Variation in performance of beech saplings of 7 European provenances under shade and full light conditions

The use of beech seedlings from South-East European and North-West (NW) provenances for underplanting in coniferous forests in North-West Europe was investigated by means of experimental shading. The effects of this treatment on survival, morphology, phenology, physiology and growth were analysed by applying an individual plant growth model integrating these aspects. It was concluded that plant performance under full-light conditions are representative of shaded conditions, so good performing provenances can be selected in a field situation. It was further concluded that good performing South-East European seedlings can be used in North-West European conditions. The modelling results indicated an interesting trade-off between height growth and biomass increase and different provenances show different strategies. This allows selection of suitable provenances for specific situations, e.g. when beech seedlings need to compete with other plant species in the understorey

Effects of light and soil flooding on the growth and photosynthesis of ramin (Gonystylus bancanus) seedlings in Malaysia

We studied the ecophysiology of ramin (Gonystylus bancanus) seedlings in an experimental set up at the Forest Research Centre in Kuching, Sarawak, Malaysia. Ramin seedlings were grown on flooded and drained peat soil under 100, 76, 46 and 23% sunlight, thus simulating effects of different light conditions (canopy gap size) and drainage that occur in natural ramin populations. Seedling growth was highest in partial sunlight (76%) and reduced with reducing light levels. Aboveground productivity and fine root development were significantly higher in seedlings grown on flooded soil compared with those on drained soil. In contrast, investment in coarse root biomass was significantly higher in seedlings grown on drained soil. It appeared that the aboveground growth benefits in flooded conditions were the result of more advantageous conditions for allocation of carbon to leaves, thus enhancing overall relative growth rates through higher light interception rates despite lower photosynthetic capacity. The results of this experiment suggested that drainage of peat swamp forests would seriously hamper natural regeneration of ramin by limiting the growth of seedlings. It is also suggested that selective logging operations which produce medium-size canopy gaps improve ramin regeneration in hydrologically undisturbed mixed swamp forest

Climate Change Impacts on the Congo Basin Region

This report presents analyses of climate change impacts in the Congo Basin on water for agriculture and hydropower, forest ecosystem functioning and carbon storage and impacts of climate variability and change on future economic development. To quantify the impacts of future climate we developed a modelling framework which links climate models with different impact models. Bias corrected climate model output was used to force the macro-hydrological model VIC and therefore it is necessary to use numerical models. For this project a modelling framework was developed which made it possible to link climate models with hydrological, agricultural and ecosystem models. In general, our analyses shows that more water will be available for hydropower in the future. So on average, climate change will have a positive impact on potential electricity production. However the river discharge will also become more variable which will increase the flood risks and could make the power production less reliable. The increased flow variability however will make dam management more complicated because the balance between flood prevention and optimal power production will be more difficult to manage. Climate change will have a range of different impacts of forest ecosystems. The higher atmospheric CO2 concentrations will probably increase forest growth and carbon capture. Higher temperatures however will have negative impacts on forest growth and reduce the amount of carbon in the forests. The impact analyses show that as a result of climate change, the Congo basin is unlikely to see a decline in forest growth such as is sometimes predicted for the Amazon basin. Instead there could be a moderate increase in ecosystem carbon. Depending on how the climate will change there could be a shift in land cover of the different ecosystems. Based on the analyses a moderate expansion to the North and South of Evergreen forests into savannas and grasslands is the most likely future scenario. In general, climatic conditions are currently not limiting agricultural production in the Congo basin region. Only on the (drier) edges of the region water limitation is sometimes reducing the potential agricultural productions. In the tropical climates too much rainfall and high humidity limits agricultural production through nutrient leaching and fungal growth. The impact of future climate on agricultural production will therefore be limited in the region. In most of the area the water stress will increase slightly in the future. However the agriculture will not suffer from structural water shortages. Only the agriculture in the savanna regions surrounding the Congo basin could potentially face water shortages in the future. In the southern savanna region analyses indicate that more frequent droughts will affect agriculture production and water stress. In several of the COMIFAC countries there is a clear correlation between annual rainfall and GDP growth. GDP and Agricultural GDP growth rates tend to be higher in years with above-average rainfall than in the dry years. The impact of climate variability on GDP growth is most pronounced during dry years. During below-average rainfall years growth is sometimes severely reduced and generally the dryer the lower the GDP growth rate. All above-average rainfall years tend to have relatively similar economic growth rates. The correlation between rainfall and GDP growth rates is stronger in countries with lower and more variable rainfall. In most countries, agricultural GDP growth rates are affected stronger by climate variability than the total GDP growth rates. In terms of future climate change impacts on economic development our analysis shows that COMIFAC countries are especially vulnerable to a reduction in rainfall and a significant increase in interannual rainfall variability. Our results show that at a continental scale, climate change is likely to have a negative impact on development in Africa. However the economies of central African countries are likely to be less affected by climate change compared to countries in West, East and Southern Africa. Also at macro scale the climate scenarios seem to be more favourable in the central African part compared to the rest of Africa. However some climate change scenarios show large increases in climate variability and this could have a negative impact on development. In conclusion the climate change impacts on the different sectors shows that the main impacts will come from a more variable climate. No major impacts are expected in terms of water availability for agriculture and future carbon storage in the tropical forests. Also the average potential energy production from hydropower will not reduce. The most severe impacts will result from a more variable hydrological regime. This will result is higher flood frequency and will complicate future dam management. Keywords: Climate change; water resources; agriculture; forestry; carbon stocks; GD

Reading tea leaves worldwide: decoupled drivers of initial litter decomposition mass-loss rate and stabilisation

The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large-scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass-loss rates and stabilization factors of plant-derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy-to-degrade components accumulate during early-stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass-loss rates and stabilization, notably in colder locations. Using TBI improved mass-loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early-stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models