Tree Litter Decomposition Research Articles

Insect Herbivores, Plant Sex, and Elevated Nitrogen Influence Willow Litter Decomposition and Detritivore Colonization in Early Successional Streams

Headwater streams are reliant on riparian tree leaf litterfall to fuel brown food webs. Terrestrial agents like herbivores and contaminants can alter plant growth, litter production, litter quality, and the timing of litterfall into streams, influencing aspects of the brown food web. At Mount St. Helens (USA), early successional streams are developing willow (Salix sitchensis) riparian zones. The willows are attacked by stem-boring herbivores, altering litter quality and the timing of litterfall. Within a established experimental plots, willows (male and female plants) were protected from herbivores using insecticides and provided with experimental additions of nitrogen. This enabled us to test the interacting influences of herbivores, nitrogen deposition, and willow sex on leaf litter quality, aquatic litter decomposition, and microbial and invertebrate detritivores. We found weak litter quality effects (higher N and lower C:N) for the herbivore treatment, but no effect of nitrogen deposition. Although litter decomposition rates were not strongly affected by litter treatments, detritivore communities were altered by all treatments. Nitrogen deposition resulted in decreased bacterial richness and decreased fungal diversity in-stream. Aquatic macroinvertebrate communities were influenced by the interacting effects of herbivory and nitrogen addition, with abundances highest in herbivore litter with the greatest N addition. Shredders showed the highest abundance in male, herbivore-attacked litter. The establishment of riparian willows along early successional streams and their interacting effects with herbivores and nitrogen deposition may be influencing detritivore community assembly at Mount St. Helens. More broadly, global changes like increased wet and dry N deposition and expanded ranges of key herbivores might influence tree litter decomposition in many ecosystems.

Travelling waves due to negative plant–soil feedbacks in a model including tree life-stages

The emergence and maintenance of tree species diversity in tropical forests is commonly attributed to the Janzen–Connell (JC) hypothesis, which states that growth of seedlings is suppressed in the proximity of conspecific adult trees. As a result, a JC distribution due to a density-dependent negative feedback emerges in the form of a (transient) pattern where conspecific seedling density is highest at intermediate distances away from parent trees. Several studies suggest that the required density-dependent feedbacks behind this pattern could result from interactions between trees and soil-borne pathogens. However, negative plant–soil feedback may involve additional mechanisms, including the accumulation of autotoxic compounds generated through tree litter decomposition. An essential task therefore consists in constructing mathematical models incorporating both effects showing the ability to support the emergence of JC distributions.In this work, we develop and analyse a novel reaction–diffusion-ODE model, describing the interactions within tropical tree species across different life stages (seeds, seedlings, and adults) as driven by negative plant–soil feedback. In particular, we show that under strong negative plant–soil feedback travelling wave solutions exist, creating transient distributions of adult trees and seedlings that are in agreement with the Janzen–Connell hypothesis. Moreover, we show that these travelling wave solutions are pulled fronts and a robust feature as they occur over a broad parameter range. Finally, we calculate their linear spreading speed and show its (in)dependence on relevant nondimensional parameters.

Effects of herbaceous covers and mineral fertilizers on the nutrient stocks and fluxes in a Mediterranean olive grove

The preservation of nutrient capital, soil fertility, and carbon (C) sequestration capacity in Mediterranean olive groves requires evaluation of agricultural practices beyond short-term productivity. We aim to contribute with a mechanistic understanding on the effects that the preservation of herbaceous cover and the use of chemical fertilizers have on the performance of olive trees and on the biogeochemical cycles of the agroecosystem. We compared nutrient fluxes and aboveground leafy stocks in an olive grove that had been organically managed for more than 60 years, in a treatment in which the annual spontaneous herbaceous cover was maintained (H), and after two years of shift to conventional management treatments in which the growth of herbaceous vegetation was avoided by the use of herbicides (NH), and where exclusion of the herbaceous cover is also combined with the supply of mineral fertilizers (NHF). Maintenance of herbaceous vegetation in H contributed to the retention of a high aboveground capital of C and nutrients, particularly nitrogen, (N), phosphorus (P) and potassium (K) that were about 2.9, 3.9 and 7.4 times greater than in NH, respectively. The permanence of herbaceous cover stimulated olive tree leaf litter decomposition rates by about 86 % and increased nutrient release. However, the H treatment led to a 37 % decrease in olive yield and lowered olive foliar N and P content as negative short-term effects. The addition of fertilizers (N, P, K, and Mg) in mineral and solid form in NHF resulted inefficient to improve olive tree nutritional status and olive production, and decelerated olive tree litter decomposition rates by 21 % and nutrient release. The nutrient retention in organic forms in the fast-growing species of herbaceous covers and the progressive nutrient release as litter decomposes may contribute to regulate and better adapt nutrient availability to the nutrient requirements of olive trees.

