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1.
The effect of precipitation variation on the chemistry of Mongolian oak (Quercus mongolica) leaf litters was examined by analyzing litters of Mongolia oak saplings under four precipitation gradients. The decomposing process of these leaf litters in the Mongolian oak dominated forest was assessed using litter bag method. Compared with the litters of the Mongolian oak saplings from the natural precipitation site (A), litters produced by Mongolian oak from the driest precipitation gradient (A450) had significantly higher concentrations of nitrogen (N), phosphorus (P) and potassium (K) while lower acid-insoluble fraction (AIF) concentration. The decomposition study showed that A450 exhibited significantly higher decomposition rate, mineralization rates of N, P and K as well as much shorter N and P net immobilization periods. On the contrary, litters produced by seedlings from wettest gradient (A850) showed a totally opposite pattern. Litters from saplings that received comparable precipitation (A650) to those at the natural site (A) had significantly higher N concentration and faster decomposition rate as well as release rates of N, P and K. The mass loss patterns for the four litter types fitted the exponential model and the decay constant (k) can be well predicted by initial AIF/N. During the decomposition period, N concentration was best related to the percentage of mass remaining of the litters with relatively higher AIF concentrations and lower N concentrations, but the percentage of mass remaining of litters with lower AIF concentrations and higher N concentrations correlates strongly with AIF con centration. Our study proved that changes in precipitation significantly altered the litter quality, and therefore indirectly changed the decay process of leaf litters. __________ Translated from Chinese Journal of Applied Ecology, 2007, 18(2): 261–266 [译自: 应用生态学报]  相似文献   

2.
Litter decomposition in a subtropical plantation in Qianyanzhou,China   总被引：1，自引：0，他引：1  
A long-term (20 months) bulk litter decomposition experiment was conducted in a subtropical plantation in southern China in order to test the hypothesis that stable isotope discrimination occurs during litter decomposition and that litter decomposition increases concentrations of nutrients and organic matter in soil. This was achieved by a litter bag technique. Carbon (C), nitrogen (N) and phosphorus (P) concentrations in the remaining litter as well as δ13C and δ15N during the experimental period were measured. Meanwhile, organic C, alkali-soluble N and available P concentrations were determined in the soils beneath litter bags and in the soils at the control plots. The dry mass remaining (as % of the initial mass) during litter decomposition exponentially declined (y = 0.9362 e−0.0365x , R 2 = 0.93, P < 0.0001), but total C in the remaining litter did not decrease significantly with decomposition process during a 20-month period. By comparison, total N in the remaining litter significantly increased from 5.8 ± 1.7 g kg−1 dw litter in the first month to 10.1 ± 1.4 g kg−1 dw litter in the 20th month. During the decomposition, δ13C values of the remaining litter showed an insignificant enrichment, while δ15N signatures exhibited a different pattern. It significantly depleted 15N (y = −0.66x + 0.82, R 2 = 0.57, P < 0.0001) during the initial 7 months while showing 15N enrichments in the remaining 13 months (y = 0.10x − 4.23, R 2 = 0.32, P < 0.0001). Statistically, litter decomposition has little impact on concentrations of soil organic C and alkali-soluble N and available P in the top soil. This indicates that nutrient return to the topsoil through litter decomposition is limited and that C cycling decoupled from N cycling during decomposition in this subtropical plantation in southern China.  相似文献   

3.
Rates of weight loss and nutrient (N and P) release patterns were studied in the leaf litter of the dominant tree species (Ailanthus grandis, Altingia excelsa, Castanopsis indica, Duabanga sonneriatioides, Dysoxylum binectariferum, Mesua ferrea, Shorea assamica, Taluma hodgsonii, Terminalia myriocarpa and Vatica lancefolia) of a tropical wet evergreen forest of northeast India. Nitrogen and phosphorus mineralization rate and decay pattern varied significantly from species to species. In general, the decay pattern, characterized by using a composite polynomial regression equation, exhibited three distinct phases of decay during litter decomposition—an initial slow decay phase (0.063% weight loss day−1), followed by a rapid decay phase (0.494% weight loss day−1) and a final slow decay phase (0.136% weight loss day−1). The initial chemical composition of the litter affected decomposition rates and patterns. Species like D. sonneriatoides, D. binectariferum, and T. hodgsonii with higher N and P content, lower carbon and lignin content, and lower C:N ratio and lignin:N ratio exhibited relatively faster decomposition rates than the other species, for example M. ferrea, C. indica and A. grandis. A slow decay rate was recorded for species such as M. ferrea, C. indica, and A. grandis. The initial N and P content of litter showed significant positive correlations with decay rates. Carbon and lignin content, lignin:N, and C:N showed significant negative correlations with decay rates. Soil total N and P, and rainfall, soil temperature, and soil moisture had positive correlations with decay rates. The rapid decomposition rates observed in comparison with other different forest litter decay rates confirm that tropical wet evergreen forest species are characterized by faster decomposition rates, indicating a faster rate of organic matter turnover and rapid nutrient cycling.  相似文献   

