plasticity index are considered as Vertisols, with a profound influence in the occurrence of landslides. The top soil predominantly contains more quartz, while subsurface horizons have considerable amounts of illite/muscovite as the dominant clay minerals, ranging from 43% to 47 %. The liquid limit, plasticity index, computed weighted plasticity index (PIw), expansiveness (ɛex) and dispersion ranging from 50, 22, 17, 10 and 23 to 66, 44,34,54 and 64, respectively also have strong implications for landslide occurrence. Landslides are not normally experienced during or immediately after extreme rainfall events but occur later in the rainfall season. By implication, this time lag in landslide occurrence and rainfall distribution, is due to the initial infiltration through quartz dominated upper soil layers, before illite/muscovite clays in the lower soil horizons get saturated. Whereas forest cover reduced from 40 % in 1985 to 8% in 2015, cultivated land and settlements increased from 16% and 11% to 52% and 25% respectively during the same period. The distribution of cultivated land decreased in lower slope sections within gradient group < 15˚ by 59%. It however increased in upper sections within gradient cluster 25˚ to 35˚ by over 85% during the study period. There is a shift of cultivated land to the steeper sensitive upper slope elements associated with landslides in the study area. More than 50% of the landslides are occurring on cultivated land, 20% on settlements while less than 15 % and 10% are occurring on grassland and forests with degraded areas respectively. Landslides in Kigezi highlands are triggered by a complex interaction of multiple- factors, including dynamic triggers and ground condition variables. Topographic hollows are convergence zones within the landscape where all the parameters interact to cause landslides. Topographic hollows are therefore potential and actual landslide sites in the study area. Characterized by deep soil horizons with high clay content dominated by illite/muscovite minerals in the sub soils and profile concave forms with moderately steep slopes, topographic hollows are the most vulnerable slope elements to landslide occurrence. The spatial temporal patterns of landslide occurrence in the study area has changed due to increased cultivation of steep middle and upper slopes. Characterized by deep soil horizons with high clay content dominated by illite/muscovite minerals in the sub soils and profile concave forms with moderately steep slopes, topographic hollows are the most vulnerable slope elements to landslide occurrence. The spatial-temporal patterns of landslide occurrence in the study area has changed due to increased cultivation of steep middle and upper slopes. A close spatial and temporal correlation between land use/cover changes and landslide occurrence is discernible. The understanding of these topographical, pedological and land use/cover parameters and their influence on landslide occurrence is important in land management. It is now possible to identify and predict actual and potential landslide zones, and also demarcate safer zones for community activities. The information generated about the area’s topographic, pedological and land cover characteristics should help in vulnerability mitigation and enhance community resilience to landslide hazards in this fragile highland ecosystem. This can be done through designating zones for community activities while avoiding potential landslide zones. It is also recommended that, tree cover restoration be done in the highlands and the farmers encouraged to re-establish terrace farming while avoiding cultivation of sensitive steep middle and upper slope sections.]]> Wed 12 May 2021 17:50:51 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:21101 Wed 12 May 2021 17:47:56 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:33180 Wed 12 May 2021 17:47:37 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:9963 Wed 12 May 2021 17:46:24 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:31448 Wed 12 May 2021 17:44:16 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:39509 Wed 12 May 2021 17:20:28 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:9075 Wed 12 May 2021 17:14:11 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:36921 Wed 12 May 2021 17:12:16 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:8512 Wed 12 May 2021 17:08:31 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:10021 Wed 12 May 2021 17:05:50 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:9717 Wed 12 May 2021 17:04:43 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:37164 Wed 12 May 2021 16:42:14 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:10494 Wed 12 May 2021 16:38:46 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:31978 Wed 12 May 2021 16:36:41 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:32479 Wed 12 May 2021 16:31:53 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:28696 Wed 12 May 2021 16:27:34 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:10604 300 cm) Rhizophora trees at Mngazana Estuary. Mortality of Avicennia marina individuals (51-150 cm) was related to tree density indicating intraspecific competition and self thinning. Selective harvesting of particular size classes of Rhizophora mucronata was recorded when comparing length of harvested poles (~301 cm) and the size class distribution of individuals. Taking into account the differences in growth rate for each size class for this species it will take approximately 13 years to attain a height of 390 cm which is the height at which trees are selected for harvesting at this estuary. This is 2.6 times slower than those individuals growing in Kenya. The feasibility of harvesting is dependent on the growth rate of younger size classes to replace harvested trees as well as the rate of natural recruitment feeding into the population. Different harvesting intensity scenarios tested within a matrix model framework showed that limits should be set at 5 percent trees ha-1 year-1 to maintain seedling density at > 5 000 ha-1 for R. mucronata. However harvesting of Bruguiera gymnorrhiza should be stopped due to the low density of this species at Mngazana Estuary. Harvesting of the tallest trees of Avicennia marina can be maintained at levels less than 10 percent ha-1 year-1. Effective management of mangrove forests in South African is important to maintain the current state, function and diversity of these ecosystems. Management recommendations should begin with determining the freshwater requirements of the estuaries to maintain the mouth dynamics and biotic communities and deter the harvesting of (whole) adult trees particularly those species that do not coppice. Further management is needed to ensure that forests are cleared of pollutants (plastic and industrial), and any further developments near the mangroves should be minimized.]]> Wed 12 May 2021 16:26:19 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:20835 Wed 12 May 2021 16:20:32 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:39196 Wed 12 May 2021 16:18:08 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:8196 Wed 12 May 2021 16:07:43 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:8190 Wed 12 May 2021 15:57:39 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:41618 Wed 12 May 2021 15:10:54 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:40107 Wed 12 May 2021 14:31:12 SAST ]]> https://commons.ufh.ac.za/vital/access/manager/Repository/vital:40836 Wed 12 May 2021 14:22:24 SAST ]]> 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