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1.
Understory vegetation plays a crucial role in carbon and nutrient cycling in forest ecosystems; however, it is not clear how understory species affect tree litter decomposition and nutrient dynamics. In this study, we examined the impacts of understory litter on the decomposition and nutrient release of tree litter both in a pine (Pinus sylvestris var. mongolica) and a poplar (Populus × xiaozhuanica) plantation in Northeast China. Leaf litter of tree species, and senesced aboveground materials from two dominant understory species, Artemisia scoparia and Setaria viridis in the pine stand and Elymus villifer and A. sieversiana in the poplar stand, were collected. Mass loss and N and P fluxes of single-species litter and three-species mixtures in each of the two forests were quantified. Data from single-species litterbags were used to generate predicted mass loss and N and P fluxes for the mixed-species litterbags. In the mixture from the pine stand, the observed mass loss and N release did not differ from the predicted value, whereas the observed P release was greater than the predicted value. However, the presence of understory litter decelerated the mass loss and did not affect N and P releases from the pine litter. In the poplar stand, litter mixture presented a positive non-additive effect on litter mass loss and P release, but an addition effect on N release. The presence of understory species accelerated only N release of poplar litter. Moreover, the responses of mass loss and N and P releases of understory litter in the mixtures varied with species in both pine and poplar plantations. Our results suggest that the effects of understory species on tree litter decomposition vary with tree species, and also highlight the importance of understory species in litter decomposition and nutrient cycles in forest ecosystems. 相似文献
2.
Leaf litter decomposition in temperate deciduous forest stands with a decreasing fraction of beech (Fagus sylvatica) 总被引:2,自引:0,他引:2
We hypothesised that the decomposition rates of leaf litter will increase along a gradient of decreasing fraction of the European
beech (Fagus sylvatica) and increasing tree species diversity in the generally beech-dominated Central European temperate deciduous forests due
to an increase in litter quality. We studied the decomposition of leaf litter including its lignin fraction in monospecific
(pure beech) stands and in stands with up to five tree genera (Acer spp., Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, Tilia spp.) using a litterbag approach. Litter and lignin decomposition was more rapid in stand-representative litter from multispecific
stands than in litter from pure beech stands. Except for beech litter, the decomposition rates of species-specific tree litter
did not differ significantly among the stand types, but were most rapid in Fraxinus excelsior and slowest in beech in an interspecific comparison. Pairwise comparisons of the decomposition of beech litter with litter
of the other tree species (except for Acer
platanoides) revealed a “home field advantage” of up to 20% (more rapid litter decomposition in stands with a high fraction of its own
species than in stands with a different tree species composition). Decomposition of stand-representative litter mixtures displayed
additive characteristics, not significantly more rapid than predicted by the decomposition of litter from the individual tree
species. Leaf litter decomposition rates were positively correlated with the initial N and Ca concentrations of the litter,
and negatively with the initial C:N, C:P and lignin:N ratios. The results support our hypothesis that the overall decomposition
rates are mainly influenced by the chemical composition of the individual litter species. Thus, the fraction of individual
tree species in the species composition seems to be more important for the litter decomposition rates than tree species diversity
itself. 相似文献
3.
Ilyas Siddique Vera Lex Engel John A. Parrotta David Lamb Gabriela B. Nardoto Jean P. H. B. Ometto Luiz A. Martinelli Susanne Schmidt 《Biogeochemistry》2008,88(1):89-101
Failures in reforestation are often attributed to nutrient limitation for tree growth. We compared tree performance and nitrogen
and phosphorus relations in adjacent mixed-species plantings of contrasting composition, established for forest restoration
on Ultisol soil, originally covered by tropical semi-deciduous Atlantic Forest in Southeast Brazil. Nutrient relations of
four tree species occurring in both planting mixtures were compared between a legume-dominated, species-poor direct seeding
mixture of early-successional species (“legume mixture”), and a species-diverse, legume-poor mixture of all successional groups
(“diverse mixture”). After 7 years, the legume mixture had 6-fold higher abundance of N2-fixing trees, 177% higher total tree basal area, 22% lower litter C/N, six-fold higher in situ soil resin-nitrate, and 40%
lower in situ soil resin-P, compared to the diverse mixture. In the legume mixture, non-N2-fixing legume Schizolobium parahyba (Fabaceae-Caesalpinioideae) had significantly lower proportional N resorption, and both naturally regenerating non-legume
trees had significantly higher leaf N concentrations, and higher proportional P resorption, than in the diverse mixture. This
demonstrate forms of plastic adjustment in all three non-N2-fixing species to diverged nutrient relations between mixtures. By contrast, leaf nutrient relations in N2-fixing Enterolobium contortisiliquum (Fabaceae-Mimosoideae) did not respond to planting mixtures. Rapid N accumulation in the legume mixture caused excess soil
nitrification over nitrate immobilization and tighter P recycling compared with the diverse mixture. The legume mixture succeeded
in accelerating tree growth and canopy closure, but may imply periods of N losses and possibly P limitation. Incorporation
of species with efficient nitrate uptake and P mobilization from resistant soil pools offers potential to optimize these tradeoffs. 相似文献
4.
