抚育间伐对人工林影响的研究进展

抚育间伐对人工林有重要影响。针对抚育间伐对人工林的林下植被多样性、生物量、凋落物分解、土壤肥力和森林生态系统碳储量影响的研究进行综述,并提出今后的研究重点应该放在抚育间伐后人工林的生物多样性和生物量的长期定位研究,抚育间伐调控人工林凋落物分解的机制和对人工林生态系统碳储量影响的研究等方面,并需要开展各地区主要森林类型、多种立地条件和不同密度森林的抚育间伐研究。     

西藏自治区森林枯落物碳储量估算

利用典型样地采样,建立了枯落物碳密度与厚度关系方程,并结合森林资源连续清查的样地坡度与枯落物厚度因子,估算出西藏自治区森林枯落物碳储量.结果表明,西藏自治区丰富的森林植被生产了巨大的枯落物层碳库,有机碳分解和碳库消耗缓慢.研究该部分碳库状况,为估算和评价陆地生态系统碳储量并据此制定相应的对策提供了基础数据.     

配施生物基质肥料对茶园土壤有机碳固持的影响

通过长期定位试验,研究连续4年配施生物基质肥料对茶园土壤有机碳固持的影响,结果表明：随着生物基质肥料施用比例的增加土壤有机碳含量呈现增加的趋势;土壤基础呼吸量以全量施用生物基质肥料最低,75%生物基质肥配施25%化肥最高;土壤微生物量碳随着生物基质肥料施用比例的增加而增加;生物基质肥料的施用显著提高了土壤微生物商,降低了土壤呼吸商;适当的施肥结构促进茶树生长和茶叶产量的提高,春茶茶叶产量以25%生物基质肥＋75%化肥处理最高,以100%生物基质肥料处理最低。综合配施生物基质肥料对茶园土壤有机碳固持和对茶树生长的影响,初步认为25%～50%生物基质肥＋75%～50%化肥适宜茶园施用。     

水稻低碳生产研究进展

 稻田是甲烷(methane,CH4)和氧化亚氮(nitrous oxide,N2O)的重要发生源。稻田中CH4和N2O的产生、消耗以及传输过程受稻田土壤类型、水分条件、肥料种类、施肥量及方法、耕作模式和制度、水稻品种等多种因素影响。CH4和N2O具有不同的排放特性,很多研究结果表明,水稻生长期间的中期排水烤田、后期干湿交替能显著降低CH4排放量,但同时也可能促进N2O的排放,因此,如何同时减少CH4和N2O的排放量是实现稻田低碳生产的关键要素;另一方面,稻田土壤的碳固定也是使稻田系统从源转变成汇的关键技术。从水稻生产过程中CH4排放、N2O排放、稻田土壤有机碳动态、减排措施四个方面综述了近年来水稻低碳生产相关研究状况,重点总结了国内外有关影响稻田CH4和N2O排放的关键影响因素、增加稻田土壤有机质含量的主要措施以及各种减排措施的全球增温潜势评价研究,并对水稻低碳生产研究作了展望。     

放牧对土壤碳、氮含量空间变异的影响

本研究检测了不同放牧强度下荒漠草原淡栗钙土的碳、氮含量,应用地统计学方法分析放牧强度对土壤碳、氮空间变异的影响。结果表明,土壤碳、氮均属中等变异程度。土壤碳、氮含量随放牧强度的加大而呈现减少的趋势。未放牧、中度放牧以及重度放牧的土壤碳、氮的空间变异主要是由区域因素引起的,空间变异大;而轻度放牧土壤碳、氮的空间变异是区域因素和放牧等随机性因素共同作用的结果,属中等程度的空间相关性。土壤碳、氮的变异总体表现为未放牧>轻度放牧>中度放牧>重度放牧。中度放牧和重度放牧后土壤碳、氮低含量斑块面积随着年度递增而增加。内蒙古四子旗短花针茅（Stipa breviflora）荒漠草原适合轻度放牧。     

贵州省古银杏资源的分布及生长特征研究

2011年8月通过访谈、查阅文献资料与实地调查,对贵州省古银杏资源的分布及生长特征进行分析。结果表明,贵州省100～4000年生古银杏共有1969株,主要分布于遵义市和六盘水市;垂直分布海拔为300～1700m,集中分布800—1100m。其中75．96％为雌株,24．04％为雄株,雌雄比为3．16：1;树高最高为50．0m,最矮为2．0m;树龄最大为4000年,最小为100年;胸径最大为479cm,最小为26cm;其平均冠幅最大为40．0m,最小为1．0m。垂乳银杏有88株,复干银杏有35株,雌雄同株仅1株。     

Quantification by allometric equations of carbon sequestered by Tectona grandis in different agroforestry systems

Non destructive methods for quantification of carbon seques-tration in tropical trees are inadequately developed. We described a stan-dardized method for estimating carbon stock in teak (Tectona grandi...     

