Does the landscape functionality approach provide insight into rangeland conditions in the Tanqua Karoo region, South Africa?

Manam Saaed; Shayne Jacobs; Mmoto Leonard Masubelele; Lesego Khomo; Igshaan Samuels

doi:10.7717/peerj.13305

Does the landscape functionality approach provide insight into rangeland conditions in the Tanqua Karoo region, South Africa?

PeerJ. 2022 May 19:10:e13305. doi: 10.7717/peerj.13305. eCollection 2022.

Authors

Manam Saaed^{1

2}, Shayne Jacobs², Mmoto Leonard Masubelele^{3

4}, Lesego Khomo⁴, Igshaan Samuels^{5

6}

Affiliations

¹ Botany Department, Faculty of Arts and Sciences, University of Benghazi, Benghazi, Libya.
² Conservation Ecology and Entomology Department, University of Stellenbosch, Stellenbosch, Western Cape, South Africa.
³ Conservation Services, South African National Parks, Pretoria, Gauteng, South Africa.
⁴ Environmental Sciences, University of South Africa, Johannesburg, Gauteng, South Africa.
⁵ Agricultural Research Council-Animal Production, University of the Western Cape, Bellville, Western Cape, South Africa.
⁶ Biodiversity and Conservation Biology Department, University of the Western Cape, Cape Town, South Africa.

Abstract

The harsh environmental conditions coupled with a long history of overgrazing have altered the ecology of the arid Tanqua Karoo rangelands in South Africa, which necessitates rehabilitation. However, a suitable method for monitoring rangeland function over time is required for sustainable management. In this study, vegetation characteristics and landscape function indices were used to rate and compare rangeland conditions in 43 sites distributed among three vegetation types: Tanqua Karoo, Tanqua Wash Riviere, and Tanqua Escarpment Shrubland, which occupy different landscapes in the Tankwa Karoo National Park. The results showed low values of vegetation volume (mean of 10.1 m³ per 100 m^-2) and low vegetated patches (mean of 29% patches vs 71% fetches). The overall landscape function indices (soil stability, water infiltration, and nutrient recycling) were low and amounted to 55%, 28%, and 17%, respectively. Amongst the various examined landscapes, the escarpment had the highest values of most of the measured landscape functionality parameters, and the open plains had the lowest values. This revealed high heterogeneity of soil properties and vegetation characteristics amongst the different vegetation types, mainly influenced by altitudinal gradients. The higher-lying landscapes on the escarpment are relatively more functional and more susceptible to improvement when compared to the lower-lying landscapes on the plains. The landscape functionality approach (LFA) approach demonstrated that some of the examined vegetation types had insignificant improvement in landscape functionality likely not to improve in the near term due to existing low patchiness, higher fetch space and low LFA indices coupled with the low annual rainfall of the region. The landscape functionality approach has provided a suitable benchmark for assessing and monitoring the diverse vegetation types in this arid part of the world.

Keywords: Fetches; Landscape function analysis; Nutrient recycling potential; Patchiness; Tankwa Karoo National Park; Vegetation types.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Ecology*
Soil*
South Africa

Substances

Soil

Grants and funding

Manam Saaed was sponsored for a PhD by the Lybian Embassy. The University of the Western Cape paid the publication costs. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.