Oscar Lanuza Fernando Casanoves Diego Delgado Karel Van den Meersche 《Restoration Ecology》2019,27(3):549-558
Active restoration strategies increase the production of leaf litter in tropical forests, but little is known about their effect on litter decomposition and subsequent nutrient release. We quantified changes in leaf litter stoichiometry during decomposition in former pasture sites under contrasting restoration strategies (natural regeneration, applied nucleation/islands tree planting and plantation), as well as in nearby primary forest. Litterbags were employed to evaluate decomposition. We used a leaf mixture of either the four planted tree species in the plantation and island treatments or the nearby primary forest and compared them under a factorial design. Decomposition rates were similar between restoration treatments (p > 0.5), but leaves decomposed faster in the forest mixture than in the plantation mixture (p < 0.01). The content of Ca, Mg, K, P, and the C:N ratio were higher in the forest mixture at the beginning and during decomposition (p < 0.05); the N content in the plantation mixture was higher at the beginning but lower during decomposition (p < 0.05), which meant greater mobilization of nitrogen per unit of carbon lost. K and P had a strong initial release, while Mg was released more gradually. N and Ca had an irregular pattern of initial fast release, immobilization, and re‐release in the later stages. We conclude that the differences in rates of decomposition and nutrient release in these systems under restoration were at least partly determined by the floristic heterogeneity and chemical quality of the leaf litter that reaches the soil. 相似文献
5.
Decomposition patterns of leaf litter of seven common canopy species in a subtropical forest: N and P dynamics 总被引:12,自引:1,他引:11
Litter decomposition, governing nutrient and C cycling, is strongly influenced by the chemical litter quality. In order to determine the interspecific variation in leaf decomposition rates and to understand the chemical basis for such variation, decomposition dynamics of seven common canopy species was investigated over 2year using the litterbag technique in a subtropical evergreen broad-leaved forest on Okinawa Island, Japan. The species studied are representatives of the vegetation in the study area and differed significantly in their chemical litter quality. Dry mass loss at the end of study varied in the order: Distylium racemosum< Quercus miyagii< Rapanea neriifolia< Symplocos confusa< Castanopsis sieboldii< Schima wallichii< Daphniphyllum glaucescens. All species showed a pattern characterized by a rapid initial decomposition followed by lower rates except for D. glaucescenswhich decomposition rate appeared to be rather constant. In the late phase, decomposition rates were correlated positively to initial N and ash contents and negatively to lignin content, lignin:N, C:N, and C:P ratios. The effects of N and lignin content or lignin:N ratio were stronger than other quality parameters. There was a wide range in patterns of N and P concentrations, from a net accumulation to a rapid loss in decomposition. The correlation between N and P release suggests that N and P dynamics may have influenced each other during litter decomposition. Analysis of initial quality for species showed that the C:P ratios were extremely high (range 1639–3811) but the N:P ratios were from 28 to 56, indicating a likely P-limitation for this forest. Our results suggest that P is an important control of litter decomposition and N and P dynamics. 相似文献
6.
