Diversity value of Afromontane forest patches within KwaZulu-Natal timber production areas

Thesis (PhD)--Stellenbosch University, 2016.ENGLISH ABSTRACT: Natural forests are important habitats for many species. In the KwaZulu-Natal Midlands of South Africa these forests naturally exist as small isolated forest patches within a grassland matrix. Recently, much of the extensive grassland matrix has been converted to exotic pine plantations. It remains unclear how this has affected the ecologically important forest arthropods. The overall aim of this study is to determine the state of arthropod diversity in natural forest patches within a timber production landscape, and how best to conserve this diversity. The specific objectives of this study are to: 1) determine the impact of natural forest interpatch distance and forest patch size on epigaeic arthropod diversity; 2) compare arthropod species richness, abundance and composition among natural forests, pine plantations and grasslands; 3) determine how each arthropod functional guild/taxon (detritivores, predators, herbivores, ants and mites) responds to pine plantations, natural forests and grassland, and assess whether exotic pine plantations are able to function as habitat extensions of natural forests compared to the natural reference of grassland. Natural forest patches and surrounding habitats were sampled for epigaeic arthropods using pitfall traps, Berlese-Tullgren funnels, and active searches. Large and small patches had similar species richness, while assemblages differed significantly. Greater ant richness was recorded in patches with closer interpatch distances, while the opposite was observed for mites. Interaction between patch size and interpatch distance led to large-close patches supporting ant, beetle and spider composition that is different from small-close patches. Additionally, small-distant and small-close patches supported different beetle and ant composition. However, large-close and large-distant patches supported similar overall assemblages. Natural forests surrounded by grassland maintain arthropod diversity better than those surrounded by pines. There were greater differences in assemblages between natural forest-grassland boundaries than between natural forest-pine boundaries, indicating edge effects between pines and natural forests. Furthermore, grassland supported higher ant richness, while the greatest richness of mites and detritivores was in natural forests. Natural forests and their surrounding habitats varied in assemblages among functional guilds, although natural forests and pines were similar in mite, herbivore and predator assemblages. Interestingly, some grassland associated species were often found in adjacent natural forests. Many natural forests associated species were also present in the surrounding pines, yet pine blocks negatively influenced natural forest associated mite species. All pine associated species were able to occupy adjacent natural forests. Small patches had higher arthropod diversity than expected, although large and close patches are of greatest conservation priority in this landscape. Nevertheless, effective maintenance of all forest patches must incorporate surrounding natural vegetation. Although pines had a negative impact on species richness, they were also important habitat for some forest species, even though this is associated with loss of grassland species. I show that pines are not true extensions of natural forests, as they do not support all natural forest arthropod species. This study highlights the important role that natural forests play in the conservation of native arthropod biodiversity in a production landscape, and by extension in maintaining ecosystem processes across this landscape.AFRIKAANSE OPSOMMING: Natuurlike woude is belangrike habitatte vir baie spesies. In die KwaZulu-Natal Middelande van Suid-Afrika bestaan hierdie woude natuurlik as klein geïsoleerde bos-kolle binne 'n grasveldmatriks. Onlangs is groot dele van die uitgebreide grasveldmatriks omgeskakel na eksotiese denneplantasies. Dit is steeds onduidelik hoe hierdie veranderings die ekologies belangrike geleedpotiges in woude affekteer. Die oorkoepelende doel van hierdie studie was om die toestand van diversiteit van geleedpotiges binne natuurlike bos-kolle in 'n hout-produksielandskap te bepaal en om vas te stel wat die beste manier is om hierdie diversiteit te bewaar. Die spesifieke doelwitte van hierdie studie was om 1) die impak van natuurlike bos inter-kol afstand en bos-kol grootte op grondbewonende geleedpotige-diversiteit te bepaal; 2) geleedpotige-spesiesrykheid, -hoeveelheid en -samestelling tussen natuurlike woude, denneplantasies en graslande te vergelyk; 3) vas te stel hoe elke geleedpotige funksionele-gilde/takson (detritivore, roofdiere, herbivore, miere en myte) op denneplantasies, natuurlike woude en grasslande reageer, en om te bepaal of eksotiese denneplantasies as habitat-uitbreidings van natuurlike woude kan funksioneer met die natuurlike graslande as verwysing. Grondbewonende geleedpotiges vanaf natuurlike bos-kolle en omliggende habitatte is versamel deur gebruik te maak van putvalle, Berlese-Tullgren tregters, en aktiewe soektogte. Bos-kol grootte het nie spesiesrykheid beïnvloed nie, terwyl spesiessamestelling opmerklik verskil het tussen groot en klein bos-kolle. Hoër mierspesiesrykheid was aangeteken in kolle met naby inter-kol afstande, terwyl die teenoorgestelde waarneming gemaak is vir myte. Interaksie tussen kol grootte en inter-kol afstand het daartoe gelei dat groot en naby kolle mier-, kewer- en spinnekopsamestellings ondersteun het wat verskil van klein en naby kolle.. Klein-ver en klein-naby kolle het ook verskillende kewer- en miersamestellings ondersteun. Maar, indien alle takson in ag geneem word, het groot-naby en groot-ver bos-kolle soortgelyke samestellings ondersteun. Natuurlike woude wat omring word deur grasveld handhaaf geleedpotige-diversiteit beter as dié omring deur dennebome. Daar was groter verskille in samestellings tussen natuurlike bos-grasveld rande as tussen natuurlike bos-dennebome rande, wat ’n aanduiding is van rand-effekte tussen denne en natuurlike woude. Grasveld ondersteun hoër mierspesiesrykheid, terwyl die grootste rykheid van myte en detritivore in natuurlike woude gevind is. Natuurlike woude en hul omliggende habitatte het verskil in hul samestellings van funksionele gildes, alhoewel natuurlike woude en dennewoude soortgelyke myt-, herbivoor- en roofdiersamestellings gehad het. Interessant genoeg, sommige grasveld-verbonde spesies is dikwels in die omliggende natuurlike woude aangetref. Baie spesies wat in natuurlike woude voorkom was ook teenwoordig in die omliggende dennewoude, maar denneplantasies het ’n negatiewe invloed op natuurlike woud-verbonde mytspesies gehad. Alle denne-verbonde spesies was in staat om die omliggende natuurlike bos te bewoon. Kleiner bos-kolle het hoër geleedpotige-diversiteit gehad as wat verwag was, alhoewel groot en naby bos-kolle van die hoogste bewaringsprioriteite in hierdie landskap is. Tog moet doeltreffende instandhouding van alle bos-kolle die omliggende natuurlike plantegroei ook inkorporeer. Alhoewel denneplantasies 'n negatiewe impak op spesierykheid gehad het, was hulle ook belangrike habitat vir sommige woudspesies; daar was egter ʼn gepaardgaande verlies in grasveldspesies. Ek wys dat dennebome nie ware uitbreidings van natuurlike woude is nie, aangesien hulle nie alle natuurlike bos geleedpotige-spesies ondersteun nie. Hierdie studie beklemtoon die belangrike rol wat natuurlike woude speel in die bewaring van inheemse geleedpotige-biodiversiteit in 'n produksielandskap en dus ook in die handhawing van ekosisteem-prosesse regoor hierdie landskap

