红壤性水稻土不同粒级团聚体有机碳矿化及其温度敏感性

采用室内培养方法,研究不同温度(15℃、25℃和35℃)条件下红壤性水稻土不同粒级团聚体(2 mm、1～2 mm、 0.25～1 mm、0.053～0.25 mm和0.053 mm)中有机碳矿化特征,分析团聚体有机碳矿化对全土有机碳矿化的贡献并探讨团聚体有机碳矿化的温度敏感性。结果表明:0.25 mm大团聚体较0.25 mm微团聚体含有更多的有机碳和全氮,碳氮比随团聚体粒级减小而降低。全土和各粒级团聚体有机碳矿化速率在培养的前7d快速下降,之后缓慢降低并在培养后期趋于稳定。25℃和35℃培养时,有机碳累积矿化量在1 mm团聚体中最高,在0.053～0.25 mm团聚体中最低,且有机碳累积矿化量与有机碳和全氮含量显著或极显著正相关。2 mm和0.25～1 mm团聚体对全土有机碳矿化的贡献最大,贡献率分别为34.6%和28.8%。培养温度的升高显著提高了全土和团聚体的有机碳矿化速率、累积矿化量和矿化率。不同粒级团聚体有机碳矿化的温度敏感性系数为1.38～2.00,与有机碳、全氮和碳氮比均极显著正相关。综上所述,0.25 mm大团聚体在红壤性水稻土有机碳矿化中发挥主导作用,升温促进了不同粒级团聚体有机碳的矿化,团聚体有机碳矿化的温度敏感性与有机质的数量和质量密切相关。     

黄土高原丘陵区地形和土地利用对土壤有机碳的影响

土壤有机碳(SOC)作为土壤中重要的组成部分及植物生长的主要元素,在地球生态系统中起着举足轻重的作用,是全球环境尤其是气候变化的重要影响因素。以黄土高原王茂沟小流域为研究对象,通过间隔为150m经纬网格分5层采集0～100cm土壤样品,采集土壤样品包括4种地形(坡顶、坡上、坡中、坡下)和5种土地利用类型(坡耕地、林地、草地、灌木、梯田),共采集土壤样品1 540个,探讨地形和土地利用方式对黄土丘陵沟壑区小流域SOC含量和分布影响,并通过Kriging插值计算流域内SOC空间分布。结果表明,黄土丘陵第一副区王茂沟小流域在0～100cm土层中,SOC平均含量坡上(4.49g·kg~(-1))和坡中(4.30 g·kg~(-1))含量最高,其次为坡下(3.97 g·kg~(-1)),坡顶SOC含量最低(3.34g·kg~(-1));坡耕地SOC含量最低。林地(4.31 g·kg~(-1))、梯田(4.25 g·kg~(-1))、草地(4.12 g·kg~(-1))和灌木(3.82 g·kg~(-1))分别较坡耕地(3.47 g·kg~(-1))SOC含量增加24.2%、22.4%、18.7%和10.1%。表层SOC更易受到环境因子的影响,梯田等水土保持措施可明显固存深层(20cm)SOC。方差成分估计表明,土地利用、地形、深度以及土地利用与地形的交互作用对流域剖面SOC含量空间分布有着极显著的影响(P0.01),其中地形对SOC含量的贡献率最高(32.50%)。土地利用与地形的交互作用在各因子的交互作用中表现出对SOC含量变异解释度最高(7.4%)。流域SOC在空间上呈斑块分布,随着深度的增加,流域SOC的空间分布向均一性发展。研究结果为黄土区水土保持措施规划及退耕还林的固碳效益评价提供了科学依据。     

The Contribution of Various Components to pH Buffering Capacity of Acrisols in Southeastern Vietnam

This paper examined the contribution of various soil components to pH buffering capacity (pH_BC) of haplic Acrisols in an upland area of Southeastern Vietnam. Sampling was conducted in 2016 in Tan Bien district, Tay Ninh province at seven sites from the surface to 60-cm depth. Soils were very acidic (pH_H2O 4.53 ± 0.05). The pH_BC were very low, 0.46 ± 0.04 and 0.44 ± 0.05 cmol H⁺ kg^?1 pH^?1, respectively, for original samples and those from which soil organic carbon (SOC, 0.52 ± 0.09%) were removed. The contribution of Al³⁺ to pH_BC was remarkable while that of SOC was of little significance. The contribution of clay minerals to pH_BC was unclear due to the low (9.37 ± 0.76%) and kaolinite-dominated clay content. The current soil conditions indicated a potential for further soil acidification. Liming would be one of the measures to remediate soil acidity in the research area.     

