利用双指数模型预测中国不同森林带土壤有机碳矿化的动态变化

本文利用土壤培养实验和双指数模型(把土壤有机碳划分为活性碳和缓效性碳库)的方法,来分析确定长白山和祁连山的土壤有机碳的动态变化。分析和拟合土壤有机碳矿化释放的CO2的速率。结果表明:活性碳库占总有机碳的1.0%–8.5%,平均驻留时间的平均值为24天;缓效性碳库占总有机碳的91%–99%,平均驻留时间的平均值为179年。根据缓效性碳的大小和平均驻留时间可以得知,祁连山森林土壤的有机碳较长白山的难分解。通过分析影响森林土壤有机碳矿化的因素––土壤粘粒含量、海拔和温度,结果显示两种森林土壤有机碳的分解快慢与其温度正相关,并且长白山和祁连山的累积的土壤有机碳和缓效性碳的含量随土壤粘粒含量的增加而呈线性增加,其相关系数分别为0.7033和0.6575,充分表明温度和土壤粘粒含量对土壤有机碳的矿化有较大的影响。     

亚热带日本落叶松中、幼龄林土壤有机碳密度和分配特征

本文基于32块样地土壤数据,对亚热带日本落叶松中、幼龄林的土壤有机碳密度及其分配特征进行了分析,结果发现:(1)中龄林的有机碳含量、有机碳密度明显高于幼龄林;(2)混交林的有机碳含量、有机碳密度明显高于纯林;(3)0~80 cm的土壤有机碳密度为172.25 t/hm2。有机碳主要集中在表土层0~20 cm处,此表土层有机碳密度分别是土层20~40 cm、40~80 cm的175.21%、129.52%。在土层相同的情况下,随着土壤深度的增加,其土壤有机碳密度呈下降趋势;(4)与适宜亚热带地区生长的造林树种——杉木相比,日本落叶松林的土壤有机碳含量、土壤有机碳密度均明显高于20年生杉木人工林,说明日本落叶松林土壤的固碳能力大于杉木人工林,从侧面也反映了同样作为亚热带地区的造林树种,日本落叶松林要优于杉木人工林。     

低温胁迫下外源有机酸对长白落叶松幼苗生理生化特性的影响

根据东北林区森林凋落物淋洗液中草酸、柠檬酸和苹果酸的浓度范围,用不同浓度的上述3种外源有机酸溶液叶面喷施长白落叶松幼苗,再置于4℃下进行低温胁迫,研究有机酸对低温逆境条件下长白落叶松幼苗多种生理生化指标的影响,探讨低温胁迫下外源有机酸对苗木抗寒性的调控机制。结果表明:适当浓度的3种有机酸均降低低温胁迫后长白落叶松的质膜透性和MDA含量,不同程度提高SOD,POD,APX和CAT等多种抗氧化酶活性及脯氨酸和可溶性蛋白含量,减缓叶绿素的下降趋势。外源有机酸能通过促进长白落叶松体内保护酶活性提高,降低膜脂过氧化程度,增强渗透调节能力和细胞清除活性氧的能力,最终明显提高其低温抵御能力。3种有机酸对上述生理生化特性的影响强弱表现为:柠檬酸>苹果酸>草酸,适宜的最佳使用浓度为5.0mmol.L-1。     

辽东山区不同林龄落叶松林分林木各器官生物量分配特征

以辽东山区落叶松人工林为研究对象,采用样地调查和实测生物量等方法,测定落叶松幼龄林、中龄林和近熟林的生物量及其在一个年龄序列上的空间分配特征。结果表明:不同林龄落叶松林分生物量分布依次为中龄林(119.39t·hm~(-2))近熟林(94.69t·hm~(-2))幼龄林(31.44t·hm~(-2))。各器官生物量大小关系略有差异,中龄林和近熟林为树干树根树枝树叶;而幼龄林为树干树枝树根树皮树叶。落叶松人工林经营应定期采取抚育间伐,改善林木生长条件,提高落叶松人工林的生产力,以实现生态系统健康、稳定发展。     

