A brief look at our recent off-campus activities and achievements.
Exploring the coastal dune forests of Kwa-Zulu Natal
By Pieter Olivier, June 2011
Coastal dune forests in South Africa are in bad shape. Some estimates suggest that between 60-80% of forests in Kwa-Zulu Natal have been destroyed during the last century while the remaining forests face destruction in the wake of sugarcane and agroforestry plantation expansion, unsustainable local resource use, urban coastal developments and mining. The problem is exacerbated by the fact that these forests fall within the Maputaland Centre of Endemism and the Maputaland-Pondoland-Albany biodiversity hotspot - areas that sustain exceptionally high biodiversity. In addition, these forests form part of Birdlife International's Southeast African Coast Endemic Bird Area. Conserving remaining coastal dune forests, as well as rehabilitating forest areas previously cleared for mining, is therefore a critical initiative to ensure the persistence of these forests and the species associated with them. CERU's research up to now has focused mainly on coastal dune forest - however it is important to note that the Indian Ocean coastal belt forests comprise dune forest, coastal lowland forest, swamp forest, sand forest, and mangrove forests. For this specific survey we focused on coastal dune forests and coastal lowland forests and where possible we distinguished between the two types. However, in some instances it was impossible to make a distinction between the two forests types as they occurred intermingled. When I therefore refer to coastal forests it includes dune forest as well as coastal lowland forest.
Morgan Trimble and Rudi van Aarde recently published in PLoS ONE that the densities of most bird species occurring in rehabilitating KwaZulu-Natal dune forests have declined sharply during the last 15 years. They speculate that it may not only be a local phenomenon, but that the observed local decline may be part of a broader regional decline considering the scale of habitat loss suffered by all forest types in KwaZulu-Natal. CERU thus became interested in gaining further insights into the extent of forest, and specifically coastal forest destruction, and how the habitat loss and subsequent fragmentation affects bird communities occurring within coastal forest fragments in the province. This is also the objective of my PhD study - to determine the structural, compositional and functional status of remaining coastal forests in KwaZulu- Natal. My study area will encompass coastal forests occurring from Durban to Kosi Bay along the KwaZulu-Natal coast.
Early this month (June 2011) myself, Dr Robert Guldemond and Dr Mandy Lombard undertook a scoping survey to get an idea of how coastal forests are distributed along the KwaZulu-Natal coast. We were interested in determining how fragmented the forests were and to make an 'on the ground' assessment of the threats facing these forests across the study area region. To do this we planned a road trip along the scenic east coast of northern KwaZulu-Natal to investigate i) the distribution of coastal forests in the region ii) the habitat matrix types that surround these forests and their fragments and iii) to interpret existing habitat vegetation maps of the area produced by Ezemvelo KZN Wildlife.
Our survey started in Durban, the southernmost part of the study area, and ended in Kosi Bay in the north (on the Mozambique border). Some of the highlights of our trip included surveying the Isimangaliso Wetland Park and exploring the remote coastal forests located around the unique Kosi Bay Lake system on narrow unmapped sandy roads.
We found that coastal dune forests exist in a continuous strip of forest along the coast and are fragmented only by coastal towns and sugarcane plantations in some instances, south of the Tugela River. As we moved further north of the river mouth, coastal dune forests extended uninterrupted along the coast. Here coastal dune forest started to occur intertwined with coastal lowland forest with no clear feature separating the forest types. In addition, these forests extended further inland and in some instances even connected with other forest types found in the region such as swamp, sand, and mangrove forests. It was surprising to find such a variety of forest types in the study area - at this stage we are unsure of the role played by the various forest types in the region and how species respond to different forest habitats.
An important finding of our survey was that coastal dune, as well as coastal lowland, forests are surrounded by a diversity of habitat types that may have significant effects on species that occur within and around the forests. In the south the forests are mostly surrounded by exotic and homogenous sugarcane and Eucalyptus plantations, while further north the forests are surrounded by natural undisturbed grasslands and woodlands. An excellent example of this was the Isimangaliso Wetland Park where pristine forest habitats still exist surrounded by an undisturbed heterogeneous habitat matrix. Contrastingly, the majority of forests further north of the Park were surrounded by rural homesteads that comprised agricultural fields, Eucalyptus woodlots, sugarcane patches and grazing areas for cattle. It is likely that many people here also depend on forest products for their livelihoods and sustainable harvesting of such products will thus always be an important factor to consider when planning conservation initiatives that focus on forests.
