Impact of forestry operations on forest soil respiration depending on stands features in Kastamonu, Turkiye

PDF HTML阅读 XML下载 导出引用 引用提醒 塔克拉玛干沙漠腹地冬季土壤呼吸及其驱动因子 DOI: 10.5846/stxb201404220795 作者: 作者单位: 1.新疆大学 资源与环境科学学院 新疆 乌鲁木齐 830046;2.中国气象局乌鲁木齐沙漠气象研究所 新疆 乌鲁木齐 830002;3.塔克拉玛干沙漠大气环境观测试验站, 新疆 塔中 841000;,2.中国气象局乌鲁木齐沙漠气象研究所, 新疆 乌鲁木齐 830002;3.塔克拉玛干沙漠大气环境观测试验站, 新疆 塔中 841000; 4.南京信息工程大学 应用气象学院, 江苏 南京 210044,2.中国气象局乌鲁木齐沙漠气象研究所, 新疆 乌鲁木齐 830002; 3.塔克拉玛干沙漠大气环境观测试验站, 新疆 塔中 841000,2.中国气象局乌鲁木齐沙漠气象研究所, 新疆 乌鲁木齐 830002; 3.塔克拉玛干沙漠大气环境观测试验站, 新疆 塔中 841000,2.中国气象局乌鲁木齐沙漠气象研究所, 新疆 乌鲁木齐 830002; 3.塔克拉玛干沙漠大气环境观测试验站, 新疆 塔中 841000 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金(41175140);公益性行业(气象)科研专项(GYHY201306066) Environmental factors driving winter soil respiration in the hinterland of the Taklimakan Desert, China Author: Affiliation: 1.College of Resources and Environmental Science, Xinjiang University, Urumqi 830046, China.2. Institute of Desert Meteorology, China Meteorological Administration, Urumqi 830002, China;3.Taklimakan Desert Atmosphere and Environment Station, Tazhong 841000, Xinjiang, China.,2.Institute of Desert Meteorology, China Meteorological Administration, Urumqi 830002, China; 3.Taklimakan Desert Atmosphere and Environment Station, Tazhong 841000, Xinjiang, China; 4. College of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing, Jiangsu 210044,China,2. Institute of Desert Meteorology, China Meteorological Administration, Urumqi 830002, China;3Taklimakan Desert Atmosphere and Environment Station, Tazhong 841000, Xinjiang, China,, 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:利用Li-8150系统测定了塔克拉玛干沙漠腹地冬季(1月)土壤呼吸,分析了环境驱动因子对极端干旱区荒漠生态系统土壤呼吸的影响。结果表明:(1)冬季土壤呼吸日变化呈现出显著的单峰曲线,土壤呼吸速率最大值出现在12:00,为0.0684μmol CO2 m-2 s-1,凌晨04:00附近出现最小值,为-0.0473μmol CO2 m-2 s-1;(2)土壤呼吸速率与各层气温,0cm地表温度均存在着极其显著或显著的线性关系,且都具有正相关性;(3)土壤呼吸速率与5cm土壤湿度存在着较为明显的线性关系,该层湿度能够解释土壤呼吸的69.5%;(4)0cm地表温度对土壤呼吸贡献最大,其次是5cm土壤湿度;(5)以0cm地表温度、5cm土壤湿度为变量,通过多元回归分析表明:土壤温度-湿度构成的多变量模型能够解释大于86.9%的土壤呼吸变化情况;(6)研究时段内土壤呼吸速率的平均值是-1.45mg CO2 m-2 h-1。 Abstract:In order to analyze the environmental drivers of soil respiration in an extreme arid desert ecosystem, we measured diurnal variation in winter soil respiration at Tazhong, a hinterland of Taklimakan Desert in northwest China. Regression analysis was performed with SPSS 21.0. We observed that:(1) Diurnal variation in winter soil respiration showed a single peak at 12:00 noon (local time), after which soil respiration began to decrease, reaching a minimum value at around 4:00 a.m. (2) Soil respiration and the air temperature at each height tested (0.5 m, 2 m) were significantly and positively correlated. Air temperature at 2 m was able to explain 67.8% of the diurnal variation in soil respiration. (3) Soil temperature at 0 cm, modeled by linear equations, was able to explain 86.3% of the diurnal variation in soil respiration, demonstrating that this process is more sensitive to temperature at 0 cm than at any other soil layer (10 cm, 20 cm, 40 cm). (4) Soil respiration exhibited a positive linear correlation with soil moisture at a depth of 5 cm. When linear regression analysis was used to model the relationship between these variables, the fitted linear model explained 69.5% of the diurnal variation in soil respiration, demonstrating that, in the extreme arid desert ecosystem, this shallow layer of moisture exerts a large effect on soil respiration. (5) The greatest contributors to soil respiration were soil temperature at a depth of 0 cm, followed by soil moisture at 5 cm. (6) Multiple regression analyses showed that a multi-variable model of temperature and soil moisture explains 86.9% of the diurnal variation in soil respiration, which is not significantly better than a single-variable model. (7) For winter soil respiration, the daily average rate of CO2 absorption was -1.45mg CO2 m-2 h-1. 参考文献 相似文献 引证文献