Epigaeic invertebrate community structure in two subtropical nature reserves, Eastern Cape, South Africa: Implications for conservation management

Volume: 52Start Page: 7End Page: 1

Commercial banana and macadamia plantations in a savanna matrix support high levels of arthropod diversity

Expansion and intensification of agroecosystems is one of the major causes of habitat loss in the savanna biome in South Africa. As such, this study sought to determine the influence of commercial subtropical fruit plantations (banana and macadamia) on species richness, abundance, and composition of surface-active arthropods compared to the savanna biome. Given that pesticides and herbicides are applied from spring to early autumn in banana and macadamia plantations, we sampled in winter to reduce the potential impact of pesticides and herbicides. Surface-active arthropods were sampled using pitfall traps. Habitat type did not affect species richness and abundance of ants and spiders, as well as species richness of beetles. However, significantly greater abundance of beetles was recorded in the macadamia plantation compared to the banana and savanna. This could have been due to greater abundance of herbivorous beetles and other insects, which would have increased the diversity of predatory beetles. Furthermore, unlike the banana plantation, the macadamia plantation was characterised by a deep leaf litter layer and the presence of weeds and grasses, which probably increased abundance of beetles. Species composition indicated that the studied arthropod taxa associate with specific habitats, as demonstrated by the three habitats supporting different species composition. Despite savanna habitat not supporting high species richness or abundance of surface-active arthropods, we recorded the highest number of unique species of ants and spiders in the savanna rather than in the plantations. These results highlight the importance of natural landscapes in conservation of surface-active arthropods

Earthworm species occurrence in agroecosystems in the Midlands, KwaZulu-Natal, South Africa

Little is known about the species composition of earthworms in agroecosystems in South Africa even though earthworms provide soil ecosystem services and are useful biological indicators of changes in the habitats. Given the land use and management impact biodiversity, the aim of this study was to document earthworm species that occur under cultivated land in the KwaZulu-Natal Midlands. A survey of nine farms that practise conservation agriculture was carried out between 2018 and 2020. Twelve earthworm species belonging to four introduced families: Acanthodrilidae (Dichogaster bolaui), Rhinodrilidae (Pontoscolex corenthrurus), Lumbricidae (Aporrectodea caliginosa, Aporrectodea rosea, Aporrectodea trapezoides, Lumbricus rubellus, Octolasion cyaneum, Octolasion lacteum), Megascolecidae (Amynthas aeruginosus, Amynthas corticis, Amynthas gracilis, Amynthas rodericensis) and juveniles from an indigenous family Tritogeniidae were recorded from cultivated fields. The type of crop (habitat) affected both species richness and abundance of earthworms significantly. However, post hoc results showed differences in species richness between the soya and the maize only, with greater species richness in the maize. Our results demonstrate that habitat type has a major influence on communities of earthworms in agroecosystems

