Taking the litters of  species  Hippophae rhamnoides ,  Medicago sativa ,  Populus simonii ,  Robinia pseudoacaci ,  Salix psammophila , and  Stipa bungeana  in the Loess Plateau of Northeast China as test objects, and by using mesh bags, this paper studied the dynamic changes of the litters mass, carbon, and nitrogen during decomposition after buried in the field in semiarid region. The litters buried were from one, two, or three of the plant species, and mixed thoroughly with equal proportion of masses. During decomposition, the mass loss rate, total carbon and nitrogen release rates, and total soluble carbon and nitrogen contents of different litters were higher at the early than at the later decomposition stage. After 412 d decomposition, the average mass loss rate of the litters was in the order of mixed litters of three plant species > mixed litters of two plant species > one plant species litter. By the end of this experiment, the average release rates of the litter total carbon and nitrogen ranked as one plant species litter > mixed litters of two plant species > mixed litters of three plant species, the litter soluble organic carbon content was mixed litters of two plant species > mixed litters of three plant species > one plant species litter, while the litter soluble total nitrogen content was mixed litters of three plant species > mixed litters of two plant species > one plant species litter. Correlation analysis showed that the litter mass loss rate had definite correlation with the litter soluble organic matter, especially soluble organic carbon. From the viewpoint of mass loss rate, the mixture of the litters of  P. simonii ,  H. rhamnoide , and  M. sativa  was the optimum. It was suggested that in the process of returning farmland into forestland and grassland in the gully and valley region of Loess Plateau, it would be required to rationally increase plant species diversity to improve soil fertility.

以黄土高原区典型植物刺槐、小叶杨、沙棘、沙柳、苜蓿和长芒草的凋落物为对象,采用网袋法研究了半干旱区(神木)分解过程中,单种、两种及3种凋落物等质量配比混合后其质量、碳和氮的动态变化.结果表明： 在整个分解过程中,不同处理凋落物的质量损失率,全碳、全氮的释放速率以及可溶性有机碳和可溶性总氮的含量均表现为前期大于后期.经过412 d的分解,3种凋落物混合后的平均质量损失率高于两种混合凋落物,单种凋落物最低.到分解试验结束时,不同处理凋落物的全碳、全氮平均释放率均表现为单种＞两种混合＞3种混合;而不同处理的可溶性有机碳平均含量表现为两种混合＞单种＞3种混合,但未达到显著水平;可溶性总氮含量则为3种混合＞两种混合＞单种,达到显著水平.凋落物的质量损失率与可溶性有机物,特别是可溶性有机碳具有一定的相关性.从质量损失率来看,小叶杨、沙棘与苜蓿凋落物的组合为最佳组合.建议在黄土高原区退耕还林还草工程建设中,合理增加植物种类多样性,促进土壤改善养分状况.

The global environment change would affect litter decomposition and nutrient cycling directly and indirectly in forest ecosystem. The effects of global warming, elevated CO2, increased UV-B radiation and N deposition on litter decomposition was reviewed in this paper based on literatures. In general, the litter substrate quality, biotic factors such as microbe and animal, and abiotic factors including temperature, moisture and soil condition were the main factors affecting decomposition rate. Global warming made both positive and negative effects on abiotic factors. Although global warming slightly influenced the litter chemistry, however, it indirectly changed litter production, chemistry composing and decay through alter vegetation component. A temperature variable (annual mean temperature, effective temperature sum or its logarithm) combined with a summer drought indictor explained the first-year mass loss of the Scots pine needle litter across Europe and North America with a higher R2 value than actual evapotranspiration. Global warming also enhanced soil microbe activity and thereby accelerated decomposition. Elevated CO2 would increase litter production and affect decomposition by altering litter quality (e.g. improving C∶N and Lignin∶N ratio) and biotic environment such as microbe quantity and activity. Increased UV-B radiation and N deposition also affected decomposition, but the results were uncertainty as the absent of data. In addition, global environment change would obviously affect the C cycling through changing litter decomposition. Therefore, it is necessary to enhance the further research of global environment change and response of litter decomposition and the reciprocity of various factors due to the complex relationship.

