长白山白桦(Betula platyphlla)纯林和白桦山杨 (Populus davidiana)混交林凋落物的分解

采用交互分解实验,研究长白山白桦叶片和白桦、山杨与水曲柳混合叶片在白桦纯林和白桦山杨混交林内的分解过程。两年的分解实验结果表明,两种类型叶片均存在一个快速分解阶段和一个慢速分解阶段,森林类型和凋落物类型对凋落物分解率的影响在快速分解阶段不显著而在慢速分解阶段显著;混交林内的环境促进了凋落物分解和养分元素释放;在同一林型内,底物质量高的混合叶片其分解率和养分元素释放率均大于底物质量低的白桦叶片;凋落物的底物质量在一定程度上可以抵消森林类型对凋落物分解的影响;白桦山杨混交林混合叶片分解速率和养分元素释放率要显著大于白桦纯林内的白桦叶片,说明白桦山杨混交林的物质循环速度和养分元素供应能力要显著大于白桦纯林。     

长白山四种森林类型凋落物分解动态

2003年5月—2004年9月在长白山自然保护区北坡4个森林类型阔叶红松林、红松云冷杉林、岳桦云冷杉林和岳桦林内,利用凋落物原位减少法对4种森林类型的凋落物分解动态进行了研究。结果表明,凋落物现存量最大的为红松云冷杉林,依次为阔叶红松林、岳桦云冷杉林、岳桦林;凋落物分解速率与时间均呈指数关系,凋落物年分解常数为0.25～0.47,分解95%所需时间为18～39年,其中阔叶红松林凋落物年分解常数最大,依次为岳桦林、红松云冷杉林、岳桦云冷杉林。同一类型森林中,不同植物组分的年分解系数不同,一般是阔叶最大,针叶最小。     

森林叶凋落物混合分解的研究I.缩微实验

采用缩微实验法,初步系统研究了杉木叶凋落物分别与火力楠、红栲和木荷３个阔叶树种之一的叶落物两两混合分解的动态变化,以探明凋落物混合分解过程中可能存在的相互作用。结果表明,杉木叶凋落物与３种阔叶树种叶凋落物两两混合分解时所表现出不同的相互作用形式：杉木与木荷表现出抑制作用,杉木与红栲或火力楠表现为较弱的促进作用。     

森林凋落物的微生物分解

森林凋落物的分解是森林生态系统中物质循环和能量流动的一个重要环节,而微生物在这一过程中起着重要作用。本文系统介绍了森林凋落物微生物分解的过程及其生态学意义,并从参与凋落物分解的微生物多样性、凋落物分解过程中的微生物数量动态及群落演替、影响微生物分解的因素及微生物分解酶学等方面综述了森林凋落物的微生物分解研究概况,探讨了未来研究的方向。     

小兴安岭不同林龄天然次生白桦林凋落物分解及养分变化

在2009年5月到2010年10月。以小兴安岭地区3种林龄的天然白桦次生林（20a,36a,82a)为研究对象,采用网袋分解法研究不同林龄的白桦林凋落物分解过程中的残留量和养分动态变化。结果表明：不同林龄白桦林在分解过程分为两个阶段：快速分解阶段(0~150 d)和缓慢分解阶段(150~540 d)。凋落物残留量随时间呈指数变化趋势。年分解常数k值在0.584～0.657,凋落物分解50%和95%所用的时间分别为1.06～1.19 a和4.56～5.13 a。3种林龄白桦天然次生林分解速率从大到小依次为82 a>36 a>20 a。在凋落物分解过程中,C和K元素浓度不断释放,而N和P元素浓度先上升后下降,最终N元素为富集,P元素为释放模式。     

森林叶凋落物混合分解的研究Ⅰ.缩微(Microcosm)实验

采用缩微实验法,初步系统研究了杉木叶凋落物分别与火力楠、红栲和木荷3个阔叶树种之一的叶凋落物两两混合分解的动态变化,以探明凋落物混合分解过程中可能存在的相互作用.结果表明,杉木叶凋落物与3种阔叶树种叶凋落物两两混合分解时所表现出不同的相互作用形式:杉木与木荷表现出抑制作用,杉木与红栲或火力楠表现为较弱的促进作用.     

森林叶凋落物混合分解的研究I.缩微(Microcosm)实验

采用缩微实验法 ,初步系统研究了杉木叶凋落物分别与火力楠、红栲和木荷 3个阔叶树种之一的叶凋落物两两混合分解的动态变化 ,以探明凋落物混合分解过程中可能存在的相互作用 .结果表明 ,杉木叶凋落物与 3种阔叶树种叶凋落物两两混合分解时所表现出不同的相互作用形式 :杉木与木荷表现出抑制作用 ,杉木与红栲或火力楠表现为较弱的促进作用 .     

