元谋干热河谷燥红土和变性土上植物叶片的元素含量及其重吸收效率

采用盆栽试验,研究元谋干热河谷燥红土和变性土上生长的植物叶片以及凋落叶营养元素含量,并分析养分重吸收效率对土壤类型与物种互作的响应.结果表明: 土壤类型对叶片N、P、Ca、Mg、Cu、Zn、Fe、N∶P以及凋落叶N、P、Mn、N∶P均有显著影响;燥红土植物叶片与凋落叶N、Mn含量和N∶P显著高于变性土,而燥红土植物叶片P、Ca、Mg、Fe、Cu、Zn和凋落叶P含量显著低于变性土.燥红土植物叶片N含量较变性土高34.8%,而P含量低40.0%;在叶片凋落时,N、P、K表现为重吸收,而其他元素呈富集状态.燥红土凋落叶Ca、Mg、Mn富集系数显著高于变性土.物种仅对叶片N含量有显著影响,物种与土壤交互作用对植物叶片和凋落叶元素含量影响不显著,表明各土壤类型对不同物种元素含量的影响方式较为一致.土壤类型对植物元素含量的影响可进一步作用于干热河谷植物凋落物分解、植物-土壤的养分反馈以及生物地球化学循环.     

金沙江干热河谷地区植物叶片中各生源要素的化学计量特征以及异速增长关系

植物生源要素的化学计量比在生物地球化学循环以及植物生理代谢中具有极为重要的作用。迄今为止, 对植物叶片的N、P元素与其他生源要素含量间相关关系的研究较少, 限制了生态化学计量学的应用广度。为了解金沙江干热河谷地区植物叶片中各种生源要素间的异速增长关系, 该研究通过对当地51个样方中107个样本的测量, 探索个体水平、物种水平和样方水平上各生源要素间的异速增长关系。结果显示: 叶片中各元素的比例N:P:K:S:Fe:Ca为100.00:6.64:88.20:11.59:2.48:91.64, N、P含量分别为11.21和0.744 mg·g ^-1, 明显低于全国平均值, 而N:P与全国平均值相当, 表明植物生长受到N、P的双重限制。各种生源要素间存在正相关增长关系, 在个体水平上, 植物叶片中N-P大致呈等速增长关系, Fe与Ca元素相对于N、P、K的增长速率显著大于1, Fe的增长速率最大, 依次为Fe > Ca > P > N > S > K; 物种水平上Fe与Ca相对于N、P、K的增长速率显著大于1; 样方水平上, Fe元素相对于N、P、K的增长速率依旧显著大于1, 但Ca、S相对于N的增长速率显著大于1, 元素增长速率为Fe > Ca > P > S > K > N, 其中N相对于P的异速增长斜率与2/3极为接近, K相对于P的异速增长斜率接近3/4。个体水平和样方水平上各种元素间的相关关系以及拟合优度不一致, 表明群落构建在介导不同层次上元素关系中发挥着重要作用。     

植物质量、模拟增温及生境对凋落物分解的相对贡献

采用凋落物袋法对比研究了茭草和杉叶藻两种初始质量差异显著的湿地植物凋落物,在模拟增温(1.5～2.0 ℃)及不同生境(大气、大气-水界面与水-土界面)下的质量残留率和不同化学组分的含量变化.结果表明: 在一年的分解周期内,凋落物残留率表现出季节性变化特征,并与环境因子之间存在显著的交互作用.各因子对凋落物分解的贡献大小不同,植物质量解释了28.8%的变异,模拟增温解释了6.3%的变异,而生境解释了34.9%的变异.随着分解时间的延长,凋落物中不同组分(难、易分解)的含量发生明显变化.杉叶藻中氮含量在分解后期显著降低了53.1%,而木质素含量显著增加了45.4%.生境是影响凋落物分解最重要的环境因子,其次是植物质量,而模拟增温对凋落物分解的影响程度较小.     

降水量变化对蒙古栎落叶分解过程的间接影响

分析了在4种不同降水量条件下蒙古栎叶凋落物基质质量的变化,并应用分解袋法研究其凋落物在蒙古栎次生林内的分解过程.结果表明：与对照相比,降水量减少条件下,蒙古栎叶凋落物的初始N、P、K浓度显著升高,初始木质素浓度显著降低,凋落物分解速率大,N、P、K矿化率高,N和P固持时间缩短;降水量增加情况下,其凋落物初始N浓度显著降低、木质素浓度显著升高,N、P、K矿化率低,N和P固持时间延长.4种类型叶片凋落物的质量损失过程均符合指数降解模型,分解速率可以由凋落物木质素/N来预测.相关性分析显示,木质素浓度高、N浓度低的两种凋落物的分解速率与N浓度相关性最大;而木质素浓度低、N浓度高的两种凋落物的分解速率与木质素浓度相关性最大.说明降水量的变化显著地改变了蒙古栎叶凋落物的基质质量,进而间接地改变了凋落物的分解过程.     

