Natural Evergreen Broad-leaved Forest Research Articles

Effects of Ganoderma lucidum cultivation in forests on soil organic carbon pool and microbial community physiological profiles

Non-timber forest products increase forests resource utilization efficiency and promote rural areas economic development. Ganoderma lucidum (Curtis) P. Karst. (Reishi) is a mushroom having great potential being cultivated as NFTPs. However, there is still a lack of effects about cultivating Reishi in forests on soil organic carbon (C) pool and microbial community, which are important for designing sustainable cultivating strategies. Therefore, this study sampled and analyzed soil from forests cultivated Reishi at 2, 4, and 6 years (LZ2, LZ4, and LZ6, respectively), and in reference natural evergreen broad-leaved forest (CK). Our results manifested that, compared with CK, LZ2 slightly increased total organic carbon (TOC), and significantly increased microbial biomass carbon (MBC) and water-soluble organic carbon (WSOC) content by 29.99% and 28.67%, respectively ( P < 0.05). Besides, compared with CK, LZ2 significantly increased the ratio of MBC/TOC and WSOC/TOC by 37.50% and 35.00%, respectively ( P < 0.05). In contrast, these parameters decreased in LZ4 and LZ6 slightly, compared with CK. Consequently, LZ2 had the highest average well-color development values and microbial functional diversity indexes, while these parameters declined in LZ4 and LZ6, compared with CK. As a result, microbial community functional structure in LZ2 was different from that in LZ4, and LZ6, while that in LZ4 and LZ6 showed similarity, according to the principal component analysis and PERMANOVA test.

The Response of Mesofauna to Nitrogen Deposition and Reduced Precipitation during Litter Decomposition

Soil mesofauna plays an important role in decomposing organic matter, recycling nutrients, and increasing nutrient availability. The effects of nitrogen (N) deposition and reduced precipitation on the litter-dwelling mesofaunal community and how this process affects litter decomposition remain poorly understood. Herein, a two-year simulated N deposition and throughfall reduction experiment was carried out in a natural evergreen broad-leaved subtropical forest to examine the effects of N deposition and reduced precipitation on soil mesofauna during litter decomposition. Four treatments were established: control (CK), N deposition (N), reduced precipitation (RP), and combined N deposition and reduced precipitation (N + RP). We collected and identified 19,782 individuals of mesofauna in litterbags during the whole experiment. Mites (Prostigmata, Mesostigmata, and Oribatida) and Collembola comprised almost 90% of the total number of individuals collected and dominated the soil mesofauna in our study. Our results revealed the negative effects of N deposition on the density of Oribatida mites and Collembola and the total density of soil mesofauna. Reduced precipitation significantly increased the density of Collembola and Oribatida mites and the total density of mesofauna and marginally significantly increased the density of Mesostigmata mites but decreased the diversity of mesofauna. The interaction effects of N deposition and reduced precipitation significantly affected the density of Prostigmata mites, Oribatida mites, Collembola, and the diversity of mesofauna. N deposition combined with reduced precipitation significantly inhibited litter decomposition, whereas no significant interaction effects were observed. Furthermore, correlation analysis indicated that litter mass loss was significantly positively correlated with the density of Prostigmata, Mesostigmata, and Oribatida, as well as the diversity of mesofauna. Overall, during the two-year decomposition process, our results suggest that N deposition and reduced precipitation interactively affected mesofaunal diversity and that N deposition adversely affected the mesofaunal community, while reduced precipitation increased the density of some groups but decreased mesofaunal diversity, consequently cascading on the decomposition of leaf litter.

