Affect Litter Decomposition Rates Research Articles

Effect of litter decomposition on mowing and plant composition change during Solidago stand restoration

Decomposition of organic matter supports important soil ecosystem services. The rate of decomposition depends mostly on the type of plant material being decomposed and the abundance and diversity of organisms that process the organic matter. Consequently, any disturbance to the soil ecosystem will affect the decomposition process. Invasive plants, such as Solidago species, pose a serious ecological threat to natural habitats, so effective and environmentally safe methods of controlling their occurrence should be developed. In this study, decomposition rates were used as indicators of soil health during grassland restoration after Solidago invasion. Different seed mixtures (grasses, grasses with legumes, seeds collected from a seminatural meadow; use of fresh hay and no seeds) were sown during a field experiment and different mowing frequencies (1, 2 and 3 times per year) were established. Two hypotheses were tested: (1) plant species composition used in the restoration process affects litter decomposition rates, and (2) mowing regimes affect litter decomposition rates. It was found that decomposition rates were higher in plots with the highest species diversity. This indicates that an increase in species diversity has a positive effect on soil processes. Secondly, mowing two and three times per season has a positive effect on the decomposition process. In conclusion, decomposition rates can be used as a tool to identify adequate grassland management.

A field assessment to validate the assumptions of the Tea Bag Index (TBI) as a measure of soil health

This study evaluated key assumptions underlying the Tea Bag Index (TBI) as a soil health assessment tool through a time series conducted under field conditions. The TBI assesses soil health by measuring the decomposition rates of standardized green and red tea over a 90-day incubation period. Our research was conducted on a degraded 33.6-ha agricultural site in North Saanich, British Columbia, where we compared two plots: a reference site and a grazed site, each representing distinct land use conditions.The first assumption evaluated was that the TBI metrics of S (stabilization rate) and k (decomposition rate) follow exponential decay models. While S adhered to this assumption, k did not, suggesting additional as yet undetermined influences on decomposition rates. We introduced new biological metrics, Bg and Br, which followed polynomial models of decay, and may reflect the decomposition of different materials over time by different soil organisms.The second assumption tested was that a 90-day incubation period adequately captures the timeframe required for labile litter consumption. Our findings indicated that decomposition variance plateaued after 105 days, and that an increase in incubation time by 35 days increased the precision of mathematical decomposition models by a mean value of 18.1 %.The final assumption tested was that litter decomposition rate varies with land use. Our findings affirm that land use does affect litter decomposition rate, although the specific sources of that variance remain unclear.TBI accuracy can be improved by extending the litter incubation time to at least 105 days. Incorporating biological metrics (Bg and Br) increases the TBI's precision. Our results reaffirm the TBI's sensitivity to land use differences, highlighting its potential as a cost-effective tool for assessing soil health under varying conditions.

Soil warming delays leaf litter decomposition but exerts no effect on litter nutrient release in a subtropical natural forest over 450 days

Litter decomposition is a fundamental ecosystem process, influencing soil carbon storage, nutrient availability, and forest productivity. Climate change may affect litter decomposition and thus nutrient dynamics via altering plant phenology, litter quality, and the composition of soil microbial communities. However, the effects of climate change on litter decomposition are not well understood, especially in tropical and subtropical forest ecosystems, which are less temperature limited. We conducted a manipulative study to assess how soil warming affects litter decomposition rates and its relation to litter chemistry, extracellular enzyme activities, and microbial biomass in an evergreen broad-leaved forest in subtropical China. The temperature at 0–10 cm soil depth was experimentally increased by 4 °C, starting from June 2016 to October 2017. Soil warming did not affect litter mass loss during the initial stage (0–270 day), but reduced litter mass loss by 12.9 % at the later stages (days 350 to 450). Structural equation modeling showed that litter moisture content was reduced by warming, but this was not the main effector leading to the reduction in late-stage litter decomposition in the warming treatment. The model suggested that warming reduced litter decomposition rates likely indirectly, through its negative effects on extractable organic carbon and microbial biomass (e.g., microbial carbon and nitrogen), and on litter enzyme activities (a composite variable of β-glucosidase, cellobiohydrolase, acid phosphatase, and phenoloxidase). These results show that warming may slow down litter carbon cycling, but this subtropical forest ecosystem did not affect litter N and P cycling and soil nutrient availability.

