Michael Timm Hoffman

University of Cape Town | UCT · Department of Biological Sciences

An overview of research for such a large and varied region as the Karoo serves several purposes. First, it brings together information about the region that is widely scattered in the literature and illustrates the progression of knowledge across major academic disciplines. In so doing, it shows how different themes and emphases have changed over t...

Most protected area impact research that uses counterfactuals draws heavily on quantitative methods, data, and knowledge types, making it valuable in producing generalizations but limited in temporal scope, historical detail, and habitat diversity and coverage of ecosystem services. We devised a methodological pluralistic approach, which supports s...

Grootbos Nature Reserve falls within the Cape Floristic Region of South Africa and comprises fynbos and forest vegetation elements, which exist as alternate stable states and are naturally maintained by feedbacks between vegetation, fire, topography and climate. The objective of this study was to investigate changes in forest extent in the Baviaans...

Global projections surrounding ecosystem vulnerability and biodiversity loss have heightened in recent decades due to climate change and land use. Mediterranean Type Ecosystems (MTEs) are projected to be highly vulnerable to global change due to changes in plant available moisture, changing fire regimes, and introduced species. Jonkershoek Nature R...

Fynbos and afrotemperate forest exist as alternate stable states in the Cape Floristic Region of South Africa. In parts of Table Mountain National Park, afrotemperate forest has expanded in recent decades. The aim of this project was to explore the drivers of this change and distinguish whether this expansion represents a recovery of forest after p...

This thesis investigated the impact of cultivation, and the efficiency of passive and active restoration of fallow fields, in Namaqualand’s Hardeveld and Renosterveld vegetation communities. The core theory of this thesis lies in the ecology of semi-arid environments and the concept of patch dynamics. In such areas plants grow together, creating co...

Book details Bollig, M, Shaping the African Savannah: from Capitalist frontier to Arid Eden in Namibia. Cambridge: Cambridge University Press; 2020. 404 pages, hardback, ISBN 9781108488488

Mediterranean environments are biodiversity hotspots in which strongly seasonal winter rainfall regimes and fire play major roles in driving ecosystem dynamics. Global predictions forecast unreliability of winter rainfall and increases in summer rainfall that are expected to result in major changes in community structure. Mediterranean systems are...

The spatial heterogeneity of vegetation in a communal grazing system provides pastoralists with a range of grazing sites to select for their livestock. When fencing spatially constrains herds, there is reduced access to ecological heterogeneity, which may have a negative impact on livestock and the grazing resource. This study investigated temporal...

Fire is a key regulator of tree cover in grassy ecosystems, but century-long changes in fire regimes have not been explicitly quantified in South Africa. This study aimed to determine changes in the fire regimes of South Africa’s grassy biomes over the past century in response to widespread human-induced changes. Using spatially explicit data, we e...

Vegetation cover estimates for trees, shrub-grass mosaics, and grassland and bare ground, were quantified in the savanna-woodland of Bwabwata National Park, north-east Namibia. Changes in woody cover were analysed using repeat photographs in combination with aerial photographs and recent satellite imagery taken between 1996 and 2019. Cover estimate...

The Eastern Cape Province, and in particular, it's interior western Karoo region, has long been subject to periodic droughts, with significant implications for it's agricultural sector. From 2015, with some recovery in 2020, the area experienced a severe multi year drought, with negative impacts for a range of sectors, including extensive livestock...

Foraging by African savanna elephant (Loxodonta africana) and other herbivores tends to result in a piosphere effect around water sources, with increasing pressure on vegetation as distance to water decreases. This study aimed to investigate the impacts of pumped waterholes on woody vegetation in the southern portion of Zimbabwe’s Zambezi National...

Ground-based repeat photography has a long history in documenting landscape change. Given the growing concern over the scale and rate of global change related phenomena, such as climate and land-use change, the benefits of involving the wider public in data collection efforts is increasingly being realised. Public involvement is particularly useful...

Over the last 50 years, studies have shown a decline in the use of mountain lands, a phenomenon termed land abandonment. We investigate the causal mechanisms of land use change in a mountain catchment important for regional water supplies in the southwestern Cape of South Africa. Uniquely, we include nature-based recreational land use types typical...