亚热带米槠天然林凋落物和根系输入变化对土壤磷组分的影响

植物残体添加和去除试验(The Detritus Input and Removal Treatments, DIRT)是研究地上凋落物以及植物根系对土壤营养物质循环过程及机制探究的一种试验设计。于2012年6月选择福建省三明森林生态系统与全球变化研究站的米槠常绿阔叶天然林, 设置5种处理：对照(CT)、去除凋落物(NL)、去除根系(NR)、去除凋落物与根系(NI)、添加双倍凋落物(DL), 在2018年12月对各处理不同土层(0-10cm、10-20cm)土壤磷组分及其影响因子进行研究, 结果表明：(1)在0-10cm土层中DL处理总磷含量显著大于NL处理, NI处理无机磷含量最低, 在10-20cm中DL处理有机磷含量显著大于其他处理；(2)DL处理活性磷(Resin-P、NaHCO₃-Pi、NaHCO₃-Po)含量在0-10cm土层中显著大于其他处理。在10-20cm土层中NR处理活性磷以及中等活性磷显著大于NL处理。残留态磷(Residual-P)含量最高, 但在各处理与土层之间并没有明显差异；(3)酸性磷酸酶在0-10 cm土层不同处理间的变化趋势明显, CT处理活性最高, NI处理活性最低。NR与NL处理在10-20cm土层的差异并不明显。冗余分析表明, 土壤磷组分的变化主要受酸性磷酸酶、土壤含水率、可溶性有机氮以及总氮的影响。凋落物的输入对促进土壤磷素增加, 改善土壤质量具有重要意义；植物根系则对土壤磷的活化与稳定具有关键作用。;The detritus input and removal treatment is an experimental design to study the effects of aboveground litter and plant roots on soil nutrient cycling process and mechanism. In June 2012, we set up five treatments, viz. control (CT), no litter (NL), no roots (NR), no input (NI), and double litter (DL), in a natural evergreen broad-leaved forest of Castanopsis carlesii in Sanming, Fujian Province. Soil phosphorus fractions and their influencing factors in different soil layers (0-10 cm and 10-20 cm) of each treatment were studied in December 2018. The results showed that: (1) in the 0-10 cm soil layer, the total phosphorus content in DL treatment was significantly higher than that in NL treatment. The inorganic phosphorus content in NI treatment was the lowest, The organic phosphorus content in DL treatment was significantly higher than other treatments in 10-20 cm soil layer; (2) The contents of easily-available phosphorus fractions (Resin-P, NaHCO₃-Pi, NaHCO₃-Po) in DL treatment were significantly higher than those in other treatments in 0-10 cm soil layer. In 10-20 cm soil layer, the easily-available phosphorus and moderately-available phosphorus in NR treatment were significantly higher than those in NL treatment. The content of residual-P was the highest, but there was no significant difference between the treatment and soil layer; (3) The change trend of acid phosphatase in 0-10 cm soil layer was obvious among different treatments. CT treatment had the highest activity and NI treatment had the lowest activity. The difference between NR and NL treatments was not obvious in 10-20 cm soil layer. Redundancy analysis showed that the changes of soil phosphorus fractions were mainly affected by acid phosphatase, soil moisture content, dissolved organic nitrogen, and total nitrogen. Adding litter could mineralize organic phosphorus by increasing soil microbial biomass and enhancing soil acid phosphatase activity, promote the transformation of soil organic phosphorus to inorganic phosphorus, and improve the availability of soil phosphorus. However, root system could absorb soil active phosphorus and mineralize other phosphorus fractions. It had positive significance to improve the structure of P in soil.

The Responses of Leaf Litter Calcium, Magnesium, and Manganese Dynamics to Simulated Nitrogen Deposition and Reduced Precipitation Vary with Different Decomposition Stages

Litter decomposition is a vital link between material circulation and energy flow in forest ecosystems and is intensely affected by global change factors, such as increased nitrogen (N) deposition and altered precipitation regimes. As essential nutrients, calcium (Ca), magnesium (Mg), and manganese (Mn) play crucial roles in plant energy metabolism, photosynthesis, and membrane transport of plants, and the major source of these nutrients is litter decomposition. However, the dynamics of Ca, Mg, and Mn during decomposition have been largely ignored. Thus, to better understand Ca, Mg, and Mn dynamics during leaf litter decomposition in the scenario of increasing N deposition and decreasing precipitation, we carried out a two-year field litterbag experiment in a natural evergreen broad-leaved forest in the central area of the rainy area of Western China. Two levels of N deposition (ambient N deposition and 150 kg·N·ha−1·y−1) and precipitation reduction (no throughfall reduction and 10% throughfall reduction) were set, i.e., control (Ctr: without nitrogen deposition or throughfall reduction), N deposition (N, 150 kg·N·ha−1·y−1), throughfall reduction (T, 10% throughfall reduction), and N deposition and throughfall reduction (NT, 150 kg·N·ha−1·y−1 and 10% throughfall reduction). We found that leaf litter Ca concentration increased in the early decomposition stage and then decreased, while Mg and Mn concentrations generally decreased during the whole period of decomposition. The amount of Ca showed an accumulation pattern, while Mg and Mn generally showed a release pattern. N deposition and throughfall reduction affected the Ca, Mg, and Mn dynamics, varying with different decomposition stages; i.e., N deposition significantly affected the concentration and amount of Ca, regardless of the decomposition stages, while throughfall reduction significantly affected the Ca concentration in the whole and early decomposition stages. N deposition significantly affected the concentration and amount of Mg in the whole and early decomposition stages, while throughfall reduction had no significant effects. Throughfall reduction significantly affected the concentration and amount of Mn in the whole and late decomposition stages, while N deposition had no significant effects. Ca concentration generally showed a significant positive linear relationship with mass loss in the early decomposition stage; Mg concentration showed a significant positive linear relationship with mass loss in the Ctr and N treatments in the early and late decomposition stages; Mn generally showed a significant negative linear relationship with mass loss, regardless of the decomposition stage. Overall, the results suggest that Ca accumulation is more likely affected by N deposition, while Mg and Mn releases are more likely affected by N deposition combined with throughfall reduction, particularly in the early decomposition stage.

Vertical differentiation of soil organic carbon in mature natural forests in China.