Response of ants, beetles and spiders to disturbance varies among taxa in a South African savannah biome

Savannahs are structurally complex ecosystems consisting of a diverse community of plants and animals such as arthropods. Arthropods are essential in many ecosystem processes that help maintain life on Earth. The anthropogenic conversion of natural landscapes into croplands, residential and industrial areas has a negative impact on surface-active arthropods that have limited dispersal abilities and narrow habitat preferences. This study investigated the effect of disturbance on assemblages of ants, beetles and spiders in the savannah vegetation in Mpumalanga province, South Africa. We compared species richness, abundance and composition of these three taxa between the pristine savannah and the savannah that is exposed to a variety of anthropogenic activities (disturbed savannah). Arthropods were collected using pitfall traps in 15 sites in pristine savannah and 15 sites in disturbed savannah. We found that disturbance affects species richness and abundance of these taxa differently. Disturbance did not affect species richness of spiders and abundance of beetles, while greater species richness of ants and beetles, as well as abundance of ants and spiders was in disturbed than in pristine savannah. Furthermore, the species compositions of all taxa were different between disturbed and pristine savannah. The disturbed savannah had twice more unique indicator species than the pristine savannah. Differences in assemblages of arthropods between pristine and disturbed habitats suggest that it may be important to consider habitats in and outside protected areas in the conservation of arthropods, particularly in areas with greater percentage of natural and semi-natural landscapes occurring outside protected areas

The Fuzzy Logic Method to Efficiently Optimize Electricity Consumption in Individual Housing

Electricity demand shifting and reduction still raise a huge interest for end-users at the household level, especially because of the ongoing design of a dynamic pricing approach. In particular, end-users must act as the starting point for decreasing their consumption during peak hours to prevent the need to extend the grid and thus save considerable costs. This article points out the relevance of a fuzzy logic algorithm to efficiently predict short term load consumption (STLC). This approach is the cornerstone of a new home energy management (HEM) algorithm which is able to optimize the cost of electricity consumption, while smoothing the peak demand. The fuzzy logic modeling involves a strong reliance on a complete database of real consumption data from many instrumented show houses. The proposed HEM algorithm enables any end-user to manage his electricity consumption with a high degree of flexibility and transparency, and “reshape” the load profile. For example, this can be mainly achieved using smart control of a storage system coupled with remote management of the electric appliances. The simulation results demonstrate that an accurate prediction of STLC gives the possibility of achieving optimal planning and operation of the HEM system

Only multi-taxon studies show the full range of arthropod responses to fire

<div><p>Fire is a major driver in many ecosystems. Yet, little is known about how different ground-living arthropods survive fire. Using three sampling methods, and time-since-fire (last fire event: 3 months, 1 year, and 7 years), we investigate how ground-living arthropod diversity responds to fire, and how species richness, diversity, abundance, and composition of the four dominant taxa: ants, beetles, cockroaches and mites, respond. We did this in the naturally fire-prone Mediterranean-type scrubland vegetation (fynbos) of the Cape Floristic Region. Surprisingly, overall species richness and diversity was the same for all time-since-fire categories. However, when each dominant taxon was analysed separately, effect of fire on species richness and abundance varied among taxa. This emphasizes that many taxa must be investigated to really understand fire-driven events. We also highlight the importance of using different diversity measures, as fire did not influence species richness and abundance of particular taxa, while it affected others, overall greatly affecting assemblages of all taxa. Rockiness affected species richness, abundance and composition of a few taxa. We found that all time-since-fire categories supported distinctive assemblages. Some indicator species occurred across all time-since-fire categories, while others were restricted to a single time-since-fire category, showing that there is a wide range of responses to fire between taxa. Details of local landscape structure, abiotic and biotic, and frequency and intensity of fire add complexity to the fire-arthropod interaction. Overall, we show that the relationship between fire and arthropods is phylogenetically constrained, having been honed by many millennia of fire events, and highly complex. Present-day species manifest a variety of adaptations for surviving the great natural selective force of fire.</p></div

Living plant refuges immediately after a fire has passed.

<p>Living plant refuges immediately after a fire has passed.</p

Effect of time-since-fire on the overall arthropod abundance.

<p>3M (3-month category), 1Y (1-year category), 7Y (7-year category).</p

Canonical analysis of principal coordinates indicating effect of rockiness and time-since-fire on overall arthropod species composition.

<p>3-month category (black), 1-year category (grey), 7-year category (clear), circles (rocky), squares (non-rocky).</p