G.G. Forsyth

Reductions in plant species richness under stands of alien trees and shrubs in the fynbos biome.

Synopsis The reduction of species richness of indigenous plants is one of the major problems associated with the presence of dense stands of invasive alien trees and shrubs in the Fynbos Biome of the Cape Province, South Africa. A synthesis was made of published and unpublished data on plant species richness in fynbos with different levels of invasion and different histories of control. Linear regressions of species richness on the log of quadrat size were significant for both uninvaded fynbos and fynbos under dense stands of alien trees and shrubs. The slopes of the regression equations did not differ significantly between invaded and uninvaded sites, but elevations were significantly different, indicating a marked reduction in richness of indigenous plant species in invaded areas. The linear regression of species richness on quadrat size for cleared areas was not significant, but quadrats at most cleared sites showed species richness values intermediate to those of uninvaded fynbos and dense stands of a...

Regeneration strategies in fynbos plants and their influence on the stability of community boundaries after fire

An analysis of the range of regeneration strategies present in fynbos communities was a major aim of the work conducted at Swartboskloof. Information on the mechanisms whereby plants survive fire (e.g. Bell et al. 1984) and the attributes which allow them to persist in vegetation subjected to repeated fire (e.g. Noble and Slatyer 1980) is required to develop a sound understanding of the dynamics of vegetation subjected to fire. Such information is often only available for all of the plants if the communities are species-poor (e.g. Hobbs et al. 1984). In species-rich communities, it is usually the case that detailed information is only available for the dominant plants. A detailed knowledge of the responses of the constituent species in fynbos is restricted to the dominant shrubs of the family Proteaceae (e.g. Bond et al 1984). A few studies have listed survival mechanisms in other species (van der Merwe 1966; van Wilgen 1981; van Wilgen and Kruger 1981), but data on other vital attributes (juvenile periods, longevity, modes of seed dispersal, and seed bank longevity) are not available for the vast majority of fynbos species. Fynbos has a rich diversity of species, and fynbos communities may differ in the spectrum of responses (and therefore in their vulnerability to fire). In this chapter we quantify the range of regeneration strategies manifested in a sample of fynbos plants subjected to fire, and examine the differences between major vegetation communities in terms of these strategies.

The prioritisation of invasive alien plant control projects using a multi-criteria decision model informed by stakeholder input and spatial data

Invasions by alien plants are a significant threat to the biodiversity and functioning of ecosystems and the services they provide. The South African Working for Water program was established to address this problem. It needs to formulate objective and transparent priorities for clearing in the face of multiple and sometimes conflicting demands. This study used the analytic hierarchy process (a multi-criteria decision support technique) to develop and rank criteria for prioritising alien plant control operations in the Western Cape, South Africa. Stakeholder workshops were held to identify a goal and criteria and to conduct pair-wise comparisons to weight the criteria with respect to invasive alien plant control. The combination of stakeholder input (to develop decision models) with data-driven model solutions enabled us to include many alternatives (water catchments), that would otherwise not have been feasible. The most important criteria included the capacity to maintain gains made through control operations, the potential to enhance water resources and conserve biodiversity, and threats from priority invasive alien plant species. We selected spatial datasets and used them to generate weights that could be used to objectively compare alternatives with respect to agreed criteria. The analysis showed that there are many high priority catchments which are not receiving any funding and low priority catchments which are receiving substantial allocations. Clearly, there is a need for realigning priorities, including directing sufficient funds to the highest priority catchments to provide effective control. This approach provided a tractable, consensus-based solution that can be used to direct clearing operations.

A Computer-Based System for Fire Management in the Mountains of the Cape Province, South-Africa

This paper describes a Catchment Management System (CMS) that provides objective procedures for managing fire. Prescribed burning is carried out in the mountain catchments of the Cape Province, South Africa, to enhance water yield, to rejuvenate the indigenous shrubland vegetation, to reduce fire hazard and to control invasive alien plants. Fire is the only practical tool for achieving these aims in the mountainous terrain. Recent research has improved understanding of the response of these systems to fire, but managing fire to achieve goals is very difficult. The CMS comprises a central geographical information system for managing and processing spatial data, linked to personal computers with DBase IV data-bases and simple rule-based models for decision-making. Current applications are: prioritization of areas for burning, monitoring the success of fire management, mapping fire hazard for fire control planning, and the production of management summaries and statistics. This paper presents examples of these applications from three areas in the Cape Province with different management problems and priorities: the Kammanassie in the southern Cape, and the Kogelberg and Table Mountain areas in the western Cape.