Liana litter decomposes faster than tree litter in a multispecies and multisite experiment

Abstract Lianas account for a small fraction of forest biomass, but their contribution to leaf or litter biomass and thus to food webs can be substantial. Globally liana exhibit fast life‐history traits. Thus, liana litter may decompose faster than tree litter, and could enhance the decomposition of tree litter (complementarity effect). The differences in decomposition may also vary with mesofauna access or across forest communities. The contribution of these factors to nutrient biogeochemical cycling is poorly understood. We examined the decomposition of litter of 20 liana and 20 tree species of three different tropical forest communities in southern China, over 1 year. (i) We incubated the litter in bags with coarse and fine mesh to distinguish mesofaunal and microfaunal effects. (ii) We used single‐species litter bags to compare decomposition rates of lianas and trees, to test which functional traits best explained decomposition, and whether those traits differed between lianas and trees, and among forest types. (iv) We used mixed‐species litter bags to test whether liana litter enhances decomposition in litter mixtures. (v) We evaluated how leaf litter nutrients decayed in relation to litter mass. Litter decayed faster in coarse‐mesh than fine‐mesh bags, but there was no interaction effect with forest type or growth form. Liana litter decayed faster than tree litter in single‐species bags with mesofauna access and in mixed bags (liana‐only mix, tree‐only mix) without mesofauna. Lianas had higher nitrogen content and specific leaf area and lower leaf dry matter content (LDMC) and toughness than trees. Decomposition rate was significantly negatively related to LDMC. Litter of evergreen broadleaved forest decomposed slower than that of other forest types. Liana litter did not enhance the decomposition of tree litter in mixtures. Liana litter released calcium slightly faster than trees. Synthesis: Leaf litter decomposes faster for lianas than trees, despite high variability of traits and decomposition rates within each growth form and overlap between growth forms, and we found no evidence for the complementarity hypothesis. Our study sheds light on the potential role of lianas within brown food webs and their importance on terrestrial biogeochemistry.

TREE LITTER PRODUCTION AND DECOMPOSITION IN FOREST ECOSYSTEMS UNDER BACKGROUND CONDITIONS AND INDUSTRIAL AIR POLLUTION

The paper provides an overview of Russian and foreign articles devoted to the study of the tree litter production and decomposition in forest ecosystems subjected to natural and anthropogenic factors. The spatial variability (below crown and between crown spaces) and the seasonal features of the tree litter production, its chemical composition, and decomposition processes are poorly studied. In addition, most of the works, both in Russia and foreign countries science, highlight the influence of natural factors on the litter production and the processes of its decomposition, while the impact of local sources of industrial air pollution is rarely considered. The study of the variability of the size, fractional and chemical composition and processes of decomposition of tree litter under conditions of industrial air pollution is important for predicting the dynamics of forest ecosystems subjected to the combined action of natural and anthropogenic factors and reducing the negative impact of production processes on forests.