Overall the survey was very successful in giving us a more informed perspective on coastal forest distribution, the threats faced by these forests and the complexities of the landscapes that surround them. It will serve as the basic platform from which I will plan my future research and answer the important question of how we can successfully conserve these coastal forests and the many plant and animal and species that associate with them, as well as the ecological processes that drive them (e.g. pollination, seed dispersal, trophic webs, water table dynamics, soil types, etc.).
Summary of Symposium Proceedings
By Pieter Olivier, April 2011
The United Nations General Assembly declared 2011 as the International Year of Forests to raise awareness on sustainable management, conservation and sustainable development of all forest types. The motto of the year 'Celebrating Forests for People' together with the logo emphasises the importance of forests and forest products for people in the world and in South Africa. It also sums up well the proceedings of the Fifth Natural Forest and Woodland Symposium that took place in Richardsbay from the 10th to the 13 of April 2011.
The symposium highlighted the diverse viewpoints and objectives of those involved with forest management and conservation in South Africa. Do we harvest trees commercially or do we protect them? Do we expand current agroforestry activities or can we fulfil our timber needs with products from indigenous forests? How do we create a balance between how people utilize a forest and conservation objectives? Can destroyed or degraded forest be restored?
During the discussion sessions some positive as well as negative aspects emerged. Some of the important positive aspects of the proceedings included i) findings that disturbed forests can potentially be structurally and functionally restored, ii) assessments that showed how harvests of forest products by local communities can be conducted sustainably and iii) reports on research that are being carried out to identify and cure diseases that might affect the wellbeing of trees in South Africa. On the contrary, the dynamics in forest systems and the biodiversity associated with it was neglected during the proceedings. Furthermore, it came to light that forests are under increasing threat of destruction from illegal harvesting, commercial logging and developments, climate change and an increasing human population.
The findings that disturbed forests can potentially be successfully restored are good news for forest conservation in South Africa. Forest restoration has always been a controversial topic with contrasting opinions widespread on the matter. However, a number of talks presented data that suggested forest structure and the processes associated with undisturbed forests can be restored if given time and the opportunity. CERU's Dr. Robert Guldemond, Teri Ott and Pieter Olivier presented talks that illustrated how coastal dune forests are starting to recover some of the characteristic ecological processes normally associated with undisturbed coastal dune forest. Regenerating stands of different ages are currently in different successional stages with species composition and processes typical of a vegetation type that is in a recovery phase. Furthermore, community composition of millipedes, birds and trees reflect the functionality of ecological processes such as colonization, dispersal, and canopy gap dynamics and suggest that coastal dune forest can be functionally restored if the correct management approaches are adopted. In addition, a field visit to the regenerating coastal dune forest sites (that included most of the delegates) further contributed to emphasise the important role that restoration can play in conservation efforts. Further evidence that disturbed forest can be restored comes from elsewhere in Africa. In Gabon slash and burn agriculture is often considered a degrading practise in tropical moist forests. However, C.A. Ombina showed that various native pioneer species establish in abandoned farm sites and facilitate the recovery of forest tree species towards diverse regrowth forest. Also, a review conducted by L. Mwabumba in Zambia's Miombo woodlands suggest that even though human-induced activities may trigger and facilitate changes in species composition, structure and functional processes that characterise Miombo successional dynamics still remain present even after disturbances. The subsequent successful regeneration of these woodlands depends on the development of ecological species groups under variable fire regimes, drought, grazing and cultivation.
The number of people that depend on forests for their livelihoods make it difficult to ensure that forest products are harvested sustainably. A number of studies showed that this may indeed be possible if the correct management systems are being put in place. Some of the most notable talks on this topic included M. Coates-Palgrave that illustrated the sustainable utilization of forest in Mozambique where forest stands are logged every 25 years and where furniture is manufactured and sold. Also Prof. C.J. Geldenhuys proposed that laths and poles can be selectively harvested in the Eastern Cape from Milettia grandis and Ptaeroxylon obliquum seedling and coppice regrowth while the biodiversity of the forest increase. A.M. Swemmer studied fuel wood harvesting around villages in the central Lowveld in Mpumalanga and suggested that it may be sustainable as no deforestation has occurred in the last decade as well as an increase in tree and stem densities. The main concern of researches was the increase in people that depend on forest products - what may be sustainable now may not be the case in the future. However, there exists a great deal of potential for community based forest conservation e.g. through sustainable use, monitoring, restoration, and alien plant control, but unfortunately the mechanisms to implement it are currently lacking. A communication gap exists between local government institutions, policymakers and communities on the ground that need to be restored before community based forest conservation can be successfully implemented.