We analyzed the effects of meteorological factors and soil properties on vertical variation of SOC, based on soil organic carbon (SOC) density in different soil layers (0-10, 10-20, 20-30, 30-50, and 50-100 cm) from 131 mature natural forests in different climate zones in China. The results showed that SOC density decreased with increasing soil depth (0-30 cm) in temperate coniferous, temperate deciduous broadleaved, subtropical deciduous broadleaved and subtropical evergreen broadleaved forests. There were significant regional variations of SOC density in 0-100 cm soil layer. SOC density of 0-100 cm soil layer in temperate coniferous forests was higher than temperate deciduous broadleaved forests, and was higher in subtropical evergreen broadleaved forests than subtropical deciduous broadleaved forests. SOC density was significantly positively correlated with soil clay content, mean annual precipitation, and aboveground net primary production, and significantly negatively correlated with soil pH and mean annual temperature. Mean annual precipitation and mean annual temperature influenced input and output of SOC, while soil pH and clay content affected SOC accumulation. Therefore, protecting mature natural coniferous and evergreen broadleaved forests would benefit forest carbon sequestration in China.

Organic and inorganic nitrogen deposition in an urban evergreen broad-leaved forest in central Japan

Chronic atmospheric nitrogen (N) deposition could influence the functioning of ecosystems as well as their biodiversity. However, N deposition in urban forest ecosystems, especially natural evergreen broad-leaved forests, is not well known. In this study, the concentrations and fluxes of dissolved inorganic N (DIN) and dissolved organic N (DON) in bulk deposition, throughfall, and stemflow were assessed in an urban evergreen broad-leaved forest site over three years, in order to clarify the characteristics of N deposition. At the study site, bulk DIN deposition was 3.7 kg N ha−1 year−1 (1.5 kg N ha−1 year−1 for NH4–N and 2.2 kg N ha−1 year−1 for NO3 + NO2–N), which is the same level as that found in rural areas. In contrast, 6.5 kg N ha−1 year−1 for bulk DON deposition contributed to 66% of the bulk N deposition, which suggests the importance of bulk DON deposition in Japanese forest ecosystems. Passing through the tree canopy, DIN was enriched by 8.8 kg N ha−1 year−1 (3.7 kg N ha−1 year−1 for NH4–N and 5.1 kg N ha−1 year−1 for NO3 + NO2–N) and DON was enriched by 1.5 kg N ha−1 year−1 as net throughfall in the evergreen broad-leaved forest. This reveals that dry deposition of DIN dominates the total DIN deposition onto the urban forest floor, compared to that found in the rural areas, due to the non-negligible N emissions from outside and possibly because of the evergreen broad-leaved forest's greater ability to capture N.

Phosphorus addition accelerates fine root decomposition by stimulating extracellular enzyme activity in a subtropical natural evergreen broad-leaved forest

Nitrogen (N) plays a vital role in litter decomposition by interacting with microbial activity in temperate and boreal ecosystems. However, in tropical and subtropical forests, where low soil phosphorus (P) availability is widespread, how P affects litter decomposition remains unclear. In the present study, litter-bag method was used to conduct fine root decomposition by P addition experiment in a subtropical natural evergreen broad-leaved forest. Fine roots were collected from two tree species: Cunninghamia lanceolata and Castanopsis carlesii, and their mixture in equal proportion as well. At the end of 2-year experiment, we found an enhancement of soil total P, available P, pH and microbial biomass carbon content, and increased abundance of all the examined microbial groups and total PLFA biomass after P addition. Annual decomposition constants of fine roots of both tree species and the mixture (0.615–1.049) were all elevated, but to different extents by P addition, with fine roots of lower initial P concentration corresponding to higher increase in decomposition rate. Average acid phosphatase activities during decomposition were significantly decreased, but there was a general increase for β-glucosidase (βG), cellobiohydrolase (CBH), phenol oxidase, peroxidase (PerOx) and N-acetyl glucosaminidase (NAG) activities. The response ratios of enzyme activities, which differed for the three experimental fine roots, corresponded to the individual increase in decomposition rates. Correlation analysis demonstrated that fine root decomposition rates were significantly related to initial P concentration, extractives and acid-insoluble fractions of fine roots, and activities of βG, CBH, NAG and PerOx as well. Taken together, our results demonstrate that fine root decomposition can be constrained by P availability through affecting microbial activity in this subtropical natural forest.