全球环境变化将对森林生态系统凋落物的分解和养分循环产生直接和间接的多重影响。就全球环境变化如全球变暖、大气CO2浓度升高、UV-B辐射增强、氮沉降等对凋落物分解影响的研究进展进行了综合述评。影响凋落物分解的内部因素为凋落物基质质量，外部因素包括生物因素（微生物和动物）和非生物因素（温度、水分和土壤性质等）。全球变暖对凋落物分解的非生物作用有正效应，也有负效应。全球变暖对凋落物化学组成虽然只有轻微的影响，但可以通过影响植被的物种组成来间接改变凋落物的产量、化学性质和分解。全球变暖对凋落物分解生物作用的主要影响是增强土壤微生物活性，从而加速凋落物的分解。CO2浓度上升将增加凋落物产量，并通过影响凋落物质量（提高C/N比、木质素/N比等）和生物环境（微生物的数量和活性）而影响分解过程。UV-B辐射和大气N沉降的增加亦对凋落物分解产生直接和间接的影响，但影响效果尚不很清楚，有待进一步的研究。总起来看，全球环境变化将通过影响凋落物的分解速率而对全球碳循环产生重要影响，但由于气候变化和凋落物分解响应的复杂性以及各因子之间的相互作用，气候变化对凋落物分解的总效应尚需更深入的研究来定量化。

An experiment was conducted to study the decomposition characteristics and carbon dynamics of leaf litter in rubber plantation of different ages（6 a, 12 a, 20 a, 28 a）during one year of decomposition using mesh bag method. And the results showed as following: （1）The leaf litter decomposition dynamics was basically consistent between four different age groups, and the residues of litter in rubber plantation of different ages was 28.33%, 30.53%, 31.59%, 33.89%，respectively, and a non-significant difference was observed between different age groups. （2）The decomposition constant ranged from 1.376 2 to 1.608 8, with an average of 1.498 2, the times required for 50% and 95% of leaf decomposition was 0.43 a, 0.45 a, 0.47 a, 0.50 a and 1.86 a, 1.96 a, 2.03 a, 2.18 a, respectively. （3）Apart from the contents of C, lignin, and C/N ratio, the initial N content, P content, lignin/N ratio, C/P ratio, and lignin/P ratio of leaf-litter were significantly affected by plantation ages. （4）The decomposition rates of leaf litter in rubber plantation of different ages were significant negatively correlated with the initial C/N ration, and a weak negatively correlated with the P contend. （5）During the whole decomposition process, the release of carbon in 4 rubber plantations accumulated 75.02%~79.41%, and it’s release process was significantly in line with polynomial model, the coefficient of determination（R2）more than 0.88.

通过网袋法，研究一年内6 a、12 a、20 a、28 a共4组不同林龄橡胶凋落物叶分解及有机碳动态变化的过程。结果表明：（1）不同林龄橡胶凋落物叶均表现为慢-快-慢的分解趋势，经1 a的分解，4组林龄组橡胶凋落叶残留率分别为28.33％、30.53％、31.59％和33.89％。（2）不同林龄橡胶凋落物叶分解系数为1.376 2~1.608 8，平均值为1.498 2，大小顺序为6 a>12 a>18 a>28 a，分解50％和95％所需时间分别为0.43、0.45、0.47、0.50 a和1.86、1.96、2.03、2.18 a。（3）林龄显著影响橡胶凋落物叶初始N含量、P含量、木质素/N比、C/P比与木质素/P比，但对C含量、木质素含量及C/N比影响不明显。（4）初始C/N比极显著影响橡胶凋落物叶分解速率，而初始P含量对凋落物分解影响不显著（5）4组林龄组橡胶凋落物叶有机碳浓度是一个先上升后下降的过程，研究结束时，4组林龄橡胶凋落物叶有机碳分别释放了77.58％、79.41％、75.89％和75.02％，其动态变化过程显著符合一元多项式模型，决定系数（R2）在0.88以上。

Response of vegetation restoration on the soil microbial biomass carbon and nitrogen and soil ecological stoichiometry characteristics will be helpful to accurately evaluate the ecological environment benefit for the vegetation restoration.5 kinds of plant communities ( Artemisia giraldii,Hippophae rhamnoides,Artemisia sacrorum,Thymus mongolicus and Phragmites australis ) as subjects in Loess Plateau were studied in this paper.The soil organic matter (SOM),total nitrogen (TN),total phosphorus (TP),available P (AV.P),available potassium (AV.K),biomass nitrogen (SMBN),biomass carbon (SMBC) and its C∶N∶P ratios had been studied.The results showed that 0-20 cm soil layer, the concentrations for SOM and TN were higher than those in 20-40 cm soil layer.These concentrations for Artemisia sacrorum were the highest, suggesting that Artemisia sacrorum could promote the accumulation of soil organic carbon and total nitrogen.The significant relationship between SOM and TN resulted in a narrow range for soil C∶N ratio ( P Artemisia sacrorum .There was significant relationships between soil C∶P ratio and soil N∶P ratios ( P Artemisia sacrorum was the highest than the other four vegetation types regardless of soil layers, indicating that Artemisia sacrorum had much greater effects on the soil microbial biomass, which could improve the soil quality.In conclusion, Artemisia gmelinii is more suitable herb species than the other vegetation types in the process of vegetation restoration in the Loess Plateau.

