不同间伐强度下天然次生林凋落物分解进程研究

以辽宁东部地区天然次生林的典型林型-柞树为主的杂木林为研究对象,在不同间伐强度的杂木林内采取埋置分解袋并定期观测的方法研究林分凋落物的分解规律。观测结果表明:辽东天然次生林凋落物分解过程存在着明显的季节变化,可划分为4个时期;用Olson指数衰减模型拟合了凋落物分解的年度变化动态,凋落物在刚凋落的前3年分解迅速,分解率50%以上。3年以后分解速率明显下降;杂木林内凋落物分解速度随间伐强度的增大而减小,间伐后湿度变小是主要原因;凋落物分解速度和林分凋落量的动态消长过程决定凋落物贮量和土壤养分状况,弱度间伐林分和未间伐林分凋落物贮量、表层土壤有机质含量明显高于中度间伐林分和强度间伐林分。     

天山森林凋落物和枯枝落时层的研究

通过１９９２－１９９５年的定位试验，对天山森林凋落物和枯枝落叶的主要性质进行了研究。结果表明，天山森林生态系统中养分运转具有独特性：（１）森林年凋落量较低，为２．１ｔ／ｈｍ＾２凋落物的季节动态变化呈单蜂型；（２）以凋落物形式的养分年归还量为Ｃａ〉Ｎ〉Ｋ〉Ｐ。在凋落之前，大部分Ｎ、Ｐ、Ｋ被转移，Ｋ的转移量最大，而Ｃａ则相对富集，归还量最小；（３）枯枝落叶层中养分贮量和蓄水量高，但有机物质分解率较低；     

间伐抚育对小五台山华北落叶松林下枯落物持水特性的影响

从涵养水源角度出发,通过野外调查与浸水实验,对河北省小五台山华北落叶松林下枯落物不同间伐强度下枯落物储量及持水特性进行了研究.结果表明,未分解层和半分解层所占总储量比例在间伐前后存在明显差异.间伐抚育前,未分解层所占总储量比例小于半分解层,间伐后则相反.枯落物储量和最大持水量在不同间伐强度间变化顺序相同,均为:弱度间伐＞对照＞中度间伐＞强度间伐＞超强度间伐.枯落物储量和最大持水量在不同间伐强度间存在显著差异(p＜o.01),最大持水率在不同间伐强度间差异不显著(p＞0.05);在以保留木数量为600株/hm2的强度间伐时,有效拦蓄量最大为162.41 t/hm2,相当于16.241 mm降水.     

抚育间伐对麻栎次生林枯落物持水性的影响

抚育间伐作为森林经营的一项重要手段,能够影响枯落物持水性能。以桥山林区麻栎次生林为对象,通过典型取样法、烘干法、浸泡法,探讨了不同间伐强度(未间伐、间伐15%—轻度间伐、间伐25%—中度间伐、间伐35%—重度间伐)对样地内枯落物持水效应的影响。结果表明:(1)间伐使枯落物总储量减少,随着间伐强度提高分解层储量先增多后减少,中度间伐时最多(3.833t/hm~2),轻度间伐次之(21.838t/hm~2);(2)轻度间伐下枯落物最大持水量最高(7.60mm),重度间伐强度下最小(6.21mm);(3)轻度间伐下枯落物总有效拦蓄量及分解层有效拦蓄量都最大,分别为56.79,38.56t/hm~2,未分解层有效拦蓄量为18.21t/hm~2,仅次于未间伐样地(22.59t/hm~2);(4)不同间伐强度下枯落物吸水速率随浸水时间的增加逐渐减小,且两者均显著相关,轻度间伐强度下吸水速率均最大。以上结果表明,轻度间伐能提高麻栎次生林枯落物持水性能,可为桥山林区麻栎次生林森林抚育间伐提供参考。     