Climate Change Impacts Due to Biogenic Carbon: Addressing the Issue of Attribution Using Two Metrics With Very Different Outcomes

Although not without its critics, considerable recognition has been given to the climate cooling benefits provided by storing carbon from biomass in various storage pools. However, it has recently been found that depending on the storage pool/period and source of biomass, the associated climate impacts may be a burden or a benefit. It is important that carbon accounting schemes and life cycle assessment practitioners take these carbon/CO₂ flux dynamics and the climate impacts that they create into consideration. In this work we illustrate these climate impacts with a Norwegian case study using a material flow analysis of the biogenic carbon in harvested wood products derived from a 2006 harvest year. We illustrate the dynamic carbon balance over time and show how the climate impacts can diverge greatly between two well-known climate impact metrics: global warming potential (GWP) and global temperature potential (GTP). We also show how these climate impacts can be attributed to contributing parties with an example of a glue laminated beam value chain which is stored in a long-lived building. We discuss the associated attribution issues that will inevitably arise and we offer recommendations on how best to minimize them.     

Soil organic carbon status and sustainability of slash-and-burn cultivation in India

ABSTRACT

The study was carried out (a) to identify the changes in the soil organic carbon (SOC) content during the different phases of slash-and-burn cultivation—i.e., before slash-and-burn (Phase 1), after slash-and-burn (Phase 2), and after harvest (Phase 3); and (b) to determine the status of soil organic carbon content in the primary undisturbed forest (Site 1) and in the secondary forests, where slash-and-burn cultivation was taken up ~25 yr (Site 2), 15 yr (Site 3), and 5 yr back (Site 4). The undisturbed forest holds the largest amount of SOC % (5.25) followed by 25 yr (3.07), 5 yr (2.86), and 15 yr (2.27) fallow. The mean percentages of SOC in the 0- to 15-cm layer fell from 3.07 in Phase 1 to 2.53 and 2.37, respectively, in Phases 2 and 3; in the subsurface 15- to 30-cm layer, they fell from 1.95 to 1.62 and 1.63, respectively. Although, the SOC in Phase 3 still seems sufficient to support another round of cultivation, further studies are needed to examine crop yields in successive cultivation cycles, suitability of other rice varieties, and weed and pest types and rates of invasion. Tribal population dynamics is another major concern, which needs assessment for monitoring future land requirements.     

Chapter 12. A Wildfire and Emissions Policy Model for the Boise National Forest

Summary

We utilized the Boise National Forest's Hazard/Risk model, along with fire history records and fire behavior models, to estimate the current and anticipated levels of large wildfires and associated greenhouse gas and particulate emissions based on the forest condition and wildfire regime on the BNF. The model indicated that the forests at greatest risk of large, intense wildfires are the dense pondero-sa pine-Douglas-fir forests that make up over 1.1 million acres on the forest. We conclude that without an aggressive treatment program to reduce large areas of contiguous heavy fuel loadings the forest will be burned at an annual average rate of about 7.5% of the remaining at-risk forest. Using recent fire data to develop average patterns of intensity in wildfires within this forest type, we estimate that emissions will average around 1 million tons of carbon (C) per year over the next 20 years as the bulk of the ponderosa pine forests are burned. An aggressive treatment program featuring the removal of fuels where necessary, and prescribed fire as a means of re-introducing fire to these ecosystems, would result in a 30-50 percent reduction in the average annual wildfire experienced in the dense ponderosa pine forests, a 14-35% decrease in the average annual C emissions, and a 10-31% decrease in particulate emissions. We argue that the most effective way to curb emissions is with an aggressive treatment program linked to a landscape-based ecosystem management plan. This would have the effect of breaking up large contiguous landscape patterns so that fires become more patchy and diverse in their environmental impact, resulting in significantly reduced emissions as well as improved landscape diversity.