研究土壤微生物生物量碳、氮及其生态化学计量学特征指标对植物群落的响应，有助于准确评价植被恢复的生态环境效益。以黄土高原丘陵沟壑区草地生态系统下5种植物群落 (茭蒿群落样地、沙棘群落样地、铁杆蒿群落样地、百里香群落、芦苇群落) 土壤为对象，对土壤有机质 (SOM)，全氮 (TN)，全磷 (TP)，速效磷 (AV.P)，速效钾 (AV.K)，土壤微生物生物量氮 (SMBN) 和土壤微生物生物量碳 (SMBC)及其化学计量特征进行研究。结果表明：5种植物群落下，表层土壤微生物生物量碳氮、有机质（SOM）、全氮（TN）显著高于下层土壤，铁杆蒿群落显著高于其他4种植物群落，其对土壤碳氮磷具有显著地累积作用，对于提高土壤碳氮磷储量具有重要的意义。土壤碳氮比（C∶N）在5种植被群落下较为稳定，土壤SOM与TN存在极显著的正相关性( P P <0.01)。0~20 cm和20~40 cm土层SMBN、SMBC均表现为：铁杆蒿群落显著高于其他植被群落，说明不同植物群落对土壤表层和下层的微生物具有明显的影响。可见，植被恢复对土壤质量的改善作用明显，铁杆蒿群落对该区土壤碳氮磷等养分的累积作用较好。

Decomposition of forest litter and simultaneous release of bioelements is one of the fundamental pathway of the flow of nutrient and energy in forest ecosystems, and an important component of the global carbon budget. The aim of this review is to summarize the changes of nutrient and chemical components during the decomposition, the factors controlling litter decay rate and its measurement. Decomposition of plant litter refers to the physical and chemical processes involved in reducing litter to its elemental chemical constituents. It includes two stages. First, litter is broken down by detritivores to small pieces which can be chemically reduced. Second, through the activities of micro-organisms (bacteria and fungi) these small pieces of organic matter are further reduced and mineralized into basic inorganic molecules. Also the course of nutrient dynamics during decomposition often can occur in three sequential phases, including an initial nutrient release through leaching, a net immobilization of nutrients by decomposer microorganisms and nutrient release from the litter, usually at a rate paralleling mass loss. However, the pattern of immobilization and release varies among species and ecosystems, and any particular litter type may not show all three phases. Litter decomposition rates are controlled by climate, litter chemistry, and by soil organisms. Climate has a direct effect on litter decomposition due to the effects of temperature and moisture. However, as a result of the climatic control of soil formation and nutrient cycling, it is to be expected that climate also has an indirect effect through the climatic impact on litter chemistry. Actual evapotranspiration (AET) is used as an index for the climatic control on decomposition. Mean AET in the humid tropical region is higher than in both the temperate and the mediterranean region and this results in rapid decomposition of litter. Especially, decomposition of litter (including root litter) contributes about 70% to the total annual carbon flux. Thus, changes in AET due to global warming will affect the global carbon budget through effects on the decomposition pathway. At a global scale, litter chemistry is only of secondary importance in explaining variation in litter decomposition rates. N and P concentrations, C/N and C/P ratios, lignin concentration and lignin/N and lignin/P ratios are considered as primary litter chemistry parameters, of which the lignin/N ratio and P related parameters exert significant influence on litter decomposition rates in the tropics. However, there is no consistent chemical predictor of litter decomposability in the temperate region. Also, there are indications that the chemical control of litter decomposition depends on the phase of the decomposition process. Generally, readily decomposable carbohydrates are lost at the initial stage, subsequently the decay-resistant materials such as lignin and cellulose are accumulated. High initial N, P and K concentrations lead to high initial decay rates, but to low long-term litter decay. Thus, there is clearly a need for more long-term studies on the chemical control of litter decomposition rates in various climatic regions. In addition, physical and chemical properties of soils and microbial communities also affect litter decomposition. Litter bag represent the most standardized method for studying litter decomposition, but it has several limitations. Litter bag may alter decomposition rates by altering litter microclimate, hindering soil contact and excluding litter macrofauna. Nevertheless, litter bags allow comparisons among species and experimental manipulations. Currently, the three most widely used indices of litter decomposition rate in forest ecosystem are release rate of CO 2 , decay constant of k value and weight loss rate of litter. Despite intensive research in the last decade, uncertainties of litter decomposition in forest ecosystems still remain for further studies: long-term in situ observation; use of uniform methods to obtain comparable data; research on the mechanism of litter decay using models; the effects of global climatic changes on litter decomposition in forest ecosystems; and the assessment of management activities controls on the litter decay and nutrient release in forests.

