Soil Respiration In Subtropical Forest Research Articles

Phosphorus addition enhances heterotrophic respiration but reduces root respiration in a subtropical plantation forest

Soil respiration (Rs) is a major component of the global carbon (C) cycle and is influenced by the availability of nutrients such as phosphorus (P). However, the response of Rs to P addition in P-limited subtropical forest ecosystems and the underlying mechanisms remain poorly understood. To address this, we conducted a P addition experiment (50 kg P ha−1 yr−1) in a subtropical Chinese fir (Cunninghamia lanceolata) plantation forest. We separated Rs into heterotrophic respiration (Rh), root respiration (Rr), and mycorrhizal hyphal respiration (Rm), and quantified soil properties, microbial biomass (phospholipid fatty acid, PLFA), fungal community composition (ITS), and the activity of extracellular enzymes. Phosphorus addition significantly increased Rs and Rh, but decreased Rr and did not influence Rm. Further, P addition increased fungal, bacterial, and total PLFAs, and phenol oxidase activity. Conversely, P application decreased root biomass and did not alter the relative abundance of symbiotrophic fungi. Phosphorus enrichment therefore enhances soil C emissions by promoting organic matter decomposition by heterotrophic activity, rather than via increases in root or mycorrhizal respiration. This advances our mechanistic understanding of the relationship between fertility and soil respiration in subtropical forests, with implications for predicting soil C emissions under global change.

Contrasting responses of soil fungal communities and soil respiration to the above‐ and below‐ground plant C inputs in a subtropical forest

The roles of soil fungal diversity and community composition in regulating soil respiration when above‐ and below‐ground plant carbon (C) inputs are excluded remain unclear. In the present study, we aimed to examine the following. (a) How does the exclusion of above‐ and below‐ground plant C inputs affect soil respiration and soil fungi singly and in combination? (b) Are changes in soil fungal diversity aligned with changes in soil respiration? A field experiment with manipulation of plant C inputs was established in a subtropical forest in southwest China in 2004 with litter removal and tree stem‐girdling to exclude inputs of the above‐ and below‐ground plant C, respectively. In 2009, we measured the rates of soil respiration with an infrared gas analyser and soil fungal community structure using Illumina sequencing. We found that the rates of soil respiration were reduced significantly by litter removal and girdling, by similar magnitudes. However, they were not decreased further by the combination of these two treatments compared to either treatment alone. In contrast, litter removal increased the diversity of soil fungal communities, whereas girdling decreased the abundance of symbiotrophic fungi but increased the abundance of saptrotrophic and pathotrophic fungi. These changes in soil fungal community might initiate CO2 emission from soil C decomposition, offsetting further decline in soil respiration when plant C inputs are excluded. These results revealed that the exclusion of the above‐ and below‐ground plant C inputs led to contrasting soil fungal communities but similar soil function. Our findings suggest that both above‐ and below‐ground plant C are important in regulating soil respiration in subtropical forests, by limiting substrates for soil fungal growth and altering the diversity and composition of the soil fungal community.Highlights Litter removal and girdling decreased soil respiration by similar magnitudes The combination of litter removal and girdling did not further decrease soil respiration Litter removal significantly increased species richness of soil fungal communities Girdling changed the abundance of functional guilds of soil fungal communities

Response of soil respiration to nitrogen addition in two subtropical forest types

Anthropogenic activities have increased nitrogen (N) deposition in terrestrial ecosystems, which directly and indirectly affects soil biogeochemical processes, including soil respiration. However, the effects of the increases in N availability on soil respiration are not fully understood. In this study, soil respiration was measured using an infrared gas analyzer system with soil chambers under four N treatments (0, 5, 15, and 30 g N m–2 year–1 as control, low N (LN), moderate N (MN), and high N (HN), respectively) in camphor tree and slash pine forests in subtropical China. Results showed that soil respiration rates decreased by 37% in the camphor tree forest and 27% in the slash pine forest on average on an annual base, respectively, in the N-fertilized treatments when compared with the control. No significant differences were found in the soil respiration rate among the LN, MN, and HN treatments in both forest types as these fertilized plots reached an adequate N content zone. In addition, soil microbial biomass carbon (C) content and fine root biomass declined in N-treated plots compared to the control. Our results indicated that elevated N deposition might alter the tree growth pattern, C partitioning, and microbial activity, which further affect soil C sequestration by reducing soil respiration in subtropical forests of China.