亚热带不同植被恢复阶段林地凋落物层现存量和养分特征

为揭示亚热带森林植被自然恢复过程中,凋落物层现存量及其养分元素储存能力的演变,采用空间代替时间的方法,在位于亚热带丘陵区的长沙县选取地域相邻、生境条件基本一致的檵木+南烛+杜鹃灌草丛（Loropetalum chinense+Vaccinium bracteatum +Rhododendron simsii scrub-grass-land,LVR）、檵木+杉木+白栎灌木林（L.chinense+Cunninghamia lanceolata+Quercus fabri shrubbery,LCQ）、马尾松+柯+檵木针阔混交林（Pinus massoniana +Lithocarpus glaber +L.chinense coniferous-broad leaved mixed forest,PLL）、柯+红淡比+青冈常绿阔叶林（L.glaber+Cleyera japonica+Cyclobalanopsis glauca evergreen broad-leaved forest,LAG）作为一个恢复序列,设置固定样地,采集未分解层（U层）、半分解层（S层）、已分解层（D层）凋落物样品,测定凋落物层现存量和主要养分元素含量、储量及其释放率,分析植物多样性指数与凋落物层现存量、养分元素含量的相关性。结果表明：1）凋落物层及各分解层凋落物现存量随着植被恢复而增加;同一恢复阶段D层凋落物现存量最高,占凋落物层现存量的41.59%-51.02%,不同分解层凋落物现存量的差异随着植被恢复而增大;各恢复阶段凋落物分解率为0.44-0.61,周转期为1.65-2.28 a。2）凋落物层及各分解层凋落物主要养分元素含量均表现为：N > Ca > Mg > K > P,随着植被恢复呈现出不同的变化特征,其中N、P含量总体上呈增加趋势,K含量LAG（除U层外）最高,PLL最低,Ca含量LCQ最高,PLL最低,Mg含量LAG（除U层外）最高,LVR最低;同一恢复阶段N、P（除PLL、LAG外）、K、Ca、Mg含量随着凋落物的分解而下降。3）不同恢复阶段凋落物层主要养分元素的储量依次为：N > Ca > Mg > K > P;凋落物层及各分解层凋落物主要养分元素总储量及各种养分元素的储量总体上随着植被恢复而增加;同一恢复阶段随着凋落物的分解,N、P储量增加,而K、Ca、Mg储量变化不大;随着植被恢复,凋落物层养分元素储存能力和转化归还能力提高,特别是N,养分元素总释放率下降,有利于养分的固持。4）乔木层、灌木层、草本层的植物多样性指数对凋落物层现存量和主要养分元素含量的影响不同,其中乔木层的影响最明显。     

林下层植物在退化马尾松林恢复初期养分循环中的作用

以鼎湖山退化马尾松 (Pinusmassoniana)林恢复过程中林下层植物凋落物、分解和养分动态为对象 ,研究了林下层植物在退化马尾松林恢复初期养分循环中的作用。结果表明 ,林下层年凋落物量除在第 5年有所下降外均随时间逐年上升 ,但其增加速率随年份不同而异 ,总平均年增长速率为 3 8%。第 4年凋落物量为 0 .2 0 t· hm- 2 · a- 1,第 1 1年为 1 .1 7t·hm- 2·a- 1。凋落物养分元素平均浓度为 (% ) :N0 .95 ,P0 .0 4,K0 .5 7,Ca0 .1 3和 Mg0 .0 8,基本上以夏季和秋季最高冬春交替月份最低。第 1 1年凋落物各元素养分归还量为 (kg· hm- 2·a- 1) :N1 1 .1 0 ,P0 .47,K6.65 ,Ca1 .48和 Mg 0 .91。凋落物在分解过程中失重率呈直线模型变化 ,第 1年的分解速率为 3 1 % ,至试验结束时凋落物的残存量占起始量的 66%。在凋落物分解过程中 ,N和 P浓度随时间逐渐上升 ,但 N增加的速度较 P快 ,其余元素浓度均下降 ,但 K下降的速度最快。在凋落物分解过程中 ,N是唯一表现残留量呈先上升然后下降变化的元素。P的残留量变化与凋落物的失重率变化几乎一致。各元素在分解试验结束时残留量占起始量的百分比分别为 :N 90 % ,P 67% ,K 9% ,Ca 3 0 %和Mg 1 4%。可见 ,林下层凋落物在退化马尾松林恢复初期碳及其它营养元素循     