Background and aimsSoil respiration is the second‐largest terrestrial carbon (C) flux, and soil temperature and soil moisture are the main drivers of temporal variation in soil respiration and its components. Here, we quantified the contribution of soil temperature, soil moisture, and their intersection on the variation in soil respiration and its components of the evergreen broad‐leaved forests (EBF), mixed evergreen and deciduous broad‐leaved forests (MF), deciduous broad‐leaved forests (DBF), and subalpine coniferous forests (CF) along an elevation gradient.MethodsWe measured soil respiration of four types of forests along the elevation gradient in Shennongjia, Hubei China based on the trenching experiments. We parameterized the relationships between soil respiration and soil temperature, soil moisture, and quantified the intersection of temperature and moisture on soil respiration and its components.ResultsTotal soil respiration (R S), heterotrophic respiration (R H), and autotrophic respiration (R A) were significantly correlated with soil temperature in all four forests. The Q 10 value of soil respiration significantly differed among the four types of forest, and the Q 10 was 3.06 for EBF, 3.75 for MF, 4.05 for DBF, and 4.49 for CF, respectively. The soil temperature explained 62%–81% of the variation in respiration, while soil temperature and soil moisture together explained 91%–97% of soil respiration variation for the four types of forests. The variation from the intersection of soil temperature and moisture were 12.1%–25.0% in RS, 1.0%–7.0% in R H, and 17.1%–19.6% in R A, respectively.ConclusionsOur results show that the temperature sensitivity (Q 10) of soil respiration increased with elevation. The intersection between soil temperature and soil moisture had strong effects on soil respiration, especially in R H. We demonstrated that the intersection effects between soil temperature and soil moisture on soil respiration were essential to understand the response of soil respiration and its components to climate change.

Variation of soil respiration at three spatial scales: Components within measurements, intra-site variation and patterns on the landscape

Warming and straw application increased soil respiration during the different growing seasons by changing crop biomass and leaf area index in a winter wheat-soybean rotation cropland

Investigating the seasonal variations in soil respiration in different crop fields and their relationships with crop productivity is crucial to understanding the key biotic controls of soil respiration. A field experiment was performed during the 2020‒2021 winter wheat‒soybean, canola‒maize and broad bean‒sweet potato growing seasons. The seasonal variations in soil respiration, soil temperature and moisture were measured. The variables that were associated with crop productivity were also determined. The results showed that crop types significantly (p < .05) affected the mean seasonal soil respiration. Most variables that were associated with crop productivity exhibited obvious seasonal variation patterns. The soil temperature, moisture and crop productivity comprehensively influenced the soil respiration, and models based on these potential controlling factors explained 45.7%‒59.2% (R 2 = 0.457‒0.592) of the variation in soil respiration in the different crop rotation fields. A model based on the mean seasonal soil temperature, moisture, leaf area index, and root carbon content explained 68.3% (R 2 = 0.683) of the variation in the mean seasonal soil respiration across the different crop fields. We demonstrated the potential of effectively characterizing the variations in soil respiration in agroecosystems using temperature, moisture and crop productivity.

