Effects of indigenous crop cultivation on mite biodiversity in a biodiversity hotspot

To be able to foretell which species will be at risk of extinction from possible expansion of agriculture into natural areas, we need to determine how land use affects animal groups especially insects with different life history traits. Intuitively, we can predict that the proportion of specialist versus generalist grasshoppers and widespread versus localised species can be an indicator of change in vegetation patterns in a landscape. As a result, the study examined the relationship between the extent of range distribution and mobility of grasshoppers and land-use type in the Cape Floristic Region (CFR) biodiversity hotspot. It aimed at examining grasshopper assemblage composition in association with different land uses. We specifically related the number and type of sites occupied by grasshopper species to their mobility and distribution type to find out which characters improve species survival under highly modified habitats. Grasshopper assemblages were dominated by highly mobile generalists that tolerated transformed landscapes, and mostly geographically widespread. This contrasts with the low- to medium-mobile, range-restricted specialists, which make up close to 30% of the total collection, with a lower tolerance for anthropogenically modified landscapes in the CFR. This study also reveal that the fynbos biome is an important habitat for low-mobility and range-restricted species, and hence require conscious conservation efforts to conserve such species to prevent possible future biotic erosion and homogenisation in this hotspot. This result can be used to assess the possible extent of biotic erosion or otherwise in order to recommend better conservation efforts in the CFR.

Endemic pollinator response to organic vs. conventional farming and landscape context in the Cape Floristic Region biodiversity hotspot

Vineyards compared to natural vegetation maintain high arthropod species turnover but alter trait diversity and composition of assemblages

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.

Farm crop diversity is often overlooked, predominantly indigenous crops’ role in this diversity. The main concentration has been on the contribution or role of exotic crops to household crop diversification. At the same time, the role played by both types of crops in household food security has only been aggregated, failing to show how indigenous crops play a key role in household food security. This research paper uses Tanzanian Panel data from waves 4 and 5 to study the factors influencing indigenous and exotic crop diversification and the role of this diversity in household food security. Using a random effect model, the author found that various factors are crucial in determining household crop diversification. Gender, household size, marital status, and expected harvest quantity are among the key factors influencing indigenous crop diversification. On the other hand, age, education, access to markets, access to irrigation services, and soil quality are the primary factors that affect the diversification of exotic crops. Moreover, the findings show that indigenous and exotic crop diversity significantly influences household food consumption. Thus, policies to increase the production of indigenous crops in order to improve household food consumption should be considered.

Fires are natural to ecosystems in many parts of the world, yet few studies have examined multi‐taxa invertebrate responses to these fires. We sampled a wide range of invertebrate taxa and feeding guilds at sites 3 months, 1 year and 3 years after fire, and in unburned control sites at the same time. A range of invertebrate sampling techniques was used on Table Mountain, in the Cape Floristic Region biodiversity hotspot, an area prone to natural and human‐induced fires. Sampling time differences strongly affected the composition of the whole assemblage, with fire having a major additional influence. Assemblages showed differential resilience to fire, especially in terms of species richness and abundance. One year after fire, the burned sites had the most compositional differences for the surface‐active species compared to control sites, while after 3 years, these sites were similar. Aerial assemblages were very different 3 years after burning, especially the pollination guild. Furthermore, these 3‐year‐old burned sites had the most unique species, suggesting that burning and longer‐term recovery is important for overall diversity. Some components of the invertebrate assemblage were remarkably resilient to fire (particularly ants), while others were far more conservative (pollinators). Nevertheless, fire allows new species to enter the ecosystem and can thus be used to promote local biodiversity if used appropriately. Ants alone should not be used to represent the whole invertebrate assemblage as they do not represent the more fire‐prone groups. A cross‐section of functional guilds is recommended in invertebrate recovery/fire management conservation programmes. These results have general significance in that a variety of feeding guilds need to be sampled when monitoring invertebrate responses to fire.

Globally plant species richness is a significant predictor of insect richness. Whether this is the result of insect diversity responding directly to plant diversity, or both groups responding in similar ways to extrinsic factors, has been much debated. Here we assess this relationship in the Cape Floristic Region (CFR), a biodiversity hotspot. The CFR has higher plant diversity than expected from latitude (i.e., abiotic conditions), but very little is known about the diversity of insects residing in this region. We first quantify diversity relationships at multiple spatial scales for one of the dominant plant families in the CFR, the Restionaceae, and its associated insect herbivore community. Plant and insect diversity are significantly positively correlated at the local scales (10–50 m; 0.1–3 km), but not at the regional scales (15–20 km; 50–70 km). The local scale relationship remains significantly positively correlated even when accounting for the influence of extrinsic variables and other vegetation attributes. This suggests that the diversity of local insect assemblages may be more strongly influenced by plant species richness than by abiotic variables. Further, vegetation age and plant structural complexity also influenced insect richness. The ratio of insect species per plant species in the CFR is comparable to other temperate regions around the world, suggesting that the insect diversity of the CFR is high relative to other areas of the globe with similar abiotic conditions, primarily as a result of the unusually high plant diversity in the region.