降水量变化对蒙古栎落叶分解过程的间接影响

分析了在4种不同降水量条件下蒙古栎叶凋落物基质质量的变化,并应用分解袋法研究其凋落物在蒙古栎次生林内的分解过程.结果表明：与对照相比,降水量减少条件下,蒙古栎叶凋落物的初始N、P、K浓度显著升高,初始木质素浓度显著降低,凋落物分解速率大,N、P、K矿化率高,N和P固持时间缩短;降水量增加情况下,其凋落物初始N浓度显著降低、木质素浓度显著升高,N、P、K矿化率低,N和P固持时间延长.4种类型叶片凋落物的质量损失过程均符合指数降解模型,分解速率可以由凋落物木质素/N来预测.相关性分析显示,木质素浓度高、N浓度低的两种凋落物的分解速率与N浓度相关性最大;而木质素浓度低、N浓度高的两种凋落物的分解速率与木质素浓度相关性最大.说明降水量的变化显著地改变了蒙古栎叶凋落物的基质质量,进而间接地改变了凋落物的分解过程.     

Leaf litter decomposition characteristics and controlling factors across two contrasting forest types

两种不同森林类型叶凋落物分解特征及影响因子研究 叶凋落物分解为森林生态系统提供了重要的能量和养分来源。除传统的环境因素外,叶凋落物的降解过程也受到绿叶功能性状和叶凋落物基质质量的影响。然而,在群落水平上,绿叶功能性状和叶凋落物基质质量对不同森林群落叶凋落物分解的相对重要性仍不清楚。因此,本研究以北京东灵山地区7种典型森林群落类型的混合叶凋落物为研究对象,利用分解袋法通过360天的野外相似环境分解实验对叶凋落物的分解过程进行了研究。这些森林群落包括6种分别以胡桃楸(Juglans mandshurica)、青杨(Populus cathayana)、棘皮桦(Betula dahurica)、白桦(Betula platyphylla)、油松(Pinus tabuliformis) 和华北落叶松(Larix gmelinii var. principis-rupprechtii) 为优势种的单优种群落,以及一种以大叶白蜡(Fraxinus rhynchophylla)、蒙古栎(Quercus mongolica)和蒙椴(Tilia mongolica)为优势种的共优种群落。研究结果表明,不同森林群落之间叶凋落物分解速率存在显著差异。群落聚合的植物功能性状和叶凋落物基质质量分别解释了群落叶凋落物分解速率变异的35.60%和9.05%,两者交互作用解释率为23.37%,表明群落聚合的植物功能性状及其与叶凋落物基质质量的共同作用是影响群落叶凋落物分解速率变异的主要因素。通过冗余分析发现,叶片氮含量、叶干物质含量、叶片单宁含量和比叶面积能显著影响群落叶凋落物分解速率的变异。因此,在对群落水平上叶凋落物分解的研究应该关注群落聚合的绿叶功能性状对分解的影响。     

不同月份采集的贝加尔针茅地上部的分解特征及影响因素

利用植物生长过程中植物组织内养分元素化学性质的季节性变化特点,在2009年生长季的不同月份(5—9月)采集了呼伦贝尔地区贝加尔针茅地上部(茎和叶),作为分解底物,采用分解袋法,研究其分解特点及其影响因素。结果表明:不同月份采集的贝加尔针茅分解底物之间的分解速度存在明显差异,依采集月份逐渐递减,5月>6月>7月>8月>9月;分解底物初始N、P、Zn、K、Mg和Mn含量与分解速度均呈显著正相关,而碳含量和C∶N与分解速度呈显著负相关,初始钙含量、N∶P与分解速度无显著相关性;土壤微生物生物量N与分解底物的残余质量(%)相关性明显;另外,土壤微生物生物量N与凋落物C、N含量也具有明显的相关性;分解底物质量损失与土壤水分含量显著正相关,而与土壤温度的相关性较弱,说明降水变化通过调节土壤湿度来影响凋落物分解。     