哀牢山亚热带常绿阔叶林森林土壤温湿特征及其对温度升高的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 哀牢山亚热带常绿阔叶林森林土壤温湿特征及其对温度升高的响应 DOI: 10.5846/stxb201403260562 作者: 作者单位: 中国科学院热带森林生态学重点实验室,中国科学院哀牢山生态站;中国科学院哀牢山生态站,日本国立环境研究所,日本,筑波,-,;日本国立环境研究所,日本,筑波,-,中国科学院热带森林生态学重点实验室,中国科学院哀牢山生态站;中国科学院哀牢山生态站,中国科学院热带森林生态学重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 云南省自然科学基金重点项目(2011FA025);国家基金-云南省联合项目(U1202234); 国家基金重大项目(31290220); 中国科学院战略性专项项目(XDA05050601, XDA05050206) Responses of soil temperature, moisture and respiration to experimental warming in a subtropical evergreen broad-leaved forest in Ailao Mountains, Yunnan Author: Affiliation: Xishuangbanna Tropical Botanical Garden, 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:为把握土壤温度对未来全球气候变暖的响应程度,评估气候变暖对亚热带森林土壤呼吸的影响,利用在哀牢山亚热带常绿阔叶林中设置的土壤增温和土壤呼吸人工控制实验2011-2013年的实测数据,通过分析,得到如下结果:环境温度的升高不会改变林内的近地层气温、土壤温度和土壤含水量的年变化和日变化规律;冬季和夜间增温效应大于夏季和昼间;增温会导致土壤含水量降低,雨季的效应大于干季;增温导致的升温效应和降低土壤水分效应具有一定的年变化,但是基本没有日变化;所设置的人工增温控制实验的年平均增温在2.0 ℃左右,所设置人工控制实验可以达到5 cm土壤增温2.0 ℃的设计要求,可为其后探讨土壤呼吸对温度升高的响应提供良好的基础保证. Abstract:The soil-surface carbon flux is comparable to that of photosynthesis in terrestrial ecosystems. Much soil carbon flux to the atmosphere is due to rhizosphere metabolism (root respiration) and the decomposition of soil microbes (microbial respiration), which are both very sensitive to temperature. With soil temperatures increasing, soil respiration will increase, thereby accelerating global change. To improve our understanding of the response of soil temperature to future warming and to assess the potential effects of global warming on soil respiration in subtropical forests, we experimentally warmed subtropical evergreen broad-leaved forest soils in Ailao Mountain Southwest, China and measured their respiration. This experiment was conducted at the Ailaoshan Station for Subtropical Forest Ecosystem Studies (24°32'N, 101°01'E; 2480 m above sea level) of the Chinese Ecological Research Network, Jingdong County, Yunnan Province. The annual mean air temperature was 11.0℃, with a maximum monthly mean temperature of 15.3℃ in July and a minimum monthly mean temperature of 5.1℃ in January. The site has strong rainy seasons (May to October) and dry seasons (November to April the following year). The average annual rainfall was 1882 mm, with 1607 mm (85.4% of the annual total) in the rainy season and 274.2 mm in the dry season (14.6% of the annual total). The soil is yellow brown in this area. Litterfall accumulates to 3-7 cm. Soil humus is dark brown and 10-15 cm thick. The mineral soil layer is loose and dominated by soil aggregates. Surface soils have high water permeability and water conservation ability, high organic carbon, and a pH of 4.5-5. Our artificial warming experiment was conducted in a subtropical forest where wind speed and radiation are both low at the surface. A multi-channel automated chamber system was used to continuously monitor soil CO2 effluxes. The system was comprised of 20 automatic chambers (length 90 cm × width 90 cm × height 50 cm) and a control box, and the 20 chambers were divided into 4 treatments (5 chambers per treatment): control, litter removal, trenching, and infrared light warming. The soil efflux of each chamber was measured automatically each hour and environmental factors were measured each half hour. When measuring soil efflux, the chamber was closed for 3 min, then opened for 57 min by opening its lid. Thus, environmental conditions (e.g., wind, rainfall, and litterfall) in chambers were similar to those outside. In the artificial warming experiment, variations in soil temperature and soil water content were observed along with soil respiration. Based on measurements from 2011 to 2013, we concluded that warming did not change the seasonal and diurnal patterns of air temperature near the soil surface, soil temperature, or soil water content of the forest. The warming effects in winter and nighttime were greater than in summer and daytime. Warming decreased soil water content to a larger extent in the rainy season than in the dry season. The temperature increase and soil water decrease resulting from warming had seasonal variations, but not diurnal variations. The experimental warming increased the annual soil temperature by about 2℃; therefore, the warming treatment reached the goal of increasing soil temperature at 5 cm by 2℃. Our infrared warming method achieved a relatively stable warming effect without time lags in soil-temperature variations in the primary subtropical evergreen broad-leaved forest in Ailao Mountain. In this subtropical evergreen broad-leaved forest, soil temperature has previously shown a significant warming trend, so this study can supply information about soil respiration responses. This study also showed that variation in local air temperature, soil temperature, and soil-water content will not change under global warming, but soil-water content will decline with increased temperature, especially in the rainy season. In the forest, soil respiration is affected not only by soil temperature, but also by soil water content. As warming decreases soil water content, the effects of soil water content variation on soil respiration should be examined in future research. 参考文献 相似文献 引证文献