Increasing inputs of invasive N‐fixing Acacia litter decrease litter decomposition and associated microbial activity in streams

Abstract Nitrogen (N)‐fixing Acacia species are often aggressive invaders outside their native range. When invading native riparian temperate forests, they can decrease tree species diversity, alter the quality of litter inputs to streams and increase water N concentration. Although the effects of riparian tree species diversity and nutrient enrichment on litter decomposition and associated microbial decomposers have been widely studied, their individual and combined effects remain poorly understood, especially in streams flowing through forests invaded by Acacia species. Here, we assessed the effects of litter diversity (species evenness) and water N concentration on the decomposition of native and Acacia litter, and the activity and community structure of associated microbial decomposers. Litter of Castanea sativa (C) and Acacia melanoxylon (A) was enclosed in fine‐mesh bags in a total of five litter evenness treatments (100%C, 75%C + 25%A, 50%C + 50%A, 25%C + 75%A and 100%A), and immersed in a stream flowing through a native forest (native stream) and a stream flowing through a forest invaded by Acacia species (invaded stream). Litter decomposition rates and microbial decomposer activity differed among litter evenness treatments, generally decreasing as the proportion of A. melanoxylon increased. When considered individually, C. sativa litter decomposition and associated microbial activity did not differ among treatments. For A. melanoxylon, decomposition rates did not differ among treatments, whereas microbial activity was generally lower in treatments with higher or even proportions of C. sativa. Litter diversity had (small) antagonistic effects on litter decomposition in streams. However, litter treatments affected by diversity (species evenness) effects differed between streams, suggesting that effects can be modulated by water N concentration. Litter decomposition rates and microbial decomposer activity were higher in the invaded than in the native stream, probably as a consequence of the higher water N concentration in the former stream. However, the magnitude of the effects was small owing to the fact that water N concentration was still in the oligothrophic range in the invaded stream. Overall, our results suggest that the increasing proportion of N‐fixing Acacia species in invaded deciduous riparian forests will affect litter decomposition rates and microbial decomposer activity, and alter aquatic hyphomycete community structure, most probably as a result of decreases in the diversity and quality of litter inputs to streams, and increases in water N concentration. However, the magnitude of the effects resulting from decreases in litter input diversity and quality (due to increases in Acacia contribution) into invaded streams will probably be larger than those resulting from increases in water N concentration, thus overall litter decomposition will decrease. These impacts will possibly alter nutrient cycles in aquatic food webs that depend on riparian detritus, with implications for stream functioning.

Fungal Communities on Standing Litter Are Structured by Moisture Type and Constrain Decomposition in a Hyper-Arid Grassland.

Non-rainfall moisture (fog, dew, and water vapor; NRM) is an important driver of plant litter decomposition in grasslands, where it can contribute significantly to terrestrial carbon cycling. However, we still do not know whether microbial decomposers respond differently to NRM and rain, nor whether this response affects litter decomposition rates. To determine how local moisture regimes influence decomposer communities and their function, we examined fungal communities on standing grass litter at an NRM-dominated site and a rain-dominated site 75 km apart in the hyper-arid Namib Desert using a reciprocal transplant design. Dominant taxa at both sites consisted of both extremophilic and cosmopolitan species. Fungal communities differed between the two moisture regimes with environment having a considerably stronger effect on community composition than did stage of decomposition. Community composition was influenced by the availability of air-derived spores at each site and by specialization of fungi to their home environment; specifically, fungi from the cooler, moister NRM Site performed worse (measured as fungal biomass and litter mass loss) when moved to the warmer, drier rain-dominated site while Rain Site fungi performed equally well in both environments. Our results contribute to growing literature demonstrating that as climate change alters the frequency, magnitude and type of moisture events in arid ecosystems, litter decomposition rates may be altered and constrained by the composition of existing decomposer communities.

Effects of exogenous nitrogen addition on litter decomposition and nutrient release in a temperate desert

A litterbag decomposition experiment was carried out in southern Gurbantunggut Desert, with four nitrogen treatments: N0(0 g N·m-2·a-1), N5(5 g N·m-2·a-1), N10(10 g N·m-2·a-1) and N20(20 g N·m-2·a-1). The aims were to examine the effects of exogenous nitrogen addition on decomposition rate and nutrient release of Tamarix ramosissima, Salicornia europaea and their mixture. Results showed that decomposition rates were significantly different among litter types. After 345 days, the decomposition rates of T. ramosissima, S. europaea and their mixture under different treatments were 0.64-0.70, 0.84-0.99 and 0.71-0.81 kg·kg-1·a-1, respectively. Both mono- and mixed-litters exhibited nutrient release during decomposition process, with the release rates being 60.6%-67.4%, 56.7%-62.6%, 57.4%-62.3%, 46.8%-63.0% for N, and 51.9%-77.9%, 59.9%-74.7%, 53.0%-79.9%, 52.3%-76.4% for P, respectively for the N0, N5, N10 and N20 treatments. Nitrogen addition did not affect litter decomposition rate. The dynamics of N and P during decomposition of different litter types showed different responses to nitrogen addition. Nitrogen addition inhibited N and P releases of S. europaea litter and P release of the mixed litter, but did not affect the nutrient release of T. ramosissima. The results suggested that nitrogen input would not promote litter decomposition in temperate desert ecosystems, but might retard the nutrient returning to soil system.