Immediate and subsequent effects of drying and rewetting on microbial biomass in a paddy soil

Many surface soils in Japan may experience more frequent and intense drying–rewetting (DRW) events due to future climate changes. Such DRW events negatively and positively affect microbial biomass carbon (MBC) through microbial stress and substrate supply mechanisms, respectively. To assess the MBC immediately after DRW and during the incubation with repeated DRW cycles, two laboratory experiments were conducted for a paddy soil. In the first experiment, we exposed the soil to different drying treatments and examined the MBC and hourly respiration rates immediately after the rewetting to evaluate the microbial stress. In the second experiment, we compared microbial growth rates during the incubation of the partially sterilized soil with a continuously moist condition and repeated DRW cycles to evaluate the contribution of the substrate supply from non-biomass soil organic C on MBC. First, all drying treatments caused a reduction in MBC immediately after the rewetting, and higher drying intensities induced higher reduction rates in MBC. A reduction of more than 20% in MBC induced the C-saturated conditions for surviving microbes because sufficient concentrations of labile substrate C were released from the dead MBC. Second, repeated DRW cycles caused increases in the microbial growth rates because substrate C was supplied from non-biomass organic C. In conclusion, MBC decreased immediately after DRW due to microbial stress, whereas MBC increased during repeated DRW cycles due to substrate C supplied from non-biomass organic C.     

滨海沙地不同树种人工林生物量及凋落物碳氮养分归还

基于福州市滨海后沿沙地上营造的人工林的调查,以9年生尾巨桉(Eucalyptus urophylla×E.grandis)、木麻黄(Casuarina equisetifolia)、纹荚相思(Acacia aulacocarpa)3种主要人工林为对象,采用Monsi分层切割法(乔木层)和样方收获法(草本层、凋落物层)获取这3种人工林的生物量,研究其生物量分配格局及凋落物碳氮养分归还。结果表明,尾巨桉乔木层地上部分生物量为49.950t·hm^-2,地下部分生物量为15.270t·hm^-2,分别占生态系统总生物量的62.08%和18.98%;草本层生物量为0.698t·hm^-2(0.87%);凋落物层生物量为14.539t·hm^-2(18.07%)。木麻黄乔木层地上部分生物量为51.630t·hm^-2,地下部分为20.270t·hm^-2,分别占生态系统总生物量的62.65%和24.60%;草本层生物量为0.017t·hm^-2(0.02%);凋落物层生物量为10.488t·hm^-2(12.73%)。纹荚相思乔木层地上部分生物量为51.130t·hm^-2,地下部分为13.760t·hm^-2,分别占生态系统总生物量的64.43%和17.34%;草本层生物量为0.093t·hm^-2(0.12%);凋落物层生物量为14.369t·hm^-2(18.11%)。3种人工林地上各器官生物量均表现为:树干>树枝>树皮>树叶。这3种人工林生态系统总生物量与乔木层生物量排序相同,表现为木麻黄(82.40t·hm^-2)>尾巨桉(80.46t·hm^-2)>纹荚相思(79.35t·hm^-2),且生物量分配格局均为乔木层>凋落物层>草本层。3种人工林的净生产力表现为木麻黄(16.21t·hm^-2·a^-1)>尾巨桉(14.00t·hm^-2·a^-1)>纹荚相思(12.51t·hm^-2·a^-1)。凋落物碳氮养分年总归还量表现为木麻黄(3.953t·hm^-2·a^-1)>尾巨桉(3.329t·hm^-2·a^-1)>纹荚相思(2.751t·hm^-2·a^-1)。     

Optimal forest rotation periods: integrating timber production and carbon sequestration benefits in Pinus tabulaeformis plantations on the Loess Plateau,P.R. China

Determining the optimal rotation period was a crucial component of forest sustainable management strategies, especially under climate change. This paper had two objectives: (1) to determine the economic benefits and optimal rotation periods for timber production when coupled to carbon sequestration, as predicted by time series prediction models for Pinus tabulaeformis plantations in China; and (2) to evaluate how different carbon prices and interest rates affected optimal rotation periods using the forest land expectation value. The results suggested that time series prediction models were valuable for estimating timber volumes and carbon sequestrations based on surveys of different-aged stands. Importantly, since integrating carbon sequestrations into timber production benefits did not increase optimal rotation periods, this should promote P. tabulaeformis plantation management. In the sensitivity analysis, a higher carbon price increased the profitability of carbon sequestration and timber production, but not optimal rotation periods, though they were reduced under higher interest rates. In conclusion, incorporating both timber production and carbon sequestration benefits would sharply increase forest-based revenues, while realizing the carbon sequestration potential of P. tabulaeformis plantations. This approach was clearly useful to the development of reforestation/afforestation projects trying to mitigate climate change and also provided a theoretical basis for sustainable forest management.     

