Michael Lawes - Research interests

Indian Ocean coastal dune forest at Cape Vidal, Eastern Shores, KwaZulu-Natal, South Africa. Photo: M.J. Lawes

Forest and Savanna Ecology and Conservation

I have a broad research portfolio with a focus on field-based interdisciplinary and applied research. In terms of forest ecology, my work explores patterns of forest disturbance and the regeneration potential of key plant species. For example, the influence of the monocarpic herb, Isoglossa woodii, on the regeneration dynamics of coastal dune forest trees in South Africa and the influence of canopy and sub-canopy gaps on seedling recruitment and diversity. I am particularly interested in theories of species coexistence in biodiverse systems such as rainforests, and have researched the roles of recruitment and dispersal limitation on patterns of tree species establishment in forests in Uganda, Australia and South Africa. Recently, I have compared the efficacy of the light-shade gap dynamics paradigm with neutral models that claim functional equivalence at the establishment or seedling stage. Neutral models argue that functional equivalence of species at establishment ensures that chance establishment maintains species diversity in rainforest trees. In contrast gap dynamics models are based on deterministic establishment of species in gaps, depending on the size of the gap and the species light requirements. International collaborative research projects have been established in Uganda with Prof. Colin Chapman (McGill University, Montreal, Canada) and Dr Patrick Omega (Makerere University, Kampala, Uganda), and in South Africa with Dr. Johan Kotze (Helsinki University, Finland), Dr Hylton Adie (University of KwaZulu-Natal, Pietermaritzburg, Soutth Africa) and Prof. Jeremy Midgley (University of Cape Town, Cape Town, South Africa).

Savanna Ecology - Resprouting

Another research interest is resprouting behaviour of savanna and forest trees. To avoid the risky seedling stage in environments prone to disturbances (such as cyclones, unstable substrate, fire, poor soil nutrients, and high levels of herbivory) many tree species reproduce vegetatively by resprouting. Resprouting individuals increase their likelihood of persisting in a habitat and occupy the persistence as opposed to the regeneration niche. Much of my research has focussed on the ecology of sprouting and how trees allocate resources (between roots and shoots) in response to disturbances. This has entailed field and greenhouse experiments and measurement of photosynthesis and growth of tree seedlings, as well as the estimation of the concentration of total non-structural carbohydrates from different plant parts. Much of this research was conducted with the late Prof. Peter Clarke at University of New England, Armidale, Australia.

Post-fire epicormic resprouting. Photo: M.J. Lawes

Typical surface fire in Litchfield National Park, NT, Australia. Photo: M.J. Lawes

Bark Thickness and Fire Regimes

I have a particular interest in the role of bark thickness as a key plant functional trait in tropical savannas that provides resistance to fire. Analysis of congeneric and conspecific bark thickness response in habitats with different fire regimes shows that bark thickness is a plastic trait driven by environmental conditions. Whether environmental productivity or fire regimes drive bark thickness is an important question. The relationship between plant resprouting capacity and bark thickness trends is also under investigation. It appears that eucalypts are uniquely adapted to fire through special bud anatomy. Their buds are arranged on meristematic strands at the level of the cambium, beneath the bark, where they receive maximum protection from fire. Eucalypts thus need less bark to protect their vascular cambium and their buds and can resprout epicormically after fire. Non-eucalypts, on the other hand, can protect their cambium with thick bark but because their buds are on the bark surface or just below it, they seldom resprout epicormically and are mostly basal resprouters if at all. This interplay between bud anatomy, how buds are protected and the availability of resources to support resprouting and/or thick bark, has led to a dichotomy in growth form among tropical savanna tree species, between tall and thin eucalypts (lanky) and shorter and wider (corky) non-eucalypts. Thus, fire is an ecological filter of tropical savanna tree species that acts upon the differential resilience and resistance of species to fire. This argument has been extended to the whole of community scale and the fire futures of the Australian continent.

Black-footed tree rat - Atherton Tableland, QLD. Photo: M.J. Lawes

Small Mammal Declines

Australia has experienced dramatic declines and extinctions of its native small mammal species over the last 200 years, particularly in southern Australia. In the tropical savanna of northern Australia significant declines have occurred only in recent decades. The later onset of these declines suggests that the causes may differ from earlier declines in the south. Together with colleagues at other Australian universities, I have examined the potential regional effects (northern versus southern Australia) on the biological and ecological correlates of range decline in Australian mammals. We have demonstrated that small mammal declines have been greater in the south than in the tropical north, are strongly influenced by phylogeny, and are consistently greater for species inhabiting relatively open or sparsely vegetated habitat. In addition, we have shown that the critical weight range of declining mammals is consistent with the prey size favoured by feral cats and foxes. Some of my research investigates the role of fire in affecting predation by feral cats on small mammals.

Avian Behavioural Ecology

I maintain a strong interest in field-based studies of avian behavioural ecology, working mainly on Euplectes (bishop birds and widows) and on brood parasitism involving the bronze cuckoo group. Ongoing research focuses on: (1) mating systems of the Euplectes (bishops and widowbirds); and (2) brood parasitism and the coevolution of the Diederik cuckoo-bishop/weaver system. In the Northern Territory I research interests in finch ecology and the behavioural ecology of great bowerbirds.

Juvenile Samango monkey (Cercopithecus mitis erythrarchus). Photo: M.J. Lawes — Juvenile Samango monkey (*Cercopithecus mitis erythrarchus*). Photo: M.J. Lawes

Primatology

Stemming from my early career and PhD on the socio-ecology and conservation of the samango monkey (Cercopithecus mitis), a red-list threatened primate species that inhabits South Africa’s sub-tropical forest, I maintain an interest in primatology. The mitis supergroup extends from southern Africe to Somalia in coastal lowland and montane forests. I have examined foraging theory and community ecology, especially the costs of group living, female relationships and male mating strategies. Much of my research concentrated on understanding the biology of the samango monkey with a view to its successful long-term conservation, and also more practical wildlife management issues such as the conservation of its forest habitat. More recently, I have become interested in broader patterns of primate evolutionary history, macroecology and biogeography, as well as the effects of forest fragmentation on the persistence of primate species in an anthropogenically altered landscape and the implications this has for their conservation. I have a collaborative long-term project with Prof. Colin Chapman, examining primate population dynamics in old-growth, logged and fragmented forests of Kibale National Park, Uganda. International collaborative research projects have been established with Dr Caroline Ross (Roehampton Institute, London), Dr Guy Cowlishaw (Institute of Zoology, London), Prof. Colin Chapman (McGill University, Canada), Prof. Hazel Chapman (University of Canterbury, NZ) and Prof. Peter Henzi (University of Lethbridge, Canada).