Characteristics of prokaryotic and fungal communities emerged in eco-engineered waste rock – Eucalyptus open woodlands at Ranger uranium mine

Diverse prokaryotic and fungal communities in soil and litters are the structural basis for driving tree litter decomposition and inherent nutrient cycling in infertile Eucalyptus open woodlands. The present investigation characterized the composition and co-occurrence network of prokaryotic and fungal communities in litter and surface soil layers in 9-year old revegetated trial landforms at Ranger uranium mine, Northern Territory, Australia. The revegetated landforms consisted of soil-subsystems engineered from waste rocks and plant-subsystems of young, novel and native Eucalyptus open woodlands. The analysis of litters and surface soil layer revealed highly diverse microbial communities in the young Eucalyptus open woodland systems, which were composed of an average 1155 prokaryotic and 236 fungal OTUs. In the microbial communities, abundant bacterial communities were affiliated to Actinobacteria (30.2%), Proteobacteria (25.3%) and Chloroflexi (16.9%); and fungal communities were highly dominated by Ascomycota (63.4%) and Basidiomycota (23.6%). These OTUs were highly connected, forming microbial modules with >50% of predicted genes associated with metabolism of organics in the open woodland. Soil microbial communities present in the wet season contained a relatively high abundance of ammonium oxidizing archaea, plant associated bacteria, and fungal groups adapted to higher N availability, particularly those from the laterite + waste rock site. The elevated microbial activities in the litters and surface soil of lateritic soil + waste rock landform were attributed to the improved water and nutrient availability by increased fine fraction of laterites. Our study provides evidence that the features of prokaryotic and fungal communities in this eco-engineered and young waste rock - open Eucalyptus woodland systems are consistent with characteristics of microbial communities of native Eucalyptus woodlands to drive the decomposition of low N tree litters.

Формирование и разложение древесного опада в лесных экосистемах в фоновых условиях и при аэротехногенном загрязнении

The paper provides an overview of Russian and foreign articles devoted to the study of the tree litter production and decomposition in forest ecosystems subjected to natural and anthropogenic factors. The spatial variability (below crown and between crown spaces) and the seasonal features of the tree litter production, its chemical composition and decomposition processes are poorly studied. In addition, most of the works, both in native and foreign countries science, highlight the influence of natural factors on the litter production and the processes of its decomposition, while the impact of point sources of industrial air pollution is rarely considered. The study of the variability of the size, fractional and chemical composition and processes of decomposition of tree litter under conditions of industrial air pollution is important for predicting the dynamics of forest ecosystems subjected to the combined action of natural and anthropogenic factors and reducing the negative impact of production processes on forests.

Herb litter mediates tree litter decomposition and soil fauna composition

Leaf litter from forest understorey species has very different characteristics (e.g. a higher nutrient content) which are regarded to be more palatable and digestible for the decomposer community compared to litter from the overstorey trees. Consequently, the decomposition of tree litter may show different dynamics when mixed with litter from herb species. To study the effect of understorey litter on tree litter decomposition, we set up a litterbag experiment in a temperate mixed deciduous forest in Belgium. We investigated the effect of spring (Anemona nemorosa) and summer (Aegopodium podagaria) herb litter on the litter decomposition of five native tree species that differ in litter quality. The spring and summer withering herb litters were added above the tree litters. After 742 days of in situ incubation, mass loss (40%–100%) and the decomposition rate (0.27–1.68 yr−1) of the litter from the five tree species were positively correlated with litter quality. The addition of summer herb litter resulted in increased mass loss and decomposition rates (k) of the underlying recalcitrant tree litter. In addition, summer herb litter increased nutrient concentration in the short-term as well as the abundance of soil fauna during litter decomposition. In contrast, spring herb litter slightly inhibited tree litter decomposition. Structural equation models showed that the effect of understorey litter on decomposition rates of tree litter acted via nutrient leaching towards the tree litter layer rather than via the alteration of soil fauna (detritivores and omnivores) abundance. Our results show that litter from understorey vegetation can alter nutrient availability in recalcitrant litters (Fagus sylvatica and Quercus robur) via increased nitrogen (N), calcium (Ca), magnesium (Mg), phosphorus (P) and potassium (K) concentrations by 9%, 21%, 22%, 41%, and 315% respectively after the summer herb litter addition. The effect on tree litter decomposition strongly depends on herb species identity and future research should focus on the generality of the observed patterns. We conclude that herb litter has a major role in accelerating carbon sequestration and nutrient cycling in temperate forests.

Do Silvi-Medicinal Plantations Affect Tree Litter Decomposition and Nutrient Mineralization?