Floodplain Preconditioning of Leaf Litter Modulates the Subsidy of Terrestrial C and Nutrients in Fluvial Ecosystems

Leaf litter can be retained in floodplains for several months before it enters rivers as lateral inputs. During this period, the environmental conditions on the floodplain can alter leaf litter chemistry and, consequently, affect its subsequent processing in the river. We analysed the effect of contrasting floodplain conditions on the chemical composition of leaf litter and its leachates, and how this affected their biodegradability and processing in rivers. To do so, we placed reed leaf litter (Phragmites australis) in open- and closed-canopy habitats of three floodplain sites with contrasting climates (semiarid Mediterranean, humid Mediterranean and continental) for 105 days. We then used litterbags in a river to examine the decomposition of preconditioned leaf litter in comparison with a control (non-preconditioned litter), and laboratory assays to examine the biodegradation of their leachates. Contrasting conditions on the floodplain prompted differences in the nutrient content of leaf litter among floodplain sites. Preconditioning caused a generalized decline in the C content and an increase in the lignin content of leaf litter. Even so, preconditioning did not affect litter decomposition rates in the river, although it did reduce decomposition efficiency and biodegradability of leachates. Shredder colonization of litter was variable and generally higher on preconditioned litter, but not significantly so. Different floodplain conditions had no influence on the aquatic processing of preconditioned litter. Our results demonstrate that the retention of leaf litter in terrestrial environments can affect C budgets of fluvial ecosystems and the recipient food web by reducing the input and the biodegradability of C and nutrients.

Litter C transformations of invasive Spartina alterniflora affected by litter type and soil source

Litter types and soil properties can affect litter decomposition rate and litter carbon (C) transformation, consequently regulating soil C cycling. Yet, litter C transformations of leaves and roots of invasive plants are poorly understood, which limits our understanding of the role of plant residues in soil C sequestration during plant invasion. In a laboratory incubation experiment lasting for 153 days, we used two types of soil which were collected from invasive S. alterniflora and native Phragmites australis marshlands, and traced the transformation of 13C from leaf and root litter of invasive Spartina alterniflora into CO2, soil-dissolved organic C (DOC), microbial biomass C (MBC), and soil organic C (SOC). The leaf litter of S. alterniflora decomposed faster than root litter, resulting in higher soil respiration and higher transformation of litter-derived 13C into CO2, MBC, and DOC. Although the root litter of S. alterniflora decomposed slowly, SOC comprised up to 24% of litter-derived 13C. Furthermore, the litter C transformations of S. alterniflora showed a positive home-field advantage effect. Soil respiration, MBC, fractions of litter-derived 13C in Gram-negative bacteria, 13C recovered in CO2, DOC, and SOC were higher in the soil colonized by S. alterniflora than in the soil colonized by P. australis, with the home-field advantage effect being more pronounced in root than leaf litter treatments. Therefore, litter type and soil source had differential impacts on litter C transformation patterns of S. alterniflora and the root litter of invasive S. alterniflora played an important role in SOC formation and C sequestration in soils from its invaded ecosystems.

Changes in seasonal precipitation distribution but not annual amount affect litter decomposition in a secondary tropical forest.

In the tropics of South China, climate change induced more rainfall events in the wet season in the last decades. Moreover, there will be more frequently spring drought in the future. However, knowledge on how litter decomposition rate would respond to these seasonal precipitation changes is still limited. In the present study, we conducted a precipitation manipulation experiment in a tropical forest. First, we applied a 60% rainfall exclusion in April and May to defer the onset of wet season and added the same amount of water in October and November to mimic a deferred wet season (DW); second, we increased as much as 25% mean annual precipitation into plots in July and August to simulate a wetter wet season (WW). Five single‐species litters, with their carbon to nitrogen ratio ranged from 27 to 49, and a mixed litter were used to explore how the precipitation change treatments would affect litter decomposition rate. The interaction between precipitation changes and litter species was not significant. The DW treatment marginally accelerated litter decomposition across six litter types. Detailed analysis showed that DW increased litter decomposition rate in the periods of January to March and October to December, when soil moisture was increased by the water addition in the dry season. In contrast, WW did not significantly affect litter decomposition rate, which was consistent with the unchanged soil moisture pattern. In conclusion, the study indicated that regardless of litter types or litter quality, the projected deferred wet season would increase litter decomposition rate, whereas the wetter wet season would not affect litter decomposition rate in the tropical forests. This study improves our knowledge of how tropical forest carbon cycling in response to precipitation change.

