Martin Kent

Fieldwork in geography teaching: A critical review of the literature and approaches

Abstract Virtually all lecturers in geography recognise the importance of fieldwork as a vital mode of teaching in the subject. This paper draws on material produced as part of a HEFCE review of teaching and learning in the field and assesses the implications of recent changes in higher education for field studies in geography. The literature on the development of, and recent changes in, fieldwork practice is reviewed and assumptions about appropriate forms of teaching and assessment are challenged. The need for carefully integrated preparation of project‐orientated fieldwork is stressed and the importance of debriefing and feedback after field visits is emphasised. Various suggestions for guidelines on good practice are presented. Finally, a range of future issues and problems in fieldwork is identified and discussed.

Seed banks as a neglected area of biogeographic research: a review of literature and sampling techniques

The article highlights a comparatively neglected area of biogeographical research - seed banks and the distribution of seeds in the soil. The article reviews some of the relevant literature on seed banks and the methods for their study. Attention is focused on aspects of seed banks of particular relevance to biogeographers, with detailed examples drawn from seed bank studies in both temperate and tropical environments. In the review of the seed bank literature, the topics covered include the seed banks of successional communities and the size of seed banks in different vegetation types. The species composition of seed banks in different plant communities is discussed, particularly the degree of correlation between the species composition of seed banks and associated ground flora. The relationships between seed persistence, depth of burial in the soil and soil properties, such as moisture and pH, are explored. Seed bank heterogeneity is examined and a number of studies which have attempted to describe and measure the spatial variability of seed banks are summarized. Ways of classifying seed banks in terms of seed bank strategies are explained. The role of seed banks in conservation is discussed, for example in restoration projects, where preferred species have been lost from the vegetation but survive in the seed bank. The relevance of seed banks for the conservation of rare species and in landscape management is considered. Lastly, the contribution of seed banks to the recovery of vegetation following disturbance in various plant communities is discussed. In the review of seed bank sampling techniques, the subjects considered include methods of sample collection, the sampling intensity required for reliable estimates of seed density, a consideration of the relative merits of random and systematic sample distribution, as well as the importance of the timing of sampling. Various methods for the estimation of seed numbers in samples are appraised; these either involve extraction of seeds from the soil, followed by seed identification or enumeration by germination and seedling identification. Problems of analysing seed bank data are considered and several useful techniques for data analysis are suggested. Finally, the article draws attention to areas of future seed bank research for biogeographers and plant ecologists.

Palaeohydrological records derived from testate amoebae analysis from peatlands in northern England: within-site variability, between-site comparability and palaeoclimatic implications:

Testate amoebae analysis was undertaken on eight cores from three mires within a restricted geographical area of northern England. This was used to assess, first, the amount of autogenically produced variability in palaeohydrological records from ombrotrophic mires, and, second, to determine whether a palaeoclimatic signal can be derived from testate amoebae analysis from peatlands. Past mean annual water tables were reconstructed by calibrating the testate amoebae record with an existing transfer function. There is a good degree of replicability between the water table reconstructions for the upper peats within each site (especially since cal. AD 600) and the magnitude and timing of most changes are similar. The results show that autogenic factors have a relatively minor control on palaeohydrological records from ombrotrophic peatlands, even for marginal locations where these effects should be greatest. Records from the centres of peatlands are compared to assess the replicability of hydrological changes between the sites to determine which of these changes are attributable to climate. The major fluctuations are well replicated in all central cores, especially for the last 2000 years, suggesting that these shifts are climatically forced and that there is an increasing climatic influence through time, even at the valley mire site. Comparisons with other proxy climatic records suggest that mire surface wetness changes occurred in concert across a broad region of northern England and southern Scotland during at least the last 2000 years.