凋落物分解主场效应及其土壤生物驱动

凋落物分解主场效应是指凋落物具有在其生长的栖息地比在别的生境分解更快的特征,土壤生物的特化作用被认为是主场效应的产生机理.主场效应是除基质质量和物理化学环境外控制凋落物分解的重要因子,可影响模拟精度的8％.凋落物分解主场效应驱动机制的深入研究对促进分解模型中纳入生物因子,提高区域尺度模拟精度具有重要作用.虽然时间和基质质量可导致主场效应强度变化,但不能全面解释主场效应强度差异特别是负效应的产生.通过分析凋落物分解过程中土壤生物的作用机理,指出凋落物分解主场效应的土壤生物驱动可能包括土壤微生物的调节性适应,土壤动物的后期插入以及物理化学环境的间接影响.为深入了解主场效应土壤生物驱动机制,更好地模拟凋落物分解过程,提出延长凋落物分解交互移置实验时间,拓展实验空间,结合室内模拟分析和构建分解模型等方法与途径.     

凋落物多样性及组成对凋落物分解和土壤微生物群落的影响

凋落物分解是生态系统营养物质循环的核心过程,而土壤微生物群落在凋落物分解过程中扮演着极其重要且不可替代的角色。随着生物多样性的丧失日益严峻,探讨凋落物多样性及组成对凋落物分解和土壤微生物群落的影响,不仅有助于了解凋落物分解的内在机制,而且可为退化草原生态系统的恢复提供参考。以内蒙古呼伦贝尔草原退化恢复群落中的草本植物为研究对象,依据植物多度、盖度、频度和物种的重要值及其在群落中的恢复程度筛选出排序前4的羊草（Leymus chinensis）、茵陈蒿（Artemisia capillaris）、麻花头（Serratula centauroides）、二裂委陵菜（Potentilla bifurca）的凋落物为实验材料,通过设置3种凋落物多样性水平（1,2,4）,包括11种凋落物组合（单物种凋落物共4种,两物种凋落物混合共6种,四物种凋落物混合共1种）,利用磷脂脂肪酸（PLFA）方法来研究分解60 d后凋落物多样性及组成对凋落物分解和土壤微生物群落的影响。结果表明：（1）凋落物物种多样性仅对C残余率具有显著影响,表现在两物种混合凋落物C残余率显著低于单物种凋落物,而凋落物组成对所观测的4个凋落物分解参数（质量、C、N残余率以及C/N）均具有显著影响;（2）凋落物物种多样性对细菌（B）含量具有显著影响,而凋落物组成对真菌（F）含量具有显著影响,两者对F/B以及微生物总量均无显著影响;（3）冗余分析结果表明凋落物组成与凋落物分解相关指标（凋落物质量、C、N残余率及C/N）和土壤微生物（真菌、细菌含量）的相关关系高于凋落物多样性。（4）进一步建立结构方程模型（Structural Equation Model,SEM）发现,凋落物初始C含量对凋落物质量、C、N残余率及C/N有显著正的直接影响;凋落物木质素含量对凋落物质量、C、N残余率有显著正的直接影响;凋落物初始N含量对N残余率有显著正的直接影响,而对C残余率及C/N有显著负的直接影响;凋落物初始C/N对凋落物质量、N残余率有显著正的直接影响,而对C/N有显著负的直接影响。此外,凋落物初始C、N、木质素含量及C/N均对真菌含量具有显著正影响,并可通过真菌对凋落物质量分解产生显著负的间接影响。以上结果表明该退化恢复区域优势种凋落物分解以初始C、木质素为主导,主要通过土壤真菌影响凋落物的分解进程,这将减缓凋落物的分解速率进而减慢草原生态系统的进程。这些结果为凋落物多样性及组成对自身分解和土壤微生物群落的影响提供了实验依据,也为进一步分析凋落物分解内在机制以及草原生态系统的恢复提供了数据参考。     