神农架常绿落叶阔叶混交林凋落物养分特征

凋落物是联结陆地生态系统植物与土壤养分的重要媒介,了解凋落物养分特征有助于理解陆地生态系统物质循环的机理。该研究于2015年收集了神农架地区常绿落叶阔叶混交林的新鲜凋落物及现存凋落物,测定其不同器官中大量元素(C、N、P、K、Ca、Mg)的含量,据此分析其养分含量、养分归还量、养分储量及化学计量比的特征。结果发现:该常绿落叶阔叶混交林新鲜凋落物的C、K养分含量显著高于现存凋落物,N、P、Ca、Mg养分含量显著低于现存凋落物;其凋落物大量元素的养分归还量及养分储量大小顺序均为C Ca N Mg K P,分别为1569.84、52.44、34.82、6.24、5.24、1.30 kg hm~(-2) a~(-1)及1835.29、87.87、51.17、12.12、3.90、1.95 kg hm~(-2) a~(-1);其新鲜凋落物及现存凋落物的C∶N∶P分别为1307.33∶27.73∶1及976.48∶26.77∶1,新鲜凋落物的C∶N、C∶P显著高于现存凋落物,N∶P无显著区别。研究表明,新鲜凋落物与现存凋落物养分含量之间的差异与不同元素在分解过程中的可淋溶性及生物固持等因素有关。该地区常绿落叶阔叶混交林凋落物养分归还量及养分储量相对于亚热带阔叶林平均水平较低;且显著低于喀斯特地区同类型森林,主要与其凋落物产量、降水量及植被类型有关。该森林生态系统新鲜凋落叶与中国及全球范围内阔叶树种凋落叶相比C∶N较低,C∶P、N∶P较高,这可能是由于该地区N沉降及P限制现象较为严重所致。     

西藏色季拉山暗针叶林凋落物层化学性质研究

The storage and chemical properties of the forest litter in dark coniferous forest of Sejila Mountain were studied. The results showed that the existing storage was 5. 863t·hm^-2 and the annual litter fall was 0. 3205 t·hm^-2 It implied that the forest litter decomposed slowly and accumulated quickly, and the turnover of nutrient circles was slow. The contents of N, Ca, Na, and Mn nutrient elements in litter layer were in the order of un-decomposed layer (U layer) > semi-decomposed layer (S layer) > decomposed layer (D layer), those of K, Fe, and Mg were in the order of D layer > S layer > U layer, and P element content was in the order of U layer > D layer> S layer. The pool of elements was 78. 483 kg·hm^-2 N, 3. 843 kg·hm^-2P, 48. 205 kg·hm^-2 K, 23.115 kg·hm^-2 Ca, 13. 157 kg·hm^-2 Na, 30.554 kg·hm^-2 Fe, 2. 113 kg·hm^-2 Mn and 27. 513 kg·hm^-2 Mg. The turnover of forest litter was the total of nutrient release accumulation. K, Fe, and Mg were enriched, and N,Ca, Na, Mn, and P were released with the turnover rate in the order of N > Ca > Na > Mn >P.     

三种苦苣苔对石灰土和红壤的适应性分析

为探讨苦苣苔科植物对其岩溶生境的适应性,该研究选取黄花牛耳朵(Primulina lutea)、紫花报春苣苔(Pri.purpurea)和桂林蛛毛苣苔(Paraboea guilinensis)三种苦苣苔科植物,将其栽种在石灰土及红壤两种不同类型的土壤中,观测记录其生长性状并对其叶片元素含量进行测定和比较。植株采集过程中,同时采集自然生境中三种苦苣苔科植物叶片及取样植物基部土壤,并对叶片及土壤元素的含量进行测定,作为今后苗圃试验的参照。结果表明:三种苦苣苔科植物在两种土壤上的生长状况及适应性具有差异,其在石灰土上生长良好,在红壤上生长较差;在两种不同土壤中,除N外,桂林蛛毛苣苔的叶片其他元素(P、K、Mn、Mg、Ca、Zn、Cu)差异极显著(P0.01);除P外,紫花报春苣苔的叶片其他元素(N、K、Mn、Mg、Ca、Zn、Cu)差异极显著(P0.01);除N、Cu、Ca外,黄花牛耳朵的叶片元素(P、K、Mn、Mg、Zn)差异极显著(P0.01);三种植物的叶片元素比值,除少数值没有差异外,大部分指标差异都极显著;对叶片元素与栽培土壤元素的相关性分析,发现植物叶片Mn元素与土壤中N、Ca、Mg、Zn、Mn、有机质含量等呈正相关,土壤P元素与叶片中N、P元素呈正相关,而与叶片中Zn元素呈负相关关系。在其他栽培条件一致的条件下,土壤因素及物种差别是造成黄花牛耳朵、紫花报春苣苔和桂林蛛毛苣苔适应性产生差异的主要原因。     

