Higher Soil Water Content Research Articles

Changes in soil N2O and CH4 emissions and related microbial functional groups in an artificial CO2 gassing experiment

Potential CO2 leakage is a major concern for carbon capture and storage (CCS). The effects of high soil CO2 concentration on microbes is a major element of impact assessments of CO2 leakage on terrestrial ecosystems. We conducted a field experiment to investigate the responses of microbial functional groups of ammonia-oxidizers, methanogens, and methanotrophs in high soil CO2 conditions. A single-point injection gassing plot (2.5 m × 2.5 m in size), which had 52.2% CO2 in the center (radius = 0.5 m) and 5.5% in the edge (radius = 1.7 m) at 10 cm depth, was employed. N2O and CH4 emissions increased after 1 day of injection because injected CO2 was instantly utilized by nitrifiers and methanogens. This suggests that the activities of the selected microbes could be stimulated by high soil CO2 concentrations. Prolonged CO2 injection has toxic effects on aerobic nitrifiers, but may favor anaerobic methanogens. However, the early stimulatory effects of high soil CO2 on N2O and CH4 production did not last to the end of injection. These results imply that increased N2O and CH4 emissions could be the minor side effects of high soil CO2. Microbes responded faster than plants to high soil CO2, with responses observed as late as 7 days after injection. The inhibition of plant absorption of soil water and nutrients by high soil CO2 concentrations may also influence microbial responses. Moreover, high soil water content could retard underground CO2 diffusion, which would magnify CO2 impacts on plants and microbes. Our results suggest that microbial response could be used as an early indicator of the impact assessments of CO2 leakage on soil ecosystems. An understanding of the interaction among soils, plants, and microbes would be helpful in assessing the biological risks of potential CO2 leakage.

Canopy transpiration and its cooling effect of three urban tree species in a subtropical city- Guangzhou, China

Quantitative evaluation of canopy transpiration and its cooling effect can contribute to the selection of suitable tree species to alleviate heat island effect in urban area. To achieve this aim, we investigated the canopy transpiration and its cooling effect of three common urban tree species (Schima superba, Eucalyptus citriodora and Acacia auriculaeformis) in a subtropical city (Guangzhou) based on continuous sap flow measurement as well as environmental factors monitoring. The interspecific differences in biological attributes that impact tree transpiration and then the cooling effects were further studied. Results indicated that the strongest canopy transpiration and its cooling effect of three species were observed in the summer along with favorable environmental factors (higher soil water content (SWC)11SWC: Soil water content; PAR: photosynthetically active radiation; VPD: vapour pressure deficit; EL: canopy transpiration and photosynthetically active radiation (PAR)). Furthermore, significant interspecific differences in cooling effect of transpiration were found in our study, S. superba has the highest canopy transpiration cooling effect among three species due to its favorable bio- and hydraulic characteristics. These findings will help to promote the ecological benefits of urban forests by efficient management practices to a certain extent.

Geophysical imaging of regolith in landscapes along a climate and vegetation gradient in the Chilean coastal cordillera

Many studies have recently shown the potential of geophysical tools in bridging the information gap between individual point-scale measurements. Here, we upscale and extend the point-scale layering information from pedons (excavated pit of 1 m2) using geophysical methods. We applied multi-frequency ground-penetrating radar (GPR) in four study areas in the extreme climate and vegetation gradient of the Chilean Coastal Cordillera. The main goals of this study were to understand how granitic based regolith material varies depending on climate, vegetation cover, aspect, and topography.GPR was successfully used in all four study areas. Reflections, which were imaged up to a depth of 8 m, could be associated with boundaries visible in the pedons. The main recognizable reflections were linked with the interface between the mobile soil and the immobile saprolite. This boundary is characterized by hyperbolic-shape features, probably connected to heterogeneities (e.g. pebbles). A deeper GPR penetration depth in south-facing hillslopes was observed than in north-facing hillslopes. This is probably due to less sun exposure in the south facing slopes, which results in higher soil water content and denser plant growth, facilitating weathering processes. Furthermore, thicker layers in the GPR profiles are visible going from north to south along the latitude. Most of these observations were in agreement with the soil pedons.These results demonstrate the utility of the GPR technique for characterizing subsurface variations in regolith properties (e.g. thickness, boundaries). Additional soil pedons should be excavated based on GPR results. Applying noninvasive geophysical methods could improve the understanding of the interactions between soil formation, vegetation, and other environmental parameters.