Interactive effects of understory removal and fertilization on soil respiration in subtropical Eucalyptus plantations

It has been well recognized that understory vegetation plays an important role in driving forest ecosystem processes and functioning. In subtropical plantation forests, understory removal and fertilization have been widely applied; however, our understanding on how understory removal affects soil respiration and how the process is regulated by fertilization is limited. Here, we conducted an understory removal experiment combined with fertilization to evaluate the effects of the two forest management practices and their interactions on soil respiration in subtropical forest in southern China. The study was conducted in a split-plot design with fertilization as the whole-plot factor, understory removal as the subplot factor and block as the random factor in subtropical Eucalyptus plantations. In total, there were four treatments: control with unfertilized and intact understory (CK), understory removal but without fertilization (UR), with fertilization but without understory removal (FT) and with fertilization + understory removal (FT + UR). Eucalyptus above- and belowground biomass increment, fine root biomass, soil temperature, soil moisture and soil respiration were measured in the present study. Understory respiration (RU) was quantified in different ways: Ru = RCK − RUR or Ru = RFT − R(FT + UR); fertilization increased soil respiration (RFI) was also quantified in different ways: RFI = RFT − RCK or RFI = R(FT + UR) − RUR. Over a 2-year experiment, our data indicate that understory removal significantly decreased soil respiration, while fertilization increased soil respiration. Understory removal decreased soil respiration by 28.8% under fertilization, but only 15.2% without fertilization. Fertilization significantly increased soil respiration by 23.6% with the presence of understory vegetation, and only increased by 3.7% when understory was removed, indicating that fertilization increased soil respiration mainly by increasing the contribution of the understory. Our study advances our understanding of the interactive effects of understory management and fertilization on soil respiration in subtropical plantations.