Evolutionary inheritance of elemental stoichiometry in phytoplankton

The elemental composition of phytoplankton is a fusion of the evolutionary history of the host and plastid, resulting in differences in genetic constraints and selection pressures associated with environmental conditions. The evolutionary inheritance hypothesis predicts similarities in elemental composition within related taxonomic lineages of phytoplankton. To test this hypothesis, we measured the elemental composition (C, N, P, S, K, Mg, Ca, Sr, Fe, Mn, Zn, Cu, Co, Cd and Mo) of 14 phytoplankton species and combined these with published data from 15 more species from both marine and freshwater environments grown under nutrient-replete conditions. The largest differences in the elemental profiles of the species distinguish between the prokaryotic Cyanophyta and primary endosymbiotic events that resulted in the green and red plastid lineages. Smaller differences in trace element stoichiometry within the red and green plastid lineages are consistent with changes in trace elemental stoichiometry owing to the processes associated with secondary endosymbioses and inheritance by descent with modification.     

Soil-plant element relationships in a tundra ecosystem

The objectives of this study were to (1) provide a baseline estimate of soil and plant element concentrations for an intensive research site at Imnavait Creek in northern Alaska, and (2) examine the relationships between soil and plant elements in an arctic ecosystem. Soil and plant element concentrations were highly variable along biotic, spatial, and temporal axes. Deciduous shrubs had higher leaf concentration of N, P. K and Mg, whereas an evergreen shrub had higher leaf concentrations of Ca, Mn, Al and Si. Based on high required solution phase turnover rates, the most likely elemental deficiencies are N > P > K > Ca = Mg. Based on low required solution phase turnover rates and high soil concentrations. Fe, Mn, Zn and Cu deficiencies are unlikely. Manganese could be present in toxic concentrations. The nutrient bottleneck in tundra ecosystems appears to be the rate of nutrient movement to the solution phase.     

Factors affecting tissue nutrient concentrations in aCarex meadow

Summary The influence of community and edaphic variables on tissue nutrient concentration was assessed for seven species on aCarex wetland in southern Quebec, Canada.Potassium and sodium tissue levels were considerably higher and Ca and Mg 35% lower than in a deciduous forest. Macronutrient concentrations decreased in the order K>N>Ca>Mg>Na>P. Micronutrient concentrations (Fe>Mn>Zn>Cu) ranged from 0.038–0.005 mg/g. This was 2–3 times less abundant than in an adjacentScirpus wetland. Inter-species coefficient of variation in N, P and K was low (14%) compared to variation in Ca, Mg, and the micronutrients (35%).Principal components analysis of interrelations between tissue elements indicated a clear distinction between N, P, K, Cu, Mn, and Zn levels and ash, Ca, Mg, Na, and Fe levels on the first component. This difference related closely to water depth and fire incidence. The coincidence of burning with water depth and the period of maximum snowmelt and runoff in the Spring suggested the loss of N, P, K, Cu, Mn and Zn by volotilization, runoff, or leaching.Stem density was the most important parameter influencing tissue N, P, and K concentrations whereas soil nitrogen levels were important in ash, Ca, and Mg concentrations. Water depth was the most important variable in the case of Cu, Fe, Mn, Na and Zn levels. Typha angustifolia had the highest level of total nutrients in green tissue,Carex lanuginosa the lowest. Principal components analysis indicated soil nitrogen, water depth, and soil potassium levels, in that order, were the three most important variables influencing the patterns of tissue element variation among species.Potassium and sodium levels in 1-year old litter were 11% and 0.4% compared to concentrations in green tissue. Iron and manganese, both subject to oxidation and adsorption to litter at the soil surface, were distinctly higher (2247% and 199%) in litter than green tissue. Concentrations of these and other elements in litter were consistent with results reported in literature and indicated litter was especially active as a site of cation exchange in the system.     