Conversion of Natural Evergreen Broadleaved Forests Decreases Soil Organic Carbon but Increases the Relative Contribution of Microbial Residue in Subtropical China

It has been recognized that land use change affects soil organic carbon (SOC) dynamics and the associated microbial turnover. However, the contribution of microbial residue to SOC storage remains largely unknown in land use change processes. To this end, we adopted a “space for time” approach to examine the dynamics of SOC and amino sugars, which was a biomarker of microbial residue C, in different natural forest conversions. Three typical converted forests were selected: an assisted natural regeneration (ANR) and two coniferous plantations of Cunninghamia lanceolata (Lamb.) Hook (Chinese fir) and Pinus massoniana Lamb. (pine) each. All of these were developed at the same time after the harvest of an old natural forest and they were used to evaluate the effects of forest conversions with contrasting anthropogenic disturbance on SOC and microbial residue C, along with the natural forest. Natural forest conversion led to an approximately 42% decrease in SOC for ANR with low anthropogenic disturbance, 60% for the Chinese fir plantation, and 64% for the pine plantation. In contrast, the natural forest conversion led to a 32% decrease in the total amino sugars (TAS) for ANR, 43% for the Chinese fir plantation, and 54% for the pine plantation at a soil depth of 0–10 cm. The ratios of TAS to SOC were significantly increased following natural forest conversion, with the highest ratio being observed in the Chinese fir plantation, whereas the ratios of glucosamine to muramic acid (GluN/MurA) were significantly decreased in the two plantations, but not in ANR. The contents of SOC, individual amino sugar, or TAS, and GluN/MurA ratios were consistently higher at a soil depth of 0–10 cm than at 10–20 cm for all of the experimental forests. Redundancy analysis showed that microbial residue C was significantly correlated with SOC, and both were positively correlated with fine root biomass, annual litterfall, and soil available phosphorus. Taken together, our findings demonstrated that microbial residue C accumulation varied with SOC and litter input, and played a more important role in SOC storage following forest conversion to plantations with higher anthropogenic disturbance.

Simulated leaf litter addition causes opposite priming effects on natural forest and plantation soils

The conversion of natural forests to tree plantations alters the quality and decreases the quantity of litter inputs into the soil, but how the alteration of litter inputs affect soil organic matter (SOM) decomposition remain unclear. We examined SOM decomposition by adding 13C-labeled leaf-litter of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) to soils from a natural evergreen broad-leaved forest and an adjacent Chinese fir plantation converted from a natural evergreen broad-leaved forest 42 years ago. Over 195 days, we monitored CO2 efflux and its δ13C, microbial biomass, and the composition of microbial groups by phospholipid fatty acids (PLFAs). To distinguish priming mechanisms, partitioning of C sources in CO2 and microbial biomass was determined based on δ13C. Leaf-litter addition to natural forest increased microbial biomass and induced up to 14% faster SOM decomposition (positive priming) than that in soil without litter. In contrast, negative priming in soils under plantation indicated preferential use of added leaf-litter rather than recalcitrant SOM. This preferential use of leaf-litter was supported by an increased fungal to bacterial ratio and litter-derived (13C) microbial biomass, reflecting increased substrate recalcitrance, the respective changes in microbial substrate utilization and increased C use efficiency. The magnitude and direction of priming effects depend on microbial preferential utilization of new litter or SOM. Concluding, the impact of coniferous leaf-litter inputs on the SOM priming is divergent in natural evergreen broad-leaved forests and plantations, an important consideration in understanding long-term C dynamics and cycling in natural and plantation forest ecosystems.

Effects of reduced precipitation on litter decomposition in an evergreen broad-leaved forest in western China

Litter decomposition is a fundamental process of biogeochemical cycles and plays a critical role in regulating carbon (C) and nutrient mineralization in terrestrial ecosystems. Examining responses of litter decomposition to altered precipitation is crucial to understand terrestrial C dynamics and its feedback to climate change. To understand the effects of reduced precipitation on litter decomposition, a two-year throughfall reduction experiment was carried out in a natural evergreen broad-leaved forest in western China. Five throughfall reduction levels were investigated: control without throughfall reduction (Ctr), 5% (W1), 10% (W2), 20% (W3) and 50% throughfall reduction (W4). Throughfall reduction significantly reduced soil moisture, which was most pronounced in W3 and W4 treatments, and this was associated by significantly reduced cumulative litter mass loss and lower decomposition constants. Also, throughfall reduction significantly altered litter C, N and P dynamics. In particular in W2, W3 and W4 treatments the release of C and N was significantly reduced, whereas in W2 and W3 the immobilization of P was increased. Overall, the results suggest that future decrease in precipitation will suppress litter decomposition, whereas microbial P limitation in litter may be aggravated in broad-leaved forest ecosystems.