模拟酸雨对亚热带典型树种叶凋落物分解的影响

通过在酸雨胁迫下中国亚热带典型树种马尾松(Pinus massoniana Lamb.)、木荷(Schima superba Gardn. et Champ.)、青冈 (Cyclobalanopsis glauca (Thunberg) oersted)叶凋落物分解的比较研究,试图分析亚热带区域日益严重的酸雨是否会对森林凋落物的分解产生影响,从而揭示酸雨胁迫下凋落物分解的变化规律.利用网袋法进行试验,共设计有3个区组:酸雨对照处理(pH5.6)、中度酸雨胁迫(pH4.0)、重度酸雨胁迫(pH2.5).试验结果表明:酸雨对3种亚热带树种凋落叶片的影响比较显著,通常会减慢凋落分解的速率.酸雨对照处理(pH5.6)、中度酸雨胁迫(pH4.0)和重度酸雨胁迫(pH2.5)三个处理对分解系数的影响,马尾松的分别为:0.49、0.34、0.25;木荷的分别为:0.70、0.34、0.32;青冈的分别为:0.64、0.23、0.21;酸雨对马尾松、木荷、青冈叶的凋落物的干重剩余率影响的大小为:pH(2.5)>pH(4.0)>pH(5.6).中度酸雨处理(pH4.0)和重度酸雨处理(pH2.5)影响叶凋落物分解95%的时间分别推迟了:马尾松2.697a、5.869a;木荷4 531a、5.082a;青冈8.344a、9.584a.     

豫西山杨林立地指数与生物量的研究

 立地指数表的编制需要较多的标准地与样点材料。笔者在豫西嵩县五马寺林场山杨林的43块标准地和60个样点的资料基础上,通过随手曲线的绘制与修匀,对主曲线进行了严格的调整,编制出豫西山杨林的立地指数表,为合理经营与利用山杨林提供了依据。豫西山杨单株地上部分生物量与胸径和树高存在良好的相关关系,由此得出的经验模型为林分产量评估和资源清查提供了便利。豫西山杨林地上部分年平均生物量介于2200～3200kg·hm-2之间,基本反映了该种在豫西地区的生产力水平。     

Nutrition and the ozone sensitivity of birch (Betula pendula)

 Cuttings of a single birch clone (Betula pendula) were grown in field fumigation chambers throughout the growing season in either filtered air (control) or 90/40 nl O₃ l^–1 (day/night). Both regimes were split into plants under high and low nutrient supply (macro- and micronutrients). The stomatal density of leaves was increased by ozone but was lowered at high nutrition, while the inner air space was hardly affected by the treatments. Ozone induced macroscopic leaf injury regardless of nutrition, but leaf shedding was delayed in the low-fertilized plants, despite O₃ uptake being similar to that in high-fertilized plants. The leaf turn-over was enhanced in the O₃-exposed high-fertilized plants, but length growth and leaf formation of stems were not affected by ozone in either nutrient regime. Leaves of high-fertilized plants showed O₃-caused decline in photosynthetic capacity, water-use efficiency, apparent carbon uptake efficiency and quantum yield earlier as compared with low-fertilized plants, whereas chlorophyll fluorescence (F_V/F_M) and leaf nitrogen concentration were rather stable. CO₂ uptake rate and rubisco activity of young leaves compensated for the O₃ injury in the ageing leaves of the low-fertilized plants. In 8-week-old leaves, however, the O₃-induced decline in CO₂ uptake did not differ between the nutrient regimes and was associated with increased dark respiration rather than changed photorespiration. The balance between CO₂ supply and demand was lost, as was stomatal limitation on CO₂ uptake. High nutrition did not help leaves to maintain a high photosynthetic capacity and life span under O₃ stress. Received: 6 July 1996 / Accepted: 4 June 1997     

Litter fall and litter decomposition in Pinus sylvestris forests of the eastern Pyrenees

Abstract. Litter fall and litter decomposition were studied in four mature stands of Pinus sylvestris (Scots pine) in the eastern Pyrenees. The stands were located in environments differing in bedrock type and exposition and were studied for two years. Mass-loss during the first year of decomposition was compared with other European P. sylvestris forests and regressed with environmental variables (temperature and rainfall) and latitude. The results suggested that the mean amount of needle fall (1760 kg-ha^-1·yr^-1) was within the range reported for northern European stands. There were more differences in the amount of litter fall between the four stands than between the two years studied. However, the needle fall pattern over the year showed significant differences between years in three of the four stands. Litter decomposition was similar in all the stands and only the one in drier conditions showed a lower decomposition rate. On the European scale the decomposition rate was positively related to mean annual temperature and annual rainfall. However, regression analysis suggests that there are other factors, not taken into account in this study, that are important for predicting the decomposition rate.     

