A comparison of fynbos and non-fynbos coenoclines in the lower Gamtoos River Valley,southeastern Cape,South Africa

Patterns in the relative importance of structural attributes and growth forms along fynbos and non-fynbos coenoclines were studied to test the hypothesis that there would be less structural variation in the former because the overriding influence of low levels of soil nutrients would be manifest in a great deal of structural convergence in fynbos. The coenoclines were ranged along identical environmental gradients of increasing altitude, rainfall and soil moisture and decreasing climatic variability. Results showed that along the entire fynbos coenocline vegetation was structurally a small-leaved sclerophyllous shrubland with a graminoid understorey and, usually, a large-leaved (proteoid) shrub overstorey. Fynbos structure was interpreted largely as a response to low levels of soil nutrients. Non-fynbos vegetation ranged from mixed succulent-sclerophyllous and spiny large-leaved thicket at lower altitudes to tall mesic forest at the upper end of the gradient. Non-fynbos structure was explained in terms of variations in soil moisture and climate. An analysis of the biogeographical affinities of sample floras at sites along the coenoclines showed that fynbos vegetation was dominated by taxa endemic to the Cape phytochorion, although phytochorological mixing was pronounced at the lower altitude sites. The level of local endemism in the fynbos coenocline was relatively high; nearly all endemics were Cape fynbos taxa and their incidence increased with increasing altitude. These data indicate that fynbos vegetation has had a lengthy history in the southeastern Cape and that high altitude sites would have comprised a refuge for Cape taxa during unfavourable climatic periods. Non-fynbos vegetation ranged from dry subtropical Tongaland-Pondoland thicket with a strong Karoo-Namib component to temperate Afromontane forest. Levels of endemism were lower than the fynbos coenocline and decreased with increasing altitude. The high number of karroid endemics found in both coenoclines at low altitudes suggests that karroid vegetation would have been more widespread in the past, probably during the last glacial which was considerably drier than the present Holocene interglacial.     

Insect diversity in Cape fynbos and neighbouring South African vegetation

Aim  It has often been suggested that South Africa's Cape fynbos shrublands, although extremely rich in plant species, are poor in insects, thus representing a notable exception from the broad plant–insect diversity relationship. The aims of this study were to compare the diversity patterns of plant-inhabiting insects in fynbos and the vegetation of three neighbouring biomes (grassland, subtropical thicket, and Nama-karoo), and to test for a general relationship between plant diversity and insect diversity across these biomes.
Location  South-western to south-eastern South Africa.
Methods  We conducted seasonal plant surveys and sweep insect sampling in 10 × 10 m plots in the Baviaanskloof Conservation Area (Eastern Cape), where all four biomes occur. We also conducted once-only collections in the core area of each biome.
Results  Fynbos plots had insect diversity values similar to those of grassland and subtropical thicket (a dense, evergreen and spinescent shrubland with a high abundance of succulents and climbers), and significantly higher than Nama-karoo (an open, semiarid shrubland). A remarkably strong positive relationship was found between plant and insect species richness.
Main conclusions  Previous generalizations were based on a few insect groups (e.g. butterflies, under-represented in fynbos), but ignored published results on other groups (e.g. galling insects, which are in fact over-represented in this vegetation). We show that, overall, insect diversity in fynbos is comparable to that of neighbouring biomes. Fynbos vegetation does not represent a significant exception from the broad positive relationship between plant diversity and insect diversity.     

Diversification rate shifts in the Cape Floristic Region: The right traits in the right place at the right time

Species diversity patterns are the product of diversification rate variation, but the factors influencing changes in diversification rates are poorly known. Radiation is thought to be the result of ecological opportunity: the right traits in the right environment at the right time. We test this in the Cape Floristic Region (CFR) of South Africa, in which pyrophytic heathland (fynbos) and non-pyrophytic Afromontane forest occur interdigitated. We infer transitions from forest to fynbos in three Cape clades (Penaeaceae, Phyliceae and Diosmeae) and test if they are associated with diversification rate shifts and the evolution of functional traits linked to fire, high insolation and seasonal drought. We estimate diversification rate shifts using maximum likelihood and use phylogenetic comparative methods to show that forest to fynbos shifts were associated with decreases in leaf area and specific leaf area and preceded or coincided with increases in diversification rates. Furthermore, we show that Penaeaceae, Phyliceae and Diosmeae species are typical members of their vegetation types in terms of their traits. The diversification rate shifts of Penaeaceae and Phyliceae are dated to the Miocene, when postulated aridification-driven changes in the CFR fire regimes may have triggered expansion of the fynbos at the cost of forest, providing an ecological opportunity for the diversification of fynbos lineages.     