喀斯特洼地土壤有机碳分布特征及影响因素

为揭示沉积在洼地不同位置土壤有机碳含量的分布特征和相关影响因素,以西南喀斯特典型小流域内洼地底部、落水洞不同部位土壤为研究对象,采集0~150 cm土壤剖面的土样,测定相关理化性质指标,分析土壤有机碳含量随空间位置的变化特征,并探讨土壤有机碳含量与理化性质的相关性。结果表明:落水洞、洼地底部土壤有机碳含量与土壤有机碳储量均为表层最高,呈表聚化现象;落水洞、洼地底部土壤有机碳含量与全氮含量均呈显著正相关,而与土壤含水率相关性不显著(P>0.05);落水洞土壤有机碳含量平均值大于洼地底部土壤有机碳含量平均值,土壤有机碳含量与土壤容重、总孔隙度分别呈极显著负相关、极显著正相关(P<0.01),与土壤pH值相关性不显著,表明落水洞土壤有机碳含量变化主要受土壤容重、总孔隙度等物理性质影响显著;洼地底部土壤有机碳含量变异系数大于落水洞土壤有机碳含量变异系数,土壤有机碳含量与土壤pH值呈显著的负相关关系(P<0.05),与土壤容重、总孔隙度相关性不显著,表明洼地底部土壤有机碳含量的分布特征主要受土壤pH值的影响。     

Soil organic carbon and aggregation under poplar based agroforestry system in relation to tree age and soil type

The poplar based agroforestry system improves aggregation of soil through huge amounts of organic matter in the form of leaf biomass. The extent of improvement may be affected by the age of the poplar trees and the soil type. The surface and subsurface soil samples from agroforestry and adjoining non-agroforestry sites with different years of poplar plantation (1, 3 and 6 years) and varying soil textures (loamy sand and sandy clay) were analyzed for soil organic carbon, its sequestration and aggregate size distribution. The average soil organic carbon increased from 0.36 in sole crop to 0.66% in agroforestry soils. The increase was higher in loamy sand than sandy clay. The soil organic carbon increased with increase in tree age. The soils under agroforestry had 2.9–4.8 Mg ha⁻¹ higher soil organic carbon than in sole crop. The poplar trees could sequester higher soil organic carbon in 0–30 cm profile during the first year of their plantation (6.07 Mg ha⁻¹ year⁻¹) than the subsequent years (1.95–2.63 Mg ha⁻¹ year⁻¹). The sandy clay could sequester higher carbon (2.85 Mg ha⁻¹ year⁻¹) than in loamy sand (2.32 Mg ha⁻¹ year⁻¹). The mean weight diameter (MWD) of soil aggregates increased by 3.2, 7.3 and 13.3 times in soils with 1, 3 and 6 years plantation, respectively from that in sole crop. The increase in MWD with agroforestry was higher in loamy sand than sandy clay soil. The water stable aggregates (WSA >0.25 mm) increased by 14.4, 32.6 and 56.9 times in soils with 1, 3 and 6 years plantation, respectively, from that in sole crop. The WSA >0.25 mm were 6.02 times higher in loamy sand and 2.2 times in sandy clay than in sole crop soils.     

不同林龄鹅掌楸人工林土壤团聚体及其有机碳状况

[目的]研究鹅掌楸人工林土壤团聚体及其有机碳状况,为合理经营鹅掌楸人工林、促进林业可持续发展提供依据.[方法]以不同林龄鹅掌楸人工林(幼龄林、中龄林、成熟林)土壤为研究对象,通过野外调查和室内分析,测定各粒级土壤团聚体及其有机碳含量,分析土壤团聚体稳定性主要指标即平均重量直径(MWD)、几何平均直径(GMD),阐明土壤...     