4.
In order to explore the release of nutrients and the effects of global warming on the decomposition rate of forest litter, an experiment is designed to reciprocally decompose forest foliar litter in two sites across climatic zones: Mt. Jianfengling in Hainan Province in the tropics and Mt. Dinghushan in Guangdong Province in the subtropics. The two sites have similar altitudes, soil types, annual mean rainfall and seasonality of dry and wet. The main difference between these two sites is the annual mean temperature with the difference of 3.7°C. Foliar litters of 10 native dominant tree species have been collected respectively from the two sites and divided into single-species litter and mixed litter. They are decomposed reciprocally in the two sites. The results indicate that litter decomposes in the tropical site 1.36–3.06 times more rapidly than in the subtropical site. Apparent Q 10, calculated on the basis of the temperature difference between the two sites, ranges from 3.7 to 7.5. The return amount of N, P and C will increase by 32.42, 1.033 and 741.1 kg/hm2, respectively in Mt. Dinghushan in the first year’s litter decomposition under the prevailing temperature condition. Only in Mt. Dinghushan is the correlation between decomposition rate constant and initial litter quality high and significant in the ratio of lignin to N, lignin, the ratio of lignin to P, HLQ and C. This is not the case at Mt. Jianfengling. __________ Translated from Journal of Beijing Forestry University, 2005, 27(1): 24–32 [译自: 北京林业大学学报, 2005, 27(1): 24–32]  相似文献   

5.
Dry evergreen forest (DEF) and dry deciduous dipterocarp forest (DDF) are major forest types extensively distributed in northeastern Thailand, exhibiting different nutrient cycling properties. This study aims to improve our understanding on the pattern of mass loss and nitrogen release from two categories of roots (fine, <2 mm and small, 2–5 mm) of Hopea ferrea at DEF and fine roots of mixed trees and dwarf bamboo (Arundinaria pusilla) at DDF sites. Decomposition experiment was performed for more than 12 months using buried litter bag technique. Initial chemistry was significantly different among the four root litters; fine root of H. ferrea exhibited a low ratios of C:N and acid-insoluble:N. The fine root of dwarf bamboo was characterized by high contents of total carbohydrate and ash. Decomposition rate constants (year−1) of ash-free weight remaining were 1.27 and 0.55 for fine and small roots of H. ferrea, and 0.73 and 0.66 for fine root of mixed trees and dwarf bamboo, respectively. At the end of the experiment, the N concentration in fine and small roots of H. ferrea increased to 1.5 times the initial concentration. Whereas, N mass of dwarf bamboo decreased during the experiment. This suggests a different pattern of root decomposition and N release in two forest ecosystems. Generally, the fine root decomposition was faster in the DEF than in the DDF. The role of initial litter chemistry was more pronounced than the climatic seasonality on the belowground decomposition pattern in our study.  相似文献   

6.
亚热带林7种林冠树种落叶分解中矿质元素动态   总被引：1，自引：0，他引：1  
应用分解网袋法对亚热带常绿阔叶林7种常见林冠树种落叶分解过程中矿质元素(K,Na,Ca,Mg,Al,Fe,Mn,Cu和Zn)动态变化进行了为期2年的研究。这些树种是研究地区森林植被的代表种,且不同树种的落叶化学组成差异明显。研究结果表明:落叶分解速率(落叶干重残留百分率和分解常数k)与矿质元素初始浓度之间没有明显的相关性。但是,大多数情况下,落叶干重残留百分率与残留落叶的矿质元素浓度之间有着显著的相关关系。落叶分解过程中不同矿质元素的迁移性大小依次为:Na=K>Mg≥Ca>N≥Mn≥Zn≥P>Cu>>Al>>Fe。各树种的K和Na浓度在分解中均表现为下降趋势,Ca和Mg浓度亦表现为下降趋势,但在分解初期偶有升高倾向。而各树种中的其它元素(Zn,Cu,Al,Fe)浓度在分解中都表现出升高趋势,唯有Mn例外,在不同树种间,其浓度的变化模式存在一定差异。大多数树种的Cu,Al和Fe等3元素在分解试验末期的绝对重量均比初始重量显著提高,其机理在很大程度上可能归因于这些元素与腐殖质的结合,而不是生物固定。  相似文献   