Nitrogen addition stimulates forest litter decomposition and disrupts species interactions in Patagonia,Argentina 总被引:1,自引:0,他引:1
Nitrogen (N) deposition and biodiversity loss are important drivers of global change, with uncertain consequences for carbon (C) and nutrient turnover in terrestrial ecosystems. We evaluated the simultaneous effects of N deposition and plant diversity on litter decomposition within a temperate forest in Patagonia. We identified ‘tree triangles’ created by the intersection of three tree‐canopies that directly controlled micro‐environmental conditions on the forest floor, and combined it with an N addition treatment. Triangles were composed of one or three Nothofagus species (N. dombeyi, N. obliqua or N. nervosa). We placed litterbags containing litter of each of the Nothofagus species and litterbags containing a mixture of the three species within all triangles and assessed mass loss over 2 years. We used a standard litter type in all triangles to independently evaluate triangle effects on decomposition. N addition had strong and positive effects on decomposition with an average 46% increase in the decomposition constant. Litter species significantly differed in their response to N addition; litter with higher lignin content and lower labile C content had larger increase in decomposition due to fertilization. Also, N addition disrupted two types of species interactions that control decomposition. The affinity relation between litter and decomposers, that enhanced decomposition of home litter (‘home‐field advantage’) that was demonstrated to be significant for all three Nothofagus species, disappeared with N addition. Second, N addition modified litter species interactions, transforming neutral effects of litter mixtures to positive, nonadditive effects on mass loss. Finally, N addition stimulated N release from decomposing litter which was modulated by plant species effects. Together, these results suggest that N addition to unpolluted forests increases C loss, contrary to what has been observed for temperate forests in industrialized areas of the world, and that alterations in nutrient pools have effects on species interactions, including the elimination of affinity effects for decomposition. 相似文献
7.
Insect herbivory can strongly influence ecosystem nutrient dynamics, yet the indirect effects of herbivore‐altered litter quality on subsequent decomposition remain poorly understood. The northern tamarisk beetle Diorhabda carinulata was released across several western states as a biological control agent to reduce the extent of the invasive tree Tamarix spp. in highly‐valued riparian ecosystems; however, very little is currently known about the effects of this biocontrol effort on ecosystem nutrient cycling. In this study, we examined alterations to nutrient dynamics resulting from beetle herbivory in a Tamarix‐invaded riparian ecosystem in the Great Basin Desert in northern Nevada, USA, by measuring changes in litter quality and decomposition, as well as changes in litter quantity. Generally, herbivory resulted in improved leaf litter chemical quality, including significantly increased nitrogen (N) and phosphorus (P) concentrations and decreased carbon (C) to nitrogen (C:N), C:P, N:P, and lignin:N ratios. Beetle‐affected litter decomposed 23% faster than control litter, and released 16% more N and 60% more P during six months of decomposition, as compared to control litter. Both litter types showed a net release of N and P during decomposition. In addition, herbivory resulted in significant increases in annual rates of total aboveground litter and leaf litter production of 82% and 71%, respectively, under the Tamarix canopy. Our finding that increased rates of N and P release linked with an increased rate of mass loss during decomposition resulting from herbivore‐induced increases in litter quality provides new support to the nutrient acceleration hypothesis. Moreover, results of this study demonstrate that the introduction of the northern tamarisk beetle as biological control to a Tamarix‐invaded riparian ecosystem has lead to short‐term stimulation of nutrient cycling. Alterations to nutrient dynamics could have implications for future plant community composition, and thus the potential for restoration of Tamarix‐invaded ecosystems. 相似文献
8.
Sandra Barantal Heidy Schimann Nathalie Fromin Stephan H?ttenschwiler 《Proceedings. Biological sciences / The Royal Society》2014,281(1796)
Plant leaf litter generally decomposes faster as a group of different species than when individual species decompose alone, but underlying mechanisms of these diversity effects remain poorly understood. Because resource C : N : P stoichiometry (i.e. the ratios of these key elements) exhibits strong control on consumers, we supposed that stoichiometric dissimilarity of litter mixtures (i.e. the divergence in C : N : P ratios among species) improves resource complementarity to decomposers leading to faster mixture decomposition. We tested this hypothesis with: (i) a wide range of leaf litter mixtures of neotropical tree species varying in C : N : P dissimilarity, and (ii) a nutrient addition experiment (C, N and P) to create stoichiometric similarity. Litter mixtures decomposed in the field using two different types of litterbags allowing or preventing access to soil fauna. Litter mixture mass loss was higher than expected from species decomposing singly, especially in presence of soil fauna. With fauna, synergistic litter mixture effects increased with increasing stoichiometric dissimilarity of litter mixtures and this positive relationship disappeared with fertilizer addition. Our results indicate that litter stoichiometric dissimilarity drives mixture effects via the nutritional requirements of soil fauna. Incorporating ecological stoichiometry in biodiversity research allows refinement of the underlying mechanisms of how changing biodiversity affects ecosystem functioning. 相似文献
9.