土壤有机碳损失及影响因子研究进展

综述了国内外关于土壤有机碳储量及分布、土壤有机碳组成及分组、土壤有机碳的迁移和流失产生的机理及其后果、土壤有机碳矿化及其影响因素、外源物质对土壤有机碳矿化的激发效应及其机理等方面的研究进展。     

Short- and long-term responses of total soil organic carbon to harvesting in a northern hardwood forest

The long-term response of total soil organic carbon pools (‘total SOC’, i.e. soil and dead wood) to different harvesting scenarios in even-aged northern hardwood forest stands was evaluated using two soil carbon models, CENTURY and YASSO, that were calibrated with forest plot empirical data in the Green Mountains of Vermont. Overall, 13 different harvesting scenarios that included four levels of aboveground biomass removal (20%, 40%, 60% and 90%) and four different rotation lengths (60 year, 90 year, 120 year, and No Rotation (NR)) were simulated for a 360 year period. Simulations indicate that following an initial post-harvest increase, total SOC decreases for several decades until carbon inputs into the soil pool from the re-growth are greater than losses due to decomposition. At this point total SOC begins to gradually increase until the next harvest. One consequence of this recovery pattern is that between harvests, the size of the SOC pool in a stand may change from −7 to 18% of the pre-harvest pool, depending on the soil pool considered. Over 360 years, the average annual decrease in total SOC depends on the amount of biomass removed, the rotation length, and the soil pool considered. After 360 years a stand undergoing the 90yr-40% scenario will have 15% less total SOC than a non-harvested stand. Long-term declines in total SOC greater than 10% were observed in the 60yr-60%, 60yr-90%, and 90yr-90% scenarios. Long-term declines less than 5% were observed in scenarios with 120 year rotations that remove 60% or less of the aboveground biomass. The long-term decreases simulated here for common management scenarios in this region would require intensive sampling procedures to be detectable.     

树龄对日本落叶松木材物理力学性质的影响

选取日本落叶松为试验材料,开展不同树龄日本落叶松物理力学性质的比较研究.结果表明:43年生、30年生和17年生日本落叶松木材气干密度分别为0.607,0.567和0.507 g/cm3,气干体积干缩率分别为7.7％,7.7％和7.1％;全干到气干体积湿胀率分别为5.1％,4.9％和4.5％;抗弯弹性模量分别为17.527,16.775和12.510 GPa,抗弯强度分别为121.1,110.3和90.9 MPa,顺纹抗压强度分别为56.8,51.8和44.0 MPa.随着树龄增大,日本落叶松木材密度、顺纹抗压强度、抗弯强度和抗弯弹性模量等各项物理力学性能指标提高,差异干缩逐渐变小.日本落叶松木材的气干密度与抗弯弹性模量、抗弯强度、顺纹抗压强度呈线性正相关,相关系数分别为0.760,0.816和0.900.     

不同林龄华北落叶松人工林林分生长与土壤养分的关系

为了给森林经营和资源保护提供科学依据,基于塞罕坝机械林场不同林龄(12a生幼龄林,27a生中龄林,40a生近熟林)华北落叶松人工林标准地的调查资料,采用Pearson相关分析对林分生长与土壤养分之间的关系进行探讨,结果表明:随着华北落叶松人工林林龄的增加,土壤pH值由5.76降到5.52,土壤酸性逐渐增强,速效磷含量变化范围为4.67~7.64mg/kg,与pH值变化一致,呈逐渐降低趋势;土壤有机质、全氮、速效钾以及全钾含量在中龄林中最高,分别为39.02g/kg、2.32g/kg、130.56mg/kg和17.6g/kg,近熟林次之,幼龄林最低。其中,全氮含量在各个林龄阶段差异显著(P0.05),全钾含量差异极显著(P0.01);土壤全磷含量和碱解氮含量随着华北落叶松人工林林龄的增加而增加,且在各个林龄阶段全磷含量差异显著(P0.05)、碱解氮含量差异极显著(P0.01)。总的来说,不同林龄华北落叶松土壤养分含量差异较大,幼龄林和中龄林对土壤养分的需求较高。     

