Kjeld Rasmussen

A simple interpretation of the surface temperature/vegetation index space for assessment of surface moisture status

Abstract A simplified land surface dryness index (Temperature–Vegetation Dryness Index, TVDI) based on an empirical parameterisation of the relationship between surface temperature (Ts) and vegetation index (NDVI) is suggested. The index is related to soil moisture and, in comparison to existing interpretations of the Ts/NDVI space, the index is conceptually and computationally straightforward. It is based on satellite derived information only, and the potential for operational application of the index is therefore large. The spatial pattern and temporal evolution in TVDI has been analysed using 37 NOAA-AVHRR images from 1990 covering part of the Ferlo region of northern, semiarid Senegal in West Africa. The spatial pattern in TVDI has been compared with simulations of soil moisture from a distributed hydrological model based on the MIKE SHE code. The spatial variation in TVDI reflects the variation in moisture on a finer scale than can be derived from the hydrological model in this case.

Adaptation to climate change in developing countries.

Adaptation to climate change is given increasing international attention as the confidence in climate change projections is getting higher. Developing countries have specific needs for adaptation due to high vulnerabilities, and they will in this way carry a great part of the global costs of climate change although the rising atmospheric greenhouse gas concentrations are mainly the responsibility of industrialized countries. This article provides a status of climate change adaptation in developing countries. An overview of observed and projected climate change is given, and recent literature on impacts, vulnerability, and adaptation are reviewed, including the emerging focus on mainstreaming of climate change and adaptation in development plans and programs. The article also serves as an introduction to the seven research articles of this special issue on climate change adaptation in developing countries. It is concluded that although many useful steps have been taken in the direction of ensuring adequate adaptation in developing countries, much work still remains to fully understand the drivers of past adaptation efforts, the need for future adaptation, and how to mainstream climate into general development policies.

Desertification in reverse? Observations from northern Burkina Faso

Abstract The idea of degradation of arid and semi-arid lands, often termed desertification in its irreversible form, due to human impact and/or climatic change has been much debated since the mid-1970s. From the time of the United Nations Conference On Desertification in Nairobi, 1976, certain areas of northern Burkina Faso have been pointed out as examples of severe desertification. Several studies demonstrated that revitalization of a series of E–W oriented fossille dunes in the Oudalan province was ongoing. The present study includes an analysis of the trends of vegetation development in the region, covering the period 1955 to 1994, with emphasis on the fossile dunes. It is demonstrated that desertification and revitalization of dunes were phenomena associated with the period between the early 1970s and the mid-1980s, and that the decline in vegetation cover on the dunes seems to have been reversed in recent years. The analysis is based upon time series of aerial photos and satellite images, field studies of vegetation, interviews with local people and review of relevant literature. The findings are discussed with reference to the debate concerning desertification and land degradation, as well as to the current revisions of the ‘range management paradigm’. The observations indicate that the environmental history of the region is complex and cannot be boiled down to ‘human-induced irreversible degradation’. Rather they support the idea of semi-arid cultural landscapes undergoing constant change in response to both human impact and climatic trends and fluctuations.

Global land-Cover Change: Recent Progress, Remaining Challenges.

Since time immemorial, humankind has changed landscapes in attempts to improve the amount, quality, and security of natural resources critical to its well being, such as food, freshwater, fiber, and medicinal products. Through the increased use of innovation, human populations have, slowly at first, and at increasingly rapid pace later on, increased its ability to derive resources from the environment, and expand its territory. Several authors have identified three different phases - the control of fire, domestication of biota, and fossil-fuel use - as being pivotal in enabling increased appropriation of natural resources (Goudsblom and De Vries 2004; Turner II and McCandless 2004).

Savanna fires in east-central Senegal: distribution patterns, resource management and perceptions.