Environmental changes and human activity since the Neolithic: Evidence from pollen and phytoliths in Hochung, Sai Kung area, Hong Kong

An excavation has revealed in Hochung, in the Sai Kung area of Hong Kong, which mainly deposited during the Middle to Late Neolithic period. Base on pollen and phytolith analysis, and combine with pervious published report reconstructed the paleoenvironmental changes around the archeological site. Results show that the settings around the Hochung site changed from river bank, lagoon to floodplain marsh and finally changed to cultivated land during Middle to Late Holocene. Evidence of pollen and phytoliths, coupled with the excavated relics, revealed that the Neolithic culture was characterized by fishing and hunting at ~4200–3500 yr BP, without evidence of rice cultivation or other agricultural activity in this area. Until the Tang and Song Dynasties, rice cultivation appeared based on pollen and phytolith assemblages, but the area of excavated site was not yet an in situ rice field. During the Ming and Qing dynasties, rice agriculture flourished, and the area turned into a local paddy field, lasting until 1960s. Meanwhile, the gradual reduction of evergreen broad-leaved trees and the increase of pioneer plants such as Dicranopteris and other secondary plants since the Tang and Song dynasties imply that the expansion of human agricultural activity caused serious damage to the natural evergreen broad-leaved forest. In the history period, the agriculture civilization has very closely relationship between the south area and the north area, especially from the Qin Dynasty to present.

模拟增温及隔离降雨对中亚热带杉木人工林土壤可溶性有机质的数量及其结构的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 模拟增温及隔离降雨对中亚热带杉木人工林土壤可溶性有机质的数量及其结构的影响 DOI: 10.5846/stxb201704250749 作者: 作者单位: 福建师范大学,福建师范大学,福建师范大学,福建师范大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然基金面上项目（31570606）；福建省自然科学基金面上项目（2015J01120） Effects of experimental soil warming and precipitation reduction on the quantity and structure of soil dissolved organic matter of Cunninghamia lanceolata plantations in subtropical China Author: Affiliation: Fujian Normal University,Fujian Normal University,Fujian Normal University, 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:温度和水分影响森林生态系统的结构与功能，而全球变暖和降雨格局的改变是未来气候变化的趋势。我国中亚热带地区森林覆盖率大，碳库丰富，可溶性有机质（DOM）作为森林生态系统的重要组成部分，气候变化对它的数量和组成具有重要的影响。本文对我国湿润亚热带地区杉木人工林土壤进行模拟增温以及隔离50%的降雨试验，利用光谱技术手段研究增温及隔离降雨对土壤可溶性有机质（DOM）的数量及其结构的影响。试验设对照（CK）、增温（W）、隔离降雨（P）、增温与隔离降雨的交互作用（WP）4种处理。结果表明，与对照相比，土壤增温后，0-10cm和10-20cm土层的土壤可溶性有机碳（DOC）和可溶性有机氮（DON）增加，但其芳香性指数和腐殖化程度降低，增温加速DOM的流失，不利于土壤有机质的稳定。季节变化影响土壤的环境，导致隔离降雨有使DOM的数量增加或减少的趋势；在旱季（2014年10月和2015年1月），隔离降雨降低了土壤DOM的数量，但其芳香性指数和腐殖化程度增加，而进入雨季（2015年4月），隔离降雨有使DOM增加的趋势，但其组分中的芳香化合物较少。增温和隔离降雨的交互作用在一定程度上促进DOM的产生，其结构比对照简单。温度和降雨对DOM的影响较为复杂，在全球气候变化背景下，只有长期对其进行观测并探讨其他因素带来的影响才能深入了解气候变暖和降雨格局的变化对土壤碳、氮的影响。 Abstract:Temperature and moisture are important to the structure and function of forest ecosystems. In future decades, global warming and variations in precipitation patterns will be the major climatic characteristics. Global warming is suggested to accelerate the decomposition of soil organic matter (SOM), and thereby to increase the carbon flux. Altered rainfall amounts might affect plant growth and soil structure. As a crucial component of forests, dissolved organic matter (DOM) plays an important role in such ecological processes. It is central to the questions of carbon decomposition/sequestration in soils and nutrient availability to microorganisms and plants. Natural evergreen broad-leaved forests make up the typical vegetation in the subtropical zone of China, but large areas of natural forests have been transformed to Cunninghamia lanceolata plantations. Therefore, it is critical that we should explore the effects of warming and precipitation variations on the dynamic changes of DOM in these plantations. In this article, we investigated the effects of simulated soil warming, 50% precipitation reduction, and the combination of the two factors on the quantity and composition of soil DOM. There were four treatments (three replicates per treatment) effects studied:(1) no warming and natural precipitation; (2) warming and natural precipitation; (3) no warming and precipitation reduction; and (4) warming and precipitation reduction. The soil samples were collected in October 2014, January 2015, and April 2015, respectively. To learn more about the relationships of DOM with temperature and moisture, we also measured the soil microbial biomass carbon and microbial biomass nitrogen. The results showed that the quantity of DOM increased after soil warming in both 0-10cm and 10-20cm soil layers. In addition, the aromaticity and humification degree of DOM decreased after warming. In our study, soil warming could accelerate the loss of DOM and restrain the stability of carbon. The impacts of the precipitation reduction treatment on DOM production showed a seasonal pattern. In particular, the quantity of DOM was reduced but its aromaticity and humification degree were enhanced in the drought season (October 2014 and January 2015), whereas in the rainy season (April 2015), the quantity of DOM had increased since the growth of microorganisms and the content of aromatic compounds were reduced simultaneously. Under the combination of warming and precipitation reduction, the quantity of DOM increased because of accelerated decomposition of SOM. Moreover, the DOM structure became simpler through the interaction of the two factors. The effects of temperature and moisture on the quantity and structure of soil DOM are sophisticated. We will continue to estimate the impacts of warming and precipitation reduction on soil microbes, organic matter, and other elements with long-term observational data to attain a more profound comprehension about carbon and nitrogen cycling under global climate change. 参考文献 相似文献 引证文献