阔叶红松林是我国东北地区地带性顶级森林群落,对维持区域生态系统稳定性具有重要作用。对阔叶红松林内主要树种凋落叶分解过程及影响因素进行研究,有助于增加长白山阔叶红松林生态系统的基础数据,为明确阔叶红松林的养分循环和物质流动提供依据。选取了长白山阔叶红松林内30个常见乔灌树种和16个凋落叶性状,采用野外分解袋法和室内样品分析等方法研究了长白山阔叶红松林内主要树种凋落叶分解速率及其与凋落叶性状的关系。1年的野外分解实验表明,30个树种的凋落叶重量损失率表现出较大差异。不同树种凋落叶的重量损失率在20.56%—92.11%之间,以红松(Pinus koraiensis)质量损失率最低,东北山梅花(Philadelphus schrenkii)质量损失率最高。不同生活型树种的凋落叶在质量损失率上存在显著差异,以灌木树种凋落叶的质量损失率最高,小乔木次之,乔木树种质量损失率最低。Olson模型拟合结果表明,不同树种凋落叶的分解速率k以红松最低,瘤枝卫矛(Euonymus verrucosus)最高,分别为0.24和1.64。不同树种分解50%和95%所需的时间分别在0.43—2.86年,1.83—... 相似文献
10.
Leaf litter decomposition and nutrient dynamics in a subtropical forest after typhoon disturbance 总被引:2,自引:0,他引:2
Decomposition of typhoon-generated and normal leaf litter and their release patterns for eight nutrient elements were investigated over 3 yr using the litterbag technique in a subtropical evergreen broad-leaved forest on Okinawa Island, Japan. Two common tree species, Castanopsis sieboldii and Schima wallichii, representative of the vegetation and differing in their foliar traits, were selected. The elements analyzed were N, P, K, Ca, Mg, Na, Al, Fe and Mn. Dry mass loss at the end of study varied in the order: typhoon green leaves > typhoon yellow leaves > normal leaves falling for both species. For the same litter type, Schima decomposed faster than Castanopsis. Dry mass remaining after 2 yr of decomposition was positively correlated with initial C:N and C:P ratios. There was a wide range in patterns of nutrient concentration, from a net accumulation to a rapid loss in decomposition. Leaf litter generated by typhoons decomposed more rapidly than did the normal litter, with rapid losses for N and P. Analysis of initial quality for the different litter types showed that the C:P ratios were extremely high (range 896 – 2467) but the P:N ratios were < 0.05 (range 0.02 – 0.04), indicating a likely P-limitation for this forest. On average 32% less N and 60% less P was retranslocated from the typhoon-generated green leaves than from the normal litter for the two species, Castanopsis and Schima. An estimated 2.13 g m–2 yr–1 more N and 0.07 g m–2 yr–1 more P was transferred to the soil as result of typhoon disturbances, which were as high as 52% of N and 74% of P inputted from leaf litter annually in a normal year. Typhoon-driven maintenance of rapid P cycling appears to be an important mechanism by which growth of this Okinawan subtropical forest is maintained. 相似文献
11.