Soil respiration is an important component of the annual carbon balance of forests, but few studies have addressed interannual variation in soil respiration. The objectives of this study were to investigate the seasonal and interannual variation in soil respiration, temperature, precipitation, and soil water content in two New England forest soils and to develop and evaluate empirical models for predicting variations in soil respiration using temperature and soil moisture content. We have been measuring soil respiration, using dynamic chambers in well‐drained upland sites and poorly drained wetland sites since 1995 at the Harvard Forest, Massachusetts, and since 1996 at the Howland Forest, Maine. The upland sites had consistently greater rates of respiration than wetlands. Prolonged drought periods in 1995, 1998, and 1999 at the Harvard Forest resulted in decreased soil respiration rates in the uplands, particularly once soil moisture contents decreased below about −150 kPa. In contrast, wetland respiration increased upon drying. The interannual variation in soil respiration at the Harvard Forest, 0.23 kg C m−2 yr−1, exceeds the interannual variation in net ecosystem exchange (NEE), 0.14 kg C m−2 yr−1 previously measured for this forest, indicating that interannual variation in soil respiration can have an important influence on NEE. Interannual variation was lower at the Howland Forest, and the effects of low soil moisture content on respiration rates were more subtle. The onset of spring was variable among years at both forests, owing to variation in both temperature and precipitation, and contributed to 33–59% of the annual variability in total carbon release. At the upland sites, parameterization of empirical regression models for respiration as a function of soil temperature was inconsistent among years, indicating an important effect of interannual variation in soil water content. The negative residuals of the Harvard Forest temperature regression model were best explained by drought conditions (soil matric potentials ≤−150 kPa). This function was only applicable during severe drought and did not account for less severe dry periods that also reduced soil moisture and soil respiration. An empirical regression model for the wetlands as a function of temperature was significantly improved with the addition of a soil moisture function, which increased respiration rates under dry conditions and decreased it under wet conditions. Climatic changes resulting in drier conditions will likely decrease soil respiration rates in uplands and increase soil respiration in wetlands.

PDF HTML阅读 XML下载 导出引用 引用提醒 旱作农田不同耕作土壤呼吸及其对水热因子的响应 DOI: 10.5846/stxb201110071460 作者: 作者单位: 中国农业科学院农业资源与农业区划研究所;北京京诚嘉宇环境科技有限公司,中国农业科学院农业资源与农业区划研究所,中国农业科学院农业资源与农业区划研究所,中国农业科学院农业资源与农业区划研究所,中国农业科学院农业资源与农业区划研究所,中国农业科学院农业资源与农业区划研究所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点基础研究发展"973"计划项目(2011CB100501);国家十二五"863"计划项目(2011AA100505);国际合作项目(2010DFA34420) Soil respiration and its responses to soil moisture and temperature under different tillage systems in dryland maize fields Author: Affiliation: Institute of Agricultural Resources and Regional Planning,CAAS,Institute of Agricultural Resources and Regional Planning,CAAS,Institute of Agricultural Resources and Regional Planning,CAAS,Institute of Agricultural Resources and Regional Planning,CAAS,Institute of Agricultural Resources and Regional Planning,CAAS,Institute of Agricultural Resources and Regional Planning,CAAS 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:为研究旱作农田春玉米生育期不同耕作土壤呼吸变化特征及其对水热因子的响应情况,在山西省寿阳县旱农试验基地采用红外气体分析法测定了传统耕作(CT)、少耕(RT)和免耕(NT)土壤呼吸速率,并同步测定了各土层土壤水分、温度。研究表明:在春玉米生育期内,土壤呼吸速率均呈单峰型变化趋势,峰值出现在8月;传统耕作与少耕土壤呼吸速率变化趋势基本一致,而免耕土壤与前两者相比波动幅度较大;土壤呼吸峰值与水分、温度之间无明显相关,其余时期土壤呼吸与水分、温度因子具有良好的相关性;双因子模型较单因子模型能更好的描述土壤呼吸与水分、温度之间关系,基于水热双因子(10-20 cm)的指数-幂模型能够解释土壤呼吸变化的81%-87%(P<0.01);3种耕作土壤呼吸对水热因子协同影响的敏感性表现为CT>NT>RT。 Abstract:Soil respiration and its responses to soil moisture and soil temperature under different tillage systems during the period of spring maize growth were investigated in Shouyang Dryland Farming Experimental Station, Shanxi Province, China. The soil respiration rate, soil moisture and soil temperature were determined by dynamic chamber-IRGA method, in the maize field, with three tillage practices, including conventional (CT), reduced (RT), and no-till (NT). The results showed that the changes in soil respiration rates had a single peak curve, and its peak appeared in August The seasonal variations in soil respiration rates under CT, RT and NT were 0.50-4.81, 1.11-5.44 and 0.40-5.89 μmol CO2 m-2·s-1, respectively. The trends in soil respiration between CT and RT were similar, while there was a larger fluctuation in soil respiration with NT. The regression analysis showed that soil respiration had a significant correction with soil moisture or temperature, but little at the peak values of soil respiration. Soil moisture (0-10 cm) could explain 57%-76% of seasonal variations in the soil respiration. The moisture sensitivities of soil respiration were NT>RT>CT. Soil temperature (15 cm) could explain 67%-82% of seasonal variations in the soil respiration. the Q10 was NT (2.47)>RT (2.02)>CT (1.59). The two-factor model y=aebTWc or y=a+bT+cW could better describe the relationship between soil respiration and combination of soil moisture and temperature than the one-factor model. The index-power model of combination of soil moisture and temperature (10-20 cm) y=aebTWc can explain 81%-87% of variations in soil respiration (P<0.01). The sensitivities of three tillage treatments to the combination of soil moisture and temperature were: RT>CT>NT. Soil respiration was affected differently by the hydrothermic factor or by each of the single factor. 参考文献 相似文献 引证文献