Growth plasticity may allow fire‐prone species to maximize their recovery rates during temporary, sporadic periods of rainfall availability in the post‐fire environment. However, moisture‐driven growth plasticity could be maladaptive in nutrient‐limited environments that require tighter control of growth and resource use. We investigated whether a...

Legislation and policy are key tools used by governments to change the socio-economic and political landscape of agrarian systems with consequences for mobile pastoralism. This study used the social-ecological systems framework to examine how pastoral mobility in the semi-arid, montane communal rangeland in South Africa adapted to the changing soci...

The comparison of matched historical and repeat photograph pairs provides an important tool to assess historical trends in vegetation and landscape change. An analysis of repeat photographs is invaluable for ground-truthing and augmenting an understanding of trajectories of vegetation change derived from other methods such as aerial photographs, re...

Global change in its various expressions has impacted the structure and function of ecosystems worldwide, compromising the provision of fundamental ecosystems services and creating a predicament for the societies that benefit from them. Restoration ecology plays a key role in securing ecological integrity and societal wellbeing, and hence represent...

South Africa is a megadiverse country in terms of biodiversity, with continental South Africa composed of nine terrestrial biomes. This diversity is in part due to the wide range of climatic and topographic conditions that exist in the country. This chapter explores how these environmental features influence biological invasions (focusing on terres...

Biome boundaries are expected to be sensitive to changes in climate and disturbance, because it is here that ecological communities are at environmental, ecological or disturbance limits. Using palaeoecology to study ecosystem dynamics at biome boundaries provides opportunities for understanding ecosystem resilience or sensitivity at ecologically m...

Although wildlife production is widely considered beneficial for semi-arid environments, few studies have reported on the long-term environmental effects of converting from livestock production to game ranching. Asante Sana Game Reserve in South Africa was stocked with domestic livestock for centuries. However, after 1996 game ranching was adopted...

In the Greater Cape Floristic Region (GCFR) of South Africa, afrotemperate forest islands persist within a broader landscape of Mediterranean-type fynbos shrubland. The co-existence of these contrasting vegetation types in the same climate space suggests interactions between broad-scale climatic parameters and localised variables (notably local dis...

Regularly spaced earthen mounds called heuweltjies dot landscapes of the succulent Karoo of western South Africa. Colonies of the western harvester termite, Microhodotermes viator typically occupy the mounds, but there is substantial, unresolved debate regarding the role (if any) played by the colonies in mound formation. Recent studies demonstrate...

Background: Akkerendam Nature Reserve is the second oldest proclaimed municipal nature reserve in the Northern Cape, yet to date no vegetation map has been produced. The possible expansion of the reserve is under consideration. Objectives: To produce a vegetation map, classification and description of the vegetation of the reserve and proposed exp...

This paper presents empirical evidence of historical vegetation and climate change in the arid Pro-Namib and hyper-arid Namib Desert spanning the late 19th century to the present based on one hundred archival landscape photographs that have been re-photographed or ‘matched’. Each photo site was evaluated for changes in woody cover and taken togethe...

We used several large data sets at a range of temporal and spatial scales to document the land-use/land-cover change (LULCC) dynamics of the semi-arid Succulent Karoo and Nama-Karoo biomes of South Africa. More than 95% of the Karoo is comprised of land classified as Natural, which has been relatively stable since 1990. Over the last 100 years cult...

We begin this essay with reflections on major research themes highlighted by the Karoo Special Issue (KSI). These include concerns over land-use change, long-term monitoring, climate change, governance and the need for more interdisciplinary research. We also identify some of the novel contributions of the KSI around these themes and highlight rese...

The Karoo is an arid to semi-arid area across the western third of South Africa, comprising the Succulent Karoo and Nama-Karoo biomes. Its environment and people have experienced considerable changes, and now face new challenges as the Anthropocene unfolds. This Karoo Special Issue (KSI) brings together new information in 20 papers, a mixture of re...

The southern harvester termite (Microhodotermes viator) is often associated with large, regularly spaced earthen mounds called heuweltjies in western South Africa. However, there is considerable debate regarding whether or not the termites play any role in either the creation of these mounds or the enrichment of mound soils with calcium carbonate (...