Effects of elevated atmospheric CO2 concentration and temperature on litter decomposition in streams: A meta‐analysis

AbstractThe metabolism of forest streams depends on the decomposition of plant litter of terrestrial origin. In turn, the rate at which litter decomposes depends on litter characteristics, decomposer activity, environmental characteristics, and their interactions. Atmospheric changes, such as increases in atmospheric carbon dioxide concentration ([CO2]) and in temperature, may affect all these variables. Here, we report the results of a meta‐analysis of 41 studies conducted worldwide between 1993 and 2017 on the effects of elevated atmospheric [CO 2], elevated temperature, or both (temperature + [CO 2]) on litter decomposition in streams. Elevated temperature significantly increased litter decomposition rates, whereas elevated [CO 2] and temperature + [CO 2] did not significantly affect litter decomposition rates. The effect of elevated temperature did not depend on the type of study (i.e., laboratory or field study, correlative field or manipulative field study) but in correlative field studies, the temperature effect was stronger over latitudinal than altitudinal gradients. Effects of elevated temperature also did not depend on the type of decomposer community (microbial or microbial and macroinvertebrates) but effects were always significant for total litter decomposition (both microbes and macroinvertebrates involved), whereas microbial‐driven litter decomposition was significantly affected only in manipulative studies. Effects of elevated temperature did not depend on the litter identity, although significant effects were found for some litter genera but not others. In terrestrial ecosystems, the elevated temperature was found to increase litter decomposition rates, whereas elevated [CO 2] decreased litter decomposition rates. Study type (laboratory or field) and litter identity were important moderators of the response of litter decomposition to elevated temperature and [CO 2] in terrestrial ecosystems. These differences between soil and stream ecosystems may be partially due to intrinsic differences (such as moisture that is not limiting in streams) between these ecosystems. In addition, our meta‐analysis is geographically biased with most studies being conducted in Europe. More studies in other parts of the world could allow for a better understanding of the effects of climate warming and [CO 2] increases on litter decomposition, the global carbon cycle, and biochemistry in streams.

Litter decomposition variation across a degradation gradient and two seasons in a critically endangered vegetation type within the Fynbos biome, South Africa

Litter decomposition is an ecosystem function essential for nutrient cycling; however until very recently it was considered of minor importance within the fire-prone Fynbos Biome. To investigate decomposition rate and litter nutrient dynamics, litterbags containing materials from three plant species from different functional types were placed in sites across a degradation gradient and over two seasons. Litterbags were removed after three and six months for both seasons to determine decomposition rates and change in nutrient concentration. Decomposition varied greatly among the species and was strongly correlated to initial nutrient values of the litter. The most nutrient rich litter type, the alien herbaceous Medicago spp., lost 65% of its original mass after six months while the most nutrient poor, the indigenous grass Pentameris eriostoma, lost 18%. Litter from Dicerothamnus rhinocerotis, an indigenous shrub, lost 27% of its original mass. For all litter types, the majority of the loss occurred during the first three months of the experiment. Season was found to significantly affect litter decomposition; however the exact mechanism behind this is unclear. Degradation level, at least defined by the metrics of this study, did not significantly affect litter decomposition rate. The faster decomposition rate shown in Medicago spp. suggests that in degraded areas where significant proportions of the species invade, nutrient cycling will be accelerated in comparison to pristine land; however broadening the species of study to include additional plant functional types, such as indigenous annuals, would help give insight into this hypothesis. This study affirms the notion that litter decomposition is an important ecosystem function within the Fynbos Biome with litter type acting as a strong controlling variable.