Influence of fire on critically endangered Swartland Shale Renosterveld in the Cape Floristic Region

Questions

The degree to which renosterveld shrublands are fire‐dependent is currently unclear. To address this issue, the following questions were asked: (1) does smoke stimulate germination of soil‐stored seeds in renosterveld; (2) does recently‐burned renosterveld display changed composition and higher diversity than unburned vegetation; and (3) how do the species compositions of renosterveld soil seed banks and standing vegetation compare?

Location

Swartland, Cape Floristic Region, South Africa.

Methods

Soil seed bank samples from a north‐ and south‐facing slope were smoke‐treated and germinated to test for smoke‐stimulated germination. Burned standing vegetation was surveyed 16 months post‐fire, as was unburned vegetation on the same slopes. Seed bank species richness and density were compared between smoke‐treated and untreated samples within and between slopes. Burned and unburned standing vegetation were compared within and between slopes in terms of species richness, abundance and aerial cover. Compositional similarity of the seed banks and standing vegetation was assessed.

Results

Seed banks were dominated by annuals and graminoids. Smoke treatment had no effect, except for driving significantly higher species richness and seedling density in south‐facing slope perennial shrubs. Species richness and seedling density were significantly higher in seed banks on the south‐facing slope compared to the north‐facing slope. Burned standing vegetation exhibited significantly higher diversity than unburned vegetation. Annuals and graminoids displayed significantly higher species richness and aerial cover in burned renosterveld. The north‐facing slope contained less than half the number of species/m² compared to the south‐facing slope. The seed banks and standing vegetation showed low to intermediate similarity (Sørensen = 31%–53%), but grouped close together on an NMDS plot, suggesting intermediate similarity overall.

Conclusions

Elevated germination of perennial shrubs in smoke‐treated seed bank samples and increased diversity of post‐fire standing vegetation suggest the renosterveld in this study shows elements of a fire‐driven system. Certain species only recruited in burned sites, suggesting fire‐stimulated germination. Aspect had a major influence on plant community composition, with the mesic south‐facing slope being more diverse than the xeric north‐facing slope. The similarity between the seed banks and standing vegetation was higher than previously shown for renosterveld, and appears to be higher than for fynbos.     

Fossil wood charcoal assemblages from Elands Bay Cave, South Africa: implications for Late Quaternary vegetation and climates in the winter-rainfall fynbos biome

Aim The aim of this paper is to analyse fossil charcoal deposits, largely identified to the species level and spanning a sequence from the late Holocene to < 40,000 BP , in order to reconstruct Late Quaternary vegetation and climatic patterns in the western (winter-rainfall) fynbos biome of South Africa. Location The charcoals were excavated from the Elands Bay Cave (32°19S, 18°20E) on the semiarid (200–250 mmyr^?1), winter-rainfall coastline of the western fynbos biome. Methods Patterns in the charcoal data set over time were sought by manual sorting of the charcoal×sample matrix, as well as by subjecting the data to multivariate analysis. Palaeoclimatic reconstruction was attempted by comparing the climatic controls on contemporary vegetation communities that resembled the fossil assemblages. Charcoal diversity was modelled using sample age and number of charcoal fragments as explanatory variables. Results The fossil assemblages ranged from xeric communities (similar to those presently occurring at the site) during the Holocene, to more mesic thicket and fynbos vegetation in the terminal Pleistocene, to Afromontane forest and riverine woodland communities after about 18,000 BP . Diversity of the charcoal samples increased monotonically with increasing sample age. Main conclusions The results suggest that, unlike the eastern fynbos biome, which is under fundamentally different climatic controls, soil moisture conditions in the western part of the biome were higher in the Last Glacial than during the Holocene. This scenario may help to explain the higher regional richness and associated diversification in the western than eastern part of the biome.     