Release of plant nutrients from decomposing leaf litter in a South Swedish beech forest

Weight loss and dynamics of plant nutrients (N, P, K, Ca, Mg, S, Fe, Mn, Na, Zn and Cu) in leaf litter were studied in a mature beech forest in South Sweden, using the litter bag technique. An initial decomposition period of about 12 to 18 months was characterized by an absolute net increase of N, P, and S contents in litter, followed by a period of net release of these elements. This development, which was most obvious for N and P, was interpreted as a change from a phase where decomposer activity was limited by the availability of nutrient elements to an energy-limited phase. A net release of nitrogen did not occur until after two years of decomposition, and a transfer of nitrogen and phosphorus between different litter layers is here proposed to work as a retention mechanism.
Potassium and sodium were quickly leached from the litter, while release of magnesium, calcium, and initially also manganese, was more associated to organic matter weight loss. Iron, zinc and copper were all strongly accumulated in the litter material. This is explained by mineral soil admixture for the former element and by atmospheric fall-out in combination with the chemical complex formation character for the latter two elements.
Finally, the importance of the different release processes in the total nutrient recycling of the forest is discussed.     

Concentrations and resorption patterns of 13 nutrients in different plant functional types in the karst region of south-western China

Background and Aims

Elucidating the stoichiometry and resorption patterns of multiple nutrients is an essential requirement for a holistic understanding of plant nutrition and biogeochemical cycling. However, most studies have focused on nitrogen (N) and phosphorus (P), and largely ignored other nutrients. The current study aimed to determine relationships between resorption patterns and leaf nutrient status for 13 nutrient elements in a karst vegetation region.

Methods

Plant and soil samples were collected from four vegetation types in the karst region of south-western China and divided into eight plant functional types. Samples of newly expanded and recently senesced leaves were analysed to determine concentrations of boron (B), calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), molybdenum (Mo), N, sodium (Na), P, sulphur (S) and zinc (Zn).

Key Results

Nutrient concentrations of the karst plants were lower than those normally found in other regions of China and the rest of the world, and plant growth was mainly limited by P. Overall, four nutrients revealed resorption [N (resorption efficiency 34·6 %), P (48·4 %), K (63·2 %) and Mg (13·2 %)], seven nutrients [B (–16·1 %), Ca (–44·0 %), Cu (–14·5 %), Fe (–205·5 %), Mn (–72·5 %), Mo (–35·6 %) and Zn (–184·3 %)] showed accumulation in senesced leaves and two nutrients (Na and S) showed no resorption or accumulation. Resorption efficiencies of K and Mg and accumulation of B, Ca, Fe and Mn differed among plant functional types, and this strongly affected litter quality. Resorption efficiencies of N, P and K and accumulation of Ca and Zn increased with decreasing concentrations of these nutrients in green leaves. The N:P, N:K and N:Mg ratios in green leaves predicted resorption proficiency for N, K and Mg, respectively.

Conclusions

The results emphasize the fact that nutrient resorption patterns strongly depend on element and plant functional type, which provides new insights into plant nutrient use strategies and nutrient cycling in karst ecosystems.     

Litter fall and nutrient dynamics in a Nigerian rain forest seven years after a ground fire

Abstract. Seasonal litter fall and mineral element content (N, P, Ca, Mg, K) of regrowth forest communities at the base and on the slope of an inselberg in Ile-Ife, Nigeria, were studied 7 yr after a ground fire ravaged the forest. Litter fall (tha^?1 yr^?1) was 4.6 (total), 4.2 (leaf), 0.3 (small wood < 2.5 cm diameter) and 0.1 (reproductive parts: fruits and flowers) in the base community and 6.4 (total), 5.4 (leaf), 0.9 (small wood) and 0.1 (reproductive parts) in the slope community. There was significant monthly variation in litter fall in the two communities with lowest amount of litter recorded during the wettest months of the year (May - August) and the highest amount during the dry season. Significant monthly variation (P<0.05) in Ca, Mg and K concentration in leaf litter and for Mg (P < 0.01) in fruit litter occurred, with the lowest concentration recorded during the wettest months (May-August). In leaf and wood litter the order of mineral element concentration was Ca>N>K> Mg > P while in fruit litter it was N > K > Ca > Mg > P. Quantities of mineral element (kg ha^-1 yr¹) returned to the soil via litterfall were N: 66; P: 4; Ca: 97; Mg: 15; K: 45 in base forest, and N: 112; P: 5; Ca: 142; Mg: 20; K: 66 in slope forest. Through leaf litter >88.5% of these elements was returned into the two communities, through wood > 4.0% and through reproductive organs > 0.3%. The order of quantities of these elements returned in leaf and wood litter was Ca > N > K > Mg > P, in fruit litter N ～ K > Ca > Mg > P. Significant monthly variation in the amounts of the various elements returned were recorded in leaf litter, but not in wood and fruit litter. The lowest amount of various elements was returned during the wettest months (May-August) which coincided with the period of the lowest element concentration and litter fall.