Forests and forests products are undoubtedly of great importance to the millions of people that depend on them for their daily livelihoods and subsistence. However, indigenous forests in South Africa support a high proportion of the country's floral and faunal diversity. For instance, it is estimated that both forest mammals and forest birds represent over 14% of the terrestrial component of these taxa in southern Africa. It is therefore unfortunate that these aspects were largely neglected during the symposium proceedings. It is difficult to assess threats to forests or predict what the impact of harvesting will be on a forest if no information is available on species interactions or ecological processes functioning within a forest. Furthermore, even though it is generally assumed that forests provide vital ecosystem services to people there was a lack of studies that investigated this aspect. Studies are needed to identify and quantify ecosystem services that can potentially be provided by forests and how people can benefit sustainably from these.
Another worrying aspect highlighted by the symposium was the severe degradation experienced by some forests in South Africa. For instance, N.B. Ndlovu showed that Dukuduku forest lost 34.4% of natural forest cover between 1992 and 2005. During this period anthropogenic disturbance increased sharply. Likewise D. Berliner studying several different types of forests on the Eastern Cape Wild Coast concludes that drastic conservation actions will be required to avert a pending crisis situation. Unfortunately, there seem to be uncertainty over the management and conservation actions that could be implemented to ensure the persistence of these threatened forests. More information on how these forests function may well contribute to the finding of lasting solutions and contribute to the work already done by forest ecologists in South Africa.
Do all species garner equal attention from scientists?
By Morgan Trimble, May 2010
There has been a long-standing debate on the prioritization of conservation projects. Some favour actions to project endangered species or habitats while some argue for broader, landscape-scale projects that do not necessarily center on threatened species. However, lacking from the debate has been a discussion of the most efficient distribution of effort and funding for conservation science. In a paper published recently in Conservation Biology, Professor Rudi van Aarde and I explore the existing biases biologists exhibit in their research.
We assessed the number of scientific papers published about each of nearly 2,000 southern African species of mammals, birds, reptiles, and amphibians in the past 14 years. There was a clear bias among taxonomic groups, with large mammals commanding the bulk of scientific attention. Contrastingly, scientists largely ignored small mammals and amphibians. Reptiles and birds were intermediately studied. Other groups such as plants, invertebrates, fungi, and algae were too poorly studied and described to consider in our analysis.
We also related scientific investment to species' threat status on the IUCN Red List-the designation authority for threatened species. On average scientific interest in threatened large mammals eclipsed that of threatened amphibians and small mammals by 500 times and 216 times respectively. Threatened reptiles also garnered more attention than birds, small mammals, and amphibians. Even within groups, scientific effort was not equally distributed-70% of scientific attention for threatened large mammals was concentrated on fewer than 30% of the species and 98% of papers about threatened reptiles were focused on fewer than a quarter of the species.
These results are worrying because the skew in research does not reflect on conservation needs-information gleaned from research on large mammals may have little value to conservation of other species. So what drives the bias? Many scientists themselves are no doubt interested in big, 'cute' animals and thus decide to study them. However, society and funding availability likely play a role as well. Scientists who study charismatic large mammals may obtain research grants more easily and get more people interested in their work than those studying, for example, rare amphibians.
There is neither enough money nor scientific expertise to go around. With such clear bias in the scientific literature, we urge scientists and funding agencies to consider carefully how their efforts can best contribute to conservation. For more information, check out the original article in Conservation Biology and the press coverage in the Guardian, New York Times, and BBC Mundo.
CERU participates in the South African Wildlife Management Symposium
By Morgan Trimble, September 2009
In September, the crew at CERU set off for Thaba 'Nchu, 60 km from Bloemfontein, to share their research at the South African Wildlife Management Association (SAWMA) Symposium. The SAWMA Symposium is an annual meeting that brings together both scientists and those responsible for conservation on the ground-wildlife managers. This year's theme was 'Ensuring Sustainability', so students and staff from all three of CERU's primary research programmes-elephant conservation, coastal dune forest restoration, and Maputaland biodiversity assessment-had the opportunity to present their work.