青海省大通县主要造林树种枯落物水文效应研究

枯枝落叶在森林生态系统中占有极其重要的地位。本文对青海省大通县主要植被类型的枯落物,从持水能力、失水特性以及有效拦蓄量3方面分析。结果表明:（1）大通县鹞子沟主要造林地枯落物最大持水量变动范围为5.85～34.16t/hm²,其中最大的云杉天然次生林为34.16t/hm²,最小的华北落叶松林为5.85t/hm²。云杉林下的枯落物最大持水量和最大持水率普遍高于沙棘林和华北落叶松林下的枯落物。（2）枯落物的持水量在失水实验开始的1～2h内迅速下降,之后速度变慢。说明枯落物拦蓄地表径流后,随着枯落物湿润程度的减小,失水能力降低,至达到枯落物的自然含水量。（3）在对枯落物有效拦蓄量的比较中发现,云杉林有效拦蓄量最大,其次是沙棘天然次生林,最小的为沙棘人工林。     

桉树凋落物对土壤微生物群落的影响:基于控制实验研究

全面认识桉树种植对土壤微生物群落结构和功能的影响及机制,对于阐明单一物种对生态系统服务功能的影响具有重要意义。通过室内小盆模拟控制试验,采用随机区组设计,以土壤碳、氮含量有显著差异的3种天然次生林土壤为对象,以不添加凋落物的处理和添加天然次生林混合凋落物的处理为对照,研究桉树凋落物对土壤微生物群落结构及功能的影响。结果表明:(1)与天然次生林的混合凋落物相比,桉树凋落物具有较高的碳含量和较低的氮含量,其碳氮比也较高;(2)添加桉树凋落物的土壤中细菌、真菌、放线菌以及磷脂脂肪酸的总丰度显著高于不添加凋落物的土壤,但是显著低于添加天然次生林混合凋落物的土壤,并且不同凋落物处理下土壤微生物群落的磷脂脂肪酸组成存在显著差异;(3)不同凋落物处理下土壤微生物群落的碳代谢方式差异显著,添加桉树凋落物的土壤微生物群落的碳代谢功能优于未添加凋落物的处理,但是显著低于天然次生林混合凋落物处理的土壤,包括:碳代谢的活性和多样性。综上所述,与天然次生林本身的凋落物相比,桉树凋落物影响下的土壤微生物群落的生物量、多样性和代谢活性均较低,表明桉树凋落物为土壤微生物群落提供生境和食物的能力较弱。     

模拟氮沉降对甜槠林分凋落物及主要养分归还量的影响

选取亚热带典型的常绿阔叶甜槠林为研究对象,从2011年4月至2013年6月进行模拟氮(N)沉降试验,以探讨甜槠林凋落物养分归还量对N沉降的响应。氮沉降水平分别为:对照(CK,0 kg N hm-2a-1),低氮(LN,50 kg N hm-2a-1),高氮(HN,100 kg N hm-2a-1),高氮+磷(HN+P,100 kg N hm-2a-1+50 kg P hm-2a-1),每个处理重复3次。在模拟氮沉降2 a后,于2012年7月开始收集各样地的凋落物样品,分析凋落物及其养分归还量。结果表明:不同处理凋落物量没有显著差异,表明氮沉降增加没有显著提高林分凋落物产量;不同处理落叶、落枝中N、P、K、Ca、Mg含量均无显著差异,表明氮沉降亦没有显著增加凋落物各养分含量;模拟氮沉降处理均增加了各养分元素年归还量,但不同元素对N沉降的响应不同。N、K和Mg年归还量与CK存在显著差异,而P和Ca年归还量与CK处理无显著差异。     

三峡库区天然次生林凋落物森林水文效应研究

对三峡库区上游四面山4种天然次生林凋落物储量、分解强度及持水力进行了研究.结果表明,4种林分凋落物储量最大的是天然阔叶林(107.09 t/hm2),天然针阔混交林(70.18 t/hm2)和天然针叶林(66.65 t/hm2)次之,楠竹林(35.37 t/hm2)最小;凋落物最大持水量和持水力均呈现出天然针阔混交林(89.95 t/hm2,2.25)最大,天然阔叶林(67.33 t/hm2,1.89)次之,而天然针叶林(39.83 t/hm2,1.66)和楠竹林(28.07 t/hm2,1.85)较差的趋势.因此,从凋落物持水特征来分析,4种天然次生林中,天然针阔混交林的森林水文效应最好,其次是天然阔叶林,而楠竹林和天然针叶林均较差,不适宜在该区域内的水土保持植被建设中应用.     