Tourism and sustainable water supply in Mallorca: a geographical analysis

Abstract Problems of sustainability of water supply in tourist resorts are becoming an increasingly common and important issue in applied geography and environmental management. This paper examines the relationships between tourism and water supply on the Mediterranean island of Mallorca, discussing both the scale of the problem and recent measures to find a solution, particularly the proposed Hydrological Plan for the Balearic Islands (published in 1998/9). Since Mallorca lies in an area likely to be seriously affected by future climate change, its potential effects are discussed and evaluated. One of the most critical problems relates to the coarse spatial resolution of general circulation models for predicting precipitation in an area where precipitation regimes grade steeply from semi-arid to humid temperate. However, it is likely that a continuation of the marked inter-annual and decadal-scale variability in precipitation seen during the recent past probably poses a greater threat to Mallorca’s water supply than the more gradual, progressive change typically predicted to accompany future global warming. Similarly, continued over-exploitation of coastal aquifers will be more critical to water quality issues than the direct impacts of any future sea level rise, although the latter would undoubtedly exacerbate these effects. The conclusion discusses the controversial new ecotasa (‘ecotax’), due to be imposed on Mallorca’s tourist industry in 2002, which is likely to represent only a partial solution to the long-term water supply problem. As the physical, cultural and economic environments of Mallorca are typical of much of the Mediterranean region, the implications of this issue extend well beyond the island’s shores.

Plant functional types: an alternative to taxonomic plant community description in biogeography?

This article critically reviews the concept of plant functional types as an alternative to the traditional taxonomic species-based approach to plant community description in biogeography and ecology. Originally formulated in the last century, there has been an acceleration in interest in the concept over the last decade. Plant functional types are nonphylogenetic groupings of species that show close similarities in their response to environmental and biotic controls. Functional classifications often cut across taxonomic classifications and may be more meaningful in terms of plant response, in addition to overcoming certain problems associated with the traditional taxonomic species-based approach. Plant functional types are derived from traits based on species morphology, physiology and/or life history, depending on the aims and scale of the research. Whilst some traits can be measured in the field, others require more detailed laboratory measurement and experimentation. A trade-off exists between the time and efficiency gained from using simple traits and those requiring more elaborate analysis, although certain ‘key traits’ may act as easily measured surrogates for others. Practical applications of plant functional types in biogeography and ecology are also reviewed. Plant functional types can aid in the understanding of ecological processes, such as the assembly and stability of communities and succession, and facilitate the detection and prediction of response to environmental change at a range of scales. Despite its potential, the plant functional type approach is probably best viewed as a complementary approach to description using traditional taxonomy.

Seed bank composition and variability in five woodlands in south-west England

This paper examines the species composition and variability of the seed banks associated with four lowland woodlands and one upland woodland in south-west England. The sites studied are conifer plantations and neglected and coniferized coppice. The sampling covers a range of stand types, stand ages and management systems, on both acidic and

Studies of vegetation burial: a focus for biogeography and biogeomorphology?

This paper examines the literature on research into the effects of burial by deposition of blown sand, volcanic deposits (tephra, lavas and lahars) or fluvial sediment on vegetation and the subsequent capacity of the vegetation for survival and regeneration. Research on this topic involves the understanding and skills of the biogeographer, the ecologist and the geomorpholo-gist and represents a potentially very interesting area for integration between these areas of physical geography. Burial is closely linked to concepts of plant succession and pedogenesis. A general model of burial stress is presented that shows how types of stress are linked to the burial environment and the characteristics of the burial event, in particular the magnitude and frequency. The importance of elasticity of response of species to burial is vital, as demonstrated by the evolution of certain species, such as those of the genus Ammophila in sand dunes that appear to respond positively to the burial process. Research into burial by dust deposition, by volcanic tephra and lavas, by sand in coastal and lake dune environments, in desert environments and by alluvium and ‘run-on’ following hydro-logical events are reviewed in turn. The significance of burial to palaeoenvironmental and palaeoecological research is then demonstrated by reference to machair sand dune stratification in the Outer Hebrides and vegetation damage and burial following proximal volcanic impacts in New Zealand. Finally, methods of experimental research into burial in both the field and in the greenhouse are summarized and the conclusion stresses the need for more holistic approaches to the study of burial that link the biogeographical aspects of plant ecophysiology and both individual species and community ecology to the various geomorphic processes of deposition and sedimentation.