PDF HTML阅读 XML下载 导出引用 引用提醒 马尾松林土壤呼吸组分对不同营林措施的响应 DOI: 10.5846/stxb201503020398 作者: 作者单位: 中国林业科学研究院森林生态环境与保护研究所 国家林业局森林生态环境重点实验室,中国林业科学研究院森林生态环境与保护研究所 国家林业局森林生态环境重点实验室,中国林业科学研究院森林生态环境与保护研究所 国家林业局森林生态环境重点实验室,中国林业科学研究院森林生态环境与保护研究所 国家林业局森林生态环境重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 中央级公益性科研院所基本科研业务费专项（CAFRIFEEP201101）；林业公益性行业科研专项（201104008） Responses of soil respiration and its components to forest management in Pinus massoniana stands Author: Affiliation: Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, State Forestry Administration Key Laboratory of Forest Ecology and Environment;National Forest Ecosystem Station of Three Gorges Reservoir in Zigui County,,Research Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, State Forestry Administration Key Laboratory of Forest Ecology and Environment;National Forest Ecosystem Station of Three Gorges Reservoir in Zigui County, 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:针对不同营林措施（对照、除灌、采伐1（15%）、采伐2（70%）后的三峡库区马尾松飞播林，采用LI-8100对其土壤呼吸组分的呼吸速率和土壤温度、湿度进行为期1年的连续观测分析表明，不同营林措施对土壤呼吸组分的影响不同。1）观测期内，各营林措施下凋落物层呼吸速率差异并不显著，对照、除灌、采伐1、采伐2的根呼吸速率均值分别为：1.00、0.83、0.86、1.11μmolCO2m-2s-1；采伐处理下矿质土壤呼吸显著高于对照和除灌（P<0.05）；2）与对照相比，营林措施并未显著改变凋落物呼吸对于土壤总呼吸的贡献率（18.78%-23.70%），但降低了根呼吸的贡献率，其中以采伐1最为显著（P<0.05）；除灌的矿质土壤呼吸贡献率（37.00%）与对照（38.32%）相近，而采伐1（45.63%）和采伐2（43.07%）均显著增加了矿质土壤呼吸的贡献率，矿质土壤呼吸的变化是造成采伐措施下土壤呼吸变化的主要土壤呼吸组分；3）营林后仅采伐2措施下土壤温湿度显著高于对照，土壤温湿度双因子模型较单因子模型能更好的解释土壤呼吸组分变化，但仅能解释其部分变化（4.6%-59.3%），仍需对营林后其他相关因子进行深入的综合研究。 Abstract:Forest soils play a critical role in the carbon cycle and carbon sequestration at both global and local scales, and forest management practices (e.g., harvesting, burning, and thinning) influence soil carbon processes by altering organic matter quality and quantity, key microclimatic conditions, microbial communities, and other factors. However, the effects of forest management on soil carbon effluxes in different ecosystems are still largely unknown, despite being critical to estimate global carbon fluxes. Quantifying the responses of soil respiration and its components to forest management is vital to accurately evaluate forest carbon balance. Thus, an aerially seeded Pinus massoniana forest was chosen in the Three Gorges reservoir area to evaluate the effects on soil respiration of different forest management practices (i.e., control; shrub-cutting:harvesting all shrubs and removing all harvest residues. Harvest strategy 1%-15% harvest intensity and removing main harvest residues without leaves and small branches; Harvest strategy 2%-70% harvest intensity and the same harvest residue management as that in harvest 1). All experimental treatments were located in similar habitats and consisted of three 20 m×20 m plots. The treatments were conducted in October 2013. A combination of trenching and litter removing methods were employed in order to partition soil respiration into components of litter layer respiration, root respiration, and mineral soil respiration. The soil temperature, soil moisture, and rate of soil respiration and its components were observed continuously for one year (from November 2013 to October 2014) using a Li-8100 system. Management did not affect litter layer respiration within the measuring period. Root respiration in the control, shrub-cutting, harvest strategy 1, and harvest strategy 2 treatments were 1.00, 0.83, 0.86, and 1.11 μmol CO2 m-2 s-1, respectively. The mineral soil respiration of harvested stands was significantly higher than that of control and shrub-cutting stands (P < 0.05). The proportion of litter layer respiration to total respiration was not significantly influenced by forest management (18.78%-23.70%), but the contribution of root respiration to total respiration was reduced, especially in the harvest strategy 1 treatment (P < 0.05). The contribution of mineral respiration to total respiration significantly increased in harvested stands, which was mainly attributed to the decrease in total soil respiration. Management effects on soil temperature and soil moisture were only observed in the stands of harvest strategy 2. A two-factor model that included soil temperature and moisture better explained the variations in soil respiration (4.6%-59.3%) than that by a model using temperature (4.2%-59.1%) or moisture (0.3%-23.5%) alone. Other factors that influence soil respiration and its components need to be further elucidated. 参考文献 相似文献 引证文献