Ecosystem type and resource quality are more important than global change drivers in regulating early stages of litter decomposition

Litter decomposition is fundamental for nutrient and carbon (C) cycling, playing a major role in regulating the Earth's climate system. Climate change and fertilization are expected to largely shift litter decomposition rates in terrestrial ecosystems, however, studies contextualizing the relative importance of these major global change drivers versus other key decomposition drivers such as substrate quality and ecosystem type are lacking. Herein, we used two independent field experiments in an Eastern Australian grassland (Experiment 1) and a forest (Experiment 2) to evaluate the role of (i) litter quality, (ii) nutrient addition (N, P and K in full factorial combination; Experiment 1), and (iii) a combination of N addition and irrigation (Experiment 2) in litter decomposition, substrate-induced respiration and microbial abundance. Regardless of experimental treatments, forest soils decomposed litter between 2 and 5 times faster than grassland soils. This was principally controlled by the greater ability of forest microbes to respire C-based substrates and, ultimately, by soil N availability. The experimental treatments accounted for only relatively small differences in our measured variables, ranging from 10 to 15% in the case of the irrigation-by-N-addition forest experiment to almost negligible in most of the grassland nutrient addition plots. In the latter experiment, decomposition and soil activity responses were associated with either K addition or interactions between K and other nutrients, suggesting a key role for this often-neglected soil nutrient in controlling litter decomposition. Our study provides evidence that while nutrient enrichment and/or irrigation have the potential to affect litter decomposition rates in grassland and forest ecosystems, land use change that results in loss or gain of forested area is likely to exert a much greater impact than these other two drivers.

Effects of simulated nitrogen and sulfur deposition on litter decomposition rate in an evergreen broad-leaved forest in the Rainy Area of Western China.

To examine the effects of nitrogen and sulfur deposition on litter decomposition rate, a one-year field experiment was conducted with the litter bag method from April 2013 to April 2014 in an evergreen broad-leaved forest in the Rainy Area of Western China. There were nine treatments with three nitrogen levels and three sulfur levels, including control (CK), low nitrogen deposition (LN, 50 kg N·hm-2·a-1), high nitrogen deposition (HN, 150 kg N·hm-2·a-1), low sulfur deposition (LS, 200 kg S·hm-2·a-1), high sulfur deposition (HS, 400 kg S·hm-2·a-1), low nitrogen and low sulfur deposition (LNLS), high nitrogen and low sulfur deposition (HSLS), low nitrogen and high sulfur deposition (LNHS), and high nitrogen and high sulfur deposition (HNHS). The results showed that the leaf litter residual rate ranged from 57.0% to 70.7% after one year decomposition. The time of half mass loss ranged from 1.47 to 2.08 years, while the time of 95% mass loss ranged from 6.33 to 9.01 years. Nitrogen deposition had no significant effect on litter decomposition rate. The decomposition rate was significantly increased in LS treatment but significan-tly reduced in HS treatment. The rate was significantly affected by LNHS and HNHS, but unaffected by LNLS and HNLS. In addition, simulated nitrogen and sulfur deposition interacted to affect litter decomposition rate, with antagonistic effects between nitrogen deposition and low-sulfur composite deposition and synergistic effects between nitrogen deposition and high-sulfur composite deposition. In conclusion, sulfur deposition and the combined nitrogen and sulfur deposition affected leaf litter decomposition rate in the evergreen broad-leaved forest, with consequences on the litter decomposition process.

Post-thaw variability in litter decomposition best explained by microtopography at an ice-rich permafrost peatland

ABSTRACT Litter decomposition, a key process by which recently fixed carbon is lost from ecosystems, is a function of environmental conditions and plant community characteristics. In ice-rich peatlands, permafrost thaw introduces high variability in both abiotic and biotic factors, both of which may affect litter decomposition rates in different ways. Can the existing conceptual frameworks of litter decomposition and its controls be applied across a structurally heterogeneous thaw gradient? We investigated the variability in litter decomposition and its predictors at the Stordalen subarctic peatland in northern Sweden. We measured in situ decomposition of representative litter and environments using litter bags throughout two years. We found highly variable litter decomposition rates with turnover times ranging from five months to four years. Surface elevation was a strong correlate of litter decomposition across the landscape, likely as it integrates multiple environmental and plant community changes brought about by thaw. There was faster decomposition but also more mass remaining after two years in thawed areas relative to permafrost areas, suggesting faster initial loss of carbon but more storage into the slow-decomposing carbon pool. Our results highlight mechanisms and predictors of carbon cycle changes in ice-rich peatlands following permafrost thaw.