In a silvi-medicinal system, the plant secondary metabolites (PSMs) released from medicinal herbs could affect tree litter decomposition and nutrient release. However, the specific effects of PSMs on arboreous litter decomposition are still not well understood. In this study, the extracts of nine types of medicinal herbs were used to treat Pinus armandii Franch. and Larix gmelinii (Rupr.) Kuzen. litter during a simulated half-year decomposition. The effects of the extracts on the decomposition and the N and P release of the conifer litter were investigated. The results indicated that most of the medicinal herb extracts significantly inhibited the late decomposition of P. armandii litter, whereas only two of them accelerated the entire decomposition process. Only a few significantly affected the decomposition of the L. gmelinii litter. Four of the nine types of extract significantly inhibited the N and P release of the P. armandii litter, while 3/9 and 6/9 inhibited the N and P release of the L. gmelinii litter, respectively. The accelerating effects of the extracts on the cellulase activity and the inhibitory effects on the polyphenol oxidase activity might be responsible for the early acceleration and late inhibition of litter decomposition, while the effects of the extracts on the activities of protease and phosphatase might not be the main reason for the inhibitory or accelerating effects on the N and P release. In general, the inhibitory effects of medicinal herbs on the nutrient cycling of ecosystems should be taken into consideration when building silvi-medicinal systems, especially in P. armandii forests.

Decomposition of tree litter: Interaction between inherent quality and environment

Abstract. Rachmawati S, Yulistyarini T, Hairiah K. 2019. Decomposition of tree litter: Interaction between inherent quality and environment. Biodiversitas 20: 1946-1952. Litter layers protect forest soils, but may not be appreciated in recreation sites such as the Purwodadi Botanical Gardens (PBG), East Java, Indonesia. We quantified litter decomposition rates in mature stands of three tree species: mahogany (Swietenia macrophylla), angsana/narra (Pterocarpus indicus), and bungur/crape myrtle (Lagerstroemia thorelii). To separate inherent litter quality and stand-level environmental factors (such as microclimate, soil), decomposition rates were quantified for each species across all three stands. A possible interaction on decomposition rates is known as ‘home-field advantage’ (HFA). Litter-weight loss from TSBF-standard litter bags was observed at 0, 1, 2, 4, 8 and 12 weeks after litter bags were installed to estimate the half-life time (t50). We also solicited visitor views on the presence of a thick litter layer on garden floor. Decomposition of angsana (t50=48 weeks) was 15% faster at its ‘own home’ than in ‘neighbors home’. No significant HFA effects were found in bungur/crape myrtle litter that decomposed slower in its home environment, while mahogany decomposition was independent of location. Generally, PBG visitors knew the benefits of litter and were not bothered by its presence; litter increased the attractiveness for visitors to enjoy their happy days under the shade of trees in a ‘tropical autumn’.

Contributions of Soil Meso- and Microfauna to Nutrient Release During Broadleaved Tree Litter Decomposition in the Changbai Mountains.

Soil meso- and microfauna (<2 mm in size) play an important role in the decomposition and nutrient release of litter. However, most research has focused on the influences of soil fauna on decomposition rates, while the impact of soil fauna on nutrient release has not been fully understood. We evaluated the influence of soil meso- and microfauna communities on nutrient release from decomposing Tilia amurensis Rupr. (Malvales:Tiliaceae) and Acer mono Maxim. (Sapindales:Aceraceae) leaves from the coniferous and broadleaved mixed forests of the Changbai Mountains. Litter decomposition and nutrient release were assessed using litterbags placed at the surface of the litter and using designs both with and without 2-mm mesh to either permit or exclude soil meso- and microfauna. The soil meso- and microfauna increased the decomposition of T. amurensis (not significantly) and A. mono (significantly, by 15%) litters. Presence of the soil meso- and microfauna accelerated the release rate of Mn in the A. mono litter by 59%, whereas it significantly decreased the release rates of Ca (in the T. amurensis litter) and P (in the A. mono litter) by 28 and 48%, respectively. These results suggest that a stronger understanding of the influence of soil fauna on nutrient cycling is necessary to understand the mechanisms of matter circulation.