7.
Nitrogen fixation during litter decomposition was studied for 34 months using litterbags containing newly fallen litter of coniferous species Cryptomeria japonica and Pinus densiflora and that of deciduous species Quercus serrata. Litterbags were set in contact with the forest floor in a deciduous broad-leaved forest near the top of a slope and in a C. japonica stand at the middle of the slope at a watershed in eastern Japan. Nitrogen-fixing activity, estimated by acetylene reduction after 16 and 19 months of incubation, was 62.65–3.86 nmoles C2H4 h−1 g−1 DW in Cryptomeria litter, but only 1.07–0.09 in Pinus and 0.72–0.04 in Quercus. The rate of N increase in decomposing litter was highest in Cryptomeria. Fungal biomass in decomposing litter, estimated by ergosterol content, increased during the initial 16 months of incubation in Cryptomeria and Quercus, and during the initial 19 months of incubation in Pinus. The litter decomposition rate was highest in Cryptomeria among the three species, due to increased N content and fungal biomass in Cryptomeria litter. Thus, N increase in decomposing Cryptomeria litter affects the subsequent N dynamics and decomposition pattern.  相似文献   

8.
We monitored the decomposition of mixed leaf litter (Quercus spp., Carya spp., and Pinusechinata) in a Missouri Ozark forest eight years after experimental harvest. Leaf litter mass losses and changes in carbon chemistry (extractive, acid soluble, and acid insoluble fractions) were measured over 32 months in field incubations to determine the effects of litter composition and stand manipulation on decomposition and nitrogen (N) concentration in the remaining litter. The decay (k) rate over this period ranged between 0.39 (±0.010) and 0.51 (±0.002) year−1 for oak, oak–hickory, and oak–pine litter. There were significant main effects of stand manipulation (p = 0.03) and litter type (p < 0.01) on decay. Mass losses of oak and oak–hickory litter were 7% (p = 0.02) and 4% (p = 0.04) higher on harvested stands than controls, respectively. Mass loss of oak–hickory litter was 3% faster than oak–pine (p = 0.03) and 6% faster than oak (p = 0.02) litter on control stands, whereas the oak–hickory litter mass loss was 5% higher than oak litter on harvested stands (p = 0.01). The decay (k) rate had a linear relationship with initial leaf litter nitrogen content and lignin-to-N ratio. The nitrogen concentration in remaining litter had a nonlinear relationship to cumulative mass loss suggesting an exogenous source of N. In summary, this study demonstrated significant effects of timber harvest and litter mixtures on decomposition and N dynamics in a managed Missouri Ozark forest.  相似文献   

9.
Litterfall and decomposition are the two main processes accounting for soil enrichment in agroforestry. The extent of enrichment in soil properties depends on the tree species, management practices and the quantity and quality of litter. A field investigation was carried out to study litterfall production, decay rates, release of nutrients and consequent changes in soil physicochemical properties under crowns of four multipurpose tree species (MPTs) in irrigated conditions in farm fields. The species were Prosopis cineraria (L.), Dalbergia sissoo (Roxb.) ex DC, Acacia nilotica (L.) Del. and Acacia leucophloea (Roxb.) Willd. Annual accretion of litter ranged from 36 to 54 kg tree−1 year−1 and was highest under D. sissoo and lowest under A. nilotica. Total litterfall production was in the order: P. cineraria > A. leucophloea > A. nilotica > D. sissoo. P. cineraria showed the highest NPK concentration in litter. For all MPTs, a large pulse of litterfall coincided with the winter season (November to February). Litter of P. cineraria decomposed fastest while that of A. nilotica was slowest. More than 95% of the leaf litter of P. cineraria decomposed in 6 months, of D. sissoo in 7 months and A. leucophloea and A. nilotica in 9 months. Decomposition rate of litter was highly correlated with neutral detergent fibre (NDF) (r = −0.94) and P (r = −0.91) concentration. N, P and K release were best correlated with NDF, acid detergent fibre (ADF), P, lignin, lignin/N and C/P ratios and NDF alone explained 88% to 94% of the variability in litter decomposition and nutrient release rates. There was significant build up of soil organic carbon and available NPK in the agrisilvicultural systems but also a decrease in soil pH. Build up in soil fertility was significantly correlated with litterfall and soil improvement was greatest under P. cineraria.  相似文献   

