不同稻草还田方式下土壤碳库管理指数的研究(英文)

[目的]明确稻草还田方式对双季稻田土壤肥力的影响。[方法]对不同稻草还田方式对土壤总有机碳(CTOC)、活性有机碳(CA)、矿化碳(CM)的影响进行分析,并计算各处理碳库活度(A)、碳库活度指数(AI)、碳库指数(CPI)和碳库管理指数(CPMI)。[结果]与不施肥对照相比,早晚稻两季稻草还田提高了土壤总有机碳、活性有机碳和矿化碳含量及其碳素有效率。等养分条件下,稻草还田处理的土壤总有机碳、活性有机碳及其碳素有效率均高于稻草烧灰还田和稻草不还田处理,且活性有机碳含量差异显著。土壤碳库管理指数处理间差异达显著或极显著,其大小趋势为稻草全量还田>稻草烧灰还田>稻草不还田。[结论]本研究为增加土壤活性有机碳含量以及增加土壤肥力提供了量化的理论依据。     

Forest soils and carbon sequestration

Soils in equilibrium with a natural forest ecosystem have high carbon (C) density. The ratio of soil:vegetation C density increases with latitude. Land use change, particularly conversion to agricultural ecosystems, depletes the soil C stock. Thus, degraded agricultural soils have lower soil organic carbon (SOC) stock than their potential capacity. Consequently, afforestation of agricultural soils and management of forest plantations can enhance SOC stock through C sequestration. The rate of SOC sequestration, and the magnitude and quality of soil C stock depend on the complex interaction between climate, soils, tree species and management, and chemical composition of the litter as determined by the dominant tree species. Increasing production of forest biomass per se may not necessarily increase the SOC stocks. Fire, natural or managed, is an important perturbation that can affect soil C stock for a long period after the event. The soil C stock can be greatly enhanced by a careful site preparation, adequate soil drainage, growing species with a high NPP, applying N and micronutrients (Fe) as fertilizers or biosolids, and conserving soil and water resources. Climate change may also stimulate forest growth by enhancing availability of mineral N and through the CO₂ fertilization effect, which may partly compensate release of soil C in response to warming. There are significant advances in measurement of soil C stock and fluxes, and scaling of C stock from pedon/plot scale to regional and national scales. Soil C sequestration in boreal and temperate forests may be an important strategy to ameliorate changes in atmospheric chemistry.     

A high temperature/low oxygen pulse improves cold storage disinfestation

Short periods of elevated temperature under controlled atmospheres (CA) effectively control insect pests. Cold treatment is also an effective non-chemical disinfestation process. If synergistic effects can be found by combining treatments, these may provide opportunities for cost reduction. Tests were performed to evaluate the tolerance of Packham's Triumph pears (Pyrus communis L.) to a range of temperatures (30–40 °C) combined with low oxygen (O₂ < 1 kPa). Treatment duration was 16–48 h and was followed by 1 month storage at 0 °C under air. When held at 30 °C, pears withstood up to 30 h of hypoxia. After cold storage, pears ripened slightly faster than controls but were undamaged. A temperature of 35 °C induced slight skin browning, and 40 °C resulted in substantial skin blackening. Some treatments were also tested on survival of lightbrown apple moth (LBAM), Epiphyas postvittana (Walker). All developmental stages were subjected to either 16 h at 30 °C, or 16 h under hypoxia, or 1 month at 0 °C, or a combination of the three treatments. With all treatments combined, all eggs, larvae and adults were killed. Only 4% of the pupae produced adults and combined treatments led to an increase in pupa mortality of 38%. A combined treatment (tolerated by pears) consisting of 30 h at 30 °C under low O₂ plus 1 month cold storage under air, killed 100% of LBAM pupae, and 100% of 5th instar larvae of both codling moth, Cydia pomonella (L.), and oriental fruit moth, Grapholita molesta (Busck). Implementation of such treatments would not require substantial investments for fruit industries equipped with CA storage facilities.     

中国土壤有机碳密度和储量的估算与空间分布分析

基于 1∶40 0万的《中华人民共和国土壤图》和第二次土壤普查数据 ,运用地理信息系统技术 ,对中国土壤有机碳密度及储量做出估算 ,并且分析了土壤有机碳密度的空间分布差异。结果表明 :10 0cm深度的土壤有机碳密度介于 1 19kgm- 2 到 176 46kgm- 2 之间 ,2 0cm深度的土壤有机碳密度介于 0 2 7kgm- 2 到53 46kgm- 2 之间 ;10 0cm和 2 0cm深度的土壤有机碳储量分别为 84 4Pg (1Pg =10 15 g)和 2 7 4Pg ;土壤有机碳密度具有高度的空间变异性 ,东北地区、青藏高原的东南部、云贵高原等森林、草甸分布的地区有机碳密度最高 ,准噶尔盆地、塔里木盆地、阿拉善高原与河西走廊、柴达木盆地等沙漠化地区的土壤有机碳密度最低 ;土壤有机碳密度的空间分布主要受气候、植被以及人类活动的影响     

陕西省能源消费碳排放及影响因素分析

研究陕西省能源消费碳排放对陕西省减少碳排放、发展低碳经济有重要意义。本文基于Kaya恒等扩展式和LMDI因素分解模型,应用LMDI分解方法对能源消费碳排放进行因素分解。定量分析陕西省2000~2011年人口、人均GDP、能源消费结构、能源消费强度、产业结构等5方面的因素对能源消费碳排放的贡献大小。结果表明:人均GDP增长是陕西省碳排放量增加最大的因素,其次是能源消费强度;人口效应和能源消费结构对碳排放量的增加有较微弱的拉动作用;产业结构效应对陕西省碳排放量增加产生负作用;产业结构和能源消费结构需要进一步调整与优化以抑制碳排放量增长。     

北京和上海终端能源碳排放量影响因素研究

运用IPCC中碳排放量公式,结合能源消费数据,对北京和上海2005～2012年碳排放终端能源总量进行估计;运用LMDI模型定量分析了经济总量、能源结构、产业结构对碳排放的影响.结果表明,2005～ 2012年经济总量上升是推动北京和上海碳排放量增长的主要因素,能源结构调整是降低碳排放量的主要原因,产业结构调整是影响碳排放量原因之一.通过对能源结构和产业结构进一步分析得出北京和上海两市应通过能源结构调整,增加清洁能源消费比率来减少碳排放,上海市应同时发展第三产业促进产业结构调整降低碳排放的结论.     

