The Anthropocene

Conrad Rider

Agent based modelling of landscape responses to farm management practices & global change

With over 6 billion people on this planet, there are few places which have not been influenced by the activities of man. Current global land cover is largely a result of human land use choices. Unfortunately, they do not always favour the environment or interests of the wider population. Poor land use decisions can have a detrimental effect on climate, biodiversity, economic status and general health. It is important that we understand how land use patterns come about and what policies, laws or education could help us make better choices for our land resources. Multiagent systems allow us to model land use, giving intuitive, individual-based representation to human decision making. Using these models we can explore the socioeconomic drivers involved in shaping land use patterns. Although the human cognition process is a key component, is often over simplified or mis-represented. More research into the human decision making process is needed, borrowing ideas from research in AI and Psychology. It is hoped that this will help us to better understand and predict land use trends.

Conrad's presentation

Fabrice Gouriveau

Remediation of agricultural diffuse water pollution by farm ponds and wetlands

Agriculture is one of the main sources of diffuse water pollution worldwide. It can cause elevated concentrations of nitrogen, phosphorus, sediments, pesticides and faecal bacteria that result in public health concerns, degradation of aquatic ecosystems, and incur considerable costs. Therefore, European agri-environmental policy and legislation, e.g. Water Framework Directive and Single Farm Payment Scheme, aim to reduce diffuse pollution from agriculture.

Although farm ponds and wetlands are recommended for remediation of steading runoff (i.e. runoff from farm yards, milking parlours, access roads and roofs), there is still limited experience and systematic study of such systems in Scotland. The extent to which they improve water quality, their optimal design, carrying capacity and long-term efficiency are not well known, nor is their contribution to farm habitat and economy.

The main aims of this project are 1) to evaluate the water treatment performance of a sample of farm ponds and wetlands, 2) to study their impact on habitat and biodiversity, and 3) to assess their cost-effectiveness.

Research will focus on ponds promoted and partially financed by SEPA (Scottish Environment Protection Agency), constructed at two contrasting farms in the Scottish Borders (Old Castles and Kennetsideheads) and selected according to their characteristics and to the nature and quantity of pollutants they receive.

The pollutant removal and water balance of the ponds will be assessed over two years by monitoring flow and water chemistry at the inlet and outlet of the systems using automatic water samplers and flow meters. Water sampling will be flow proportional and triggered by storm events, allowing collection of water samples when maximum pollution is anticipated to occur. Pond hydraulic residence time under different flow conditions will be evaluated using tracers, sediment depth will be measured along transects, and the fate of pollutants will be investigated through sediment analysis. The size of the outlets will be modified to alter water residence times in the ponds and sediments will be removed from the systems, allowing the effects of these management practices on water treatment to be explored. A treatment model for the main pollutants (suspended solids, phosphorus, NH4+, organic carbon and faecal bacteria) will be developed to explore the scientific basis of differential treatment effects. Additionally, pond habitat value will be assessed from vegetation and macroinvertebrate surveys based on the methodology developed by Pond Action, the results of which will be modelled using PSYM (Predictive SYstem for Multimetrics). Questionnaires given to farmers will allow technical and economic data on farm practices, pond construction and maintenance to be collected, and will help to assess farmers’ acceptance of treatment ponds. Finally, a cost-benefit analysis of the ponds will be undertaken including other treatment ponds in Scotland.

The study will provide new recommendations for farm pond/wetland design, maintenance and monitoring, complementing the recommendations existing for Sustainable Urban Drainage Systems. It will ensure provision of better information to farmers and environmental regulators and will help in optimizing and anticipating water treatment efficiency, biodiversity conservation value and cost-effectiveness of ponds and wetlands under local conditions and variable constraints.

Fabrice's presentation

Sophie Bertin

Physiological ecology of understorey trees in alternative management systems

Alternative management systems to clearfelling are being adopted in Great Britain as a means of increasing species and structural diversity of plantation forests. These regimes are often termed Continuous Cover Forestry (CCF). CCF is characterised by favouring natural regeneration processes for seedling recruitment.