10.
Homegardens are one of the oldest forms of managed land use systems characterised by high diversity and complexity of their species structure which in turn contribute to efficient nutrient cycling. Litterfall and decomposition are the two major processes that replenish the soil nutrient pools and endow sustainability to these agroforests. A study was carried out in the village Dargakona, Barak Valley, northeast India to understand the pattern of litter production and litter decomposition in the traditional homegardens. Annual litter production was 6.27 Mg ha−1 with a bimodal distribution pattern and the nitrogen input through litterfall accounted for 48.17 kg ha−1 year−1. Litter decomposition studies for ten multipurpose trees revealed Sapium baccatum and Toona ciliata to be the most labile litter species and the decay rate coefficients varied among the species with differing rates of nutrient release pattern. Such studies can provide information regarding the litter quality of indigenous tree species and help validate farmers planting and management of multiple species which allows for efficient nutrient cycling of the system.  相似文献   

11.
From 2001 to 2003, the litter decomposition dynamics of dominant tree species were conducted using a litterbag burying method in the broadleaf-Korean pine forest, spruce-fir forest and Ermans birch forest, which represents three altitudinal belts in Changbai Mountain, northeast China. The spatial and temporal dynamics of litter decomposition and the effects of litter properties were examined. Furthermore, the decomposition trend of different species was simulated by the Olson model, and results showed that annual mass loss rates increased over time, but was not significantly correlated. Leaf decomposition rates increased after decomposing for 638 days (1.75 years), and the order of dry weight remaining rates of leaf litter for different species is: Asian white birch (Betula platyphylla) (24.56%) < Amur linden (Tilia amurensis) (24.81%) < Korean pine (Pinus koraiensis) (38.48%) < spruce (Picea jezoensis var. microsperma) (41.15%) < Ermans birch (Betula ermanii) (41.53%) < fir (Abies nephrolepis) (42.62%). The dry weight remaining rates of twig litter was smaller than that of leaf litter, and followed the order of Amur linden (44.98%) < fir (64.62%) < Korean pine (72.07%) < spruce (73.51%) < Asian white birch (77.37%) < Ermans birch (80.35%). The simulation results by the Olson model showed that, in leaf, the 95%-decomposition rates ranged from 4.5 to 8.0 years, and annual decomposition rate (k) followed the order of Amur linden (0.686) > Asian white birch (0.624) > Korean pine (0.441) > spruce (0.406) > fir (0.397) > Ermans birch (0.385); in twig, it ranged from 7.8 to 29.3 years, and k follows the order: Amur linden (0.391) > fir (0.204) > Korean pine (0.176) > spruce (0.157) > Asian white birch (0.148) > Ermans birch (0.102). In general, the differences of decomposition rate are evident between leaf and twig litter and among species, and were higher in broad-leaved species compared with coniferous species at the same elevation, and decreased with the ascending of elevation. __________ Translated from Acta Ecologica Sinica, 2006, 26(4): 1,037–1,046 [译自: 生态学报]  相似文献   