Most projections of climate change for southern Africa describe a hotter and drier future with catastrophic consequences for the environment and socio-ecological sustainability of the region. This study investigated whether evidence of the projections for the climate and vegetation of the subcontinent is already evident. Analysis of the climate rec...

This study used a fence-line contrast approach to investigate the long-term impact of high grazing pressure on the vegetation at a site in Namaqualand, South Africa. Forty pairs of permanently marked plots were surveyed in 1996, 2006 and 2016. The main objective was to investigate changes in the vegetation structure and species composition between...

The idea of alternate stable states (ASS) has been used to explain the juxtaposition of distinct vegetation types within the same climate regime. ASS may explain the co‐existence of relatively inflammable closed‐canopy Afrotemperate Forest patches (“Forest”) within fire‐prone open‐canopy Fynbos in the Cape Floristic Region (CFR) on sandstone‐derive...

Pastoral systems are regarded as complex social-ecological systems with components that interact and change over a range of spatial and temporal scales. As such, herd mobility has traditionally been used to respond to the dynamic nature of these systems. However, mobile pastoral systems around the world are becoming more constrained and increasingl...

The Elands Bay and Lamberts Bay areas have received dedicated attention over the last 40 years. Broad chronological patterns have been established and tested by numerous research projects in the last two decades. Nevertheless, this large corpus of data also reveals that despite much research effort, some periods are better understood than others. F...

Exploring the long-term influence of climate and land use on vegetation change allows for a more robust understanding of how vegetation is likely to respond in the future. To inform management, this study investigated the relationship between vegetation productivity trends and potential drivers of change in the 110 000 ha of the Tswalu Kalahari Res...

The deposition of fine aeolian sediment profoundly influences the morphology of several different landscapes of the arid and semi-arid western portion of South Africa. Such landscapes and features include: (1) regularly-spaced mounds known as heuweltjies of the succulent Karoo region, (2) barren stone pavements in the more arid regions, and (3) hil...

Ecological baselines are important in informing conservation management targets. Baselines can shift, however, depending on the timescale of observation. Using observations from the past few years or decades can give a misleading impression of the normal range of variability of an ecosystem, and the extent of recent human transformation. Palaeoecol...

The mega-diverse, Mediterranean-type fynbos biome may be vulnerable to future changes in climate and associated fire regimes, in particular to increasing summer-drought intensity and associated potential expansion of adjacent semi-arid vegetation types. Studying Holocene vegetation dynamics at the fynbos–succulent karoo boundary may provide insight...

Vegetation monitoring of arid and semi-arid environments using remotely sensed vegetation indices over long periods of time is essential to improve the understanding of the processes related to change. In this paper, 30 years of biweekly AVHRR NDVI3g (1982–2011) were used to examine the spatial and temporal patterns of vegetation productivity and p...

The horticultural industry is recognised as a major pathway for the introduction and spread of invasive alien plants (IAPs). The Conservation of Agricultural Resources Act (CARA) of 1983 (Act No. 43 of 1983) listed and categorised invasive species with an aim to curb their spread. The more recently enacted Alien and Invasive Species Regulations und...

Temperate forests are globally important carbon stores that are, in the face of recent improvements in their conservation, likely to increase their storage capacity in the future. Despite this, these ecosystems are poorly understood, especially over longer time periods. To remedy this and to better understand these important ecosystems, we monitore...

In this chapter we review and assess the potential impacts of fracking on Karoo ecosystems, based on related research from across the world, and interpreted in terms of the ecological characteristics and features of Karoo ecosystems. We highlight the dominant vegetation types, habitats and species which are characteristic or of conservation signifi...

This is a condensed version of an article that was published online in Biodiversity and Conservation in October 2016. It has been adapted from the abstract of the article, with a few added details, illustrated by an image from the published article and a photo supplied by Karin Van der Walt. Comparative images from the original article: A–C: Enceph...

Background: Conifer populations appear disproportionately threatened by global change. Most examples are, however, drawn from the northern hemisphere and long-term rates of population decline are not well documented as historical data are often lacking. We use a large and long-term (1931–2013) repeat photography dataset together with environmental...

In 1945, the Royal Society of South Africa published a wide-ranging report, prepared by a committee led by Dr C.L. Wicht, dealing with the preservation of the globally unique and highly diverse vegetation of the south-western Cape. The publication of the Wicht Committee’s report signalled the initiation of a research programme aimed at understandin...