Relationship between root distribution characteristics of Mongolian pine and the soil water content and groundwater table in Horqin Sandy Land, China

Affected by soil moisture and groundwater table, Mongolian pine roots displayed an hourglass-type distribution characteristic, the high roots density distributed in the shallow and deep layers on sand soil. Mongolian pine (Pinussylvestris var.mongolica) is widely planted in arid and semiarid sandy land and serves as an important wind control and sand fixation species. In order to understand the effects of soil moisture and groundwater table on root distribution characteristics of Mongolian pine, we examined root distribution characteristics and determined the soil moisture and groundwater table under Mongolian pine plantations. The results indicated that the vertical distribution of Mongolian pine roots displayed an hourglass-type characteristic that indicated high density in the shallow (5–35 cm) and deep (85–145 cm) layers, but a low density in the middle layer (35–85 cm). Fine roots, which have a strong relationship with water utilization, displayed typical hourglass-type distribution characteristics. The proportion of fine roots in shallow soil layers (5–35 cm), middle layers (35–85 cm) and deep layers (85–145 cm) was 44.67%, 11.8% and 43.53%, respectively. Corresponding to root distribution characteristic, the shallow (0–40 cm) layer and the deep (90–150 cm) layer have a high soil water content than the middle layer. From May to October, the depth of groundwater table in the Mongolian pine plantation showed an increasing trend, from 185 to 291 cm, and the average groundwater table depth was 251 cm. The average height of capillary fringe above the groundwater table was 75.27 cm. Rainfall and groundwater have effects on the soil water content in a Mongolian pine plantation, and that determines the root distribution characteristics of Mongolian pine. The deep root system of Mongolian pine was effectively supplemented by groundwater, which is a necessary condition to maintain Mongolian pine survival and growth in the western Horqin Sandy Land.

Wheat drought-tolerance to enhance food security in Tunisia, birthplace of the Arab Spring

Abstract The beginning of the ‘Arab Spring’ in 2011, a regional revolution which started in the Tunisian city of Sidi Bouzid in late 2010, occurred in part as a result of drought-triggered high wheat prices, which in the past led to ‘bread riots’ across several Middle East and North Africa (MENA) nations. Here we present, for the first time, an analysis of possible amelioration of wheat yield loss and greater stability in bread supply resulting from the incorporation of putative drought-tolerant traits into wheat cultivars grown in Tunisia. To this end, we used a simulation crop modeling approach using SSM-Wheat to evaluate yield loss or gain resulting from three types of water-saving traits that have been recently identified in wheat. These consisted in partial stomatal closure at high soil water content, overall decrease in transpiration rate (TR), and partial stomatal closure under elevated vapor pressure deficit (VPD). To capture large gradients in seasonal precipitation across wheat growing areas over a small country such as Tunisia, a grid pattern of 29 × 29 km was established as a basis for the geospatial simulation. Surprisingly, the simulation reflected opposite strategies in terms of water use (water-saving vs aggressive water use). The highest yield gain (30%) resulting from water-saving modification was found to occur in the food-insecure region of Sidi Bouzid. Traits enabling aggressive water use were found to be generally favorable across Tunisia, with one trait leading to up to 80% and 40% increases in yield and its stability in the food-challenged south of the country. However, major yield penalties were found to occur if water-saving traits were to be deployed in the ‘wrong’ region. Those findings could be used as a blueprint to navigate complex trait × environment interactions and to better inform local breeding and management programs to improve wheat yield and it stability in Tunisia and the MENA region in general.