Simulated nitrogen deposition significantly suppresses the decomposition of forest litter in a natural evergreen broad-leaved forest in the Rainy Area of Western China

Litter, an essential component of forest ecosystems, plays an important role in maintaining soil fertility, sequestering carbon (C) and improving soil biodiversity. However, litter decomposition is affected by increased nitrogen (N) deposition. Numerous reports have presented N deposition experiments in different forest ecosystems to investigate the effects of N deposition on litter decomposition, but the effects remain unclear, especially in ecosystems receiving increasingly higher levels of ambient N deposition. To address this gap, we performed a litterbag experiment to understand the effects of increasing N deposition on the litter decomposition process in natural evergreen broad-leaved forest in the Rainy Area of Western China. A 2-year field litter decomposition experiment was conducted using the litterbag method. Four levels of N deposition were established: control (CK; 0 kg·N·ha−1·year−1), low N deposition (LN; 50 kg·N·ha−1·year−1), medium N deposition (MN; 150 kg·N·ha−1·year−1), and high N deposition (HN; 300 kg·N·ha−1·year−1). The simulated N depositions ranged from 50% to 320% of the ambient rate of wet N deposition. Simulated N deposition significantly increased the remaining mass, C, N, lignin and cellulose of the litter. The LN treatment decreased the remaining phosphorus (P); conversely, the HN treatment increased it. In the late stage of the study period, the mass remaining was positively closely correlated to the lignin and cellulose remaining during the decomposition process. Simulated N deposition significantly suppressed the litter decomposition in the natural evergreen broad-leaved forest, despite the high rate of ambient N deposition, and the inhibitory effects increased with the N deposition levels. The suppressive effect of N deposition on litter decomposition may be primarily explained by the inhibition of lignin and cellulose degradation by the exogenous inorganic N. With ongoing N deposition in future, N deposition may have a potentially significant impact on C and N cycles in such forest ecosystems.

Response of carbon and nitrogen release to simulated nitrogen deposition in natural evergreen broad-leaved forests in a rainy area in Western China

Over the last several decades, human activities have increased the nitrogen input in terrestrial ecosystem, and the alteration of the N cycle has profoundly affected the cycles of many other elements, especially carbon (C). Litter decomposition is an important ecosystem process that plays a key role in the balance of global carbon and nitrogen cycles. To investigate the effects of simulated nitrogen (N) deposition on litter decomposition, a one-year field experiment on litter decomposition following N addition treatments was conducted in a natural evergreen broad-leaved forest in a rainy area of Western China. Beginning November 2013, we conducted a field experiment using the litterbag method that included four treatments: 0, 50, 150, and 300kgNhm−2a−1 as the control (CK), low (L), medium (M), and high (H) nitrogen deposition, respectively. Every 15days, NH4NO3 was added to the N-treated plots. The results indicated that after one year of decomposition, the remaining rate in each treatment was between 54.71% and 63.52%, L, M, and H rates were 4.18%, 6.53%, and 8.81% higher, respectively than the CK. N deposition significantly increased the remaining rate and inhibited the decomposition of leaf litter in this ecosystem because of the addition of N. Greater increases in N strengthened the inhibition effect. N addition significantly increased the concentration of carbon and nitrogen in leaf litter. The decomposition coefficient of C and N were in the order k(CK)>k(L)>k(M)>k(H), although N was released faster. The time for 95% C decomposition of foliar litter increased by 0.92–2.20 a from 4.09 a (T95% of CK) because of N addition, and that for N decomposition increased by 0.64–1.22 a from 3.73 a. After decomposing for 1 a, the C remaining rates for L, M, and H were 6.00%, 9.89%, and 14.11%, respectively, higher than CK, whereas the N remaining rate was 4.13%, 6.75% and 10.08%, respectively. Thus, nitrogen addition significantly increased the C and N remaining rates and significantly inhibited the release of carbon and nitrogen. The L, M, and H treatments increased the C/N ratio of the leaf litter by 3.33%, 5.40% and 6.38%, respectively, suggesting that the M and H treatments significantly increased the C/N ratio. Nitrogen treatments weakened the correlation between the mass remaining and C and N remaining, but strengthened the correlation between mass remaining and the C/N ratio. The correlation coefficient of mass remaining and C and N remaining was reduced by N deposition, whereas the C/N ratio was increased. Under simulated N deposition, C remaining was still a good indicator of litter decomposition relative to the N remaining and C/N ratio.