浙江古田山亚热带常绿阔叶林不同干扰强度下土壤呼吸的日动态与季节变化

The aims of this study were to investigate the diurnal and seasonal variations in soil respiration in different broad-leaved forest types with different degrees of human disturbance, to identify the major abiotic and biotic factors affecting the daily and seasonal patterns of soil respiration, and to evaluate the effects of different forest management types and human disturbance on soil respiration in subtropical forests. We selected four different 1 hm2 forests with different degrees of human disturbance in Gutianshan, Zhejiang Province: An old-growth forest (OF, almost no human disturbance); two secondary forests (SF1, a secondary forest regrown after clear cutting about 50 years ago, and SF2, a secondary forest regrown after clear cutting about 50 years ago and selective cutting about 20 years ago); and a plantation forest (AF, planted about 20 years ago). We measured the diurnal and seasonal changes in soil respiration rates in each plot every month from May 2011 to July 2012. We also measured soil temperature and water content of the surface soil layer during sampling. The annual means of daily accumulated soil carbon release were 1.48, 1.48, 1.51, and 0.87 g C m-2 d-1 in OF, SF1, SF2, and AF plots, respectively. The soil respiration rate in AF was significantly lower than those in the other three forest types. On the diurnal scale, there were no significant variations in soil respiration rates among the four forest types. Our results indicated that the rate of soil respiration measured any time during the day can be used to predict daily accumulated soil carbon release. Significant positive relationships were found between soil respiration and surface soil temperature ( R 2=0.88-0.94) for all four forest types. There were no significant relationships between soil respiration and soil water content. The Q10 value of OF was significantly higher than those of the other three forest types. The results showed that the soil respiration rate and its sensitivity to temperature were significantly decreased in the plantation with the most intense human disturbance (AF). The soil respiration rates and Q10 values of both SF forests were similar to those of OF forest. Soil temperature was the most important driving factor for soil respiration. Together, our results implied that different degrees of human disturbance had different effects on soil respiration in these forests. This information is important to estimate the role of human interference in regional carbon cycles. Also, the finding that there was no significant variation in the diurnal soil respiration rates is very important for guiding further research on soil respiration in related regions.

Temporal and spatial patterns of soil respiration in subtropical forests of eastern China

Aims Soil respiration shows spatio-temporal differences at all scales because it is affected by diverse abiotic and biotic factors.Our objectives were to understand the seasonal dynamics and regional patterns of soil respiration in subtropical forests of eastern China and explore the possible underlying reasons.Methods We examined seasonal variations of soil respiration using a LI-8100 Soil Respiration System in 8 sub-tropical forests,belonging to three regions of eastern China,from August 2009 to October 2010.Soil temperatures at 5 cm depth were measured at the same time.We evaluated apparent Q10 values and annual CO2 efflux from soil to atmosphere at each site using the exponential relationship between soil respiration and soil temperature.Important findings Seasonal differences in soil respiration appeared at all sites,ranging from 2.64 to 6.24 μmol CO2·m-2·s-1.Soil respiration was higher in summer and lower in winter,following the seasonal dynamic of soil temperature.Soil temperature can explain 58.3%-90.2% of the variance of soil respiration for the year.Annual Q10 values from different sites ranged from 1.56 to 3.27.Annual soil CO2 efflux ranged from 1 077 to 2 058 g C·m-2·a-1 among all research sites in 2010,a high level of ecosystem CO2 efflux at the global scale.

Effects of forest type, stand age, and altitude on soil respiration in subtropical forests of China

An automated chamber system was used to study how soil respiration (R S) differed with stand age (SA), altitude (AL), and forest type (FT), in subtropical China. From 2006 to 2008, measurements of soil-surface CO2 efflux and associated environmental factors were made in an evergreen broad-leaved forest (EB), and five aged Chinese fir [Cunninghamia lanceolata Hook.] plantations (CF), and three altitudinal Moso bamboo [Phyllostachys pubescens Mazel ex J. Houz.] plantations (MB), in Dagangshan mountain range, Jiangxi Province. Multivariate analysis of covariance with soil temperature (T) and soil water content (SWC) as the covariates showed that FT and AL as the independent factors had a significant effect on R S (P<0.01, P<0.05, respectively). The R S in the CF differed significantly from EB and MB (P<0.001), but not between EB and MB. The R S was positively correlated with T, and responded to changes in SWC at higher Ts. The correlation between R S and SWC was improved when the R S was normalized to 10°C. Annual mean R S differed significantly with SA and were ranked in the order (from high to low) of 21–25, 26–35, 11–20, >36, and 1–10 years. The conclusion of this study is that T, SWC, AL, FT, and SA all have significant effects on R s in subtropical China.