Tree species effects on litter decomposition in pure stands on afforested post-mining sites

Abstract Tree litter decomposition on disturbed post-mining sites has been mainly studied within successional gradients, whereas almost no results were shown from afforested spoil heaps. Litterfall and its decomposition rate are considered the most important ecological processes for soil restoration during stand development on such initial forest habitats. These processes allow development of a functional ecosystem and productive forest stands. Moreover, the pedogenesis process on such “soilless”’ habitats can be significantly improved and accelerated by tree species selection during afforestation. The main aim of the study was to determine litter decomposition rates of nine tree species used for afforestation of a lignite mine spoil heap. We assumed that leaf litter decomposition rates would differ among tree species studied and that the site conditions would significantly influence this process. Our study was conducted on the spoil heap of the lignite open cast mine in Belchatow, central Poland. We studied leaf litter decomposition of Alnus glutinosa, Betula pendula, Pinus sylvestris, Quercus robur, Q. rubra and Robinia pseudoacacia in pure stands of these species (home stands), and litter decomposition of Acer pseudoplatanus, A. glutinosa, Fagus sylvatica, Prunus serotina, Q. rubra, and R. pseudoacacia in Scots pine stands. We used the litterbag method. The experiments lasted for three years and the samples were collected every three months. Leaf litter decomposition calculated for home stands after three years of decomposition was 94.4% of the initial leaf mass for A. glutinosa, 70.9% for R. pseudoacacia, 70.1% for P. sylvestris, 68.3% for B. pendula, 66.9% for Q. rubra and 61.5% for Q. robur. In Scots pine stands, after three years of the experiment, 92.3% of the initial leaf mass decomposed for P. serotina, 85.7% for A. glutinosa, 83.5% for A. pseudoplatanus, 65.2% for R. pseudoacacia, 50.9% for Q. rubra and 40.1% for F. sylvatica. A. glutinosa, R. pseudoacacia and Q. rubra leaves decomposed significantly faster in home stands than in Scots pine stands. Site aspect significantly influenced litter decomposition of the species studied, with higher rates mostly on the western slope. Our study revealed that the decision on tree species used for afforestation might shorten the period needed for soil restoration and achievement of sustainability of novel ecosystems. Proper selection of main and admixture tree species for afforestation of the post-mining sites might reduce the renewal period of the soilless and newly created habitats, which may provide noticeable ecological and economical effects during stand management.

Decomposition of Mongolian pine litter in the presence of understory species in semi-arid northeast China

The effects of understory plant litter on dominant tree litter decomposition are not well documented especially in semi-arid forests. In this study, we used a microcosm experiment to examine the effects of two understory species (Artemisia scoparia and Setaria viridis) litter on the mass loss and N release of Mongolian pine (Pinus sylvestris var. mongolica) litter in Keerqin Sandy Lands, northeast China, and identified the influencing mechanism from the chemical quality of decomposing litter. Four litter combinations were set up: one monoculture of Mongolian pine and three mixtures of Mongolian pine and one or two understory species in equal mass proportions of each species. Total C, total N, lignin, cellulose and polyphenol concentrations, and mass loss of pine litter were analyzed at days 84 and 182 of incubation. The chemistry of pine litter not only changed with the stages of decomposition, but was also strongly influenced by the presence of understory species during decomposition. Both understory species promoted mass loss of pine litter at 84 days, while only the simultaneous presence of two understory species promoted mass loss of pine litter at 182 days. Mass loss of pine litter was negatively correlated with initial ratios of C/N, lignin/N and polyphenol/N of litter combinations during the entire incubation period; at 182 days it was negatively correlated with polyphenol concentration and ratios of C/N and polyphenol/N of litter combinations at 84 days of incubation. Nitrogen release of pine litter was promoted in the presence of understory species. Nitrogen release at 84 days was negatively correlated with initial N concentration; at 182 days it was negatively correlated with initial polyphenol concentration of litter combinations and positively correlated with lignin concentration of litter combinations at 84 days of incubation. Our results suggest that the presence of understory species causes substantial changes in chemical components of pine litter that can exert strong influences on subsequent decomposition of pine litter.