Effects of alien pine plantations on small mammal community structure in a southern African biodiversity hotspot

Commercial plantations and alien tree invasions often have substantial negative impacts on local biodiversity. The effect of plantations on faunal communities in the fire‐adapted fynbos vegetation of the Cape Floristic Region biodiversity hotspot is not yet well quantified. We studied small mammal community structure in alien Pinus radiata plantations and adjacent fynbos regenerating after clear‐felling of plantations on the Cape Peninsula, South Africa. Small mammal sampling over 1,800 trap‐nights resulted in 480 captures of 345 individuals (excluding recaptures) representing six species. Significantly more species, individuals (12 X) and biomasses (29 X) of small mammals occurred on recovering fynbos sites compared to plantations. This was commensurate with a higher diversity of plant growth forms, vegetation densities and live vegetation biomass. Only one small mammal species, the pygmy mouse (Mus minutoides), was consistently trapped within plantations. Fynbos sites were dominated by three small mammal species that are ecological generalists and early successional pioneer species, rendering the recovering fynbos slightly depauperate in terms of species richness and evenness relative to other studies done in pristine fynbos. We make three recommendations for forestry that would facilitate the restoration of more diverse natural plant communities and progressively more diverse and dynamic small mammal assemblages in a key biodiversity hotspot.     

Elevational changes in vascular plants richness,diversity, and distribution pattern in Abune Yosef mountain range,Northern Ethiopia

The aim of this research is to investigate the patterns of vascular plant species richness,diversity,and distribution along an elevation gradient in the Abune Yosef mountain range,Ethiopia.Preferential systematic sampling was employed to collect vegetation and environmental data along the elevation gradient.We found that plant species richness declines monotonically from low to high elevations.Specifically,vascular plant species richness and diversity were lower in the Afroalpine grassland(high elevation)than in the Dry evergreen Afromontane forest and Ericaceous forest(low elevations).In contrast,endemic vascular plant richness was significantly higher in the Afroalpine grassland than in the Dry evergreen Afromontane forest and Ericaceous forest.Elevation showed a significant impact on the richness,diversity,and endemism of vascular plants.According to Sorensen's coefficient,the similarity between Dry evergreen Afromontane forest and Ericaceous forest vegetation types is higher(32%)than the similarity between Ericaceous forest and Afroalpine grassland(18%).Only 5%similarity was recorded between the Dry evergreen Afromontane forest and Afroalpine grassland.Growth forms showed different elevationai richness patterns.Trees and liana increased monotonically up to 3300 m.Shrub and herb richness patterns followed a hump-shaped and inverted hump-shaped pattern along the elevation gradient.The elevation patterns of vascular plant species richness,diversity,and growth form in the present study may be attributed to differences in management intensity,spatial heterogeneity,microclimatic variations,and anthropogenic disturbances.     

Diversity,composition and guild structure relationships between soil-stored seed banks and mature vegetation in alien plant-invaded South African fynbos shrublands

We investigated vegetation-seed bank relationships at three fynbos sites on the Cape Peninsula, South Africa, and the impacts to these sites of invasion by the alien tree Acacia saligna. Soil-stored seed banks in uninvaded fynbos were of a similar density to those previously measured in fynbos (ca. 1100–1500 seeds m^-2) and were dominated by mostly short-lived species. Lack of similarity between mature vegetation and seed banks, suggests that seed banks are poor predictors of mature vegetation composition and structure in fynbos. This lack of correspondence was attributed to the ephemerals (present only in the soil seed bank) and the dominance of serotinous (aerial seed bank) and sprouting (soil seed bank low to absent) species, in mature vegetation. Long-lived seeders were among the 10 most abundant species in the seed banks at all sites and at two sites shrub species contributed more to seed bank richness than any other growth form. Soil-stored seed banks, therefore, boost species richness and diversity both in early post-fire and later seral stages.There was a decline in fynbos species richness, diversity and abundance both in the standing vegetation and seed banks with increasing duration of invasion by the alien tree, Acacia saligna. However, the rate of decline was higher for the vegetation than the seed banks, suggesting that many fynbos species have long-term persistent seed banks. At two sites, there was no obvious shift in community composition associated with Acacia invasion: invaded sites were depauperate versions of the uninvaded site. However, at a third site, the vegetation composition shifted towards a community dominated by bird-dispersed thicket species and its seed bank shifted towards a community dominated by wind-dispersed perennials. Community composition of the soil seed banks under dense, recent Acacia was very similar to that of the corresponding uninvaded fynbos at all sites, indicating that there is good potential to return to species-rich fynbos vegetation after removal of the alien Acacia. Most seed bank species persisted in the soil seed bank of the long-invaded fynbos at low frequency and density, indicating high seed longevity in many species. We suggest that either a thick Acacia litter layer or a deep (>5 cm) burial moderated the fire and ambient temperature effects, preventing these seeds from germinating after fire and thus preventing loss from the seed bank.     