系统评述森林凋落物的分解过程、凋落物分解及养分释放的影响因素、分解研究的方法等。森林凋落物的分解既有物理过程,又有生物化学过程,一般由淋溶、自然粉碎、代谢作用等共同完成。凋落物分解过程先后出现分解速率较快和较慢2个阶段,元素迁移一般呈现淋溶-富集-释放的模式。凋落物分解主要受气候、凋落物性质、微生物和土壤动物的影响,气候是最基本的影响因素,常用实际蒸散(actual evapotranspiration 简称AET)作为指标。凋落物分解速率呈明显的气候地带性,与温度、湿度等紧密相关。从全球尺度来讲,凋落物质量对分解速率的影响处于次要地位,但在同一气候带内因AET变化较小,则起了主导作用。N、P和木质素浓度、C/N、C/P、木质素与养分比值是常见的凋落物质量指标,其中C/N和木质素/N最能反映凋落物分解速率。凋落物化学性质对其分解的影响作用又与分解阶段有关。凋落叶中N、P、K初始浓度高使得初期分解较快,而后期分解放慢。土壤理化性质及微生物区系也将不同程度地影响凋落物分解。尼龙网袋法(litter bag method)操作简单,是野外测定森林凋落物分解速率最常用的方法。除此之外,缩微试验也得到了广泛应用。目前普遍采用的衡量凋落物分解速率大小的指标主要有CO 2 释放速率、凋落物分解系数( k 值)及质量损失率。在此基础上提出了指数衰减、线性回归等模型来模拟凋落物分解过程。尽管对凋落物分解在森林生态系统C、N、P循环、土壤肥力维持等方面已进行了较深入的研究,但未来研究应侧重以下方向:长期的定位观测;采用相对统一的研究方法,获得可比性强的数据进行综合;深化凋落物分解机理研究;探讨全球气候变化对森林凋落物分解的影响;评价营林措施(如林分皆伐、造林、施石灰和肥料等)对凋落物分解与养分释放的调节作用。

摘　要： 采用空间代替时间的方法,以川西高山亚高山云杉（Picea asperata）人工林、冷杉（Abies faxoniana）天然林、杜鹃（Rhododendron lapponicum）矮曲林和白桦（Betula platyphylla Suk.）天然林4种典型林分类型下的3个层次[新鲜凋落物层（L）、发酵层（F）、腐殖质层（H）]凋落物为研究对象,分别模拟凋落物分解的前期、中期和后期阶段,对凋落物的基质质量,包括水溶性组分（WSC）及有机溶性组分（OSC）、酸溶性组分（ASE）及酸不溶性组分（AIR）的含量进行分析,以揭示亚高山森林不同分解阶段凋落物的质量特征。结果表明：4种林分类型凋落物的WSC、OSC、ASE含量均随分解的进行不断减少,且分解前期的淋溶释放量高于分解中后期,而AIR含量及表征4种凋落物酸溶性和酸不溶性组分含量相对比例的LCI指数（lignocellulose index）随分解的进行却呈现上升趋势。4种林分凋落物L层的WSC含量及白桦、冷杉、云杉凋落物L层OSC含量均显著高于相应F、H层,而F、H层间差异不显著;而杜鹃凋落物OSC含量则表现为L层〉F层〉H层,且各层间均差异显著。林分类型对凋落物分解过程中的WSC、OSC、AIR含量有极显著影响,但对ASE和LCI指数影响却不显著。4个林分比较而言,阔叶林凋落物的WSC、OSC含量高于针叶林,AIR含量低于针叶林,白桦WSC含量在L、F层均最高。研究认为,分解阶段和林分类型对川西亚高山森林凋落物基质质量具有重要影响,但对各组分的影响有所差异。研究结果对深入理解亚高山森林生态系统的物质循环具有重要意义。