Background and Aims An understanding of spatial variation in soil respiration is critical to determining the carbon balance in grapevines. The effect of soil water content on soil respiration during different phenological stages in two grapevine cultivars, Grenache and Tempranillo, was studied over two seasons (2013 and 2014). Methods and Results Soil respiration was measured from five locations confined to within and between rows of vines at five phenological stages between budburst and postharvest under irrigated and non-irrigated conditions. Vine phenology influenced the in-row soil CO2 efflux to a greater extent than the between-row CO2 efflux, while irrigation resulted in in-row soil respiration 65% higher than that of the between-row positions. In contrast, the flux from the in-row positions of the non-irrigated treatment was only 25% higher than that of the between-row positions. Soil moisture and vine phenological stages appeared to have a greater influence on soil respiration than soil temperature. Conclusions Significant correlations existed among soil respiration, irrigation and the vine phenological stages. Soil respiration increased from budburst to pea-size berry stage; thereafter, it decreased until the ripening stage before increasing again during the postharvest stage. Significance of the Study The study showed that soil water availability and vine phenology play an important role in influencing soil respiration under field conditions.

Many cities are currently interested in becoming climate-neutral (European Commission 2022), which has increased the need to understand the biogenic carbon cycle in urban areas; a topic still lacking a comprehensive, measurement-based understanding. Soil respiration, i.e. the biogenic carbon flux through soil surface as a result of belowground plant and microbial activity, is a key part of the carbon cycle (Ryan and Law 2005). Its magnitude is principally regulated by soil temperature, soil moisture, soil microbial community, and decomposable substrate availability, as well as the dominant vegetation and its metabolism. Microclimatic variability is likely to induce fine-scale spatial variation in soil respiration through various pathways, as all of these drivers are either part of the naturally varying microclimate (soil moisture, soil temperature), or subjected to it (substrate availability, plant and microbial communities and their metabolism) (Bramer et al. 2018). To study the connection of microclimate and soil respiration especially in urban areas, we performed a field measurement campaign over two consecutive growing seasons (2023-2024) in Kumpula botanic garden in Helsinki, Finland. A network of 46 microclimate stations was established to continuously measure soil moisture, soil temperature, and near-surface air temperature in high temporal resolution and dense spatial coverage across the garden. Manual chamber measurements of soil respiration were conducted bi-monthly in June-August at 33 measurement points divided between six measurement sites within the garden, together with manual measurements of soil moisture and temperature. The soil respiration measurement sites were situated under tree canopies: three sites under conifers and three sites under broadleaved trees. Stand characteristics were inventoried at all sites, and soil organic carbon and nitrogen contents were determined from soil samples. We aimed to quantify: how much of the observed variation in soil respiration was attributed to variation in soil temperature and soil moisture and how large the role of the site-specific soil and stand characteristics was. how much of the observed variation in soil respiration was attributed to variation in soil temperature and soil moisture and how large the role of the site-specific soil and stand characteristics was. Based on this, we estimate whether the microclimatic data collected by the logger network could be utilised for reliable spatial upscaling of the manual soil respiration measurements to cover the entire garden area. Overall, our results shed light on urban soil respiration characteristics and help in establishing a more comprehensive understanding of the biogenic carbon cycle in urban green space.

