Trees are the matrix upon which forest communities are built, with their characteristics and distribution shaping the environment for the organisms which live on and around them. My research tackles this from an explicitly spatial perspective, identifying patterns formed by trees within forests and the processes that underpin them. Research is being conducted in a range of locations, from boreal to tropical. For up-to-date news and details of other members of the group see ecology.nottingham.ac.uk.
Spatial organisation of boreal forests
Local-scale patterns of trees in forests can be caused by many different processes, including dispersal, resource competition, environmental heterogeneity and inter-specific interactions. Since 1998 I have been working in Kamchatka, Far East Russia, establishing permanent plots in which all individual trees have been mapped. These are providing information on the structure and dynamics of forests in the region.
Stone birch (Betula ermanii Cham.) dominates the forests of Kamchatka over large areas.
More specifically, I am interested in whether the spatial patterns formed by particular species of trees, and the ways in which individual trees interact in space, determine whether or not certain species are able to co-exist. Kamchatka forms an ideal study site for such tests, as its forests have remained intact over very large areas, and a range of forest types exist which are composed of a relatively small number of species.
Mapping stems in a stone birch forest in Central Kamchatka. Photo: Tim Kell.
In the centre of the peninsula the forests are mainly composed of white birch (Betula platyphylla Sukacz.) and larch (Larix cajanderi Mayr), which can either form single-species or fully-mixed stands. By comparing the spatial patterns formed by each species when growing alone or in combination, the manner in which the different species integrate in space can be revealed.
A study plot in Central Kamchatka dominated by larch (Larix cajanderi Mayr)
In addition, data has been collected on seedling regeneration, understorey communities and soil properties, all of which are being brought together in an effort to understand how the entire structure of the forest is assembled.
Related work investigates patterns within ancient woodlands in Nottinghamshire and the spatial organisation of populations of an endemic shrub in the central caldera of Tenerife on different lava flows (Lauren Gough, PhD student).
Regeneration of tropical forests
One of the great mysteries of ecology is how so many species are maintained in tropical rain forests. More tree species can be found in a single hectare of rain forest in Borneo than in the whole of Europe or North America. How can so many species co-exist? The answer is not simple, and is likely to be found in the complex interactions between tree species and their environment.
In tropical rain forests, the seedling stage is thought to be the most crucial phase in the life cycle of trees. This is because a large number of species compete to fill gaps in the canopy, of which usually only one survives to become a reproductive adult tree. Which seedling succeeds in this intensely competitive system depends on a wide variety of factors.
What determines which of these seedlings will fill the gap in the canopy above? Photo: Jake Snaddon.
In Sabah, Malaysian Borneo, a large-scale experiment has been running since 2000 with the intention of revealing differences among tree species in the survival and growth of their seedlings across a range of environmental conditions. Initially 3000 seedlings of five tree species were planted in gap and shade conditions, across both alluvial and sandstone soil types, and they have been monitored regularly ever since. It is clear that each species has a range of tolerances that determine its likelihood of success in any given conditions.
The manner in which variations in local-scale interactions among species change along environmental gradients can be responsible for transitions in vegetation. Using datasets collected by collaborators in Alaska and Russia I am investigating the link between inter-specific interactions and changes in the composition and structure of plant communities.
Viewed from above, continuous gradients are evident in the composition of these boreal forests in Kamchatka.
The effects of gradients in both nitrogen deposition and climate on the composition of British heathlands are being studied by PhD student Ed Tripp as part of the OPAL project: http://www.opalexplorenature.org/?q=HeathlandResearch
- Ecology of malaria and dengue vectors in Thailand
As part of the RISKMODEL project (Predicting the RISKs of MOsquito-borne DisEases from Land use change), my research investigated the influence of local land-use, detected using remote-sensing techniques, on the abundance and community composition of mosquito vectors in Thailand. Of particular interest were the effects of forests, which are diminishing in extent and becoming increasingly fragmented within the region, and orchards, which are replacing subsistence agriculture as the dominant land-use in many villages.
Systems of farming with trees have existed in Europe for thousands of years, and an emerging interest in sustainable farming has recognised the benefits of agroforestry in erosion protection, drainage control and diversification of rural incomes, as well as more unexpected features such as improved nutrient use efficiency and a reduced reliance on pesticides. Novel systems are being developed in addition to the rediscovery of traditional methods. My main interest is in how ancient farming systems might inform future agricultural sustainability. For more information, see the SAFE (Silvoarable Agroforesty For Europe) website at http://www.montpellier.inra.fr/safe/.
- Herbivory of tropical rain forest tree seedlings
As part of the BITRF project (Biological Interactions in Tropical Rain Forests), I investigated interactions between tree seedlings and their insect herbivores. This included the effects that herbivores have upon the seedlings, in terms of their rates of damage, growth and survival, but also how characteristics of the seedlings such as their defence (chemical and physical) and nutritional value influence the communities of insect herbivores feeding on them. Markus' research was recently featured in the newsletter of GARNet (the BBSRC sponsored UK Plant Science Network), together with other plant science research at the University of Nottingham.
I am interested in all aspects of the spatial organisation of natural systems, and would welcome suggestions for research collaborations or applications from graduate students wishing to work in this field.