Annual burning drives plant communities in remnant grassland ecological networks in an afforested landscape

Joubert, Lize; Pryke, James S.; Samways, Michael J.

doi:10.1016/j.sajb.2014.02.009

Cited by 19 publications

(17 citation statements)

References 39 publications

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“…Also, we found no relationship among plant and grasshopper species richness. In fact, the greatest number of grasshopper species in this study was documented in annually-burned areas with heavy grazing, while this management practice was absolutely detrimental to indigenous plant conservation (Joubert et al 2014). Noncongruence between plant and grasshopper species richness concurs with findings of a regional study conducted in Inner Mongolia (Hao et al 2015).…”

Section: Discussionsupporting

confidence: 83%

Is cattle grazing more important than landscape heterogeneity for grasshoppers in Afromontane grassland?

Joubert¹,

Pryke²

2018

JOR

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Overgrazing is a major driver of habitat degradation, especially in southern Africa. Although grasshoppers are adapted to and benefit from natural disturbances, such as grazing by indigenous game and burning, we do not know how they respond to heavy cattle grazing, and how this response interacts with different fire regimes. We also do not know whether grasshoppers respond principally to these disturbances, to changes in the vegetation layer, or to larger landscape attributes (e.g. elevation). We addressed these questions in the topographically heterogeneous Central Midlands of KwaZulu-Natal Province, South Africa. We compared grasshopper assemblages among sites differing in grazing intensity (light, moderate and heavy), fire regime, rocky outcrops and vegetation structure, and attributes of landscape heterogeneity. The local environment (rocky outcrops, bare ground cover, grass height and total vegetation cover) was more important than landscape attributes for all measures of diversity. Grasshopper species richness was best explained by grazing intensity, with the specific response determined by fire regime. Greatest species richness was consistently recorded in heavily-grazed grassland. Thus, we found no evidence in support of the Intermediate Disturbance Hypothesis. Grasshopper assemblage composition of areas with light grazing was different from those with heavy grazing, but areas with light grazing were similar to those with moderate grazing under all fire regimes. Different suites of grasshopper species were adapted to changes in the local environment, with greatest diversity (Shannon H') associated with elevated levels of bare ground and sparse vegetation cover. The greatest proportion of rare, endemic and sensitive grasshoppers (incl. Lentula minuta, Machaeridia conspersa and Qachasia fastigiata) was associated with a greater proportion of vegetation cover. The sensitivity of grasshopper assemblages to fire-grazing interactions, and the habitat requirements of different suites of species necessitates consideration of different types (fire and grazing) as well as levels of disturbances when adjusting management practices. We recommend that conservation of rare, endemic and sensitive grasshoppers should be prioritized, as these are most vulnerable to local extirpation.

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Section: Discussionsupporting

confidence: 83%

Is cattle grazing more important than landscape heterogeneity for grasshoppers in Afromontane grassland?

Joubert¹,

Pryke²

2018

JOR

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“…Fire is important in two respects (1) to protect the timber compartments from runaway fires (O’Connor et al 2004 ), and (2) to mimic the natural fire regime in this naturally fire-driven ecosystem (Uys et al 2004 ; Little et al 2012 ; Joubert et al 2014 ) and for the establishment of firebreaks for protection of the plantation trees from runaway fires, a serious threat to production stands in this geographical area (Fig. 4 b).…”

Section: Terrestrial Biodiversity Conservationmentioning

confidence: 99%

“…When fire frequencies are high (e.g., annual burning of firebreaks both in ENs and PAs), there is homogenization of plant assemblages but not a reduction of plant species richness in the burned areas compared to those in wide corridors of the ENs and in the PAs (Joubert et al 2014 ). Regularly burned areas also favor a particular grasshopper assemblage characterized by early colonizers (Bazelet and Samways 2011b ).…”