The Contribution of Photodegradation to Litter Decomposition in Semiarid Mediterranean Grasslands Depends on its Interaction with Local Humidity Conditions, Litter Quality and Position

Understanding how UV radiation interacts with prevailing climatic conditions and litter quality to determine leaf litter decomposition is fundamental for understanding soil carbon cycling pathways and ecosystem functioning in drylands. We carried out a field manipulative experiment to investigate how litter quality (labile and nitrogen-rich Retama sphaerocarpa vs. recalcitrant and nitrogen-poor Stipa tenacissima), position (on the ground vs. standing) and different UV radiation levels (UV pass vs. UV block) affect litter decomposition rates at two semiarid Mediterranean steppes with contrasting climates (continental vs. maritime) in a fully factorial experimental design. As expected, Retama litter decomposed faster than that of Stipa, and litter placed on the ground decayed faster than standing litter. However, and surprisingly, contrasting effects of UV radiation on litter decomposition were observed between the two sites. At the continental site, UV radiation increased litter decay constants by 21% on average, although the contribution of photodegradation was larger when litter was placed on the ground rather than in standing litter. At the maritime site, decay constants were 15% larger in the absence of UV radiation regardless of litter position. Significant litter type × UV exposure radiation and litter type × position interactions indicate that photodegradation contributes more to litter decomposition under less favorable moisture and substrate availability conditions for microbial decomposers. Our results emphasize the need to consider interactions between moisture availability, litter quality and UV radiation in litter decomposition models to fully understand litter decomposition impacts on soil carbon cycling and storage in drylands under climate change.

Litter traits and palatability to detritivores: a case study across bio-geographical boundaries

The activity of the litter-feeding macrofauna affects litter decomposition rates at the local scale, and their preference for particular litter types is mediated by litter traits. Environmental changes such as invasion by exotic plants may change the characteristics of the litter at a local scale, with consequences to ecosystem processes. Here we evaluated the feeding preferences of four detritivores (terrestrial isopods) from two biogeographic regions (neotropical and palearctic), offering them native or non-native litter in cafeteria experiments. Our results show that isopods from different geographical regions exhibit essentially the same food preference, irrespective of whether or not they previously had encountered the litter tested. Combining the isopods' preference ranks with the principal component analysis of nine litter traits, we show that preference increases with increasing nitrogen and calcium contents and decreases with increasing toughness, C:N ratio and thickness, irrespective of the geographical origin of both litter and detritivores. We conclude that the palatability of a non-native litter to the native detritivore community can be predicted from their respective litter traits and thus, native detritivores will feed on a particular non-native litter type as likely as do detritivores in the native range of the plant. As the combination of traits that indicates palatability to the isopods also indicates litter decomposability, it could be possible to predict ecosystem responses in terms of litter decomposition rates upon changes in litter composition.