Decomposition and nutrient release patterns of mistletoe litters in a semi‐arid savanna,southwest Zimbabwe
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Nutrient loss from litter plays an essential role in carbon and nutrient cycling in nutrient‐constrained environments. However, the decomposition and nutrient dynamics of nutrient‐rich mistletoe litter remains unknown in semi‐arid savanna where productivity is nutrient limited. We studied the decomposition and nutrient dynamics (nitrogen: N, phosphorous; P, carbon: C) of litter of three mistletoe species, Erianthemum ngamicum, Plicosepalus kalachariensis, and Viscum verrucosum and N‐fixing Acacia karroo using the litter‐bag method in a semi‐arid savanna, southwest Zimbabwe. The temporal dynamics of the soil moisture content, microbial populations, and termite activity during decomposition were also assessed. Decay rates were slower for A. karroo litter (k = 0.63), but faster for the high quality mistletoe litters (mean k‐value = 0.79), which supports the premise that mistletoes can substantially influence nutrient availability to other plants. Nitrogen loss was between 1.3 and 3 times greater in E. ngamicum litter than in the other species. The litter of the mistletoes also lost C and P faster than A. karroo litter. However, soil moisture content and bacterial and fungal colony numbers changed in an opposite direction to changes in the decomposition rate. Additionally, there was little evidence of termite activity during the decay of all the species litters. This suggests that other factors such as photodegradation could be important in litter decomposition in semi‐arid savanna. In conclusion, the higher rate of decay and nutrient release of mistletoe than A. karroo litter indicate that mistletoes play an important role in carbon and nutrient fluxes in semi‐arid savanna. 相似文献
12.
We investigated the linkages between leaf litter quality and decomposability in a savanna plant community dominated by palatable-spinescent
tree species. We measured: (1) leaf litter decomposability across five woody species that differ in leaf chemistry; (2) mass
decomposition, nitrogen (N); and carbon (C) dynamics in leaf litter of a staple browse species (Acacia nigrescens) as well as (3) variation in litter composition across six sites that experienced very different histories of attack from
large herbivores. All decomposition trials included litter bags filled with chopped straw to control for variation in site
effects. We found a positive relationship between litter quality and decomposability, but we also found that Acacia and straw litter mass remaining did not significantly vary between heavily and lightly browsed sites. This is despite the
fact that both the quality and composition of litter returned to the soil were significantly different across sites. We observed
greater N resorption from senescing Acacia leaves at heavily browsed sites, which in turn contributed to increase the C:N ratio of leaf litter and caused greater litter
N immobilization over time. This, together with the significantly lower tree- and herb-leaf litter mass beneath heavily browsed
trees, should negatively affect decomposition rates. However, estimated dung and urine N deposition from both browsers and
grazers was significantly greater at high- than at low-herbivory sites. We hypothesize that N inputs from dung and urine boost
litter N mineralization and decomposition (especially following seasonal rainfall events), and thereby offset the effects
of poor leaf litter quality at chronically browsed sites.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
13.
在半干旱草地,关于放牧和封育管理对草地植物枯落物分解及其与土壤动物互作关系的研究一直是该区域生态系统物质循环与生态恢复过程研究的重要科学问题。以放牧和封育样地中赖草(Leymus secalinus)、牛枝子(Lespedeza potaninii)及其混合枯落物为研究对象。于2017年9月、2018年5月和9月、2019年5月和9月,采用2种不同孔径(30目和250目)网袋量化中小型土壤动物的作用,调查了宁夏半干旱草地枯落物碳、氮和磷元素分解与土壤动物群落分布及其对放牧和封育样地的响应规律。结果显示:(1)封育样地中,枯落物碳元素最终残留率均表现为3种枯落物处理间无显著差异;但250目网孔中枯落物氮、磷元素最终残留率和30目网孔中氮元素最终残留率均表现为牛枝子显著高于赖草和混合物,而后两者间无显著差异;仅30目网孔中磷元素最终残留率表现为牛枝子和混合物显著高于赖草,而前两者间无显著差异。放牧样地中,250目网孔的碳、磷元素最终残留率和30目网孔中的氮、磷元素最终残留率均表现为牛枝子显著高于混合物,而赖草居中;氮元素最终残留率表现为牛枝子显著高于赖草和混合物,后两者间无显著差异。(2)... 相似文献
14.