用δ~(13)C法研究黑土添加有机物料后有机碳的变化规律

通过室内短期培养实验,利用δ13C的方法研究了外源有机物料分解过程中黑土有机碳的变化规律。结果表明:黑土中添加有机物料后,土壤有机碳的数量明显增加。在有机物料分解过程中,随着培养时间的延长,土壤有机碳的总量在逐渐下降,总的变化趋势是先快后慢,渐趋平缓,到培养结束(30天),有机物料在土壤中净残留率小于50%。黑土有机碳的δ13C值受进入土壤中有机物料的种类所影响,从数量上土壤有机碳的δ13C值可以反映土壤中不同来源有机碳的变化。在小麦秸秆分解过程中,新进入黑土中的有机碳转化较快,而土壤中固有的有机碳转化较慢,添加有机物料可以增加土壤中有机碳的固定。     

Effect of tree species on carbon stocks in forest floor and mineral soil and implications for soil carbon inventories

Forest soil organic carbon (SOC) and forest floor carbon (FFC) stocks are highly variable. The sampling effort required to assess SOC and FFC stocks is therefore large, resulting in limited sampling and poor estimates of the size, spatial distribution, and changes in SOC and FFC stocks in many countries. Forest SOC and FFC stocks are influenced by tree species. Therefore, quantification of the effect of tree species on carbon stocks combined with spatial information on tree species distribution could improve insight into the spatial distribution of forest carbon stocks.We present a study on the effect of tree species on FFC and SOC stock for a forest in the Netherlands and evaluate how this information could be used for inventory improvement. We assessed FFC and SOC stocks in stands of beech (Fagus sylvatica), Douglas fir (Pseudotsuga menziesii), Scots pine (Pinus sylvestris), oak (Quercus robur) and larch (Larix kaempferi).FFC and SOC stocks differed between a number of species. FFC stocks varied between 11.1 Mg C ha⁻¹ (beech) and 29.6 Mg C ha⁻¹ (larch). SOC stocks varied between 53.3 Mg C ha⁻¹ (beech) and 97.1 Mg C ha⁻¹ (larch). At managed locations, carbon stocks were lower than at unmanaged locations. The Dutch carbon inventory currently overestimates FFC stocks. Differences in carbon stocks between conifer and broadleaf forests were significant enough to consider them relevant for the Dutch system for carbon inventory.     

Seasonal variation and fire effects on CH4, N2O and CO2 exchange in savanna soils of northern Australia

Tropical savanna ecosystems are a major contributor to global CO₂, CH₄ and N₂O greenhouse gas exchange. Savanna fire events represent large, discrete C emissions but the importance of ongoing soil-atmosphere gas exchange is less well understood. Seasonal rainfall and fire events are likely to impact upon savanna soil microbial processes involved in N₂O and CH₄ exchange. We measured soil CO₂, CH₄ and N₂O fluxes in savanna woodland (Eucalyptus tetrodonta/Eucalyptus miniata trees above sorghum grass) at Howard Springs, Australia over a 16 month period from October 2007 to January 2009 using manual chambers and a field-based gas chromatograph connected to automated chambers. The effect of fire on soil gas exchange was investigated through two controlled burns and protected unburnt areas. Fire is a frequent natural and management action in these savanna (every 1-2 years). There was no seasonal change and no fire effect upon soil N₂O exchange. Soil N₂O fluxes were very low, generally between −1.0 and 1.0 μg N m⁻² h⁻¹, and often below the minimum detection limit. There was an increase in soil NH₄⁺ in the months after the 2008 fire event, but no change in soil NO₃⁻. There was considerable nitrification in the early wet season but minimal nitrification at all other times.Savanna soil was generally a net CH₄ sink that equated to between −2.0 and −1.6 kg CH₄ ha⁻¹ y⁻¹ with no clear seasonal pattern in response to changing soil moisture conditions. Irrigation in the dry season significantly reduced soil gas diffusion and as a consequence soil CH₄ uptake. There were short periods of soil CH₄ emission, up to 20 μg C m⁻² h⁻¹, likely to have been caused by termite activity in, or beneath, automated chambers. Soil CO₂ fluxes showed a strong bimodal seasonal pattern, increasing fivefold from the dry into the wet season. Soil moisture showed a weak relationship with soil CH₄ fluxes, but a much stronger relationship with soil CO₂ fluxes, explaining up to 70% of the variation in unburnt treatments. Australian savanna soils are a small N₂O source, and possibly even a sink. Annual soil CH₄ flux measurements suggest that the 1.9 million km² of Australian savanna soils may provide a C sink of between −7.7 and −9.4 Tg CO₂-e per year. This sink estimate would offset potentially 10% of Australian transport related CO₂-e emissions. This CH₄ sink estimate does not include concurrent CH₄ emissions from termite mounds or ephemeral wetlands in Australian savannas.