12.
[目的]探讨竹林与其林下植被凋落物叶之间相互影响的潜在机制,为合理经营管理毛竹林林下植被提供理论参考。[方法]采用原位分解袋法研究了四川长宁毛竹与林下植被芒箕凋落物叶分解和养分释放过程。[结果](1)芒箕凋落物叶初始C、N、P含量和羟基碳高于毛竹(P 0. 05),而C∶N、C∶P、烷基碳、氧烷基碳和芳香碳低于毛竹(P 0. 05)。(2)凋落物叶分解和养分释放速率芒箕整体高于毛竹,芒箕和毛竹分解常数(k)分别为0. 58±0. 03和0. 73±0. 02,C、N、P养分释放均表现为净释放。(3)凋落物叶混合对分解速率没有显著影响,但抑制了N、P元素整个分解周期和C元素中后期的释放。(4)凋落物叶分解过程中元素含量变化格局表现为C含量和C∶N比整体呈下降趋势,N含量和N∶P比有小幅上升,P含量有微弱的下降趋势,C∶P比呈波动性变化。(5)凋落物叶分解速率与土壤温度、初始凋落物叶N和P含量呈显著正相关(P 0. 01),与初始凋落物叶的C∶N和C∶P呈极显著负相关(P 0. 01),与土壤含水量相关不显著。[结论]单独分解过程中,毛竹凋落物叶分解速率低于林下植被芒箕,养分释放特征均表现为直接释放;混合分解过程中,毛竹和芒箕凋落物叶分解速率无显著混和效应,但养分释放的混合效应表现出一定负效应和不同阶段性。  相似文献   

13.
Two-year-old seedlings ofPinus koraiensis, Pinus sylvestriformis andFraxinus mandshurica were treated in open-top chambers with elevated CO2 concentrations (700 μL·L−1, 500 μL·L−1) and ambient CO2 concentrations (350 μL·L−1) in Changbai Mountain from June to Sept. in 1999 and 2001. The net photosynthetic rate, dark respiration rate, ribulose-1,5-bisphosphate carboxlase (RuBPcase) activity, and chlorophyll content were analyzed. The results indicated the RuBPcase activity of the three species seedlings increased at elevated CO2 concentrations. The elevated CO2 concentrations stimulated the net photosynthetic rates of three tree species exceptP. sylvestriformis grown under 500 μL·L−1 CO2 concentration. The dark respiration rates ofP. koraiensis andP. sylvestriformis increased under concentration of 700 μL·L−1 CO2, out that ofF. mandshurica decreased under both concentrations 700 μL·L−1 and 500 μL·L−1 CO2. The seedlings ofF. mandshurica decreased in chlorophyll contents at elevated CO2 concentrations. Foundation item: This paper was supported by the National Natural Science Foundation of China (No. 30070158). Knowledge Innovation Item of Chinese Academy of Sciences (KZCX2-406) and “Hundred Scientists” Project of Chinese Academy of Sciences. Biography: Zhou Yu-mei (1973-) Ph. Doctor, Assistant Research fellow Institute of Applied Ecology. Chinese Academy of Sciences. Shenyang 110016. P.R. China. Responsible editor: Song Funan  相似文献   

14.
Multipurpose trees, the integral components of homegardens, contribute significantly to the closed nutrient cycling processes and sustainability of the ecosystem. Although, the litter production and probable nutrient returns via litter in homegardens have been documented, quantification and characterization of the decomposition and bioelement release from the litter have received relatively little scientific attention. The objective of the present study is to explore the litter dynamics of six locally important multipurpose trees (Mangifera indica L., Artocarpus heterophyllus Lamk., Anacardium occidentale L., Ailanthus triphysa Dennst., Artocarpus hirsutus L. and Swietenia macrophylla L.), in an agroforestry homegarden in Southern Kerala, India. Litterfall and nutrient additions in the six species ranged from 383 to 868 g m−2 yr−1, nitrogen, 6.4 to 8.8, phosphorus, 0.17 to 0.42 and potassium, 1.1 to 2.8 g m−2 yr−1. The annual litter output in the homegarden was 425 kg with A. hirsutus, M. indica, A. heterophyllus and A. occidentale recording significantly higher litter and nutrient additions. Leaf litter decay studies revealed A. heterophyllus and A. occidentale to be the most labile litter species and S. macrophylla the most recalcitrant. The decay rate coefficients varied significantly among the species. Foliage decomposition rates related to the initial chemical composition of the litter revealed best correlation with lignin. NPK release was almost complete by the end of decay in all species inspite of the initial phases of accumulation observed for nitrogen and phosphorus. Two-way analysis of variance test revealed significant differences in the contents of the three elements as a function of species and time elapsed. Macronutrients were released in the order K>N/P. The higher rates of decay and nutrient turnover in M. indica, A. heterophyllus and A. occidentale foliage indicated the potential of using these species’ litter as nutrient inputs in agriculture while A. triphysa, A. hirsutus and S. macrophylla perform better as organic mulches taking a longer time for decay and hence nutrient release.  相似文献   