Section: Terrestrial Biodiversity Conservationmentioning

confidence: 99%

Large-scale ecological networks do work in an ecologically complex biodiversity hotspot

Samways

Pryke

2015

Ambio

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Landscape-scale ecological networks (ENs) are interconnected conservation corridors of high-quality habitat used to mitigate the adverse effects of landscape fragmentation and to connect with protected areas. The effectiveness of ENs for biodiversity conservation and ecosystem function has been challenged. Here we show how an extensive system of ENs of remnant historic land was put in place at a large spatial scale (>0.5 million ha) in a plantation forestry context in a global biodiversity hotspot in southern Africa. These ENs can maintain indigenous and historic compositional and functional biodiversity, even in an area prone to the challenging effects of El Niño. Furthermore, ENs increase the effective size of local protected areas. Socio-ecological solutions and financial viability are also integrated as part of practical implementation of ENs. By adopting a retrospective analytical approach, biodiversity is maintained while also having productive forestry, making this a powerful agro-ecological approach on a large conservation-significant scale.

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“…However, there are parts of ecological networks where overgrazing has jeopardized the biodiversity value of these grasslands (Joubert et al. ). Determining whether disturbances function as equalizing mechanisms (i.e.…”

Section: Introductionmentioning

confidence: 99%

Moderate grazing sustains plant diversity in Afromontane grassland

Joubert

Pryke

Samways

2017

Applied Vegetation Science

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Abbreviations DBERG = Drakensberg Foothill Moist Grassland; DEM = Dynamic Equilibrium Model; IDH = Intermediate Disturbance Hypothesis; KZN = KwaZulu-Natal; MBELT = Midlands Mistbelt Grassland; RB = recently burned i.e. burned <12 months prior to sampling; UB = unburned i.e. not burned <12 months prior to sampling. Nomenclature Mucina et al. (2006) for grassland types; Plants of southern Africa (http://posa.sanbi.org/) for vascular plants AbstractAims: Natural disturbances drive plant assemblages in Afromontane grassland.Our aim is to assess how intensity of cattle grazing and time since last fire influence plant species richness, dominance and assemblage composition.Location: Central Midlands, KwaZulu-Natal province, South Africa.Methods: Sites differed in grazing intensity (light, moderate and heavy) and time since last fire: recently burned (RB) vs unburned (UB). We sampled plants in 24 vegetation quadrats (1-m 2 ) randomly located within each site (~1000 m 2 ). We used linear regression models for species richness and dominance, IndVal to identify indicator species and CCA for assemblage composition. All analyses were conducted at quadrat and site level.Results: Species richness was significantly influenced by time since last fire (RB > UB), grazing intensity (light < moderate > heavy) and the fire-grazing interaction at quadrat level. Dominance reciprocated the response of species richness to time since last fire (UB > RB), but did not respond consistently to grazing intensity (light > moderate > or < heavy). Plant assemblage composition was significantly influenced by time since last fire, grazing intensity and vegetation structure (live vegetation cover and vegetation height). Indicator species of species-poor, heavily grazed sites included alien species, such as Cirsium vulgare and Conyza bonariensis.Conclusion: Response of species richness to grazing intensity conforms to the predictions of the intermediate disturbance hypothesis. Burning and moderate grazing should be part of grassland management. To prevent species loss and influx of alien species, heavy grazing should be minimized. As development of grassland ecological networks in a timber matrix is being pioneered in South Africa, these findings indicate a way forward for the management of similar systems elsewhere in the world.

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Annual burning drives plant communities in remnant grassland ecological networks in an afforested landscape

Cited by 19 publications

References 39 publications

Is cattle grazing more important than landscape heterogeneity for grasshoppers in Afromontane grassland?

Is cattle grazing more important than landscape heterogeneity for grasshoppers in Afromontane grassland?

Large-scale ecological networks do work in an ecologically complex biodiversity hotspot

Moderate grazing sustains plant diversity in Afromontane grassland

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