A traits-based test of the home-field advantage in mixed-species tree litter decomposition

Litter often decomposes faster in its environment of origin (at 'home') than in a foreign environment ('away'), which has become known as the home-field advantage (HFA). However, many studies have highlighted the conditional nature of the HFA, suggesting that current understanding of this phenomenon is not yet sufficient to generalize across systems. The HFA hypothesis was tested for mono-specific and mixed-species litter using a tree-based experiment that manipulated the functional identity and diversity of the host tree community. Litter types of varying quality were transplanted between several host tree communities and decomposition rates were measured using litterbags. Since the decomposer community should respond to traits of the litter input and not their taxonomic identity, a traits-based index of litter-tree similarity was developed. Mono-specific litter exhibited HFA, but when the same litter was decomposed in mixture, this trend was not observed. Mixed-species litter decomposed on average no faster or slower than monoculture litter and exhibited both positive and negative species interactions. These non-additive interactions of decomposition rates in mixture were influenced by the degree of similarity between litter and tree traits. Both synergistic and antagonistic interactions decreased in magnitude with increasing litter-tree similarity such that mixture rates were predictable from monocultures. The HFA occurred more strongly for mono-specific litter than for the litter types mixed together because interactions between species may have masked this effect. However, when expressed as a function of trait similarity between litters and tree communities, the HFA was not detected.

高浓度CO2对树木生理生态影响研究进展

PDF HTML阅读 XML下载 导出引用 引用提醒 高浓度CO2对树木生理生态的影响研究进展 DOI: 10.5846/stxb201306101603 作者: 作者单位: 中国科学院沈阳应用生态研究所,中国科学院沈阳应用生态研究所,中国科学院沈阳应用生态研究所,中国科学院沈阳应用生态研究所,中国科学院沈阳应用生态研究所,中国科学院沈阳应用生态研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31170573,31270518);国家科技支撑项目(2012BAC05B00);国家水专项基金(2012ZX07202-008) Research advance in effect of elevated CO2 on eco-physiology of trees Author: Affiliation: Institue of Applied Ecology, Chinese Academy of Sciences,Institue of Applied Ecology, Chinese Academy of Sciences,Institue of Applied Ecology, Chinese Academy of Sciences,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:大气CO2浓度升高已成为世界范围内的重要环境问题。CO2浓度升高势必会对植物的生理生态变化产生重要影响。综述了国内外有关高浓度CO2对树木生理生态影响研究的最新进展,具体包括高浓度CO2对树木生长发育、光合和呼吸作用、抗氧化系统、树木代谢物质、挥发性有机化合物以及树木凋落物等方面的影响。高浓度CO2一般会促进树木地上植株的生长和发育,但也因树种差异而有所不同。最新研究表明,高浓度CO2促进了树木细根周转,树木根系生长在大气CO2浓度升高条件下表现为促进作用,这种作用加快了全球森林生态系统的C循环。高浓度CO2虽然在一定程度上促进树木光合速率的增加,但长期熏蒸也往往会发生光合驯化,这种现象产生的生理学机制目前仍无定论。高浓度CO2对树木呼吸作用尤其是根系呼吸的影响将是未来研究的重点和难点。高浓度CO2一般会提高树木抗氧化酶活性与抗氧化剂含量,但不同树种响应高浓度CO2的过程和机理也有所差异。研究表明,高浓度CO2一般对树木凋落物的分解产生不利影响,但也因树种而异。需要强调的是,目前关于树木地下部分、树木对高浓度CO2的适应机理和重要过程(碳氮水耦合及基因调控等)以及多个树种包括不同类型树种及不同品种之间比较研究较少;关于某一重要生理生态机制(如根系生理代谢)尤其是多个生态因子复合条件下缺乏长期深入的研究。在此基础上给出了大气CO2浓度升高下树木生理生态学研究的未来发展方向,包括高CO2浓度条件下树木根系生理代谢及机制、树木碳氮水耦合的生理过程及机制、不同生态因子复合作用对树木生理影响机制以及树木分子作用机理等方面的研究。这些研究不仅将丰富森林树木应对未来气候变化的有关科学理论,也为全球气候变化背景下实现森林树种生态功能的优化选择及森林生态系统的可持续发展与经营提供重要的生理生态学理论依据和参考。 Abstract:Rising atmospheric CO2 concentration has been regarded as a key global environmental problem today: it is expected to influence changes in plant eco-physiology. The research advances on the effects of elevated CO2 concentration on tree eco-physiology were reviewed: this included the effects of elevated CO2 on growth and development, photosynthesis and respiration, antioxidative systems, volatile organic compounds (VOCs), and litter decomposition of trees. Generally, elevated CO2 enhances the growth and development of trees and the results vary with tree species. The turnover in fine roots of trees was accelerated by elevated CO2, which may play an important role in the cycle of global carbon in forest ecosystems. Elevated CO2 increases net photosynthetic rate for most tree species. However, photosynthetic acclimation in some tree species sometimes occurred under elevated CO2 concentrations, and it was still uncertain as to whether it revealed the physiological mechanism underpinning the occurrence of photosynthetic acclimation of trees to date. The effect of elevated CO2 on root respiration of trees will be an important aspect of the study of forest ecosystems under a changing climate. The activities of antioxidative enzymes and the contents of antioxidants in trees were generally maintained at high levels under elevated CO2 concentrations. The process and mechanism of antioxidative system response to elevated CO2 concentration were associated with certain tree species. Although the adverse effect of elevated CO2 on the decomposition of tree litter has been observed in recent studies, it also depends on tree species. Numerous studies were focused on the apparent physiological responses of trees to elevated CO2. However, little is known about the physiological processes including coupling of carbon, nitrogen, and water, or gene regulation under elevated CO2 concentrations, particularly in the underground parts of trees. Many studies have been carried out based on individual plant levels, but there has been a lack of comparative studies of the response of different tree species or varieties to elevated CO2 concentrations. Little information exists about the long-term study of the key processes and mechanisms of physiological metabolism of fine roots under the action of multiple environmental factors. The perspectives in studies of tree eco-physiology under elevated CO2 concentrations were summarized, including research into the physiological mechanisms of tree root metabolism, coupling in carbon, nitrogen and water processes, responses and adaptations to multiple environmental factors, and related molecular mechanisms under elevated CO2 concentrations. This research will enrich the knowledge relating to the responses and adaptations of forest trees to climate change, especially for the sustainable management and operation of forest eco-systems and the selection of tree species. 参考文献 相似文献 引证文献