不同梯度氮沉降对亚热带甜槠林凋落物及养分的影响

[目的]分析不同梯度氮沉降作用下亚热带常绿阔叶甜槠(Castanopsis eyrei)林凋落物量及养分变化规律,从而为亚热带地区氮沉降研究提供数据参考与理论依据。[方法]对安徽省仙寓山地区设置不同梯度施氮对照试验,长期实地监测甜槠林凋落物量及其养分的响应状况。[结果]凋落物量大小顺序为:高氮加磷(HN+P)低氮(LN)高氮(HN)对照CK,不同处理间的差异未达到显著水平;但是落叶量LN与CK之间差异显著(p=0.023)。各处理凋落物量的月变化模式均呈双峰型,分别在4和11月达到峰值;凋落物中各组分所占比例从大到小均为:叶果枝碎屑花皮;施肥处理不同程度上改变了落果量的比重:HN+P(27%)HN(25%)CK=LN(23%)。甜槠林C,N,P,K,Ca,Mg这6种大量元素的养分年归还量共计:HN+P 4.62t/(hm2·a)CK 4.44t/(hm2·a)HN 4.17t/(hm2·a)LN 3.96t/(hm2·a);不同处理各养分(K除外)归还量均表现为上述关系,且HN+P与CK之间的N,P的养分归还量差异显著(p=0.047;0.023)。对于各组分而言,落叶的养分归还量占年养分归还量的52%~58%。[结论]模拟不同梯度的氮沉降处理在一定程度上改变了甜槠林凋落物总量的大小及其组成比例,且影响到其他养分的吸收及归还量。     

鄂中低丘区不同演替阶段森林凋落物和土壤水文特征

采用空间代替时间的方法,研究鄂中低丘区太子山林场针叶林、针阔混交林和落叶阔叶林3个不同演替阶段(共8类林分)林下凋落物和土壤的水文特性.结果表明:太子山林场3个演替阶段的林下凋落物总量以针阔混交林最大(介于9.76～12.01 t/hm2之间),林下凋落物最大持水率以落叶阔叶林最高;针阔混交林与落叶阔叶林林下凋落物对降水的有效拦蓄量较高,但两者差异不显著,其中麻栎混交林的有效拦蓄量最大(16.81 t/hm2);各林分类型0-40 cm土层滞留贮水量与饱和贮水量排序均为针叶林＜针阔混交林＜落叶阔叶林,麻栎混交林的饱和贮水量最大(2 145.8 t/hm2).综合分析表明,落叶阔叶林的持水效果最优,该区植被恢复时要注意促进林分向落叶阔叶林的方向演替.     

华北山地6种天然次生林土壤氮素的空间异质性特征

 利用地统计学理论和方法研究华北山地次生林区6种天然次生林土壤氮素的空间异质性特征。结果表明:1)次生阔叶林土壤总氮质量分数相对较高（3 1004 500 mg/kg）,而针叶林相对较低（9001 300 mg/kg）,各森林类型土壤中有效NH4+-N质量分数均高于有效NO3--N,形成以NH4+-N占优势的氮营养生境;2)针阔混交林中,土壤全氮的变异强度最大,变异的空间相关性较差（随机性变异占总变异的42.7%）,针叶林中,全氮空间变异强度相对较弱,但以自相关变异为主（结构方差比为72.2%81.0%）,呈现弱的斑块分布特征;3)阔叶林中,NH4+-N具有很强的空间自相关变异,NO3--N异质性程度相对较弱,针叶林中,NH4+-N变异强度较小,而NO3--N空间变异却相对明显;4)不同森林类型对土壤全氮及各有效氮形态的空间异质性特征有影响;5)植被种类、植被组成、植被多样性等因素的差异及由此导致的树种空间分布格局是影响总氮量及氮矿化,进而导致氮素不同形态在林分间甚至林分内不同空间样点间异质性形成的重要原因。     