One area of limited knowledge is the critical levels of below-canopy light required for survival and growth of young trees. Seedlings of Sitka spruce (Picea sitchensis (Bong) Carr.), the most important commercial tree species in Great Britain, are not expected to survive for long periods under the low light conditions of a closed canopy plantation. Tolerance of shade can also be influenced by other factors.

The green spruce aphid (Elatobium abietinum) is the main defoliator of Sitka spruce in Great Britain. Infestations by green spruce aphid result in substantial reduction in Sitka spruce seedlings biomass.

Understorey trees have been observed to be more susceptible to insect attack than overstorey trees and, as a result, to suffer higher rates of mortality than trees planted in open areas restructured after traditional clearfelling. The combined effects of light availability and aphid attack on Sitka spruce seedlings growth and survival are not well understood, but this understanding is crucial in order to ensure successful management of regeneration within CCF systems.

The project aims to assess the influence of green spruce aphids on Sitka spruce seedling responses to variation in the light environment by looking at the effect on growth architecture and physiology under controlled and natural conditions.

We predict that a combination of low light conditions and aphid infestation will result in poorer Sitka spruce seedling growth than would be found if the plant was only affected by either low light level or aphid infestation.

During 2006, exploratory experiments mimicking different light levels, such as are found below CCF canopy, and aphid infestation will be conducted using pot-plant experiment and field based experimentation. In 2007 and 2008, detailed experiments on the physiological and morphological response of seedlings to light availability and insect attack will be studied in established CCF trials and in a common garden experiment.

Sophie's presentation

Laura Packham

Modelling of N₂O emissions from Irish agriculture

Nitrous oxide (N₂O) is a major greenhouse gas (GHG) with a global warming potential of 310, that is, with a radiative forcing capacity 310 times that of CO₂. N₂O is also of interest as it indirectly destroys stratospheric ozone through the formation of nitric oxide. A major anthropogenic source of N₂O is from agriculture, especially pasture. In Ireland this is a particularly big source as 90% of land use is grassland soils. Of Ireland’s total GHG emissions from agriculture, N2O accounts for 38%. Agriculture emits 30% of the total GHG emissions for Ireland. In Scotland agriculture emits only 11%. As a result of these large emissions and others, Ireland is not meeting its Kyoto Protocol targets of a 13% maximum increase above 1990 levels by 2010. Emissions in 2003 were 25% above 1990 levels.

N₂O emissions models are necessary for helping to create a GHG inventory for the use in understanding the scale of mitigation required and for studying the impact of climate change on future N₂O emissions.

Agriculture is a major source of N2O due to the enhancement of the natural soil process of denitrification by the use of fertilisers. Denitrification occurs when soil bacteria brake down nitrate to nitrite to N₂O in anaerobic conditions in order to obtain energy. The major limiting factors of denitrification in Irish soils are water filled pore space, soil temperature and soil mineral nitrogen availability. There are limiting thresholds below which emissions remain low even when other parameters are high.

My work is based on data collected by B. Hyde for his PhD on N₂O emissions from grazed grassland. The data is being used to adapt a computer model that was designed to predict N2O emissions from Scottish agricultural land due to fertiliser use. The basic relationship of WFPS and soil temperature on N2O emissions has been studied using a boundary line model as in Conen et al. (2000). Boundary lines are fitted to grouped emissions data to show the upper limits of WFPS and soil temperature for a certain N2O emissions range. This N2O emissions model is a sub-model in the Simile model known as the Simile B-Line2 model, created for the Scottish report by J. Massheder and K. Smith. Other sub-models include soil characteristics, meteorology, and applied mineral nitrogen.

Thus far I have modified the boundary line model using Irish data and I have inserted it into the Simile B-Line2 model. Now I have to collect soil characteristic data, applied mineral nitrogen data and met data for each area in Ireland that is to be modelled so that I can run the model to predict N₂O emissions.

Laura's presentation