An overview of the Cape geophytes

The Cape Region (here treated as the winter rainfall region of southern Africa, thus including fynbos, renosterveld and succulent karoo vegetation) is the world's foremost centre of geophyte diversity. Some 2100 species in 20 families have been recorded from this area, 84% of them endemic. The most important families, with more than a hundred geophyte species each, are Iridaceae, Oxalidaceae, Hyacinthaceae, Orchidaceae, Amaryllidaceae and Asphodelaceae. Although southern Africa does not appear to have been the main diversification centre for the plant orders with highest geophyte representation (Asparagales and Liliales), it represents an active centre of transition to geophytism, such transitions having occurred independently in numerous plant groups, often followed by rapid speciation. Several Cape geophyte groups have consequently expanded across Africa to the Mediterranean Basin, and possibly to other winter rainfall regions. Remarkably high local species diversity in renosterveld vegetation, even in relatively homogeneous environments, suggests that pollinator specificity and phenology play an important role in niche partitioning. However, character diversity is also high in storage organs and leaves, and this could account for the high species diversity values recorded at larger spatial scales, especially across environmental gradients. Long-term climatic stability, combined with topoclimatic and edaphic diversity and regular fire occurrence, is likely to be responsible for the remarkable geophyte diversity of the Cape, as compared to other mediterranean-climate regions.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 87 , 27–43.     

How much evolutionary history in a 10 x 10 m plot?

We use a fully dated phylogenetic tree of the angiosperm families to calculate phylogenetic diversity (PD) in four South African vegetation types with distinct evolutionary histories. Since the branch length values are in this case represented by the ages of plant lineages, PD becomes the cumulative evolutionary age (CEA) of assemblages. Unsurprisingly, total CEA increases with family and with species diversity and observed values are the same as expected from random sampling of family lists. However, when random sampling is done from species lists, observed CEAs are generally lower than expected. In vegetation types which have undergone recent diversification-grassland, fynbos and Nama-karoo-co-occurring species are more closely related than expected, but in subtropical thicket the observed CEAs are well described by random sampling. The use of CEA has great potential for assessing the age of biotic assemblages, particularly as the dating of genus and species-level phylogenies become more accurate.     

Do spider diversity and assemblages change in different contiguous habitats? A case study in the protected habitats of the humid chaco ecoregion, northeast Argentina

Spiders are a megadiverse group that can be useful indicators of the overall species richness and health of biotic communities. The spider diversity in subtropical forests of the Neotropical region are not yet well known, especially in Argentinean subtropical forests where systematic fieldwork has not been done until recently. The Great Chaco is very important as the unique dry subtropical forest of the earth, but it is suffering increasing degradation by the advance of agriculture. Spider communities have been shown to be more directly influenced by vegetation architecture than vegetation species composition. In this study, we aim to assess whether spider diversity and assemblages change in adjacent habitats with different types of vegetation. We compare the diversity and spider assemblages in two different contiguous protected habitats (hygrophilous woodland and savannah parkland) of the Mburucuyá National Park, (Humid Chaco ecoregion). Seasonal samples were obtained using three types of sampling methods: pitfall trapping, beating, and manual litter extraction. The spider assemblages were different in the studied areas, and the abundance, diversity, evenness, and species richness were higher in the hygrophilous woodland than the savannah parkland. These differences in spider diversity and assemblages indicate that both types of habitats are important if the biodiversity is to be conserved in the Chaco ecoregion, where different types of habitat are shown as a patchy distribution.     