木荷林凋落物的归还动态及分解特性

通过对杭州常绿阔叶林中凋落物的定位观测研究表明,该系统中年均凋落物量为5.85t/hm2,其中以叶最多,占总量的79.5%,枝果较少,分别占7.1%和13.4%。归还动态呈双峰型,即4月和9月为2次高峰。凋落物的半分解时间为1.59a,分解动态呈指数衰减规律。凋落物的年养分归还量达223.69kg/hm2。木荷林中凋落物的现存量为7.47t/hm2。平均分解率为45.18%。林分中凋落物量还处于增长阶段。     

基于RUSLE的2010年商南县土壤侵蚀特征分析

[目的]以长江源头陕西省商南县为例,分析县域土壤侵蚀空间分布,为正确认识与防治长江上游水土流失和做好水土保持防治工作提供科学依据。[方法]基于Landsat TM7和ETM+影像,获取商南县2010年土地利用信息,采用修正通用土壤流失方程(RUSLE)确定方程中各影响因子,对商南县土壤侵蚀现状进行定量评价。[结果]林地是商南县主要土地利用类型,占县域总面积的87.05%,其次是耕地(9.43%)、居民地(2.82%)、水体(0.64%)、未利用地和草地(0.06%)。受坡耕地和低覆盖林草地的影响,商南县2010年土壤侵蚀较严重,平均侵蚀模数4 953.76t/(km2·a)。受侵蚀(轻度以上)面积1 319.3km2,占总面积的57.03%。强度和极强度侵蚀级别面积所占比例为24.10%,其次为轻度侵蚀级别,面积为14.31%,中度和剧烈侵蚀级别面积分别为6.23%,12.39%。剧烈和强度侵蚀主要分布在北部、中部及东南部的山区地段的坡耕地。虽然强度和剧烈侵蚀级别面积比例不是很高,但对该县总侵蚀量的贡献最大,达到52.29%。[结论]不适宜的土地利用是引起严重土壤侵蚀的主要原因;应将县域北部、中部及东南部山区的坡耕地作为防治的重点。     

Studies on Material Cycling in Evergreen Broad-Leaved Forest Ecosystem in Hangzhou: Ⅱ . Dynamics and Decomposition Characteristics of Litter

Through the long-term plot study on the litter and its decomposition in the evergreen broad-leaved forest ecosystem in Hangzhou for more than two years,it was resulted that the annual litter production was 5.85 t ha^-1,most of which was the fallen leave (79.5 percent) and the withered branches and fruits were far less (7.1 and 13.4 percents respectively).The dynamics of the fallen litter was shown as a curve of two-peak pattern which appeared in April and September each year.The half-life of the litter was 1.59 years.The decay rate of the litter attenuted as an exponential function.The annual amount of the nutrient returned to the ground through the litter was as large as 223.69kg ha^-1.The total current amount of the litter on the ground was 7.47t ha^-1.The decay rate in the first half of a year was 45.18 percent.This ecosystem remained in the stage of litter increasing with time.     

贵州省喀斯特阔叶林降雨截留分配特征

[目的]对贵州省喀斯特阔叶林降雨截留分配特征进行研究,为喀斯特地区水土保持和森林生态功能分析提供参考。[方法]以贵州喀斯特阔叶林的降雨分配特征为研究对象,利用2015年9月至2016年3月间野外实测的25场降水数据对森林林冠层、灌木层的降雨截留分配特征进行研究。[结果]观测期内降雨以小雨和中雨为主,降雨总量为208.25mm;树干流总量为21.83mm,占降雨总量的10.48%,变化范围为0~14.3%;林间穿透雨总量为186.89mm,占降雨总量的89.7%。灌木层截留总量为34.86mm,占降雨总量的16.74%;林冠截留的总量为22.58mm,占同期降雨的10.84%。当林外降雨量大于1.15mm时,研究区内开始产生树干流,且树干流与林外降雨量呈线性正相关关系;灌木截留量随着降雨量的增大而增大,但林冠层截留率与降雨量之间没有明显的相关关系。[结论]喀斯特阔叶林对降雨具有较强的截留和再分配作用,对区域水量平衡和水土保持具有重要影响。     