白桦天然次生林土壤有机碳的空间分布特征

为了了解冀北地区白桦天然次生林土壤有机碳的分布特征,以承德市围场县、丰宁县和张家口赤城县白桦天然次生林为研究对象,对其土壤有机碳含量进行了测定分析。结果表明:4个地区的白桦天然次生林各层土壤有机碳含量由高到低顺序依次为赤城县黑龙山、围场县孟滦、丰宁县四岔口、围场县燕格柏,其0~10cm的土壤有机碳含量依次为108.07g/kg、65.61g/kg、52.33g/kg和30.04g/kg;土壤有机碳含量有随海拔升高而上升的趋势;各地区白桦天然次生林的土壤有机碳含量都以表层最高,随着土层深度的增加,土壤有机碳含量呈现逐渐降低的趋势,且随深度的增加,土壤碳含量下降速度逐渐趋缓。     

不同栽培林龄和轮次的杨树人工林土壤理化性质

采用空间代替时间的方法,构建了不同栽培林龄和轮次的杨树人工林试验样地,测定了土壤主要物理化学性质.结果表明,不同栽培轮次土壤密度值表现为1轮11年生＞2轮9年生,随着林龄增加,土壤密度呈逐渐下降趋势,表现为2轮3年生＞2轮6年生＞2轮9年生,且各样地之间呈显著差异;土壤饱和持水量、毛管持水量、毛管孔隙度和总孔隙度在各样地之间的变化无明显差异,而土壤非毛管孔隙度的变化则呈显著差异,在不同林龄样地上呈极显著差异.试验结果还显示,表层0～10 cm土壤中各养分元素的含量都对应地高于10～ 30 cm土层的含量,而pH值则呈相反的变化趋势;在不同栽培轮次和林龄的杨树人工林样地上对应土层土壤养分元素无明显的变化规律.     

Effects of harvest management practices on forest biomass and soil carbon in eucalypt forests in New South Wales,Australia: Simulations with the forest succession model LINKAGES

Understanding long-term changes in forest ecosystem carbon stocks under forest management practices such as timber harvesting is important for assessing the contribution of forests to the global carbon cycle. Harvesting effects are complicated by the amount, type, and condition of residue left on-site, the decomposition rate of this residue, the incorporation of residue into soil organic matter and the rate of new detritus input to the forest floor from regrowing vegetation. In an attempt to address these complexities, the forest succession model LINKAGES was used to assess the production of aboveground biomass, detritus, and soil carbon stocks in native Eucalyptus forests as influenced by five harvest management practices in New South Wales, Australia. The original decomposition sub-routines of LINKAGES were modified by adding components of the Rothamsted (RothC) soil organic matter turnover model. Simulation results using the new model were compared to data from long-term forest inventory plots. Good agreement was observed between simulated and measured above-ground biomass, but mixed results were obtained for basal area. Harvesting operations examined included removing trees for quota sawlogs (QSL, DBH >80 cm), integrated sawlogs (ISL, DBH >20 cm) and whole-tree harvesting in integrated sawlogs (WTH). We also examined the impact of different cutting cycles (20, 50 or 80 years) and intensities (removing 20, 50 or 80 m³). Generally medium and high intensities of shorter cutting cycles in sawlog harvesting systems produced considerably higher soil carbon values compared to no harvesting. On average, soil carbon was 2–9% lower in whole-tree harvest simulations whereas in sawlog harvest simulations soil carbon was 5–17% higher than in no harvesting.     