Geostatistics, spatial rate of change analysis and boundary detection in plant ecology and biogeography

Over the past decade, biologists and ecologists rather than geographers have been primarily responsible for developments in spatial analysis and geostatistics that are of great potential importance to both biogeography and community/landscape ecology. These advances in geostatistics, rate of change analysis and boundary detection and their application to floristic and environmental data at the community scale are reviewed. Issues of scale, spatial autocorrelation and terminology are introduced. Approaches to the description of spatial pattern in plant assemblages and environmental data, the quantification and removal of spatial autocorrelation, the spatial interpolation of data, techniques for the description and analysis of spatial rate of change and finally boundary detection are all reviewed in turn. Despite the development of new methods, the extent to which they have been applied more widely within both plant ecology and biogeography is limited. The paper concludes that perhaps the time is right for biogeographers to reassess the potential significance of these areas for the subject.

Possible interactions between environmental factors in determining species optima

Abstract Questions: 1. Indicator values, such as those of Ellenberg, for different environmental factors are seen as independent. We tested for the presence of interactions between environmental factors (soil moisture and reaction) to see if this assumption is simplistic. 2. How close are Ellenberg indicator values (IVs) related to the observed optima of species response curves in an area peripheral to those where they have been previously employed and 3. Can the inclusion of bryophytes add to the utility of IVs? Location: South Uist, Outer Hebrides, Scotland, UK. Methods: Two grids (ca. 2000 m × 2000 m) were sampled at 50-m intervals across the transition from machair to upland communities covering an orthogonal gradient of both soil pH (reaction) and soil moisture content. Percentage cover data for vascular plants, bryophytes and lichens were recorded, along with pH and moisture content of the underlying sand/soil/peat. Reaction optima, derived from species response curves calculated using HOF models, were compared between wet and dry sites, and moisture optima between acidic and basic samples. Optima for the whole data set were compared to Ellenberg IVs to assess their performance in this area, with and without the inclusion of bryophytes. Results: A number of species showed substantially different pH optima at high and low soil moisture contents (18% of those tested) and different soil moisture optima at high and low pH (49%). For a number of species the IVs were poor predictors of their actual distribution across the sampled area. Bryophytes were poor at explaining local variation in the environmental factors and also their inclusion with vascular plants negatively affected the strength of relationships. Conclusions: A substantial number of species showed an interaction between soil moisture and reaction in determining their optima on the two respective gradients. It should be borne in mind that IVs such as Ellenbergs may not be independent of one another. Nomenclature: Stace (1997) for vascular plants; Watson (1981) for mosses and liverworts; Jahns (1983) and Gilbert (2000) for lichens.

Plant species and community responses to sand burial on the machair of the Outer Hebrides, Scotland

Abstract Question: Is there a critical depth of burial by sand beyond which species and communities fail to recover, and does repeated incremental burial have a greater impact than a single large deposition? Location: The machair on the calcareous sand dunes on South Uist, in the Outer Hebrides of Scotland, UK. Methods: Eight turves were collected from each of four machair sub-community types. After acclimatization in an unheated polythene tunnel, they were buried with sterilized machair shell sand, either by one single burial to 5 cm or by five applications of 1 cm of sand at approximately seven-week intervals. Species response was recorded on five occasions. Results: Within machair sub-communities, burial by sand reduced the abundance (local rooted frequency) of plants more than it reduced species richness. Intermittent burial was more damaging than a single burial event. Those species with the highest pre-burial frequencies tended to dominate recovery in the sub-community as a whole. Species occurring across all four sub-community types exhibited varying responses to community burial between the differing types. Samples from slack sub-communities had distinctly different response characteristics from those of foredunes and unploughed and three-year fallow dune grassland. Conclusions: The perennial life-form of many machair species has been evolutionarily selected for and dominates throughout the machair habitat. Account needs to be taken of competitive interaction between species in relation to burial response. The results of the investigation show that the hypotheses of Gilbertson et al. and Kent et al. on ‘machair stratification’ require refinement in that frequency of shallow burial can be as important as overall burial depth. Nomenclature: Stace (1997); Dobson (1992) for lichens; Watson (1981) for mosses and liverworts.