15.
This study investigated the effects of Ips typographus (L.) damage on initial litter quality parameters and subsequent decomposition rates of oriental spruce tree species [Picea orientalis (L.) Link]. The needle litter was collected from highly damaged, moderately damaged and control stands on two aspects (north and south) and two slope position (top and bottom) on each aspect. The litter was analyzed for initial total carbon, lignin and nutrient (nitrogen, phosphorus, potassium, calcium, magnesium and manganese) concentrations. The variability in nitrogen and calcium concentrations and ratios of C:N, lignin:N and lignin:Ca was significantly affected by the insect damaged levels. While nitrogen concentrations in needle litter increased with increasing insect damage (and consequently the ratios of C:N and lignin:N decreased), calcium concentrations decreased (and consequently the ratio of lignin:Ca increased). Aspect and slope positions explained most of the variability in carbon, lignin, phosphorus, potassium, magnesium and manganese concentrations and lignin:P ratio between all studied stands. Litter decomposition was studied in the field using the litterbag technique. The litter from highly damaged stands showed highest decomposition rates followed by moderately damaged and control stands. The mass loss rates were significantly positively correlated with initial nitrogen concentration and negatively with C:N and lignin:N ratios. The effects of microclimate resulting from canopy damage on litter decomposition was also examined at the same time using standard litter with the same litter quality parameters, but they showed no significant differences among the insect damage levels indicating that alteration of the litter quality parameters produced by I. typographus damage played a more important role than altered microclimate in controlling needle litter decomposition rates. However, changes in microclimate factors due to topography influenced decomposition rates.  相似文献   

16.
[目的]探讨南亚热带西南桦和尾巨桉人工纯林的凋落叶分解动态及其与土壤化学性质之间的相关关系.[方法]采用原位分解袋法研究凋落叶的分解过程.[结果]表明:西南桦、尾巨桉人工林凋落叶分解系数分别为0.96 a-1和0.88 a-1.在为期12个月的分解试验中,2种凋落叶有机C含量在整个分解过程中呈逐渐下降趋势;全K含量和C/N比在分解前期迅速下降,之后趋于平缓;全N含量和全P含量在整个分解过程中呈逐渐上升趋势;2种凋落叶N/P比则呈先升高后下降的趋势.无论是分解前期还是分解后期,凋落叶质量损失与N含量均呈显著正相关(前期R=0.877;后期R=0.855),与C/N均呈显著负相关(前期R=-0.735;后期R=-0.697).与尾巨桉林地土壤性质相比,西南桦凋落叶分解提高了林地0~10、10~20 cm土壤的有机C、全N、全P、全K、N/P,对2030 cm土壤有机C、全K、pH值、C/N、N/P则未产生显著影响.相关分析表明:凋落叶初始有机C含量与土壤有机C、全N、全P、全K、N/P显著相关;凋落叶初始全N含量与土壤全N、pH值、C/N显著相关.[结论]凋落叶的养分含量与土壤养分的关系紧密;与尾巨桉相比,西南桦凋落叶的养分含量明显较高,分解速率更快,释放到土壤中的养分也更多.  相似文献   

17.
[目的]为了解雷州半岛尾巨桉速生人工林生态系统的C、N、P分配格局及化学计量特征。[方法]采用空间换时间的方法,选取雷州半岛4种不同林龄(1、3、5、7 a)的尾巨桉人工林为研究对象,对尾巨桉叶片、凋落物及土壤的C、N、P含量及化学计量特征进行测定分析。[结果]表明:C、N含量表现为叶片凋落物土壤,P含量表现为叶片土壤凋落物,且3个库间差异显著;土壤的C含量随林龄增加而增加,N、P含量差异不显著,土壤C∶N随林龄的增加而增加,说明土壤有机质分解速率逐渐下降;凋落物的C∶N为54. 07 92. 18 ( 25),表明尾巨桉林下凋落物分解速率较慢,N元素成为主要限制凋落物分解的元素,凋落物的C∶N随林龄的增加先增加后下降,凋落物分解速度先降低后升高;叶片的N∶P为10. 80 12. 98,说明中幼林龄尾巨桉受N限制较明显。相关性分析表明:凋落物养分元素含量受叶片限制,土壤养分含量受凋落物限制,表明生态系统内部C、N、P元素在植物、凋落物与土壤之间实现了运输和转换。[结论]雷州半岛尾巨桉中、幼林龄时期土壤有机质及凋落物分解速率较慢;随林龄的增加,土壤有机质、凋落物分解速率下降,N元素成为其主要分解限制性元素,林分生长受N限制明显。  相似文献   