Professor van Aarde opened the first session of the symposium with an overview of recent progress in CERU's elephant conservation programme with his talk 'The megaparks for metapopulations research initiative: where are we and where are we going?'. Subsequently, students working on elephant conservation issues filled in the details. From a population dynamics perspective, Pieter Olivier presented the results from the last chapter of his Msc study: 'Demographic support for metapopulation structure amongst southern Africa's elephants'. PhD student Cornelio Ntumi, MSc student Tamara Lee, and Hons student Alida de Flamingh presented work on the spatial approach to elephant conservation in their respective talks: 'Dealing with human-elephant conflict; a landscape approach in Mozambique', 'Elephant and people in the landscape: a case study in the Caprivi region', and 'Environmental determinants of spatial use by elephants: a case study in Zambia'.
PhD students Matt Grainger and Theresia Ott presented their work under CERU's coastal dune forest restoration programme. Matt spoke about the influence of invasive species on restoration success in his talk 'Stranger danger? Non-native plant invasion in habitat restoration'. Theresia presented her work that takes a landscape approach to restoration ecology in 'Do historical changes in landscape patterns dictate colonization? A case study on regenerating coastal dunes'. Morgan Trimble used monitoring data from the restoration programme to track changes in bird populations over time and delivered the results in 'An alarming decline of several coastal dune forest bird assemblages'.
Dr Rob Guldemond presented the results of some of his work for CERU's Maputaland biodiversity assessment. His talk was titled 'Forest patchiness as a driver of bird diversity in Maputaland'.
View abstracts for all of the CERU presentations.
Besides sharing their science with fellow academics and wildlife managers, other highlights for CERU at SAWMA included a dinner speech on photography by Professor Rudi van Aarde, good food, great conversation, and sightings of aardwolf, African wildcat, aardvark and several other species at nearby Maria Moroka Nature Reserve.
How does resource limitation influence elephant populations?
By Morgan Trimble, June 2009
The recently published 'Drivers of megaherbivore demographic fluctuations: inference from elephants' by Morgan Trimble, Sam Ferreira, and Rudi van Aarde seeks to elucidate how resource limitation (i.e. lack of food) affects elephant populations. This is a big question in elephant conservation because it relates to how elephant populations might experience density dependence-the intrinsic processes that relate the size of populations to resource availability. The paper also provides information about how the number of individuals in a population might vary in respond to environmental changes that determine plant productivity, such as drought and global warming.
It is difficult to elucidate population responses to resource limitation in elephants and other long-lived species because traditional methods require long periods of study. However, our paper presents a novel approach to study population responses-we compared deviations in the shape of age distributions of 17 elephant populations in Africa to the availability of food in the past. An age distribution is simply a way to describe the makeup of the population in terms of age classes. The number of elephants in each age class should decrease at a constant proportional rate as age increases, so deviations from this expectation indicate changes in birth or survival rates of specific age groups. For example, if an age distribution indicates that there are fewer three-year-old elephants than predicted, we can investigate what might have caused the discrepancy by looking at conditions in the past. We used satellite derived NDVI values, a measure of plant productivity, to quantify changes in food availability over time.
This allowed us to assess the population level consequences of varying resource availability during conception, gestation, elephant calves' first year of life, and the subsequent years of elephants' lives. In dry savannas, the conditions during the first year of life seem to drive population changes-probably due to the susceptibility of young elephants to drought. However, in savannas that receive more rainfall, food availability during conception and gestation is the most important determinant of deviations from the expected age structure. This means that first-year survival drives population responses in dry savannas while, in wetter savannas, variation in birth rates generates population change. The latter is an unexpected pattern for mammals because, according to a theory published by Eberhardt in 2002, populations should first respond to resource limitation through a decrease in juvenile survival and only secondly with decreased reproductive rates. However, we posit that the pattern makes sense for elephants and other extremely large mammals because investment in reproduction is so substantial. At 22-months, gestation in elephants is longer than that of any other mammal. Therefore, evolution might have selected mechanisms to delay reproduction until the environmental conditions were most favorable. Check out the original article from the Journal of Zoology.
Kim Young investigates spatial aspects of elephant management in two new papers
By Morgan Trimble, May 2009
CERU PhD candidate Kim Young has been busy for the past few months. Kim, who also works part-time as an ecologist for the New Zealand Department of Conservation, published two manuscripts recently based on her research into the landscape determinants of elephant spatial distribution. She also traveled to many of the elephant reserves in South Africa to get the facts on management strategies and perceptions towards elephants.