Impacts of human activities on species diversity, species composition and cover of pteridophytes : A comparison of natural evergreen broad-leaved forests and secondary deciduous broad-leaved forests in south Yunnan, China

Impacts of human activities on species diversity, species composition and cover of pteridophytes : A comparison of natural evergreen broad-leaved forests and secondary deciduous broad-leaved forests in south Yunnan, China

Effects of simulated nitrogen deposition on soil microbial biomass carbon and nitrogen in natural evergreen broad-leaved forest in the Rainy Area of West China

To understand the effects of increasing nitrogen deposition on soil microbial biomass carbon (MBC) and nitrogen(MBN), an in situ experiment was conducted in a natural evergreen broad-leaved forest in Ya'an City, Sichuan Province. Four levels of nitrogen deposition were set: i.e., control (CK, 0 g N·m-2·a-1), low nitrogen (L, 5 g N·m-2·a-1), medium nitrogen (M, 15 g N·m-2·a-1), and high nitrogen (H, 30 g N·m-2·a-1). The results indicated that nitrogen deposition significantly decreased MBC and MBN in the 0-10 cm soil layer, and as N de-position increased, the inhibition effect was enhanced. L and M treatments had no significant effect on MBC and MBN in the 10-20 cm soil layer, while H treatment significantly reduced. The influence of N deposition on MBC and MBN was weakened with the increase of soil depth. MBC and MBN had obvious seasonal dynamic, which were highest in autumn and lowest in summer both in the 0-10 and 10-20 cm soil layers. The fluctuation ranges of soil microbial biomass C/N were respectively 10.58-11.19 and 9.62-12.20 in the 0-10 cm and 10-20 cm soil layers, which indicated that the fungi hold advantage in the soil microbial community in this natural evergreen broad-leaved forest.

Above and below ground biomass allocation on herb layer of natural evergreen broad-leaved forest and Chinese fir plantation with different age classes.

Above and below ground biomass allocation on herb layer of natural evergreen broad-leaved forest and Chinese fir plantation with different age classes.

Effects of simulated nitrogen deposition on lignin and cellulose degradation of foliar litter in natural evergreen broad-leaved forest in Rainy Area of Western China.

In order to detect the effects of simulated nitrogen deposition on litter decomposition and degradation of lignin and cellulose, a one-year field experiment of simulated nitrogen deposition has been conducted using litter bag method from November 2013 to November 2014 in an evergreen broad-leaved forest, Rainy Area of West China. Four levels of nitrogen deposition were set, i.e., control (0 g N·m-2·a-1), low (5 g N·m-2·a-1), medium (15 g N·m-2·a-1) and high (30 g N·m-2·a-1) nitrogen deposition. The results indicated that foliar litter decomposed faster in summer, obviously faster than in the other seasons. N deposition significantly inhibited the decomposition of foliar litter in this evergreen broad-leaved forest. As N deposition increased, the inhibition effect was enhanced. The time of 95% mass loss (T95%) of foliar litter due to simulated N deposition was increased by 0.53-1.88 years compared with T95% of control (4.81 years). N deposition significantly inhibited the degradation of lignin and cellulose. The mass remaining after one year of decomposition of lignin and cellulose in the medium and high nitrogen deposition treatments were significantly higher than that in the control. There was a significant positive linear relationship among mass remaining rate and lignin and cellulose remaining rates. The inhibiting effects of inorga-nic N on degradation of lignin and cellulose explained the inhibitory effect of N on foliar litter decomposition.

Large amounts of easily decomposable carbon stored in subtropical forest subsoil are associated with r-strategy-dominated soil microbes

Subsoils store over 50% of the total soil organic carbon (SOC) in terrestrial ecosystems, but the stability of this fraction of SOC and the contributions of the associated soil microbes to C dynamics remain unclear. A natural evergreen broad-leaved forest and a Chinese fir plantation converted from natural forest in Fujian Province, China, were used to test if differences in soil C decomposability and soil microbial characteristics between topsoil (0–10 cm) and subsoil (40–60 cm) were associated with the prevalence of microbes expressing a characteristic growth strategy (r-versus K-strategies). A combined approach, including modified Michaelis-Menten kinetics, substrate-induced respiration, soil C decomposition, soil basal respiration measurements, and phospholipid fatty acid (PLFA) analysis was used. Compared with topsoil, the subsoil had 3.6 and 1.6 times higher concentrations of readily decomposable C substrate (as glucose equivalents) estimated in terms of Michaelis-Menten kinetics, and 2.7 and 2.8 times faster mineralization per unit SOC, respectively, under the natural and plantation forests. Soil microbes in the subsoil tended to be r-strategist-dominated in both forests, characterized by higher maximum rate of soil respiration and half-saturation constant, higher maximal specific growth rate, higher relative abundance of Gram-negative bacteria, and higher metabolic quotient, the latter indicating smaller C use efficiency. In contrast, soil microbes in the topsoil tended to be K-strategist-dominated. Soil microbial communities shifted from K-strategy to r-strategy in the topsoil of Chinese fir plantation, reflecting lower microbial C use efficiencies, compared with natural forest. It is concluded that a substantial pool of easily decomposable C accumulated in subsoils of these two subtropical forests, a product partly of r-strategists replacing K-strategy microbes. These findings improve our understanding of the mechanisms regulating C dynamics between topsoil and subsoil and have implications for the effects of forest conversion on soil C storage.

