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The terrestrial biosphere is an important global carbon (C) sink, with the potential to drive large positive climate feedbacks. Thus a better understanding of interactions between land use change, climate change and the terrestrial biosphere is crucial in planning future land management options. Climate change has the potential to alter terrestrial C storage since changes in temperature, precipitation and carbon dioxide (CO2) concentrations could affect net primary production (NPP), C inputs to soil, and soil C decomposition rates. Climate change could also act as a driver for land use change, thus further altering terrestrial C fluxes. The net balance of these different effects varies considerably between regions and hence the case studies presented in this paper (the GEFSOC project countries Kenya, Jordan, Brazil, and India) provide a unique opportunity to study climate impacts on terrestrial C storage. This paper first presents predicted changes in climate for the four case study countries from a coupled climate-C cycle Global Circulation Model (HadCM3LC), followed by predicted changes in vegetation type, NPP and soil C storage. These very coarse assessments provide an initial estimate of large-scale effects. A more detailed study of climate impacts on soil C storage in the Brazilian Amazon is provided as an example application of the GEFSOC system. Interestingly in the four cases studied here precipitation seems to control the sign of the soil C changes under climate change with wetter conditions resulting in higher soil C stocks and drier conditions in lower soil C stocks, presumably because increased NPP in wetter conditions here will override any increase in respiration. In contrast, globally, it seems to be temperature that controls changes in C stocks under climate change. Even if there is a slight increase in precipitation globally, a decrease in C stocks is predicted—in other words, the regional response to precipitation differs from the global response. The reason for this may be that whilst temperature increases under climate change were predicted everywhere, the nature of precipitation changes varies greatly between regions. [Copyright &y& Elsevier]

The establishment of enclosures has become an important measure to combat land degradation in many of the world's semi-arid rangelands. In view of the increased pressure exerted by this land reclamation strategy on the neighbouring agricultural lands, knowledge of the time required for restoring vegetation cover and soil health, and of the potential positive impact of an adapted management strategy, is highly required. This paper assesses the vegetation and soil rehabilitation in a 23-year chronosequence of two different enclosure management types. In the severely degraded, semi-arid Njemps Flats plain of the Lake Baringo Basin in Kenya communal enclosures characterised by high quality inputs and strict control, and private enclosures managed by individual farmers, were installed since the 1980s. Six communal enclosures (3–17 years since establishment) and six private enclosures (13–23 years since establishment) were selected. Vegetation cover was estimated along three 50m transects set within each enclosure and in the adjacent open grazing area using the point-to-line transect method. Five 0.5m2 quadrats systematically placed alongside each transect were sampled for herbaceous standing biomass and topsoil physical, chemical and biological analyses. Grass cover and herbaceous biomass production proved to be the most responsive biotic parameters under both management types, whereas the recovery of the forbs was unsuccessful. Under communal management, the biomass production fully recovered up to its optimal level as recorded in the neighbouring nature reserves. Within private enclosures however, the adopted management strategies seriously restricted biomass production to a significantly lower level. Soil quality generally recovered more slowly with time. Significant improvements compared to the open rangeland were recorded in topsoil bulk density, organic C and total N stocks, and microbial biomass C and N stocks of the communal enclosures... [Copyright &y& Elsevier]

Alley-cropping has successively been overestimated and despised, due to unrealistic expectations of this “more natural” type of agriculture and the disappointment thereafter, when the negative effects of trees on crops became evident over time. In this paper we examine the performance and underlying mechanisms of a Calliandra (Calliandra calothyrsus Meissn.)–maize (Zea mays L.) alley-cropping system on a phosphorus (P) limiting Ferralsol in Western Kenya. The system performance analysis methods of [The ‘dark side’ of intercropping: manipulation of soil resources. In: Sinoquet, H., Cruz, P. (Eds.), Proceedings of the International Conference on Ecophysiology of Intercropping. INRA, Paris, France, pp. 45–66] and [Agric. Ecosyst. Environ. 80 (2000) 87] were used as well as mechanistic research into availability, uptake and balances of below ground resources. The Calliandra–maize system performed worse than sole maize (I=-66%, according to Ong’s method) Calliandra affected the less limiting resource nitrogen (N) positively, but the negative effect of Calliandra on P-availability, the main limitation of the environment outweighed the positive or fertility effect, according to Kho’s performance analysis method. However, after P application, when the main limiting resource for maize in our environment shifted to N, the Calliandra had still only a marginal positive effect on maize yields (insignificant 5% increase of alley-cropping compared to sole maize). This was explained by a negative total N balance in the soil of -30 kg ha-1, and a negative inorganic N balance in the soil of -277 kg ha-1 over the seven seasons. The difference between total and inorganic N balance was due to a mineralisation of only 20% of the N in all the Calliandra mulch applied over the seven seasons. Net negative nutrient balances also explain the general trend of decreasing yields of 40–90% over the seven seasons. We conclude that the combination of Ong’s simple method, Kho’s resource-base explanation and further investigation of long-term supply and availability of the resources that are the main limitation(s) of an environment can give an understanding needed to create productive and sustainable alley-cropping systems. [Copyright &y& Elsevier]