Impact of tree litter decomposition on soil biochemical properties obtained from a temperate secondary forest in Northeast China

Conversion of secondary forests to larch plantations results in a reduction in quantity and quality of plant litters entering the soil and may reduce the soil nutrient cycling rate. As a major process influencing soil nutrient cycling and biochemical properties, leaf litter decomposition has received little attention in temperate secondary forest systems. This study aimed to assess the decomposition of tree litters of varying quality and its impacts on the chemical and biological properties of soils obtained from a temperate secondary forest in a short-term experiment. In this study, impact on soil biochemical properties of tree litter originating from five dominant tree species in Northeast China (Quercus mongolica, Juglans mandshurica, Fraxinus rhynchophylla, Fraxinus mandshurica, and Acer mono) were tested. A 42-day laboratory decomposition experiment was conducted to determine the short-term influences of the decomposition of the five tree species leaf litters on secondary forest soil carbon (C) decomposition, nitrogen (N) mineralization, soil microbial biomass, soluble organic compounds in microbial biomass, enzyme activities, soluble organic C, and pH. Carbon decomposition, equivalent to 29–41 % of leaf litter C, occurred during the incubation. F. mandshurica and A. mono leaf litters decomposed faster than those of Q. mongolica, J. mandshurica, and F. rhynchophylla due to their low lignin concentration and lignin-to-N ratio and high labile C pool. In contrast, F. mandshurica and A. mono leaf litters immobilized less N than the other three leaf litters, which affected N availability. Soil amended with F. mandshurica leaf litter had higher microbial biomass C than the other four leaf litters, indicating that F. mandshurica could increase soil nutrient cycling. The five leaf litter types all increased activities of exoglucanase, s-glucosidase, and N-acetyl-s-glucosaminidase, but there were no effects on phenol oxidase activity. This study suggested that litter of F. mandshurica incorporated in soils tends to decompose faster than litter of other species and increases the microbial biomass. F. mandshurica is, therefore, more advantageous than the other studied tree species for increasing nutrient cycling in a temperate secondary forest soil in this short-term laboratory incubation experiment. Future studies should consider the interactions among soil types, different climates, and long-term decomposition of leaf litters.