亚热带常绿阔叶林6个常见树种凋落叶在不同降雨期的分解特征 总被引:2,自引:0,他引:2
地处长江上游的四川盆地亚热带常绿阔叶林具有典型雨热同季的气候特点,季节性干湿交替可能显著影响凋落物分解,但迄今缺乏相应的报道。因此,采用凋落物分解袋法,研究了常绿阔叶林区最具代表性的马尾松(Pinus massoniana)、柳杉(Cryptomeria fortunei)、杉木(Cunninghamia lanceolata)、香樟(Cinnamomum camphora)、红椿(Toona ciliata)、麻栎(Quercus acutissima)等6种凋落叶在第1年不同雨热季节的分解特征。结果表明,经历1a的分解,6种凋落叶质量残留率大小顺序依次为:红椿(27.90%)柳杉(41.39%)杉木(48.93%)麻栎(49.62%)马尾松(68.82%)香樟(72.23%),6种凋落叶在不同干湿季节质量损失差异显著(P0.05)。阔叶树种在旱季(MRS、SRS和WRS)的质量损失显著高于针叶树种。雨季(ERS和LRS)对6种凋落叶质量损失的贡献率(69.73%—89.68%)均明显大于旱季(10.32%—30.27%)。6种凋落叶在不同时期中质量损失速率差异显著(P0.05),且6种凋落叶在雨季的质量损失速率明显高于旱季。相关分析结果表明,凋落叶质量损失及其速率均与降雨量和温度呈极显著(P0.01)正相关关系。凋落叶质量损失与初始C、木质素含量及C/N、木质素/N极显著(P0.01)负相关,与N含量极显著(P0.01)正相关。这些结果表明亚热带地区森林凋落物分解的质量损失主要发生在雨季,雨季温湿度的改变可显著影响凋落物分解过程。 相似文献
15.
The carbon (C) and nitrogen (N) status in forest ecosystems can change upon establishment of plantations because different
tree species have different nutrient cycling mechanisms. This study was carried out to evaluate C and N status of litterfall,
litter decomposition and soil in three adjacent plantations consisting of one deciduous (larch: Larix leptolepis) and two evergreen (red pine: Pinus densiflora; rigitaeda pine: P. rigida × P. taeda) species planted in the same year (1963). Both the pine plantations showed comparatively higher C input from needle litter
but significantly lower N concentration and input than the larch plantation (P < 0.05). During the decomposition process, the deciduous larch needle litter showed low C concentration and C remaining in
soil, but high N concentration and N remaining in soil compared to the two evergreen pine needle litters. However, the soil
C and N concentration and their content at a soil depth of 0–10 cm were not affected significantly (P > 0.05) by the plantation type. These results demonstrate the existence of considerable variation in C and N status resulting
from needle litter input and litter decomposition in these three plantations grown at sites with similar environmental conditions. 相似文献
16.
This study compared litter production, litter decomposition and nutrient return in pure and mixed species plantations. Dry
weight and N, P, K, Ca, Mg quantities in the litterfall were measured in one pure Cunninghamia lanceolata plantation (PC) and two mixed-species plantations of C. lanceolata with Alnus cremastogyne (MCA) and Kalopanax septemlobus (MCK) in subtropical China. Covering 6 years of observations, mean annual litter production of MCA (4.97 Mg·ha−1) and MCK (3.97 Mg·ha−1) was significantly higher than that of PC (3.46 Mg·ha−1). Broadleaved trees contributed 42% of the total litter production in MCA and 31% in MCK. Introduction of broadleaved tree
species had no significant effect on litterfall pattern. Total litterfall was greatest in the dry season from November to
March. Nutrient returns to the forest floor through leaf litter were significantly higher in both MCA and MCK than in PC (P < 0.05). The amounts of N, K, and Mg returned to the forest floor through leaf litter were highest in the MCA, and P and
Ca returns were highest in the MCK. Percent contribution of broadleaf litter to total nutrient returns ranged from 41.7% to
86.9% in MCA and from 49.3% to 74.8% in MCK. The decomposition rate of individual leaf litter increased in the order: C. lanceolata < K. septemlobus < A. cremastogyne. Litter mixing had a positive effect on decomposition rate of the more recalcitrant litter and promoted nutrient return.
Relative to mass loss of A. cremastogyne decomposing alone, higher mass loss of the mixture of C. lanceolata and A. cremastogyne was observed after 330 days of decomposition. These results indicate that mixed plantations of different tree species have
advantages over monospecific plantations with regards to nutrient fluxes and these advantages have relevance to restoration
of degraded sites.
Responsible Editor: Alfonso Escudero. 相似文献
17.