Although South African cycads are known to be declining in the wild, there is at present no broad-scale, quantitative analysis to support this view. In this study the fate of 626 individual cycads was assessed from 107 repeat photographs taken at 53 locations over three time-steps (broadly 1940s, mid-1990s and 2014). Of the cycads photographed in t...

Aim Previous research suggests that equatorward populations of the iconic arborescent succulent Aloe dichotoma Masson are contracting in response to recent anthropogenic climate change (ACC) in southern Africa. However, previous studies did not account for small‐scale spatial heterogeneity, latitudinal climatic disjunctions or when mortality occurr...

Namaqualand is especially vulnerable to future climate change impacts. Using a high-resolution (0.5°x0.5°) gridded data set (CRU TS 3.1) and individual weather station data, we demonstrated that temperatures as well as frequency of hot extremes have increased across this region. Specifically, minimum temperatures have increased by 1.4 °C and maximu...

Globally, mediterranean-climate ecosystem vegetation has converged on an evergreen, sclerophyllous and shrubby growth form. The particular aspects of mediterranean-climate regions that contribute to this convergence include summer droughts and relatively nutrient-poor soils. We hypothesised that winter-precipitation implies stressful summer drought...

The intra-annual variability of NDVI (variability = (max-min)/min) for each vegetation type (Fynbos separated into strandveld, renosterveld and fynbos). Different letters indicate significant (P < 0.05) differences between vegetation types as determined by one-way ANOVA followed by post-hoc Tukey tests. (TIF)

Variation of total exchangeable bases (TEB) with water availability (P-PET) for all the individual sites sampled. The solid, dashed and dotted lines represent the 95%, 50% and 5% quadratic quantiles, respectively, estimated using the ‘quantreg’ package [60] in R [57]. (TIF)

The average ± SE for each South African vegetation type of the months during which temperature (T), precipitation (P), normalized difference vegetation index (NDVI) and precipitation—potential evapotranspiration (P–PET) were maximum. Vegetation types are as defined by Mucina and Rutherford [8], but with the Fynbos separated into strandveld, renoste...

Map of the variation in annual averages of monthly water availability (precipitation—potential evapotranspiration, P-PET, mm) for South Africa. National and provincial borders are indicated. (TIF)

In Paulshoek, Namaqualand, three research projects focusing on medicinal plants were developed concurrently. The projects were based in the disciplines of anthropology, botany and chemistry. In this paper, we explore how these projects related to one another and describe the conversations that occurred in the process of searching for transdisciplin...

We synthesize recent literature concerned with the nature, extent and rate of vegetation change in the Albany thicket, Grassland and Nama-karoo biomes of the semi-arid, south-eastern interior of South Africa at a range of spatial and temporal scales in relation to local and global drivers. The change in cover of three main growth forms (grasses, dw...

Long-term changes in the distribution of Western Cape Afrotemperate Forest and Western Cape Milkwood Forest in Table Mountain National Park (TMNP) were examined using paired aerial and repeat ground-based photographs. All forest patches mapped on the aerial photographs taken in 1944 and 2008 were visited and boundaries between forest and adjacent v...

QuestionsHow has the vegetation of the major biomes (Grassland, Nama-karoo, Albany Thicket, Azonal) of southeastern South Africa changed over the course of the 20th century? How do changes in climate and land-use drivers relate to long-term changes in vegetation? What are the implications of these findings for land degradation hypotheses and future...

South Africa covers less than 1% of the world’s land surface area and is home to nearly 10% of the world’s plant species, about 7% of the world’s vertebrates and 5.5% of all known insect diversity, making it a biodiversity treasure trove. South Africa’s biodiversity is a spellbinding natural draw card for a lucrative nature-based tourism industry....

The action of organisms in shaping landforms is increasingly recognized; the field of biogeomorphology and the conceptual framework of ecosystem engineering have arisen in response to the need for integrated studies of the interactions between biotic and abiotic components of landscapes. Pathways by which organisms influence landscape development m...

Bush encroachment has been recognised in southern Africa since the late nineteenth century. Our review of 23 studies showed that the rate of woody cover change has ranged from −0.131 to 1.275% y−1. Encroachment was most rapid on small protected areas, intermediate under commercial tenure, and slowest under communal tenure and large, natural environ...