Validating tree litter decomposition in the Yasso07 carbon model

Up-to-date and accurate information of ecosystem state and functioning becomes ever more critical for decision-making and policy. For complex ecosystems such as forests, these demands can in some cases not be met by field observations only, especially at larger scales. Additionally, methodological requirements include comparability and transparency. To satisfy these needs, models can provide an important supplement or alternative.We examined the validity of the litter decomposition and soil carbon model Yasso07 in Swiss forests based on data on observed decomposition of (i) foliage and fine root litter from sites along a climatic and altitudinal gradient and (ii) of 588 dead trees from 394 plots of the Swiss National Forest Inventory. Our objectives were to (i) examine the effect of the application of three different published Yasso07 parameter sets on simulated decay rate; (ii) analyze the accuracy of Yasso07 for reproducing observed decomposition of litter and dead wood in Swiss forests; and (iii) evaluate the suitability of Yasso07 for regional and national scale applications in Swiss forests.From the three examined parameter sets, the set was identified which resulted in the best agreement between Yasso07 results and observed decomposition. No significant differences were found between simulated and observed remaining C in foliage and fine root litter after 10 years and in lying dead trees after 14–21 years. The model overestimated the decomposition of standing dead trees. We concluded that Yasso07 can provide accurate information on temporal changes in C stocks in litter and deadwood in Swiss forests in a transparent manner that is valid for, e.g., reporting purposes under the UNFCCC and the Kyoto Protocol.

Mixing Effects of Understory Plant Litter on Decomposition and Nutrient Release of Tree Litter in Two Plantations in Northeast China

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.

No ‘home’ versus ‘away’ effects of decomposition found in a grassland–forest reciprocal litter transplant study

Plant litter often decomposes faster in the habitat from which it was derived (i.e. home) than when placed in foreign habitats (i.e. away), which has been called the home–field advantage (HFA) of litter decomposition. We tested whether the HFA of litter decomposition is driven by decomposer communities being specialized at decomposing litter in their home habitat, by reciprocally transplanting litter from grassland to early-successional forest. Unexpectedly, we found an overall disadvantage for at-home decomposition despite large differences in litter quality (lignin:N) between the two habitats. We found more evidence for habitat specialization among secondary decomposers (mites) than the primary decomposers (bacteria and fungi), suggesting that soil animals may be important in driving HFA patterns where they do exist. Grass litter decomposition in forest slowed down and became more fungal-based, while tree litter decomposition in grassland increased yet showed no shift to being bacterially-based, relative to ‘at home’ decomposition. This suggests a biological explanation for why a positive HFA was not observed. Our results highlight that both environmental context and soil biology can play an important and sometimes counter-intuitive role in modifying decomposition. A better understanding of the interaction between all three primary drivers of decomposition (the environment, litter quality and soil organisms) is necessary for reliable prediction of decomposition at global scales.

Subtropical montane tree litter decomposition: Links with secondary forest types and species' shade tolerance

Abstract Litter decomposition plays an important role in secondary forest recovery in the tropics. In this study we assessed the decomposition rates of tree litter in species from different secondary forest types and with different shade tolerances. The three secondary forest types analysed are related to the effects of different previous land use intensities. The typical forest type (TYP) is related to low land use intensity, Alnus acuminata-dominated forest (ALN) type is related to medium land-use intensity and Amomyrtella güili-dominated forest type (AMO) is related to high land use intensity. The effect of shade tolerance was assessed using maximum height of each species as an indicator of its light requirements. Associations with leaf functional traits such as specific leaf area (SLA), and tensile strength (LTS) were also assessed. We found that leaves of species from the TYP forest type decompose faster than those of the ALN and AMO forest types. These changes were consistent with differences in the SLA of the species, which was higher in the TYP forest type than in the ALN and AMO forest types. SLA, LTS and decomposition were not significantly correlated with tree maximum height. Our results show that the secondary forest types, which are related to land use intensities prior to abandonment have an important influence on litter decomposition. This implies potential long-term effects on soil properties and species composition.