间伐对华北落叶松人工林凋落物和土壤理化性质的影响研究

为了了解间伐对华北落叶松人工林凋落物和土壤理化性质的影响,利用试验测定和定量统计的方法,分析比较了河北省塞罕坝机械林场间伐和未间伐华北落叶松人工林凋落物层和土壤层(0~10cm、10~20cm)的理化性质,结果显示:与未间伐林分相比,50%强度间伐6a后林分内凋落物层生物量、质量含水量、有机质含量和全氮含量分别提高了17.25%、6.05%、9.08%、31.94%;土壤层的质量含水量、土壤容重和有机质含量有所上升(0~10cm土壤层分别增加4.84%、11.11%、15.67%;10~20cm土壤层分别增加10.25%、12.50%、28.97%),而全氮含量呈下降趋势(0~10cm土壤层减少20.83%;10~20cm土壤层减少16.67%);土壤pH值亦有所下降。研究进一步证实,通过间伐能够增加地表凋落物生物量,改变有机质分解速率,从而在一定程度上影响土壤的理化特性。     

Forest structure and C stocks in natural Fagus sylvatica forest in southern Europe: The effects of past management

Managed forests often differ substantially from undisturbed forests in terms of tree structure and diversity. By altering the forest structure, management may affect the C stored in biomass and soil. A survey of 58 natural stands located in the south-westernmost limit of European beech forests was carried out to assess how the C pools are affected by the changes in tree structural diversity resulting from past management. The mean tree density, basal area and the number of large trees found in unmanaged forests were similar to those corresponding to virgin beech forests in Central Europe, whereas large live trees were totally absent from partially cut stands. Analysis of the Evenness index and the Gini coefficient indicated high structural diversity in the three stand types. The results of the Kolmogorov–Smirnov test used to compare the diameter distributions of each group revealed significant differences between stand types in terms of distributions of total tree species and of Fagus sylvatica.

The mean C stocks in the whole ecosystem – trees, litter layer and mineral soil – ranged from 220 to 770 Mg ha⁻¹ (average 380 Mg ha⁻¹). Tree biomass (above and belowground), which averaged 293 Mg C ha⁻¹, constituted the main C pool of the system (50–97%). The statistical test (Kolmogorov–Smirnov) revealed differences in the distribution of C pools in tree biomass between unmanaged and partially cut stands. As a consequence of the presence of large trees, in some unmanaged stands the C stock in tree biomass was as high as 500–600 Mg C ha⁻¹. In the partially cut stands, most of the C was mainly accumulated in trees smaller than 20 cm dbh, whereas in unmanaged stands the 30% of tree C pool was found in trees larger than 50 cm dbh. Furthermore, many unmanaged stands showed a larger C pool in the litter layer. The C content of mineral soils ranged from 40 to 260 Mg C ha⁻¹ and it was especially high in umbrisols. In conclusion, the implementation of protective measures in these fragile ecosystems may help to maintain the highly heterogeneous tree structure and enhance the role of both soils and trees as long-term C sinks.     

不同间伐强度对长白落叶松-红松林植物多样性和土壤特性的影响

为了提高长白落叶松-红松林的生产力和生物多样性,2005年秋对长白落叶松人工林进行疏伐,伐后林冠下栽植4年生红松。2012年秋又对上层长白落叶松进行生长伐,设计轻度、中度和强度3种间伐强度和1组未间伐林分(对照),分析5年后不同间伐强度对林下植物多样性和土壤理化性质的影响。结果表明:①抚育间伐能提高林下植物多样性,林下灌木层植物丰富度随着间伐强度的增加而增加,轻度、中度和强度间伐差异显著(p<0.05)。林下灌木层植物多样性指数随着间伐强度的增加而增加,对照与中度间伐、强度间伐差异显著(p<0.05),但中度间伐和强度间伐差异不显著。林下草本层植物的丰富度和多样性指数随着间伐强度的增加而增加,各间伐强度均与对照差异显著(p<0.05),但轻度间伐和中度间伐差异不显著。②适度抚育间伐能改善土壤的理化性质,随着间伐强度的增加,土壤容重有所降低,土壤孔隙度和持水量有所提高;土壤pH值呈现先升高后略有降低的趋势,全K、速效K、全P、速效P、全N、速效N含量先升高后略有降低,其中中度间伐效果最好。综合考虑,对长白落叶松林分进行中度间伐较为适宜。     