In 'The influence of increasing population size and vegetation productivity on elephant distribution in the Kruger National Park', Kim and co-authors Dr. Sam Ferreira and Prof. Rudi van Aarde investigate the effect of increasing population size on the distribution of elephants throughout the park. This is of key importance because although many elephant management decisions in the past depended solely on population numbers (e.g. the decision to cull elephants in Kruger), a more important consideration is the spatial distribution of elephants and the intensity at which they utilize landscapes. This is because the extent to which elephants affect other species is not dependent on numbers alone. For example, a given number of elephants that stay in one area at high density all year will have different consequences for the landscape than an equal number of elephants diffusely distributed across the landscape and constantly on the move. By analyzing count data and distribution records from Kruger, the authors found that the area of Kruger occupied by elephants did increase as the population grew and that the distribution of elephant groups became more homogenous. Thus, when formulating conservation plans, park managers need to consider the influence of numbers on elephant distribution and the associated variation in intensity of impact. Check out the original paper published in Austral Ecology.
Kim Young, Dr. Ferreira, and Prof. van Aarde take a closer look at the intensity at which elephants utilize their landscape in 'Elephant spatial use in wet and dry savannas of southern Africa'. CERU has fitted elephants throughout southern Africa with satellite collars that allow us to track their movements. For this study, the authors used data generated by collared elephants in Etosha and Khaudum in Namibia, Ngamiland 11 in Botswana, Kafue and Luangwa in Zambia, and Lower Zambezi on the border of Zambia and Zimbabwe. To find out how elephants in high-rainfall wet savannas utilize space differently than elephants in low-rainfall dry savannas, the authors looked at home range size (the area in which an elephant spends most of its time), evenness of utilization within home ranges, and how often elephants revisit an area where they have already been. They found that dry savanna elephants range over an area 3 to 4 times bigger than those in wet savannas do. However, the evenness with which elephants use their home range is similar in both savanna types. On the other hand, wet savanna elephants revisit the same locations within their range more often than do their dry savanna counterparts. These differences can be explained by the higher density of food resources in wet savannas and imply that wet savanna elephants use their space more intensively. Thus, as mentioned before, elephant management plans must consider spatial distribution, particularly that elephants in different locations use space differently. This article is available from the Journal of Zoology.
For a new research project, Kim embarked on an epic road trip to investigate management strategies and perceptions in many of the elephant inhabited areas of South Africa. Recently, she visited conservation managers in Kruger National Park, Pilansberg Game Reserve, Addo Elephant National Park, Tembe Elephant Park, Mkhuze Game Reserve, and Hluhluwe-Imfolozi Game Reserve to name but a few. Keep an eye out for this exciting research.
Millipedes and early mornings
By Morgan Trimble, January 2009
Two CERU field teams have kick started the year with January field work in KwaZulu-Natal for the coastal dune forest rehabilitation project in Richards Bay. This project seeks to monitor and map the progress of areas of coastal dune forest once stripped bare for mining as they regenerate back into functional forest. To do this, we monitor a variety of organisms-the field work this January focuses on birds and millipedes.
The bird team, Matt and Thabile, and the millipede team, Rob, Jo, Morgan, Laura, Buyi, C.J., and Tarryn head out every day to gather data on the abundance of different bird and millipede species. The birders walk transects through forest stands of varying age since last disturbance and record all the birds they see. With a few hundred different bird species in the area, it takes practice to get to grips with them all. We have just added a new species, the swee waxbill, to our records for the area. On the other hand, the millipeders look to the ground to identify and record millipede species in the leaf litter and undergrowth. With only twenty-some species to identify, the position of millipeder is easier to attain but decidedly more hands-on as it is necessary to examine some millipedes close up to identify them. The bird and millipede teams also work in pristine coastal dune forests in the area to get an idea of what the species assemblages of the rehabilitating forest patches should one day look like.
This area of Natal is a birders paradise, and we see many interesting life forms in the forest, but the field work is not all fun and games. It takes a lot of coffee and insect repellent for the teams to survive the 3:45am wake-up calls and mosquitoes in the forest. A few showers a day and a midday nap help to combat the heat, while a nice afternoon stroll on the beach and dip in the Indian ocean is just the cure for the dreaded millipeders' back and birders' neck.