The temporal and spatial distribution of fires for an area in east-central Senegal was determined on the basis of multi-temporal NOAA AVHRR satellite images. Three years of data (1990–1992) were analyzed defining the boundary between two different fire regimes: very few and scattered fires to the north with the majority of fires south of the boundary. This boundary was stable for the three dry seasons examined and was identical to the northernmost extension of fires as determined by visual inspection of a hard copy Landsat image mosaic. Fire frequencies were analyzed in relation to dominant vegetation types and yearly precipitation, and the findings compared to results of a field survey of the local populations perceptions of the causes and implications of fires. Survey results clearly showed that the use of fire in the study area is closely linked to the utilization of the environment for livestock grazing and crop production. We conclude that the local population has a high degree of awareness about the application of fire, that different fire use practices concerning can be identified respectively in the grasslands of the northern and the savanna of the southern parts of the study area, and that these practices reflect a well adapted production strategy. Finally, we recommend policy decisions be more flexible in the light of local understanding of fire use.

Conformations of disaccharides by empirical force-field calculations: part II, β-cellobiose

Abstract Conformations of β-maltose have been studied by using convergent energy minimisation in a simple force field. Parameters for the force field were taken from similar studies on α- and β- d -glucopyranose. Four local minima are found on the φ,ψ-map; the free enthalpy differences are 2.8, 3.4, and 5.6 kJ.mol-1 above the lowest, corresponding to a distribution of 59:19:15:7. These minima are surrounded by a manifold of minimum conformers differing only in exocyclic torsions. Conformations of the two lowest minima are close to X-ray structures, and (φ,ψ) of the lowest minima are very close to what can be derived from n.m.r. experiments. The path on the φ,ψ-map of conformational interchange between the two lowest minima has been investigated, and barrier heights and rates of conversion estimated. Conversion is fast on the n.m.r. time-scale. The distribution-weighted average of a crucial H---H distance agrees with n.m.r. measurements. The possible existence of several minima for maltose can explain known irregularities in some amylose conformations.

Field expansion and reallocation in the Sahel – land use pattern dynamics in a fluctuating biophysical and socio-economic environment

Abstract The paper addresses the dynamic relationship between the human use of land and alterations in the biophysical environment, demographic pressure or socio-economic conditions. An empirical study from the Sahelian zone in northern Burkina Faso illustrates the dynamics of cultivation pattern at the village level and the changing priorities given to different landscape units over time. Field measurements, aerial photos and satellite images from seven successive years provide information on land use pattern changes from 1945 to 1995. A household survey illustrates how socio-economic and cultural parameters enable and constrain land use strategies at the farm level.

Potential energy function for calculation of structures, vibrational spectra and thermodynamic functions of alkanes, alcohols, ethers and carbohydrates

Abstract A potential energy function is devised, comprising harmonic terms for bond length and valence angle deformations, and Lennard—Jones and Coulomb terms for non-bonded interactions. Atomic charges are selected semi-automatically to approximate the results of Mulliken population analysis, and all other parameters are fitted to reproduce the structures of 8 alkanes, 5 alcohols, 7 ethers and 2 carbohydrates. Gross features of selected vibrational spectra and thermodynamic functions of the alkanes are also reproduced. Dipole moments are given with a precision comparable to that of most theoretical work. Peculiarities in the individual terms of the crucial non-bonded interactions are discussed.

Infrared and far infrared spectra of dihalo(ethylenediamine) palladium(II) and platinum(II)

Abstract Infrared and far i.r. room temperature spectra of solid square planar mono(ethylenediamine) halide complexes of Pd and Pt are obtained. Group vibrations are assigned with the use of two C-deuterated compounds. A comparison of factor group and site group analyses shows that the former is necessary to explain the finer details of the spectra. Crystal data of [PdenCl2] and [PtenI2] are reported.

Climate change on three Polynesian outliers in the Solomon Islands: impacts, vulnerability and adaptation

Abstract Geografisk Tidsskrift—Danish Journal of Geography 109(1):1–13, 2009 Past and current impacts of climate change on three smalt islands, Ontong Java, Bellona and Tikopia, in the Solomon Islands are studied on the basis of a survey of production systems, household questionnaires and key informant and group interviews. Perceptions of the local population are compared to regional observations on climate variability and change. The adaptive measures taken in the past are identified. It is concluded that the capacity to cope with and adapt to climate variability and extreme weather events is well developed, and the social resilience of island communities appears to be high. It is further shown that the differences between islands are large with regard to the types of climate change observed, the exposure of the islands to the changes and the perceptions of the severity. The differences are due to location, bio-physical and terrain conditions and socio-economic factors, including the level of integration into a greater economic and demographic context, the importance of different productive activities and the social organization.