三峡库区马尾松林土壤-凋落物层酶活性对凋落物分解的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 三峡库区马尾松林土壤-凋落物层酶活性对凋落物分解的影响 DOI: 10.5846/stxb201305261185 作者: 作者单位: 中国林业科学研究院亚热带林业研究所,中国林业科学研究院森林生态环境与保护研究所,中国林业科学研究院森林生态环境与保护研究所,中国林业科学研究院森林生态环境与保护研究所,中国林业科学研究院亚热带林业研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 林业公益性行业科研专项（201104008）；“十二五”科技支撑资助项目（2011BAD38B04） Effect of soil-litter layer enzyme activities on litter decomposition in Pinus massoniana plantation in Three Gorges Reservoir Area Author: Affiliation: Research Institute of Subtropical Forestry,Chinese Academy of Forestry,Fuyang,Zhejiang,Key Laboratory of Forest Ecology and Environment,the State Forestry Administration,Key Laboratory of Forest Ecology and Environment,the State Forestry Administration,Key Laboratory of Forest Ecology and Environment,the State Forestry Administration,Research Institute of Subtropical Forestry,Chinese Academy of Forestry,Fuyang,Zhejiang 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:凋落物的彻底降解是在凋落物和土壤酶系统的综合作用下完成，酶活性的提高有利于凋落物-土壤有机物质的分解和养分释放。通过对三峡库区30年生马尾松林凋落物分解、凋落物-土壤层酶活性季节动态及其对分解的影响进行研究，结果表明：30年生马尾松林凋落物经过540 d的分解后干重剩余率是59.80%；凋落物层酶活性季节动态明显，氧化还原酶活性均是11月最低，3月最高；土壤过氧化物酶活性季节变化显著且均是11月最低，多酚氧化酶活性9月较高，而过氧化物酶活性则是6月较高。马尾松林凋落物层酶活性与土壤层酶活性差异较大，且水解酶活性差异较氧化还原酶活性差异大，凋落物层脲酶活性、纤维素酶活性和蔗糖酶活性11月、6月、9月分别是0-5 cm土壤层的6.33倍、3.24倍、10.29倍，68.14倍、16.16倍、24.81倍，25.07倍、31.88倍、29.20倍。凋落物分解速率均与土壤、凋落物层氧化还原酶活性呈极显著“S”形曲线，与凋落物层水解酶活性呈二次函数关系，与土壤层水解酶均呈极显著的线性关系。凋落物质量能引起凋落物-土壤层酶活性变化，酶活性的改变反过来影响凋落物的分解，因此，凋落物-土壤层酶活性差异与凋落物分解阶段和对共同影响因素（凋落物质量、土壤温度、水分含量和土壤养分等）的敏感性不同有关，凋落物-土壤层酶的相互作用共同影响森林生态系统的物质循环和养分循环过程。 Abstract:The complete degradation of litter results from the combined enzyme activities in litter layer and soil layer, and their improvement is helpful to organic matter decomposition and nutrient release. Litter decomposition and the seasonal dynamic of soil-litter layer enzyme activities were studied on 30-year-old P. massoniana forest in Three Gorges Reservoir Area. The results showed that the remaining mass was 59.80% after 540 days decomposition. The decomposition rate was relatively fast during the decomposition 0-180 d, and relatively slow during 180-270 d. The period of 50% mass loss and 95% mass loss was 2.11 a and 9.15 a, respectively. The litter layer enzyme activities exhibited a remarkable seasonal dynamics, with the lowest enzyme activity occurring in November and the highest in March for oxidoreductase activity. Polyphenoloxidase activity and peroxidase activity of litter layer in March were 4.60 times and 6.07 times as high as those in November, respectively, while the dynamic of hydrolase activity in litter layer was irregular variation. The seasonal dynamics of soil layer peroxidase activity was remarkable with the lowest value occurring in November, and the highest in June. Polyphenoloxidase activity was the highest in September. The seasonal dynamics of soil layer hydrolase activity was irregular variation, the seasonal dynamical of soil urease activity was not significant (P>0.05), while the cellulose activity and sucrase activity was significant (P<0.05) with the sequence of September < June < November for sucrase activity, and the sequence of November < September < June for cellulose activity. Soil enzyme activity in the vertical direction was decreased gradually with soil depth except peroxidase activity. There was a notable difference in enzyme activity between litter layer and soil layer, and the difference in hydrolase activity was greater than in oxidoreductase activity. Litter layer urease activity, cellulase activity and sucrase activity were 6.33 times, 3.24 times, 10.29 times as high as those in 0-5 cm soil layer in November; 68.14 times, 16.16 times, 24.81 times in June, and 25.07 times, 31.88 times, 29.20 times in September, respectively. Litter polyphenoloxidase activity in November, June and September were 1.76 times, 1.45 times and 2.07 times as high as those in 0-5 cm soil layer, and the corresponding value were 0.40 times, 0.64 times and 0.56 times for peroxidase activity, respectively. There was a close relationship between litter-soil enzyme activities. Litter decomposition rate was significantly correlated in S-shaped curve with oxidereductase activity both in litter and soil layer, probably because oxidoreductase activity dynamic is complex and influenced by soil pH value, nutrient content, soil layer distribution and so on. There were significant quadratic function (P<0.01) between litter decomposition rate and hydrolase activity in litter layer, while litter decomposition rate was significantly linearly related (P<0.01) to the hydrolase in soil layer. Litter quality could change the enzyme activity in litter and soil layer, in return, enzyme activity could affect litter decomposition rate. Therefore, the difference of enzyme activity between litter and soil layer is related with litter decomposition stage and the different sensitivity of the common impact factors including litter quality, soil temperature, water content and soil nutrients. The interactions of litter-soil layer enzyme activity influence material circulation and nutrient cycling process of forest ecosystem. 参考文献 相似文献 引证文献

The Afterlife of Interspecific Indirect Genetic Effects: Genotype Interactions Alter Litter Quality with Consequences for Decomposition and Nutrient Dynamics