Jennifer L. Funk 《Biogeochemistry》2005,76(3):441-451
Few studies have examined the invasion of understory species into closed-canopy forests and, despite inter-specific differences
in litter quality and quantity between understory and dominant canopy trees, the influence of understory invasions on soil
nitrogen (N) cycling remains unknown. This paper examines litter quality and decomposition of kahili ginger (Hedychium gardnerianum), an invasive understory herb, to determine the influence of this species on N cycling in a Hawaiian montane rainforest. To
examine the potential feedback between increased soil N availability and litter decomposition, litter from the invasive ginger,
a native tree, and native tree fern was collected from unfertilized and fertilized plots and decomposed in a reciprocal transplant
design. Hedychium litter decomposed faster than litter from the two native species. Across species, decomposition rates were negatively correlated
with litter lignin content. Despite rapid decomposition rates of Hedychium litter, soil nitrogen availability and rates of net mineralization in the soil were similar in invaded and uninvaded plots.
Nitrogen cycling at this site may be more strongly influenced by native species, which contribute the most to overall stand
biomass. A negative effect of fertilization on the decomposition of Hedychium litter suggests that a negative feedback between litter quality and soil N availability may exist over longer timescales. 相似文献
18.
漓江流域岩溶区檵木群落不同恢复阶段凋落物分解初期动态 总被引:2,自引:2,他引:2
为探究漓江流域岩溶区檵木群落不同恢复阶段凋落物的分解情况,运用凋落物袋法研究其凋落物分解初期动态。结果表明:经过1a的分解,檵木群落凋落物失重大小顺序为:灌木阶段乔灌阶段乔林阶段。檵木群落灌木阶段、乔灌阶段和乔林阶段凋落物分解50%所需的时间分别为1.28a、1.38a、1.41a,分解95%所需的时间分别为5.54a、5.97a和6.09a。经过1a的分解,凋落物养分动态变化为:灌木阶段和乔灌阶段C含量总体上升,乔林阶段C含量总体下降;3个恢复阶段N和纤维素含量总体上升;灌木阶段和乔林阶段P含量总体下降,乔灌阶段P含量总体上升;灌木阶段木质素含量总体上升,而乔灌阶段和乔林阶段木质素含量总体下降。相关分析表明,灌木阶段凋落物分解速率分别与C,N,P,C/P,N/P之间呈显著或极显著相关性,乔灌阶段凋落物分解速率与N和木质素/N之间呈显著或极显著相关性,乔林阶段凋落物分解速率分别与N,纤维素、C/N和木质素/N之间呈显著或极显著相关性。 相似文献
19.
Invasive species have the capacity to substantially alter soil processes, including rates of litter decomposition. Currently,
the few remaining native-dominated lowland wet forests in Hawai’i are being invaded by Falcataria moluccana, a large, fast-growing, N2-fixing tree. In this study, we sought to determine the extent to which Falcataria invasion alters decomposition in these lowland wet forests, and whether changes resulted from differences in litter substrate
type, lava flow age and type, forest stand type and associated soil biota, or some combination of these factors. We measured
decomposition rates and nitrogen (N) and phosphorus (P) dynamics of Metrosideros
polymorpha and Falcataria leaf litter in native-dominated and Falcataria-invaded stands on 48- and 300-year-old a’a lava flows and a 213-year-old pāhoehoe flow in the Puna district of eastern Hawai’i.
Despite significant differences in the initial quality of Metrosideros and Falcataria litter, in nearly all cases mass remaining of the two litter types did not differ within a given forest stand, whether native-dominated
or invaded. Instead, stand type accounted for large differences in the decomposition of both litter types, and litter decomposed
two to 10 times faster in Falcataria-invaded stands than it did in their native-dominated counterparts on each lava flow. Dynamics of N (that is, immobilization
or release) during decomposition were affected by stand, litter, and lava flow type; P dynamics were affected by stand and
flow type, but not litter type. Although not definitive proof of causality, the decay rates of both species were positively
correlated to previously measured inputs of N mass and P mass via litterfall as well as availability of soil N and P, characteristics
that all increased substantially with Falcataria invasion. Given the degree of change to a host of ecosystem processes, including decomposition, after invasion by Falcataria, these transformed forest ecosystems may best be viewed as fundamentally new and different, in both structure and function,
from the native ecosystems they have replaced. 相似文献