Species composition and diversity of small Afromontane forest fragments in northern Ethiopia

In the highlands of northern Ethiopia, remnants of the original Afromontane forest vegetation are largely restricted to church yards and other sacred groves in a matrix of cropland and semiarid degraded savanna. To assess the potential for natural forest regeneration, species composition and diversity of all forest fragments (10) in a study area of 13,000 ha were analyzed in relation to environmental and soil variables. Using a random design and a density of approximately one plot per 2 ha in all fragments, 31 20×20 m plots were sampled. Indicator species analysis and MRPP tests yielded five communities representing two forest types and one degraded savanna habitat. The forest fragments had a species-poor tree and shrub community in which plots were rather homogeneous and most species abundant. NMDS and analysis of variance indicated that a topographical gradient correlated to soil phosphorus, soil depth, stoniness and the proximity to the river system explained the major differences in species composition and separated moist and dry Afromontane forest communities. The grazing intensity further partitioned the habitats. Present communities and their environmental correlates indicate that the secondary climax forest in the area probably consisted of dry Afromontane forest interlaced by broad strips of moist Afromontane forest along rivers and streams and not a continuous, mono-dominant Juniperus forest as is often presumed. Negative effects of the degraded matrix on forest fragments increased with decreasing patch area and increasing shape irregularity. Nevertheless, all remaining fragments are important for their role in the landscape ecology of the region as refuges and species pools and should be protected and managed accordingly. If seed dispersal from forest fragments into exclosures and subsequent tree recruitment are both successful, the vegetation type most likely to establish is Afromontane savanna woodland, and if managed properly, eventually dry Afromontane forest may arise. Increasing the size of small patches and placing forest plantations and exclosures in the vicinity of small forest fragments is expected to yield the most immediate results. This approach may increase the likelihood of patch colonisation by frugivorous forest birds and thus foster the regeneration of native woody species.     

Comparative footprint of alien, agricultural and restored vegetation on surface-active arthropods

Both invasive alien trees and agricultural conversion have major impacts on biodiversity. We studied here the comparative impact of these two types of land transformation on a wide range of surface-active arthropod species using pitfall traps, with evergreen sclerophyllous natural vegetation (fynbos) as the control. The study was in the Cape Floristic Region, a global biodiversity hotspot, where alien trees are of major concern and where vineyards replace natural fynbos vegetation. Surface-active arthropods were selected as they are species rich, relatively immobile, and occur in high abundance. We hypothesized that the impact of the two types of land cover transformation would produce similar qualitative and quantitative effects on the arthropods. We also compared the results in the transformed and natural areas with those in areas cleared of alien trees. Arthropod species richness in cleared areas was higher than in vineyards and more similar to that in natural fynbos, while alien trees had the lowest. Overall abundance scores were highest in cleared areas, closely followed by fynbos, then vineyards and lowest in alien trees. Several species were restricted to each vegetation type, including alien trees. In terms of assemblage composition, all vegetation types were significantly different, although fynbos and vineyards grouped, suggesting that vineyards have less impact on the arthropod community than do alien trees. When rare species were excluded, vineyards and cleared sites grouped, indicating some recovery but only involving those species that were common and habitat tolerant. Our results suggest that vineyards retain a greater complement of indigenous species than alien trees, but that clearing of these aliens soon encourages establishment of indigenous species. Although there were significant differences in soil moisture and litter depth within and between vegetation types, we did not record them as significantly affecting species richness or abundance, even in alien vegetation, an encouraging sign for restoration.     

The application of multiple discriminant analysis to the reconstruction of the vegetation history of Fynbos,southern Africa

The fynbos biome of southern Africa is floristically diverse and explanations of this diversity have frequently invoked historical processes, in particular environmental change. Few sites exist within the region which facilitate palaeoecological reconstructions, but a relatively deep sequence of organic sediments in the Cederberg mountains in the south-western Cape Province of South Africa has been analysed for fossil pollen content. Conventional zonation of the resultant absolute pollen diagram reveals an apparent absence of marked vegetation change during the last 14500 years. Pollen analysis has its limitations under circumstances where the high plant diversity and incompleteness of reference material entails that pollen identifications may usually be made only down to family level. In order to assess whether the presumed stability of vegetation communities during the late Pleistocene and Holocene is an artefact of these taxonomic limitations, a comprehensive contemporary pollen sampling programme was conducted. Multiple discriminant analysis was applied to the contemporary data and suggests that contemporary pollen spectra are accurate reflections of the surrounding vegetation. Discriminant analysis is further able to identify analogue communities prevailing at various times during the sedimentation period. Rather than being truly stable, the vegetation of these mountains is shown to have been dynamic in response to changes in precipitation inputs, fire regime and human activity. Nevertheless, the vegetation history is characterised by relatively subtle changes in plant community patterns, a fact which may have played an important role in the evolution of prolific species diversity. It is concluded that contemporary pollen rain studies, combined with multiple discriminant analysis, may be especially valuable interpretive tools in situations of high plant species richness.     