Woody plant encroachment is frequent in dry savannas. Grazing is often considered to be a major cause of encroachment in dry savannas because grasses are removed by livestock, leaving bare areas for trees to colonise in wetter years. Earlier experiments conducted in the Kimberley area of the Northern Cape showed that neither fire nor grazing was im...

Using an analysis of aerial photographs from 1942, 1985 and 2004 we assessed the impact of changing land tenure and land-use regimes on the cover of thicket vegetation on the Grahamstown commonage. Land-use impacts were examined by comparing plant species composition within three vegetation types between sites incorporated into commonage for differ...

We examined the effect of changes in land use and land tenure on bush encroachment and vegetation condition. An analysis of aerial photographs from three time steps (1949, 1985 and 2004) was used to document changes in woody plant density in different vegetation types on commonage and an adjacent commercial farm in Fort Beaufort, South Africa. Rang...

An online decision support system derived from research and expert knowledge was developed for arid rangeland management in central Namibia. The expert system emphasises the control of bush thickening and is divided into three forms of decisions: adaptive, reactive and ongoing good management. Adaptive decisions are mostly related to periods of pro...

Land use and land cover have changed significantly in South Africa since the 1913 Natives Land Act, in response to a wide range of political, social, cultural and environmental influences. This review examines the response of the vegetation of three biomes to these changing patterns. Vegetation change over the last 100 years is described along an a...

Repeat photography was used to illustrate long-term changes occurring in coastal habitats in the Western Cape, South Africa. Historic images were sourced from books and theses, the public and subject specialists, and repeat photographs were then taken from the same perspectives. Visible changes could be categorised into four types: (1) changes in s...

In many parts of the world the boundaries between grassland and shrubland biomes have changed substantially over the course of the last century. Many are projected to shift further from being grass-dominated to shrub-dominated by 2050 under global climate change and land use change projections. This paper used long-term surveys and repeat photograp...

A more complete picture of the timing and patterns of the ENSO signal during the seasonal cycle for the whole of Africa over the three last decades is provided using the normalized difference vegetation index (NDVI). Indeed, NDVI has a higher spatial resolution and is more frequently updated than in situ climate databases, and highlights the impact...

Windthrow, the uprooting of trees during storms associated with strong winds, is a well-established cause of mortality in temperate regions of the world, often with large ecological consequences. However, this phenomenon has received little attention within arid regions and is not well documented in southern Africa. Slow rates of post-disturbance r...

QuestionsWhat are the effects of root competition from mature plants and soil type on the survival and growth of dominant grass and succulent shrub seedlings at an ecotonal site between arid grassland and succulent shrubland? Do these factors explain the occurrence of separate grass-dominated and shrub-dominated communities along the ecotone? Locat...

Archaeological research along the West Coast of South Africa has unveiled a diversity of Holocene adaptive strategies as shown by the different type, size, composition, and distribution of sites and their faunal and artifactual contents. Some differences and similarities are apparent between the northerly semi-desert of Namaqualand and the more cen...

Fixed-point photo monitoring supplemented by animal census data and climate monitoring potential has never been explored as a long-term monitoring tool for studying vegetation change in the arid and semi-arid national parks of South Africa. The long-term (1988–2010), fixed-point monitoring dataset developed for the Camdeboo National Park, therefore...

Seed production and seedling survival are under-researched in savannas. We investigated these in a population of a major thickening species, Acacia mellifera, in an arid Namibian savanna over a nine year period (late 1998–early 2007) We asked the following questions: (i) How does viable seed production vary with rainfall and tree size, (ii) when do...

Pastoralists in Namaqualand, South Africa, use herd mobility to manage livestock and rangeland resources. However, their socioeconomic conditions and ecological landscapes are changing and we explore the options that are available for pastoralists to respond to these changes. This paper presents five possible scenarios for managing livestock in ran...

Impacts on the environment as a result of drought, land cover change, and invasive alien species have been extreme in some cases, with a concomitant reduction in ecosystem services and a decrease in several quality of life indicators for the most vulnerable people in the region. The effect of these different impacts on the provision of ecosystem se...