18.
We investigated decomposition and nutrient release patterns of leaf and sheath litter of two important highland bamboo species (viz. Phyllostachys bambusoides Sieb. (Zucc.) and Arundinaria racemosa Munro) by using a litter bag technique. Our objective was to improve understanding of the addition of organic matter and nutrients to soil from the litter of two abundant highland bamboo species, species that support the local population of the region in many ways. N concentration and N/P ratio were significantly higher (p<0.01) in leaf litter of P. bambusoides. Significantly, larger values of lignin concentration, C/N ratio, and lignin/N ratio were found in the sheath litter of A racemosa. Weight loss of both leaf and sheath litter was strongly positively correlated with N and N/P ratio, and significantly negatively correlated (p<0.01) with C/N ratio. Lignin/N had a negative correlation with decay rate. In both species, only lignin concentration of the litter showed strong positive correlation with N release. Litter decomposition and N release patterns were similar for the two bamboo species, whereas, P release rate from leaf litter was higher in P. bambusoides and differed significantly between sheath and leaf litter for both species. The complex pattern of nutrient release through mineralization and immobilization during litter decomposition ensures nutrient availability in both managed and natural bamboo stands subjected to anthropogenic disturbances.  相似文献   

19.
Biomass and nutrient transfer (N, P, K, Ca, Mg) of bilberry (Vaccinium myrtillus L.) leaf litter fall, as well as decomposition and nutrient release, were studied in four mature forest stands situated in Central and South Sweden. Bilberry leaf litter fall amounted to between 33 and 55 kg ha‐1 yr‐1 in the four stands. Only minor differences between sites were noted for litter concentrations of N, P and Ca, whereas K and Mg showed somewhat larger variability. Relative amounts of the five nutrient elements in the litter fall were generally in the order N > Ca > K > Mg > P. The amounts of nutrients returned to the forest floor by the annual leaf litter fall in the stands ranged from 0.4 to 0.8 kg ha‐1 for N, 0.4 to 0.6 kg ha‐1 for Ca, 0.2 to 0.7 kg ha‐1 for K, 0.1 to 0.2 kg ha‐1 for Mg and 0.04 to 0.08 kg ha‐1 for P.

The decomposition of the local bilberry leaf litter was followed by means of litterbags during three years. At all sites there was an extremely rapid mass loss from the litter (between 45% and 54%) during the first four to five months of decomposition. After this initial phase, the decomposition rates decreased markedly and after three years the accumulated mass losses of the litters varied between 64% and 78% at the studied sites. After two and three years of decomposition, three of the sites exhibited almost similar litter mass losses whereas at the fourth site the litter was decomposed to a significantly lower degree. The pattern of nutrient release from the decomposing bilberry leaf litter differed somewhat from site to site. Minor differences were, however, noted for P, Ca and Mg while N and K were more strongly retained in the litter at one of the sites.  相似文献   

20.
The effects of tree species on the dynamics of nutrient transformations during leaf-litter decomposition are not well understood in tropical rain forests. To examine differences in the dynamics of C, nutrients, and organic constituents during decomposition among tree species, the leaf-litter decomposition of 15 trees was assessed using a litter-bag method in a lowland tropical rain forest in Sarawak. The dynamics of C was parallel to that of weight loss. The dynamics of nutrients were grouped into three patterns. The dynamics of K was characterized by a high leaching loss in the initial stages, and that of Ca and Mg generally showed a gradual decrease over the course of decomposition. The dynamics of N and P showed highly different patterns with the weight loss, and was characterized by relatively higher remaining mass at the end of the experiment. The variations or exceptions of nutrient dynamics among tree species were considered to be related to the initial concentration of each nutrient. For the dynamics of organic constituents, water-soluble carbohydrates disappeared quickly at the initial stages, and acid-soluble carbohydrates were the second fastest decomposing fraction; the decomposition of acid-insoluble residue (AIS) was the slowest. The release of limiting nutrients (N and P) generally followed the disappearance of AIS, but was independent of the disappearance of AIS when the initial concentrations of these nutrients were very low.  相似文献   

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