Foliar decomposition in a broadleaf-mixed Korean pine (Pinus koraiensis Sieb. Et Zucc) plantation forest: the impact of initial litter quality and the decomposition of three kinds of organic matter fraction on mass loss and nutrient release rates

Foliar litter decomposition of nine species in broadleaf-mixed Korean pine plantation forests, northeast China was assessed over a 34-month field experiment using litterbag method. Litter mass loss generally followed a sequential decomposition of water-soluble fraction (WSF), acid-soluble fraction (ASF), and acid-insoluble fraction (AIF). WSF decomposition contributed most of litter mass loss in the first 6 months, while ASF accounted for most of litter mass loss thereafter. There existed significant autocorrelations among the initial litter quality indices. Initial N, K, Ca, AIF, AIF/N, ASF/N, and WSF/N were significantly related to the percent remaining of litter mass, N, P, Ca, and Mg in both month 12 and month 34. No litter quality can significantly predict the percent remaining of AIF and K. N and P were immobilized by all litters, but Ca, Mg, and K exhibited minor or no immobilization phase. N was the most limiting element in this forest based on the results of correlation analysis and nutrient elements release dynamics. The relationships between WSF, ASF, and AIF loss and N or P release rate fitted the polynomial regression. The decomposition of WSF and ASF were faster than N and P were mineralized during the study. AIF loss rate relative to N and P loss varied greatly among species, with high-N litter showing slower AIF decomposition rates than N and P. The loss rates of WSF and ASF were in proportion to that of K, Ca, and Mg, while AIF decomposed slower than K, Ca, and Mg. This suggested that the decomposition of WSF and ASF caused the net release of K, Ca, and Mg. Responsible Editor: David E. Crowley.     

黄土高原小叶杨与其他树种枯落叶混合分解对土壤性质的影响

将小叶杨分别与其他11个树种枯落叶粉碎混合后进行室内分解培养,分析不同树种枯落叶混合分解对土壤性质的影响及其相互作用.结果表明:12个树种枯落叶单独混土分解均明显提高了土壤脲酶、脱氢酶、磷酸酶活性和有机质、碱解N含量,但对土壤速效P含量和土壤阳离子交换量(CEC)的影响差异较大,其中柠条和紫穗槐枯落叶改善土壤性质的效果明显.小叶杨分别与油松、侧柏、刺槐、白榆枯落叶混合分解,对土壤微生物数量的影响存在相互促进作用;小叶杨分别与侧柏、柠条枯落叶混合分解对土壤有机质、速效P、速效K含量和CEC的影响存在相互促进作用,但对土壤大部分酶活性的影响却存在相互抑制作用;小叶杨与落叶松枯落叶混合分解对土壤多数酶活性和养分含量的影响存在相互促进作用,而与樟子松枯落叶混合分解时则有抑制作用.总体上,小叶杨分别与白榆、油松、落叶松和刺槐枯落叶混合分解可促进土壤性质的改善,而与侧柏、柠条、樟子松、沙棘和紫穗槐枯落叶混合分解时则相互抑制.     

Ecological role of reindeer summer browsing in the mountain birch (<Emphasis Type="Italic">Betula pubescens</Emphasis> ssp. <Emphasis Type="Italic">czerepanovii</Emphasis>) forests: effects on plant defense,litter decomposition,and soil nutrient cycling

Mammalian herbivores commonly alter the concentrations of secondary compounds in plants and, by this mechanism, have indirect effects on litter decomposition and soil carbon and nutrient cycling. In northernmost Fennoscandia, the subarctic mountain birch (Betula pubescens ssp. czerepanovii) forests are important pasture for the semidomestic reindeer (Rangifer tarandus). In the summer ranges, mountain birches are intensively browsed, whereas in the winter ranges, reindeer feed on ground lichens, and the mountain birches remain intact. We analyzed the effect of summer browsing on the concentrations of secondary substances, litter decomposition, and soil nutrient pools in areas that had been separated as summer or winter ranges for at least 20 years, and we predicted that summer browsing may reduce levels of secondary compounds in the mountain birch and, by this mechanism, have an indirect effect on the decomposition of mountain birch leaf litter and soil nutrient cycling. The effect of browsing on the concentration of secondary substances in the mountain birch leaves varied between different years and management districts, but in some cases, the concentration of condensed tannins was lower in the summer than in the winter ranges. In a reciprocal litter decomposition trial, both litter origin and emplacement significantly affected the litter decomposition rate. Decomposition rates were faster for the litter originating from and placed into the summer range. Soil inorganic nitrogen (N) concentrations were higher in the summer than in the winter ranges, which indicates that reindeer summer browsing may enhance the soil nutrient cycling. There was a tight inverse relationship between soil N and foliar tannin concentrations in the winter range but not in the summer range. This suggests that in these strongly nutrient-limited ecosystems, soil N availability regulates the patterns of resource allocation to condensed tannins in the absence but not in the presence of browsing.