Understanding the link between species traits and how they use various elements in a heterogeneous agro-natural landscape is essential for conservation planning. Land-use and season affect the availability of resources for herbivorous insects such as grasshoppers. Also, the level at which these herbivores utilise these resources on the landscape depend on their traits. We focus here on the Cape Floristic Region biodiversity hotspot, which is rich in both endemic plants and narrow-range grasshoppers. We assessed dispersion patterns and abundance of the grasshopper species across the agro-natural mosaic, while specifically focusing on species traits and how they change over two seasons (spring and summer). We found that land-use and species traits played major roles in grasshopper spatial dispersion across the landscape, with season a highly significant variable. Not surprisingly, highly mobile, generalist feeders were abundant and widely dispersed across the landscape. Importantly however, this was especially the case in late season, when they could take advantage of high plant productivity in the vineyards. In contrast, low mobility, specialist feeders were limited to occupying only natural fynbos vegetation in both seasons. Generally, the highly mobile generalists benefitted in two ways: occupation of transformed areas, and receiving a population boost late season. This was not the case for the low-mobility specialists, which were doubly disadvantaged: not able to move far, and lacking their specific host plants in the transformed areas. From a conservation perspective, our results indicate the importance of improving functional connectivity using natural fynbos for conservation of the endemic specialists, while the generalists can largely look after themselves across this agro-natural mosaic.

The City of Cape Town (City) covers 2460 km 2 in the southwestern corner of the Cape Floristic Region biodiversity hotspot. Established in 1654, by 1700 there were no animals larger than 50 kg within 200 km of the City. However, apart from an appreciation that timber and firewood were becoming scarce, it was only in the 1930s that the first farm near Cape Point was set aside for conservation. Table Mountain was declared a National Monument in 1958, while it was largely covered by pine and gum plantations. Conservation of the montane areas thereafter expanded, whereas the lowlands were largely ignored, except for a few bird sanctuaries. Only in 1982 was the plight of the lowlands highlighted. Although ad hoc conservation planning was undertaken subsequently, 1997 saw the first priority categorization and conservation plan. The current situation is perilous: a huge effort will be required to meet basic conservation targets for the lowland vegetation types and threatened species. Local and international partners and funders will be key to achieving this. In eight of the City's 19 national vegetation types the minimum conservation targets are not achievable. Of the 3250 plant species estimated to occur in the City, 13 are extinct and 319 are threatened according to the IUCN Red List: this is 18% of the threatened Red List species in South Africa. Now for the first time, implementation is being attempted holistically across the metropole with discussion between internal City and external stakeholders to implement the conservation plan. However, the interim plans towards achieving this — that 60% of the unproclaimed target is secured by 2014, requires that over 40 km 2 be conserved per annum. This leaves 340 km 2 that should be secured by 2020 when projections from City spatial growth indicate that the last critical remnants will be urbanized.

Recently diverged or diverging populations can offer unobstructed insights into early barriers to gene flow during the initial stages of speciation. The current study utilised a novel insect system (order Mantophasmatodea) to shed light on the early drivers of speciation. The members of this group have limited dispersal abilities, small allopatric distributions and strong habitat associations in the Cape Floristic Region biodiversity hotspot in South Africa. Sister taxa from the diverse family Austrophasmatidae were chosen as focal species (Karoophasma biedouwense, K.botterkloofense). Population genetics and Generalized Dissimilarity Modelling (GDM) were used to characterise spatial patterns of genetic variation and evaluate the contribution of environmental factors to population divergence and speciation. Extensive sampling confirmed the suspected allopatry of these taxa. However, hybrids were identified in a narrow region occurring between the species' distributions. Strong population structure was found over short geographic distances; particularly in K.biedouwense in which geographic distance accounted for 32% of genetic variation over a scale of 50km (r=.56, p<.001). GDM explained 42%-78% of the deviance in observed genetic dissimilarities. Geographic distance was consistently indicated to be important for between species and within population differentiation, suggesting that limited dispersal ability may be an important neutral driver of divergence. Temperature, altitude, precipitation and vegetation were also indicated as important factors, suggesting the possible role of adaptation to local environmental conditions for species divergence. The discovery of the hybrid-zone, and the multiple allopatric species pairs in Austrophasmatidae support the idea that this could be a promising group to further our understanding of speciation modes.