Available phosphorus forms in forest soils and their possible ecological significance

Abstract

For a range of northern N.S.W. forest soils typical of Australian east coast forests, both inorganic and organic P have been determined on sequential soil extracts. Organic P was present in each extract, and in most extracts was a high proportion of the total P, regardless of soil type. Using the sum of the P concentrations in the most neutral extracts as an index of available P, the organic component ranged from 352 to 88% of the total available P. Soil parent material appeared to exert the strongest influence on both soil total P and on the proportion of organic P/total P which ranged from 26% to 81%. The results have been discussed in relation to soluble organic P and its availability in forest ecosystems. The soil organic P results have been discussed in relation to P availability and supply within the forest ecosystem.     

Conversion of a tropical forest into agroforest alters the fine root-related carbon flux to the soil

Large areas of remaining tropical forests are affected by anthropogenic disturbances of various intensities. These disturbances alter the structure of the forest ecosystem and consequently its carbon budget. We analysed the role of fine root dynamics in the soil carbon budget of tropical moist forests in South-east Asia along a gradient of increasing disturbance intensity. Fine root production, fine root turnover, and the associated carbon fluxes from the fine root system to the soil were estimated with three different approaches in five stands ranging from an old growth forest with negligible anthropogenic disturbance to a cacao agroforestry system with planted shade trees. Annual fine root production and mortality in three natural forest sites with increasing canopy openness decreased continuously with increasing forest disturbance, with a reduction of more than 45% between the undisturbed forest and the forest with large timber extraction. Cacao agroforestry stands had higher fine root production and mortality rates than forest with large timber extraction but less than undisturbed forest. The amount of carbon annually transferred to the soil carbon pool through fine root mortality was highest in the undisturbed forest and generally decreased with increasing forest use intensity. However, root-related C flux was also relatively high in the plantation with planted shading trees. In contrast, the relative importance of C transfer from root death in the total above- and below-ground C input to the soil increased with increasing forest use intensity and was even similar to the C input via leaf litter fall in the more intensively managed agroforest. We conclude that moderate to heavy disturbance in South-east Asian tropical moist forests has a profound impact on fine root turnover and the related carbon transfer to the soil.     

退化第四纪红粘土重建森林模式及其土壤恢复研究

以江西严重退化第四纪红粘土为研究对象,选择其中9种模式重建的林龄10年的森林,调查土壤理化性状,结果表明:(1)土壤有机质、全N、速效N、全P、速效P明显增加,而且增加幅度最大的是有机质;土壤全钾、有效钾都较大程度提高。(2)土壤有机质、全氮浓度随土层深度明显下降,有效磷、有效钾、有效氮浓度则随土层深度平缓下降,全磷、全钾浓度随土层变化不明显。(3)各重建森林模式的土壤容重、非毛管孔隙度也呈较大幅度降低;毛管持水量、毛管孔隙度呈不同幅度增加;不同重建模式总孔隙度变化的差异较大。     

The relationship between the organic matter composition of a forest floor and the structure of a soil arthropod community

The relationship between the amount and conposition of organic matter of a forest floor and the structure of the soil arthropod community was investigated in a temperate mixed forest of beech and pine trees. Seven enivronmental variables, i.e. broad leaves, pine needles, twigs, roots, others, total organic matter (sum of broad leaves, pine needles, twigs and others) and water content, were related to the soil arthropods in the statistical analysis. Pearson correlation was used to analyze the relation between environmental variables and total abundance of Collembola, Oribatida and Mesostigmata. Total abundance of Collembola and Oribatida did not show a clear correlation with total organic matter. Total abundance of Mesostigmata showed the positive correlation with broad leaves or total organic matter. The result in this study might be due to the fact that ‘organic matter’ treated in this study was the material which was left on the 2 mm mesh sieve, and most of small fragmental organic matter in the F or H layer was not included. Canonical correspondence analysis (CCA) was used to relate the variables of the organic matter to the community organizations of Collembola and Oribatida. CCA ordination indicated that the total amount of organic matter was the most important variable for the organization of both communities. These results suggest that the amount and composition of organic matter influenced the community organization of soil arthropods in a mixed forest.