Aims Litter decomposition is a key process of energy flow and nutrient cycling in terrestrial ecosystems that might be sensitive to the loss of biodiversity. Our objective in this study was to investigate the potential effects of plant litter diversity on decomposition processes and nutrient release in an Inner Mongolia grassland ecosystem. Methods We placed aboveground litter (stems and leaves) of four dominant species ( Stipa krylovii , Astragalus scaberrimus , Potentilla acaulis and Leymus chinensis ) individually and in mixture in litterbags in the field on October 27, 2006. We collected the litter bags after 0, 162, 252 and 341 days and determined mass loss and N and P content in the remaining litter. Important findings After 341 days, the remaining mass of litter of individual species was significantly negatively correlated with initial litter N content. There was no significant difference between the observed and expected mass remaining for most litter mixtures, except the A. scaberrimus - P. acaulis mixture, in which mass remaining was 7.5% higher than the expected. Nevertheless, most litter mixtures affected the dynamics of N and P during decomposition. N releases of S. krylovii - A. scaberrimus and S. krylovii - L. chinensis were facilitated in the early stages of decomposition, in which remaining N was 4.7% and 10.0% lower, respectively, than the expected. Meanwhile, either release or accumulation of P in four of five litter mixtures was also promoted in different decomposition stages, and the P remaining significantly differed from the expected in S. krylovii - P. acaulis , S. krylovii - L. chinensis and S. krylovii - A. scaberrimus (31.1%, 23.1% and 21.8%, respectively in the early, middle, and later stage of decomposition). Our results show that litter diversity has significant effects on nutrient dynamics, especially for P, but not on mass loss rates of most decomposing mixtures, and the effects of mixing are complex.

混合凋落物的研究对预测生态系统群落水平的分解以及相应的养分释放和进一步的循环等生态学过程具有重要意义。该研究使用网袋法, 对克氏针茅( Stipa krylovii )、糙叶黄芪( Astragalus scaberrimus )、星毛委陵菜( Potentilla acaulis )和羊草( Leymus chinensis ) 4种凋落物单种及其混合物的分解速率及分解过程中的养分动态进行了野外实验研究, 以探讨凋落物多样性对内蒙古典型草原生态系统分解速率和过程的影响。通过对凋落物分解速率和养分含量变化历时1年的实际测定, 得到下列研究结果: (1)分解341天后, 单种凋落物的剩余重量与初始氮(N)含量呈显著负相关关系( p r = – 0.979)。混合凋落物中, 糙叶黄芪-星毛委陵菜组合剩余重量的实测值比期望值高7.5%, 表明凋落物混合具有显著的正效应, 但在其他几种组合中没有发现显著的凋落物混合效应; (2)在分解初期的N释放阶段, 克氏针茅-糙叶黄芪和克氏针茅-羊草组合的实测N剩余率分别比期望值低4.7%和10.0%, 表明混合凋落物对初期N元素释放具有显著的负效应。不同凋落物混合组合的磷(P)释放或累积在不同分解时期都得到了一定程度的促进, 尤其是星毛委陵菜-克氏针茅、克氏针茅-羊草和克氏针茅-糙叶黄芪组合, 它们在分解前期、中期和后期, 实测P剩余率与期望值的差异分别为31.1%、23.1%和21.8%。研究结果表明, 在内蒙古典型草原生态系统, 多数混合凋落物对分解速率不产生显著的混合效应; 相反, 大多数混合凋落物对分解过程中的养分动态, 尤其是P元素, 具有显著的混合效应, 而混合效应的方向(正或负)可能是十分复杂的。

The relationships between litter decomposition rate and their initial quality of 14 representative plants in the alpine forest ecotone of western Sichuan were investigated in this paper. The decomposition rate  k  of the  litter ranged from 0.16 to 1.70. Woody leaf litter and moss litter decomposed much slower, and shrubby litter decomposed a little faster. Then, herbaceous litters decomposed fastest among all plant forms. There were significant linear regression relationships between the litter decomposition rate and the N content, lignin content, phenolics content, C/N, C/P and lignin/N. Lignin/N and hemicellulose content could explain 78.4% variation of the litter decomposition rate ( k ) by path analysis. The lignin/N could explain 69.5% variation of  k  alone, and the direct path coefficient of lignin/N on  k  was -0.913. Principal component analysis (PCA) showed that the contribution rate of the first sort axis to  k   and the decomposition time ( t ) reached 99.2%. Significant positive correlations existed between lignin/N, lignin content, C/N, C/P and the first sort axis, and the closest relationship existed between lignin/N and the first sort axis ( r =0.923). Lignin/N was the key quality factor affecting plant litter decomposition rate across the alpine timberline ecotone, with the higher the initial lignin/N, the lower the decomposition rate of leaf litter.