South African farming households face several challenges regarding food security, poverty, micronutrient deficiencies and hidden hunger. This is due to millions of households lacking access to food and an adequate food basket. Consumption of indigenous crops has been proposed to help sustain vulnerable households since these crops have low production costs and are climate-resilient. However, research has found the consumption of these crops across South Africa to be relatively low. This study aims to examine the factors associated with the consumption of indigenous crops among farming households in the KwaZulu-Natal province of South Africa. A sample of 260 farming households was selected using simple random sampling. The results showed that farmers commonly cultivate exotic crops, such as spinach, cabbage, carrot, and butternut, more than any indigenous crops, except for a few cultivating taro and sweet potato. The binomial logit regression results revealed that an increase in the number of females and children within a household and farmers' experience increased the likelihood of consuming indigenous crops, whilst monthly food expenses decreased the likelihood of consuming indigenous crops. There is a considerable gap between the consumption and production of indigenous crops. The findings established that although many farming households indicated that they consume indigenous crops, this was not reflected in their cultivated crops. The study also concluded that farming households may be more aware of the nutritional benefits of indigenous crops, since an increase in the number of children in a household was linked to an increase in consumption of these crops. Additionally, experience in farming is vital, as it increases the consumption of indigenous crops. The study recommends government interventions that include increasing the production of indigenous crops by including them alongside the cultivation of exotic crops. Future work should also focus on awareness programs to promote the nutritional benefits of consuming indigenous crops. This, coupled with training centered on indigenous crops, could incentivize farming households to cultivate more of these crops for easier access.

We asked whether (a) variation in species composition of parasite assemblages on the same host species follows a non-random pattern and (b) if so, manifestation of this non-randomness across space and time differs among parasites, hosts and scales. We assessed nestedness and its contribution to β-diversity of fleas and gamasid mite assemblages exploiting small mammals across three scales: (a) within the same region across different locations; (b) within the same location across different times and (c) across distinct geographic regions. We estimated (a) the degree of nestedness (NCOL) and (b) the proportional contribution of nestedness to the total amount of β-diversity across locations, times and regions (βNESP). In the majority of host species, parasite assemblages were nested significantly across all three scales. In mites, but not fleas, NCOL correlated with the contribution of nestedness to the total amount of β-diversity. In fleas, NCOL did not differ among assemblages at the two local scales, but was significantly lower at regional scale. In mites, NCOL was the highest in assemblages at local spatial scale. βNESP was significantly higher (a) in flea than in mite assemblages at both local scales and (b) in mite than in flea assemblages at regional scale. In fleas, βNESP was higher at both local scales, whereas in mites it was higher at both local temporal and regional scales. Sheltering habits and geographic range of a host species did not affect either NCOL or βNESP in flea assemblages, but both metrics significantly decreased with an increase of geographic range of a host species in mite assemblages. We conclude that flea and mite assemblages across host populations at smaller and larger spatial scales and at temporal scale were characterized by nestedness which, in turn, contributed to an important degree to the total amount of β-diversity of these assemblages.

Pollination of exotic fruit crops depends more on extant pollinators and landscape structure than on local management of domestic bees

Plant and animal communities, as well as their interaction networks in agricultural landscapes, face threats of biotic homogenization due mostly to intensive management and cropland expansion. It is unclear whether agri-environmental schemes that promote environmentally friendly farming approaches can reduce the effects of these threats which cause reduction in regional (beta) diversity. Here, we examined biotic homogenization of insect–flower interactions in vineyards managed under agri-environmental schemes in the Cape Floristic Region (CFR). The interaction networks studied are of significant conservation value in the fragmented CFR agricultural landscape. Assessment was done using permutational distance-based test for homogeneity of multivariate dispersion to determine whether vineyards contributed to loss of diversity across the landscape through homogenization of their insect–flower interaction networks and flower visitor community. Vineyards did not show significant homogenization of interaction networks and flower-visitor community when compared to natural sites. Organic viticulture, integrated vineyard management and on-going protection of natural vegetation close to vineyards, as practiced in the CFR, are possibly contributing to the reduction in biotic homogenization observed here. Further vineyard expansion must however be prevented to avoid future biotic losses. These measures should be supported by all stakeholders in the conservation sector to achieve wine production while at the same time conserving the natural complement of biodiversity.

In dry areas, natural and artificial ponds experience frequent water level fluctuation, affecting conditions for some aquatic and amphibiotic taxa. Water beetles, bugs, and dragonflies make up much of pond diversity, and are responsive to changes in environmental conditions. Using a drought-prone pondscape within the Greater Cape Floristic Region biodiversity hotspot, we determine (1) the relative extent to which species richness, abundance, and composition are affected by pond water level fluctuation, (2) the effects of environmental variables and vegetation characteristics relative to fluctuating water levels, and (3) make recommendations to improve pondscape conservation. We found that the degree of fluctuation had a significant effect on beetle species richness, but had no significant effect on the other focal taxa. Water temperature, pH, and conductivity, and vegetation cover and composition were drivers of aquatic insect species richness, abundances, and assemblage structures. Habitat heterogeneity supported rich aquatic insect assemblages. We recommend that a range of ponds with various degrees of water level fluctuation should be maintained, along with naturally diverse marginal vegetation. Such a dynamic pondscape can contribute greatly towards maintenance of local and regional aquatic insect diversity in drought-prone regions and should be considered as a main focus in conservation efforts.