模拟氮沉降对华西雨屏区天然常绿阔叶林凋落叶分解过程中基质质量的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 模拟氮沉降对华西雨屏区天然常绿阔叶林凋落叶分解过程中基质质量的影响 DOI: 10.5846/stxb201601080054 作者: 作者单位: 四川农业大学,四川农业大学,四川农业大学,四川农业大学,四川农业大学,四川农业大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家“十二五”科技支撑资助项目（2010BACO1A11）；四川省“十二五”农作物育种攻关资助项目（2011NZ0098-10） Effects of simulated nitrogen deposition on the substrate quality of foliar litter in a natural evergreen broad-leaved forest in the Rainy Area of Western China Author: Affiliation: Sichuan Agricultural University,Sichuan Agricultural University,Sichuan Agricultural University,Sichuan Agricultural University,Sichuan Agricultural University,Sichuan Agricultural University 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:为理解氮沉降对华西雨屏区天然常绿阔叶林凋落物分解过程的影响，采用立地控制实验和凋落物分解袋法，研究了低氮沉降（L，50 kg N hm-2 a-1）、中氮沉降（M，150 kg N hm-2 a-1）和高氮沉降（H，300 kg N hm-2 a-1）对华西雨屏区天然常绿阔叶林凋落叶分解过程中基质质量的影响。结果表明：N沉降抑制了凋落叶的分解，并随着N沉降量的增加，抑制作用增强。N沉降遏制了凋落叶的C、N释放和纤维素降解，促进了P释放。N沉降提高了凋落叶的C/P比，中氮和高氮处理提高了凋落叶C/N比。N沉降显著增加了凋落叶N、木质素和纤维素的含量，分解1年后，各N沉降处理的木质素/N和纤维素/N均显著高于对照。N沉降提高了质量残留率与C/N、木质素/N和纤维素/N的相关性，降低了与C/P的相关性。可见，模拟N沉降显著影响了华西雨屏区天然常绿阔叶林凋落叶分解过程中的基质质量，进而影响了凋落叶的分解过程。 Abstract:Litter, an essential component of the forest ecosystem, plays an important role in maintaining site fertility, sequestering carbon, and nursing soil biodiversity. However, the substrate quality of decomposing litter is affected by increasing nitrogen deposition mainly because of fossil fuel combustion and chemical fertilizer production and use. Theoretically, decomposition of atmospheric nitrogen may have a strong impact on litter decomposition in three ways. The first approach is that nitrogen deposition may alter the chemical components of litter by direct nitrogen addition. The second approach is that nitrogen addition can change the growth of plants and carbon and nutrient allocations in plant tissues and indirectly lead to changes in litter substrate quality. The third approach is that nitrogen deposition may result in soil acidification, and, in turn, have strong effects on litter substrate quality indirectly. To date, there is limited information on the changes in litter substrate quality due to atmospheric nitrogen deposition in the Rainy Area of Western China. To understand the effects of increasing nitrogen deposition on the litter decomposition process in natural evergreen broadleaved forests in the Rainy Area of Western China, a field litter decomposition experiment was conducted in a natural evergreen broad-leaved forest in Ya'an City. Between November 2013 and November 2014, we conducted the field experiment by using the litterbag method. Four levels of nitrogen deposition were set:control (0 kg N hm-2 a-1), low nitrogen (50 kg N hm-2 a-1), medium nitrogen (150 kg N hm-2 a-1), and high nitrogen (300 kg N hm-2 a-1). The results indicated that nitrogen deposition significantly influenced litter substrate quality, and concentrations of carbon, nitrogen, and cellulose in the leaf litter were found to increase significantly with nitrogen addition. Nitrogen deposition also affected C/P and C/N of the leaf litter; all nitrogen deposition treatments significantly increased C/P, whereas medium nitrogen and high nitrogen treatments significantly increased C/N. Since nitrogen deposition significantly increased the nitrogen concentration of the litter, exacerbating the accumulation of litter lignin and cellulose, after decomposing for 1 a, lignin/N and cellulose/N after each nitrogen deposition treatment were significantly higher than those in the control. The correlation coefficient of mass remaining of foliar litter with C/N, lignin/N, and cellulose/N was increased by nitrogen deposition, while C/P was reduced. Thus, simulated nitrogen deposition influenced the substrate quality of foliar litter in natural evergreen broad-leaved forest in the Rainy Area of Western China, and influenced the decomposition process of the litter. 参考文献 相似文献 引证文献