对我国川西高山林线交错带14种代表性植物凋落叶分解速率与初始质量的关系进行研究.结果表明:  高山林线交错带植物凋落叶分解速率（ k ）为0.16～1.70,乔木和苔藓凋落叶分解较慢,灌木凋落叶次之,草本凋落叶分解最快.凋落叶分解速率与N、木质素、酚类物质、C/N、C/P、木质素/N均具有显著的线性回归关系.通径分析得出,木质素/N和半纤维素含量可以解释 k 变异的78.4%,其中木质素/N可以解释 k 变异的69.5%,木质素/N对 k 的直接通径系数为-0.913.主成分分析表明,第1排序轴 k 、分解时间（ t ）的贡献率达99.2%,木质素/N、木质素含量、C/N、C/P与第1排序轴呈显著正相关,其中木质素/N与第1排序轴的相关关系最强( r =0.923).木质素/N是影响川西高山林线交错带植物凋落叶分解速率的关键质量指标,且凋落叶初始木质素/N越高,分解速率越低.

利用网袋法对九寨沟主要森林类型的凋落物的分解作用进行了研究.结果显示,九寨沟各林型凋落物的分解率k以白桦林最高,达0.7864,巴山冷杉林最低,为0.2705.九寨沟6个主要类型群落中,除巴山冷杉林的年分解率为23.70%,与一般温带针叶林分解率相似外,其余皆在30.20%至54.45%之间,高于温带森林凋落物的平均分解速率20%～30%.在实验期内五次取样的失重率与时间的关系有两类,它们以海拔2400m为界.在海拔2400m以下的白桦林、青杆林和油松林群落中,凋落物的失重率变化呈S形;在海拔2400m以上的辽东栎林、红桦林和巴山冷杉林群落中,凋落物的失重率变化呈山字形.这6种类型森林群落凋落物的分解作用受多种因素影响.一般地,海拔相同时阔叶林群落凋落物分解比针叶林群落快.

采用网袋法,对0～360 d内杉木[Cunninghamia lanceolata (Lamb. ) Hook. ]、楠木[Phoebe bournei (Hemsl. ) Yang]和木荷(Schima superba Gardn. et Champ. )叶凋落物在杉木人工林下的分解特征及营养元素(N、P、K和C)含量的变化动态进行了比较分析.结果显示,经过360 d的分解,杉木、楠木和木荷叶凋落物的干质量损失率分别为40.6%、42.0%和51.6%,平均腐解率分别为0.001 3、0.001 6和0.002 0 d-1,叶凋落物的分解半衰期分别为537、482和372 d.在整个分解过程中,3个树种叶凋落物中P含量总体上均呈波动且缓慢的上升趋势;K含量在分解过程前期均急剧下降,然后随分解时间的延长变化趋缓;N含量变化差异较大,随分解时间的延长,杉木叶凋落物中N含量呈缓慢上升趋势,另外2个树种叶凋落物中N含量总体上呈先下降后上升的变化趋势;C含量基本上呈前期上升、中期下降、后期又略有上升的趋势,而C/N比则呈前期略上升而后期逐渐下降的趋势.3个树种叶凋落物分解过程中N、P、K和C的释放率及其动态变化也存在一定差异.3个树种叶凋落物中K的释放率均较高、变化趋势较接近,且均处于净释放状态;杉木叶凋落物中N、P和C的释放率总体上低于另2个树种,且木荷叶凋落物中N、P和C基本均处于单调净释放状态,而杉木叶凋落物中N、P和C以及楠木叶凋落物中P和C在分解过程前期均略呈净富集状态,之后N和C基本上呈净释放状态、P则呈波动式净释放状态.结果表明,在杉木人工林下,阔叶树种(楠木和木荷)叶凋落物比针叶树种(杉木)叶凋落物易分解,且阔叶树种叶凋落物中的营养元素也较易释放.