The management of fire-adapted ecosystems in an urban setting: the case of Table Mountain National Park, South Africa.

Copyright: 2012 The authors. Ecology and Society, vol. 17(1), DOI: http://dx.doi.org/10.5751/ES-04526-170108

The Climate of Swartboskloof

The research programme in Swartboskloof evolved with the aim of providing further understanding of the functioning of mountain fynbos ecosystems, through comparison with other fynbos ecosystems, and with mediterranean-type ecosystems on other continents (see Preface). This chapter provides a description of the salient features of the climate of the Swartboskloof study site to facilitate these comparisons. We begin by examining the climate of Swartboskloof in a mediterranean-climate context. We describe features of the climate that influence the biota and hydrology, namely rainfall, temperature, vapour pressure deficit, radiation, evaporation, wind and droughts. We also describe the fire climate of the study site.

Survival of eight woody sprouting species following an autumn fire in Swartboskloof, Cape Province, South Africa

The survival of Widdringtonia nodiflora (L.) Powrie, Aulax pallasia Stapf, Mimetes cucullatus (L.) R.Br., Leucadendron salignum Berg., Brunia nodiflora L., Nebelia paleacea (Berg.) Sweet, Penaea mucronata L. and Erica coccinea L. was monitored after an autumn fire in montane fynbos near Stellenbosch in the Cape Province, South Africa. Discriminant and correlation analyses were used to determine the relationships between measures of pre-fire plant size and vigour, the degree of damage caused by the fire, and whether, firstly, plants survived the fire itself, and secondly, the survivors survived the subsequent summer. Pre-fire plant size was important in predicting whether plants survived the fire. Pre-fire plant vigour and the degree of damage caused by the fire were important predictors of whether plants survived the fire and the subsequent summer. Mortality due to the fire and during the following summer was highest for E. coccinea, P. mucronata, N. paleacea and B. nodiflora. Seedling recruitment varied widely between the different species. The populations of all species except W. nodiflora and A. pallasia increased as seedling recruitment exceeded adult mortality.

Do Small Mammals Govern Vegetation Recovery After Fire in Fynbos

Fynbos vegetation is of low nutritive quality for mammals (Bigalke 1979b). Palatable grasses are scarce (Cowling 1983b) have low protein and phosphorus values and deficiencies in some trace elements (Louw 1969). The low productivity of fynbos vegetation, apart from the first few years after fire (Kruger 1977a; see also Chap. 9; Sect. 9.3.2), also limits the availability of food for mammals (Fox et al. 1985). In contrast with the foliage the seeds of some fynbos plants are large and rich in both energy and nutrients and are therefore a valuable food resource for animals (Bond and Breytenbach 1985).

Coexistence of Seeders and Sprouters in a Fire-Prone Environment: the Role of Ecophysiology and Soil Moisture

The wide variety of flowering plant species that occur in fynbos communities can be divided into two broad categories on the basis of their mode of regeneration after fire: sprouters and non-sprouters (or seeders; see Chap. 4) The loss of the ability to sprout is considered to be a specialized developmental trait in woody dicotyledons, with sprouting being considered conservative in evolutionary terms (Wells 1969; see Chap. 7). Sprouters tend to be more resilient under a range of fire regimes than seeders often showing remarkable powers of vegetative recovery. Keeley (1977) and Specht (1981b) suggested that the relative dominance of sprouters in fire-prone shrubland communities is a consequence of the competition between adult sprouters and seedlings of non-sprouters. Generally, sprouters have a competitive advantage over seeders after fires because they grow more rapidly reach reproductive maturity sooner, and are better competitors tor light moisture and space. During long fire-free intervals, sprouter adults become self-thinning, and mortality is driven by density-dependent competition and senescence (Parker 1984). This results in the formation of gaps in the vegetation canopy after fire due to the lack of recovery of senescent sprouters. These gaps can be exploited by seedlings.