Plant invasions,restoration, and economics: Perspectives from South African fynbos

Restoration is gaining importance in the management of plant invasions. As the success of restoration projects is frequently determined by factors other than ecological ones, we explored the ecological and financial feasibility of active restoration on three different invaded sites in South Africa's Cape Floristic Region. The aim of our study was to identify cost-effective ways of restoring functional native ecosystems following invasion by alien plants. Over three years we evaluated different restoration approaches using field trials and experimental manipulations (i.e. mechanical clearing, burning, different soil restoration techniques and sowing of native species) to reduce elevated soil nutrient levels and to re-establish native fynbos communities. Furthermore we investigated the possibility of introducing native fynbos species that can be used for sustainable harvesting to create an incentive for restoration on private land.Diversity and evenness of native plant species increased significantly after restoration at all three sites, whereas cover of alien plants decreased significantly, confirming that active restoration was successful. However, sowing of native fynbos species had no significant effect on native cover, species richness, diversity or evenness in the Acacia thicket and Kikuyu field, implying that the ecosystem was sufficiently resilient to allow autogenic recovery following clearing and burning of the invasive species. Soil restoration treatments resulted in an increase of available nitrogen in the Acacia thicket, but had no significant effects in the Eucalyptus plantation. However, despite elevated available soil nitrogen levels, native species germinated irrespective whether sown or unsown (i.e. regeneration from the soil seed bank).Without active introduction of native species, native grasses, forbs and other shrubs would have dominated, and proteoids and ericoids (the major fynbos growth forms) would have been under-represented.The financial analysis shows that income from flower harvesting following active restoration consistently outweighs income following passive restoration, but that the associated increase in income does not always justify the higher costs. We conclude that active restoration can be effective and financially feasible when compared to passive restoration, depending on the density of invasion. Active restoration of densely invaded sites may therefore only be justifiable if the target area is in a region of high conservation priority.     

地带性森林群落物种多样性的比较研究

在群落调查以及文献收集的基础上,对暖温带地区、暖温带和亚热带过渡地区、亚热带地区以及热带地区的典型地带笥植被不同群落类型群落多样性进行了分析和研究。结果发现这４类地区物种多样性的变化具有一定的规律性,具体表现在热带地区群落乔木层的物种丰富度和多样性为最高,然后依次是亚热带地区、秦蛉地区和东灵山地区;灌木层的物种丰富度和多样性则以亚热带地区为最高,其次是秦岭地区,热带地区的则仍高于东灵山地区;灌木层     

Invasion and persistence of bird-dispersed,subtropical thicket and forest species in fire-prone coastal fynbos

Abstract. Seedling abundance at four microsites (open fynbos, beneath emergent fynbos shrubs, beneath thicket, and beneath forest) was determined at three coastal dune landscapes, located along a gradient of increasing summer rainfall and where fire-dependent fynbos was the predominant vegetation. At all sites thicket seedlings were most common beneath emergent fynbos shrubs and under thicket clumps; seedlings of forest species were most abundant at forest microsites although some individuals were recorded beneath thicket. Very few thicket seedlings were observed in open fynbos. Birds play a keystone role in facilitating establishment of the fleshy fruit-bearing thicket flora. Seedling abundance at microsites of different thicket and forest species was generally unrelated to fruit abundance. Germination success of most species was highest under shaded conditions; soil organic content had no effect on germination. Removal of pulp and birdingestion enhanced the germination, relative to untreated controls, of two out of three species tested. A simple Markov model predicted a gradual increase in cover of the thicket and forest component and a gradual decline in fynbos under a ‘normal’ (20-yr interval) fire regime simulated over 10 cycles. Although inter-fire seedling establishment under emergent fynbos shrubs is important in the initial colonisation of fynbos by obligate resprouting thicket shrubs, these species persist and expand by vegetative recruitment after and between fires, respectively. In the prolonged absence of fire, the endemic-rich and fire-dependent fynbos flora would be replaced by species-poor forest and thicket.     