湖南天然林生物因子与土壤养分、物理特性的关系

天然林林地土壤资源及特性的调查，采样，化验分析，获得了64个森林类型306个天然林标准地林地土壤资料，分析测试土壤样品1465个，测定理化指标26780项次，对天然林土壤剖面进行了较全面的调查和分析，研究出天然林生物因子与其土壤理化因子相关紧密，总结出天然林林地土壤粗腐殖质，有机质，氮，磷的全量及速效量的含量，总孔隙度，非毛管孔隙度与水文特性均是落叶阔叶林＞常绿阔叶林＞针叶林的规律。     

不同土地利用方式对土壤有机碳、氮含量的影响

土壤有机C、N的定量动态变化是评价不同土地利用方式对土壤质量影响的重要内容。本文比较了研究地区种植黑麦草(Lolium multiflorum Lam．)、百喜草(Paspalum notatum Flugge．)、桔树(Citrus reticulata Blanco．)和马尾松(Pinus Massoniana Lamb．)的四种土地利用方式对植物生物量和土壤有机C、N多年变化的影响。试验初期，四种土地利用方式的植物生物量几乎处于同一水平。经过10年长期试验后，黑麦草和百喜草的累计生物量分别是桔树的3．68和3．75倍，马尾松的2．06和2．14倍。地下部生物量的差异更为明显，黑麦草和百喜草两种草类地下部累计生物量都较桔树和马尾松高10倍之多。这表明草类较之乔木更有利于提高土壤有机C、N的含量。土壤有机C、N的含量变化主要发生在0．40cm土层。统计计算表明，10年期问，种植黑麦草和百喜草可使土壤有机C、N贮量每公顷分别约增加1．5吨和0．2吨，而种植桔树使土壤有机C、N贮量每公顷分别约减少1．2吨和0．02吨，种植马尾松使土壤有机C、N贮量每公顷分别约减少0．4吨和0．04吨。表4参10。     

Estimation of biomass and carbon stocks in plants,soil and forest floor in different tropical forests

An accurate characterization of tree carbon (TC), forest floor carbon (FFC) and soil organic carbon (SOC) in tropical forest plantations is important to estimate their contribution to global carbon stocks. This information, however, is poor and fragmented. Carbon contents were assessed in patula pine (Pinus patula) and teak (Tectona grandis) stands in tropical forest plantations of different development stages in combination with inventory assessments and soil survey information. Growth models were used to associate TOC to tree normal diameter (D) with average basal area and total tree height (H_T), with D and H_T parameters that can be used in 6–26 years old patula pine and teak in commercial tropical forests as indicators of carbon stocks. The information was obtained from individual trees in different development stages in 54 patula pine plots and 42 teak plots. The obtained TC was 99.6 Mg ha⁻¹ in patula pine and 85.7 Mg ha⁻¹ in teak forests. FFC was 2.3 and 1.2 Mg ha⁻¹, SOC in the surface layer (0–25 cm) was 92.6 and 35.8 Mg ha⁻¹, 76.1 and 19 Mg ha⁻¹ in deep layers (25–50 cm) in patula pine and teak, respectively. Carbon storage in trees was similar between patula pine and teak plantations, but patula pine had higher levels of forest floor carbon and soil organic carbon. Carbon storage in trees represents 37 and 60% of the total carbon content in patula pine and teak plantations, respectively. Even so, the remaining percentage corresponds to SOC, whereas FFC content is less than 1%. In summary, differences in carbon stocks between patula pine and teak trees were not significant, but the distribution of carbon differed between the plantation types. The low FFC does not explain the SOC stocks; however, current variability of SOC stocks could be related to variation in land use history.