豫东南沙地4种人工林土壤团聚体稳定性及有机碳分布研究

为探究林分类型对土壤团聚体稳定性及有机碳分布特性的影响,以豫东南沙地4种典型人工林(桂花、合欢、栾树和女贞)为研究对象,通过野外调查、取土壤样品和室内试验对土壤团聚体和有机碳进行测定、分析。结果表明,①4种林分类型下土壤大团聚体(>0.25mm)含量最高,占林地土壤总团聚体的69.63%%~97.30%,粒径0.25~0.15mm团聚体含量最低,且不同林分类型下各层土壤团聚体的质量分数呈现不同的差异。②表层(0~10cm)土壤团聚体平均质量直径(MWD)、几何平均直径(GMD)均表现为栾树>合欢>桂花>女贞,分形维数(D)排序则与之相反,变化范围为2.515~1.653,栾树的土壤结构稳定性最强。③随土壤团聚体粒径的减小,4种林分土壤有机碳含量总体上呈现先升后降趋势,土壤剖面上也表现出随土层加深而下降。不同林分类型下,土壤有机碳含量差异性表现为合欢最高,栾树最低,变化范围分别为45.76~7.65和17.78~3.49g/kg。④回归分析表明,女贞林分下土壤大团聚体与有机碳含量相关性最强,土壤有机碳可解释17.5%土壤大团聚体含量的变化。研究得出该地区栾树林下土壤团聚体稳定性较强,合欢林下土壤有机碳含量最高。     

云南省思茅松林碳储量动态变化研究

依据云南省历次森林资源清查数据,采用云南省林业调查规划院建立的思茅松生物量与蓄积量模型和碳系数,计算各调查年份的生物量和碳储量,分析云南省39年来思茅松林碳储量、碳密度变化情况。结果表明,思茅松幼龄林碳储量变化趋势为稳中略升,碳密度变化趋势为稳步增大;中龄林碳储量急剧减少,碳密度略有降低;近熟林碳储量稳步增加,碳密度小幅提升;成熟林碳储量变化趋势为减少,碳密度变化趋势为增大;过熟林碳储量变化趋势为减少,碳密度变化趋势为增加。人工林碳储量总体变化趋势为增加,碳密度总体变化趋势为小幅增加;天然林碳储量总体变化趋势为下降,碳密度总体变化趋势为增加。思茅松龄组、起源等结构上的变化趋势有增有减、有升有降,但生物量和碳储量的总体变化趋势为减少,碳密度呈上升趋势。     

一种用水蒸气活化法制活性炭的立式活化炉设计

为了开发新型高效的水蒸气活化法制活性炭的活化设备,选择高铝耐火砖和耐高温、耐腐蚀的310S不锈钢为主要材料,设计一种机械自动匀速加料和出料的立式活化炉,在该活化炉的活化段四周设置冷炉预热用燃气烧嘴,在活化炉中安装多层活化圆盘和刮料耙叶,在活化圆盘上设置环形蒸汽管,并在蒸汽管上均匀开设小孔,使水蒸气与炭料均匀接触,利用活化炉的高温预热水蒸气,确保水蒸气与炭料的活化反应均匀高效。该活化炉具有占地面积小、自动连续加料和出料、活化产量较高的优点。     

森林经营单位级碳储量动态变化研究——以广西热林中心为例

中国林业科学研究院热带林业实验中心从2008年开始进行人工林近自然经营,为了评价经营效果对森林固碳能力的影响,以热林中心2011年、2013年、2015年对238块系统抽样样地数据为基础,采用现有的生物量方程和碳转换系数乔木林碳储量进行估算。结果表明,乔木林碳储量由2011年的605826.95t增加到2015年的721847.04t,年平均增加29005.02t,碳密度由2011年的35.94t·hm^-2增加到2015年的42.34t·hm^-2,但仍小于全国和世界的平均数。针叶林碳储量高于阔叶林,由2011年的413753.07t增加至2015年的479611.05t,年均增加16464.50t,栎类的增长幅度最大,年均增长率64.00%,碳储量最大的树种是马尾松,占总碳储量的62.92%。证明近自然经营能够有效促进森林固碳能力。