Soil respiration releases a major carbon flux back to atmosphere and thus plays an important role in global carbon cycling. Soil respiration is well known for its significant spatial variation in terrestrial ecosystems, especially in fragile ecosystems of arid land, where vegetation is distributed sparsely and the climate changes dramatically. In this study, soil respiration in three typical arid ecosystems: desert ecosystem (DE), desert-farmland transition ecosystem (TE) and farmland ecosystem (FE) in an arid area of northwestern China were studied for their spatial variations in 2012 and 2013. Along with soil respiration (SR), soil surface temperature (ST), soil moisture (SM) and soil electrical conductivity (ECb) were also recorded to investigate the spatial variations and the correlations among them. The results revealed that averaged soil respiration rate was much lower in DE than those in TE and FE. No single factor could adequately explain the variation of soil respiration, except a negative relationship between soil temperature and soil respiration in FE (P < 0.05). Geostatistical analysis showed that the spatial heterogeneity of soil respiration in DE was insignificant but notably in both TE and FE, especially in FE, which was mainly attributed to the different vegetation or soil moisture characteristics in the three ecosystems. The results obtained in this study will help to provide a better understanding on spatial variations of soil respiration and soil properties in arid ecosystems and also on macroscale carbon cycling evaluations.

Examining the relationship between seasonal variations in soil respiration and abiotic factors and vegetation indexes is crucial for modeling soil respiration using upscaled remote sensing satellite data. A field experiment including control (CK), warming (WA), straw application (SA), and warming and straw application (WASA) treatments was performed in a winter wheat-soybean rotation cropland on the north shore of the lower reaches of the Yangtze River. Soil respiration, abiotic factors, crop hyperspectral vegetation indexes, leaf area index (LAI), and chlorophyll content (represented as the SPAD value) were measured during the 2018-2020 rotation growing seasons. The results indicated that the mean annual soil respiration was 2.27 ± 0.04, 3.08 ± 0.06, 3.64 ± 0.08, and 3.95 ± 0.20 μmol m-2 s-1 in the CK, WA, SA, and WASA plots, respectively, during the 2-year experimental period. Soil respiration was significantly (P < 0.05) correlated with soil temperature, soil moisture, hyperspectral vegetation indexes, LAI, and SPAD value in all plots. Models that included temperature, moisture, hyperspectral vegetation indexes, LAI, and SPAD value explained 50.5-74.7% of the seasonal variation in soil respiration in the CK, WA, SA, and WASA plots during the 2-year experimental period. A model including the seasonal mean NDVI, DVI, EVI, PRI, and LAI explained 72.4% of the interseasonal and intertreatment variations in seasonal mean soil respiration in the different plots across the four different crop-growing seasons. Our study indicated the potential applicability of hyperspectral vegetation indexes, LAI, and SPAD value to the estimation of soil respiration at a regional scale.

Soil respiration is a key component of the global carbon cycle, and even small changes in soil respiration rates could result in significant changes in atmospheric CO2 levels. The conversion of tropical forests to rubber plantations in SE Asia is increasingly common, and there is a need to understand the impacts of this land-use change on soil respiration in order to revise CO2 budget calculations. This study focused on the spatial variability of soil respiration along a slope in a natural tropical rainforest and a terraced rubber plantation in Xishuangbanna, Southwest (SW) China. In each land-use type, we inserted 105 collars for soil respiration measurements. Research was conducted over one year in Xishuangbanna during May, June, July and October 2015 (wet season) and January and March 2016 (dry season). The mean annual soil respiration rate was 30% higher in natural forest than in rubber plantation and mean fluxes in the wet and dry season were 15.1 and 9.5 Mg C ha-1 yr-1 in natural forest and 11.7 and 5.7 Mg C ha-1 yr-1 in rubber plantation. Using a linear mixed effects model to assess the effect of changes in soil temperature and moisture on soil respiration, we found that soil temperature was the main driver of variation in soil respiration, explaining 48% of its seasonal variation in rubber plantation and 30% in natural forest. After including soil moisture, the model explained 70% of the variation in soil respiration in natural forest and 76% in rubber plantation. In the natural forest slope position had a significant effect on soil respiration, and soil temperature and soil moisture gradients only partly explained this correlation. In contrast, soil respiration in rubber plantation was not affected by slope position, which may be due to the terrace structure that resulted in more homogeneous environmental conditions along the slope. Further research is needed to determine whether or not these findings hold true at a landscape level.

Biotic and abiotic factors controlling the spatial and temporal variation of soil respiration in an agricultural ecosystem

Soil moisture and salinity as main drivers of soil respiration across natural xeromorphic vegetation and agricultural lands in an arid desert region