Legume diversity patterns in west central Africa: influence of species biology on distribution models

Objectives

Species Distribution Models (SDMs) are used to produce predictions of potential Leguminosae diversity in West Central Africa. Those predictions are evaluated subsequently using expert opinion. The established methodology of combining all SDMs is refined to assess species diversity within five defined vegetation types. Potential species diversity is thus predicted for each vegetation type respectively. The primary aim of the new methodology is to define, in more detail, areas of species richness for conservation planning.

Methodology

Using Maxent, SDMs based on a suite of 14 environmental predictors were generated for 185 West Central African Leguminosae species, each categorised according to one of five vegetation types: Afromontane, coastal, non-flooded forest, open formations, or riverine forest. The relative contribution of each environmental variable was compared between different vegetation types using a nonparametric Kruskal-Wallis analysis followed by a post-hoc Kruskal-Wallis Paired Comparison contrast. Legume species diversity patterns were explored initially using the typical method of stacking all SDMs. Subsequently, five different ensemble models were generated by partitioning SDMs according to vegetation category. Ecological modelers worked with legume specialists to improve data integrity and integrate expert opinion in the interpretation of individual species models and potential species richness predictions for different vegetation types.

Results/Conclusions

Of the 14 environmental predictors used, five showed no difference in their relative contribution to the different vegetation models. Of the nine discriminating variables, the majority were related to temperature variation. The set of variables that played a major role in the Afromontane species diversity model differed significantly from the sets of variables of greatest relative important in other vegetation categories. The traditional approach of stacking all SDMs indicated overall centers of diversity in the region but the maps indicating potential species richness by vegetation type offered more detailed information on which conservation efforts can be focused.     

Palynological evidence for the impact of colonial settlement within lowland fynbos: A high‐resolution study from the Verlorenvlei,southwestern Cape Province,South Africa

The present distribution of lowland fynbos of the southwestern Cape coastal forelands occupies a unique yet threatened existence. Long renowned for its extraordinary species richness, the lowland fynbos now reveals a decline in diversity following the impact of recent European settlement. Fine resolution pollen analysis, conducted on a dated sediment core from the Verlorenvlei, reveals a 250 year pattern of debilitating vegetation transformations. The arrival of European colonists in the area circa 1700 is noted in the sedimentary sequence, not only with respect to changes in the pollen spectra, but also through concomitant changes in the nature and timing of sedimentation. The rapid extermination of large mammalian fauna, overgrazing by domestic stock and decades of agricultural mismanagement in a marginal landscape are considered to be the principal factors responsible for deliterious alterations of the natural disturbance regime.     

What saplings can tell us about forest expansion over natural grasslands

Questions: 1. Do the species composition, richness and diversity of sapling communities vary significantly in differently sized patches? 2. Do forest patches of different sizes differ in woody plant colonization patterns? Location: São Francisco de Paula, Rio Grande do Sul, Brazil, 29°28'S,50°13'W. Methods: Three woody vegetation types, differing in structural development (patch size) and recovering for 10 years from cattle and burning disturbances, were sampled on grassland. We analysed the composition and complexity of the woody sapling communities, through relative abundance, richness and diversity patterns. We also evaluated recruitment status (residents vs. colonizers) of species in communities occurring in different forest patch size classes. Results : 1. There is a compositional gradient in sapling communities strongly associated with forest patch area. 2. Richness and diversity are positively correlated to patch area, but only in poorly structured patches; large patches present richness and diversity values similar to small patches. 3. Resident to colonizer abundance ratio increases from nurse plants to large patches. The species number proportion between residents and colonizers is similar in small and large patches and did not differ between these patch types. 4. Large patches presented a high number of exclusive species, while nurse plants and small patches did not. Conclusions: Woody plant communities in Araucaria forest patches are associated with patch structure development. Richness and diversity patterns are linked to patch colonization patterns. Generalist species colonize the understorey of nurse plants and small patches; resident species cannot recruit many new individuals. In large patches, sapling recruitment by resident adults precludes the immigration of new species into the patches, limiting richness and diversity.