Carbon Dynamics in Woody Biomass of Forest Ecosystem in China with Forest Management Practices under Future Climate Change and Rising CO_2 Concentration

It is critical to study how different forest management practices affect forest carbon sequestration under global climate change regime. Previous researches focused on the stand-level forest carbon sequestration with rare investigation of forest carbon stocks influ- enced by forest management practices and climate change at regional scale. In this study, a general integrative approach was used to simulate spatial and temporal variations of woody biomass and harvested biomass of forest in China during the 21st century under dif- ferent scenarios of climate and CO2 concentration changes and management tasks by coupling Integrated Terrestrial Ecosystem Carbon budget （InTEC） model with Global Forest Model （G4M）. The results showed that forest management practices have more predominant effects on forest stem stocking biomass than climate and CO2 concentration change. Meanwhile, the concurrent future changes in cli- mate and CO2 concentration will enhance the amounts of stem stocking biomass in forests of China by 12%-23% during 2001-2100 relative to that with climate change only. The task for maximizing stem stocking biomass will dramatically enhance the stem stocking biomass from 2001~100, while the task for maximum average increment will result in an increment of stem stocking biomass before 2050 then decline. The difference of woody biomass responding to forest management tasks was owing to the current age structure of forests in China. Meanwhile, the sensitivity of long-term woody biomass to management practices for different forest types （coniferous forest, mixed forest and deciduous forest） under changing climate and CO2 concentration was also analyzed. In addition, longer rotation length under future climate change and rising CO2 concentration scenario will dramatically increase the woody biomass of China during 2001~100. Therefore, our estimation indicated that taking the role of forest management in the carbon cycle into the consideration at regional or national level is very important to project the forest carbon sequestration under future climate change and rising atmospheric CO2 concentration.

Mapping Cropland in Ethiopia Using Crowdsourcing

The spatial distribution of cropland is an important input to many applications including food security monitoring and economic land use modeling. Global land cover maps derived from remote sensing are one source of cropland but they are currently not accurate enough in the cropland domain to meet the needs of the user community. Moreover, when compared with one another, these land cover products show large areas of spatial disagreement, which makes the choice very difficult regarding which land cover product to use. This paper takes an entirely different approach to mapping cropland, using crowdsourcing of Google Earth imagery via tools in Geo-Wiki. Using sample data generated by a crowdsourcing campaign for the collection of the degree of cultivation and settlement in Ethiopia, a cropland map was created using simple inverse distance weighted interpolation. The map was validated using data from the GOFC-GOLD validation portal and an independent crowdsourced dataset from Geo-Wiki. The results show that the crowdsourced cropland map for Ethiopia has a higher overall accuracy than the individual global land cover products for this country. Such an approach has great potential for mapping cropland in other countries where such data do not currently exist. Not only is the approach inexpensive but the data can be collected over a very short period of time using an existing network of volunteers.

Spatial Analysis of the Soil Carbon Sequestration Potential of Crop-residue Return in China Based on Model Simulation

Crop-residue return is a recommended practice for soil and nutrient management and is important in soil organic carbon(SOC)sequestration and CO2 mitigation.We applied a process-based Environmental Policy Integrated Climate(EPIC)model to simulate the spatial pattern of topsoil organic carbon changes from 2001 to 2010under 4 crop-residue return scenarios in China.The carbon loss(28.89 Tg yr–1)with all crop-residue removal(CR0%)was partly reduced by 22.38 Tg C yr–1 under the status quo CR30%(30% of crop-residue return).The topsoil in cropland of China would become a net carbon sink if the crop-residue return rate was increased from 30%to 50%,or even 75%.The national SOC sequestration potential of cropland was estimated to be 25.53 Tg C yr–1 in CR50%and 52.85 Tg C yr–1 in CR75%,but with high spatial variability across regions.The highest rate of SOC sequestration potential in density occurred in Northwest and North China while the lowest was in East China.Croplands in North China tended to have stronger regional SOC sequestration potential in storage.During the decade,the reduced CO2 emissions from enhanced topsoil carbon in CR50%and CR75% were equivalent to 1.4% and 2.9%of the total CO2 emissions from fossil fuels and cement production in China,respectively.In conclusion,we recommend encouraging farmers to return crop-residue instead of burning in order to improve soil properties and alleviate atmospheric CO2 rises,especially in North China.