Aboveground-belowground linkages are recognized as divers of community dynamics and ecosystem processes, but the impacts of plant-neighbor interactions on these linkages are virtually unknown. Plant-neighbor interactions are a type of interspecific indirect genetic effect (IIGE) if the focal plant’s phenotype is altered by the expression of genes in a neighboring heterospecific plant, and IIGEs could persist after plant senescence to affect ecosystem processes. This perspective can provide insight into how plant-neighbor interactions affect evolution, as IIGEs are capable of altering species interactions and community composition over time. Utilizing genotypes of Solidago altissima and Solidago gigantea, we experimentally tested whether IIGEs that had affected living focal plants would affect litter decomposition rate, as well as nitrogen (N) and phosphorous (P) dynamics after the focal plant senesced. We found that species interactions affected N release and genotype interactions affected P immobilization. From a previous study we knew that neighbor genotype influenced patterns of biomass allocation for focal plants. Here we extend those previous results to show that these changes in biomass allocation altered litter quality, that then altered rates of decomposition and nutrient cycling. Our results provide insights into above- and belowground linkages by showing that, through their effects on plant litter quality (e.g., litter lignin:N), IIGEs can have afterlife effects, tying plant-neighbor interactions to ecosystem processes. This holistic approach advances our understanding of decomposition and nutrient cycling by showing that evolutionary processes (i.e., IIGEs) can influence ecosystem functioning after plant senescence. Because plant traits are determined by the combined effects of genetic and environmental influences, and because these traits are known to affect decomposition and nutrient cycling, we suggest that ecosystem processes can be described as gene-less products of genetic interactions among the species comprising ecological communities.

Changes in dominance among species in aquatic hyphomycete assemblages do not affect litter decomposition rates

Fresh waters are threatened worldwide by water pollution and extraction, changes in ripar- ian vegetation and global warming. Changes in com- munity dominance are expected as an early outcome of anthropogenic stresses, later followed by a reduc- tion in species number and changes in species iden- tity, which might impair ecosystem processes. Here, we addressed the effect of changes in dominance among species in fungal assemblages on the decom- position of alder leaves and associated fungal activ- ity. In laboratory microcosms, we inoculated alder leaf discs with 2 fungal assemblages, each composed of 3 species known to dominate communities during early decomposition (early assemblage) and late decomposition (late assemblage). For each assem- blage type, the identity of the dominant species was tentatively manipulated by inoculating the micro- cosms with distinct proportions of conidia in 4 inoc- ula: an even inoculum and 3 uneven inocula (each dominated by a different species). Over the incuba- tion time, all early assemblages became dominated by the same aquatic hyphomycete species, while manipulation of the number of conidia in the inocula successfully determined the dominant species in late assemblages. Total conidial production and respira- tion rates differed among early assemblages, but no differences were found in litter decomposition and associated fungal variables among late assemblages. The absence of a relationship between community dominance/identity of the dominant species and community performance/litter mass loss suggests that assemblages, even those composed of a low number of species, have the capacity to buffer changes in processes due to changes in species dominance.

Frequency of prescribed burning in an upland oak forest determines soil and litter properties and alters the soil microbial community

Prescribed burning is commonly used in forests to reduce fuel load, prevent encroachment of exotic species, maintain biological diversity and improve wildlife habitat. The low intensity burns that are conducted at intervals of 1–10 years may have long-term effects on the abiotic and biotic components of the soil. We assessed how prescribed burning altered litter, soil physical and chemical properties, and soil microbial communities in upland oak forests subjected to prescribed burning at frequencies of 0 (unburned), 2.5 and 5 fires per decade (FPD) over a 20 year period. Prescribed burning at 5 FPD reduced soil organic matter by 60% and soil organic carbon by 64% and increased bulk density by 20%. Compared to unburned controls, litter nitrogen was reduced by 20% and 21% and C/N ratio increased by 25% and 28% in sites burned at 2.5 and 5 FPD, respectively. Litter lignin/N ratio was reduced 28% at 2.5 FPD, compared to litter from unburned sites. We found no changes in soil pH, total N, NO 3-N, NH 3-N, plant-available Ps or K due to prescribed burning. Microbial biomass of Gram negative bacteria, as determined by phospholipid fatty acid (PLFA) analyses, decreased from 25% of biomarker abundance at the unburned sites to 20% at the 5 FPD sites. No other microbial functional group was significantly influenced by fire frequency. Our results indicate prescribed burning with low intensity fires in upland oak forests do not have major effects on the soils if these fires occur infrequently, i.e. less frequent than 2.5 FPD. However, frequent burning of these upland oak forests (5 FPD) resulted in important changes in the litter and soil that may adversely affect litter decomposition rates, soil carbon storage, soil water holding capacity, and soil erosion rates. Our findings indicate prescribed burning can be an important management tool, however, at high fire frequencies there may be tradeoffs between vegetation management goals and long-term adverse affects on the soil.