Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
The extent of bush encroachment and its effects on the ecosystem services of a mixed bushveld of Makapanstad rangelands, North-West Province, South Africa
Thesis (PhD (Pasture Science))--University of Pretoria, 2020.
Saved in:
| Other Authors: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
University of Pretoria
2020
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613480414085120 |
|---|---|
| access_status_str | Open Access |
| author2 | Madakadze, Ignacio Casper |
| author_browse | Madakadze, Ignacio Casper |
| author_facet | Madakadze, Ignacio Casper |
| collection | Thesis |
| dc_rights_str_mv | © 2019 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis (PhD (Pasture Science))--University of Pretoria, 2020. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/75684 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:36:49.219Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2020 |
| publishDateRange | 2020 |
| publishDateSort | 2020 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/75684 The extent of bush encroachment and its effects on the ecosystem services of a mixed bushveld of Makapanstad rangelands, North-West Province, South Africa Madakadze, Ignacio Casper u15024114@tuks.co.za Nherera-Chokuda, Florence Dube, Sikhalazo Ramoelo, Abel Mndela, Mthunzi UCTD Woody cover Bush clearing Water loss Atmospheric carbon uptake Herbaceous vegetation Soil seed bank Thesis (PhD (Pasture Science))--University of Pretoria, 2020. The encroachment of rangelands by woody plants causes an imbalance in the grass:bush ratio leading to decline in ecosystem services including grazing capacity, biodiversity, and water yield. This study assessed the historical changes in woody cover, and the effects of bush clearing on water loss, atmospheric carbon uptake, herbaceous vegetation, and soil seed bank (SSB) dynamics. The study was conducted at Makapanstad (Radi and Maseding) and Kgomokgomo rangelands, North-West Province, South Africa. Landsat imagery was used to assess woody cover over 34 years (1984 - 2018) in a total area of 16 397 ha. Evapotranspiration (ET) and gross primary productivity (GPP) were assessed in cleared sites and their adjacent uncleared sites from 2013 to 2018. Woody plant densities, herbaceous composition, ground cover and biomass production were assessed in 24, 5×5-m plots distributed equally in three 2500-m2 bush-encroached blocks in each rangeland in February 2016. Three samples for soil nutrient analysis were collected 20-cm deep in each plot. Thereafter, half (1250-m2) of each block was mechanically cleared to make three replicates of cleared and uncleared microsites. Post-treatment survey of vegetation was conducted in February 2017. SSB was assessed for samples collected in April 2016 before bush clearing and in August, October and December 2016, and April and August 2017 in paired microsites. In 1984, herbaceous cover (humid + arid grasslands) dominated, accounting for 36% of the total area followed by woody cover (shrublands + bushlands) and unvegetated cover (bare soils + abandoned croplands), with respective proportions of 33 and 31%. There were substantial land cover changes over time, with shrub cover increasing linearly (r2 = 0.94, p < 0.05) at a rate of 0.26% year-1, increasing the total woody cover (TWC) to 38% in 2018. Cropland abandonment was the main driver of increase in shrub cover in the study area. Herbaceous cover declined with increase in TWC (r2 = 0.69), whereas bare soil cover increased (r2 = 0.70) with TWC over time. The main encroachers were Vachellia tenuispina at Radi, Vachellia tortilis at Maseding and Dichrostachys cinerea and V. tortilis at Kgomokgomo. Most of the woody species correlated with total N and clay content (r = 0.96; p < 0.05) in black vertic clay soils of Radi and Maseding, whereas non-leguminous species correlated with total N and C:N in the red-yellow apedal soils of Kgomokgomo. ET and GPP varied interannually in all rangelands and both declined significantly (p < 0.05) after bush clearing at Radi and Kgomokgomo but not at Maseding. ET increased with GPP in cleared (r2 = 0.50-0.59) and uncleared sites (r2 = 0.82-0.93) at Radi and they showed a strong relationship (r2 >0.70) in both sites at Maseding and Kgomokgomo. ET ranged from 0.26-0.46 and 0.48-0.97 Kg H2O m-2 day-1 in cleared and uncleared sites, respectively, at Radi and from 0.44-0.98 and 0.63-1.24 Kg H2O m-2 day-1 at Kgomokgomo. Total SSB densities (constituted mostly by early successional species) increased significantly (p < 0.05) to 2470, 1872 and 693 seeds m-2 at Radi, Maseding and Kgomokgomo, respectively, in cleared microsites in August 2017. Similarly, biomass production (BP) and basal cover (BC) were highest in cleared relative to uncleared microsites. Overall, increase in woody cover reduced herbaceous cover and this calls for bush control in the studied rangelands. The decline in ET after bush clearing suggested that bush clearing could be used to increase rangeland water yield. Increased SSB densities, BP and BC indicated that bush clearing facilitates passive restoration. Agricultural Research Council National Research Foundation Plant Production and Soil Science PhD (Pasture Science) Unrestricted 2020-08-13T08:16:56Z 2020-08-13T08:16:56Z 2020-09 2020-08-12 Thesis Mndela, M 2020, The extent of bush encroachment and its effects on the ecosystem services of a mixed bushveld of Makapanstad rangelands, North-West Province, South Africa, PhD (Pasture Science) Thesis, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/75684> S2020 http://hdl.handle.net/2263/75684 en © 2019 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | UCTD Woody cover Bush clearing Water loss Atmospheric carbon uptake Herbaceous vegetation Soil seed bank The extent of bush encroachment and its effects on the ecosystem services of a mixed bushveld of Makapanstad rangelands, North-West Province, South Africa |
| title | The extent of bush encroachment and its effects on the ecosystem services of a mixed bushveld of Makapanstad rangelands, North-West Province, South Africa |
| title_full | The extent of bush encroachment and its effects on the ecosystem services of a mixed bushveld of Makapanstad rangelands, North-West Province, South Africa |
| title_fullStr | The extent of bush encroachment and its effects on the ecosystem services of a mixed bushveld of Makapanstad rangelands, North-West Province, South Africa |
| title_full_unstemmed | The extent of bush encroachment and its effects on the ecosystem services of a mixed bushveld of Makapanstad rangelands, North-West Province, South Africa |
| title_short | The extent of bush encroachment and its effects on the ecosystem services of a mixed bushveld of Makapanstad rangelands, North-West Province, South Africa |
| title_sort | extent of bush encroachment and its effects on the ecosystem services of a mixed bushveld of makapanstad rangelands north west province south africa |
| topic | UCTD Woody cover Bush clearing Water loss Atmospheric carbon uptake Herbaceous vegetation Soil seed bank |
| url | http://hdl.handle.net/2263/75684 |