Geographica Helvetica Jg. 63 2008/Heft 1

Physical geographic research in transitional environmentsIntroduction to the special issue

Nikolaus J. Kuhn, Basel

Modern physical geographic research focuses ondynamic interaction between surface and climate,especially the impact of climate change on spatialand temporal patterns of surface processes and land-scape development (e.g. Goudie & Stokes 2007). Ona Continental scale, the effects of climatic gradients onsurface processes and landforms are well understood.However, the relatively small changes of rainfall and

temperatures predicted for the next 100 years pro-duce a highly variable ränge of geomorphic responsesin landscapes altered by human activities. Issues suchas the «Missing Land Carbon» (IntergovernmentalPanel on Climate Change, IPCC, 2007) illustrate theresearch needs on small to medium-scale landscapeSystems and their reaction to environmental change.Our understanding of the impact environmentalchange will have on surface processes and landscapedevelopment is limited in two ways. Firstly, climateand land use are in a quasi-permanent State of tran-sition, which affects both the nature and the spatialand temporal patterns of surface processes. Sec-

ondly, over time, soils and Vegetation will be alteredin response to changing processes, generating them-selves a feedback on surface processes. In the 21st Cen¬

tury, continuing climate change, probably also accom-panied by further land use change, is likely to createenvironments characterised by a permanent State oftransition. Such «Transitional Environments» there-fore cannot still be considered to be in a dynamic ormetastabile equilibrium with their external Control¬ling factors. Therefore, the impact of changing landuse and climate on surface processes and landscapedevelopment cannot be addressed, as is commonlydone, by simply linking future climate to runoff ratiosand erosion rates observed under current surface con¬ditions. This approach ignores the dynamic nature ofsurface-climate interaction. Currently, the reactionsof soil and Vegetation to environmental change andtheir feedback on System functions and functioning,e.g. ecohydrology and ecogeomorphology (e.g. Arbelet al. 2005; Kuhn 2007), are of particular relevance forphysical geographic research in particular, but alsofor environmental sciences, politics and economics ingeneral.

The selection of studies published in this issue ofGeographica Helvetica illustrates issues for andapproaches to physical geographic research in tran¬

sitional environments. Naomi Holmes shows howenvironmental reconstruction on Iceland can con-tribute towards greater understanding of the complexinteraction between climate, land cover and surfaceprocesses. Milica Kasanin-Grubin's analysis of cli¬mate change impacts on badlands illustrates howseemingly small changes in external factors can altersurface processes and trigger a new direction of land¬

scape development. While still relatively simple innature, badlands can serve as useful analogue modeisfor larger, more complex geomorphic and landscapeSystems. Richard Guthrie's and Kendrick Brown'sstudy of landslides on Vancouver Island indicateshow even in complex and dynamic landscapes, a goodunderstanding of surface processes and the Control¬ling factors for mass wasting events help reduce com-plexity and support the assessment of past and futureSystem reaction to change. The final two papers con-tinue the theme of impact assessment. Hao Chen,Abdelkader El Garouani and Laurence Lewisshow how the initially simple stochastic approach ofthe Universal Soil Equation has been developed andmodified in the past 20 years and can now be used toassess the multiple risks of soil erosion in a changinglandscape in a land like Morocco, which is character¬ised by high data uncertainty Finally, Nikolaus Kuhnand Honglei Zhu present a combined Seid measure-ment and GIS-based modelling approach for estimat-ing the risks of runoff generation and routing duringextreme events. The study focuses on slopes that untilnow were not considered to generate runoff evenduring extreme events and were for this reason notincluded in catchment-scale modelling. Their Undingsindicate that a better understanding of runoff genera¬tion and routing on slopes is essential for the manage-ment of risks associated with extreme events expectedto characterise the 21st Century.

ReferencesArbel, Y, Yair, A. & S. Oz (2005): Effect of topo-graphy and water repellent layer on the non-uniformdevelopment of planted trees in a sandy arid area. - In:Journal of arid environments 60,1:67-81.Goudie, A. & S. Stokes (2007): Environmental changethrough the Quaternary. - Cary, North Carolina:Oxford University Press.

Intergovernmental Panel on Climate Change(IPCC), Solomon, S., Qin, D., Manning, M, Marquis,M., Averyt, K.,Tignor, M.M.B., Miller, Jr., HL & Z.Chen (eds) (2007): Climate change 2007. The physical

Physical geographic research in transitional environments Nikolaus J Kuhn

science basis. - Contribution of Working Group 1 tothe Fourth Assessment Report of the Intergovern¬mental Panel on Climate Change. - Cambridge: Cam¬

bridge University Press.

Kuhn, N.J. (2007): Erodibility of soil and organicmatter: independence of organic matter resistanceto interrill erosion. - In: Earth surface processes andlandforms 32,5:794-802.Viles, H. (ed.) (1988): Biogeomorphology. - Oxford:Basil Blackwell.

Prof. Dr. Nikolaus J. Kuhn, Department of Environ¬mental Sciences, Institute of Geography/PhysicalGeography and Environmental Change, University ofBasel, Klingelbergstrasse 27, CH-4056 Basel, Switzer-land.e-mail: Nikolaus.Kuhn@unibas.ch