Nitrogen release dynamics of a slow release urea pellet and its effect on growth, yield, and nutrient uptake of sweet basil (Ocimum basilicum L.)

Manure urea pellets were produced and their nitrogen release rate was evaluated in soil incubation at different water contents of 90, 75, and 60% soil filed capacity (FC). In another experiment, sweet basil growth was evaluated during eight months (with three shoot harvests) under the pellet application. The nitrogen release and pellet dispersion rates were slow after two months or at lower soil water content (60% FC), but they were significant after four months of soil incubation, or at higher soil water content (75 or particularly 90% FC). Application of pelleted urea reduced plant growth and yield at first harvest than urea treatment. However, at second and particularly at third harvest (and the average of three harvests) significant improvement in growth parameters of SPAD value, leaf area, plant height, shoot fresh weight, pot yield, and` leaf N and K concentrations were achieved by application of pelleted urea fertilization.

Two-dimensional monitoring of soil water content in fields with plastic mulching using electrical resistivity tomography

Plastic mulching (PM) has become an important agricultural practice to improve crop yields worldwide, while there is still a lack of methods to quantify the complex spatial variations of soil water content (SWC) in the PM field. In this study, a methodology for using Electrical Resistivity Tomography (ERT) to get SWC information in the PM field was presented. Its performance in monitoring SWC was validated, and the spatial variation of SWC was analyzed using the ERT results. A simplified Waxman and Smits model was selected to calibrate the pedo-physical relationship, and it showed good performance (coefficient of determination > 0.92). With the calibrated model, the SWC obtained using ERT showed good agreement with soil moisture sensors in different soil layers (RMSE < 0.027 cm3 cm−3). The ERT results showed that rainfall and drying events have different effects on SWC at different growing stages. At the early stage, rainfall and drying events mainly influenced SWC on the bare strip, while at the later stage, rainfall and drying events had more obvious effects on the zone near the planting hole. On a seasonal scale, a higher SWC was not only found in the middle part of the mulched strip, but also in the bare strip, while a lower SWC was found in positions near the planting hole. At the same time, a high-resolution ERT measurement revealed that the SWC was also largely influenced by the soil heterogeneity. As such, SWC in the mulched strip was not necessarily higher than in the bare strip as we had supposed, but showed a high degree of irregularity in two dimensions. Considering the irregularity of SWC in two dimensions, our study calls for replacing point-scale measurement with two-dimensional monitoring methods when acquiring SWC information in a field with PM.

Biochar improves diary pasture yields by alleviating P and K constraints with no influence on soil respiration or N2O emissions

Dairy pastures can be a major source of soil nitrous oxide (N2O) emissions due to the combination of intensive nitrogen (N) fertiliser use and high soil water content, from either rainfall and/or irrigation. Biochar application is a promising approach to lower soil greenhouse gas emissions, particularly under high soil moisture conditions where denitrification is the primary N-transformation pathway. In a replicated field trial, we evaluated the effects of two contrasting biochars derived from poultry litter and from hardwood on soil N2O emissions, soil ammonium (NH4+) and nitrate (NO3−) status, pasture productivity and herbage nutrient content. A liming treatment to mimic the liming equivalence of the poultry litter biochar was used to separate any effects observed from changes in soil pH. To further separate the effects of biochars on soil N status, N2O emissions and pasture N uptake, high and low N fertiliser doses (annual application of 672 kg N ha−1, 336 kg N ha−1) were superimposed across all of the treatments. The N fertiliser dose had no significant impact on pasture yield. Application of poultry litter biochar resulted in significant increases in pasture productivity under both high and low N inputs. This was achieved by alleviating soil P, and possibly K nutritional constraints that are typical in Australian Ferralsols. Under the high N fertiliser dose, emissions of N2O from the treatments and control were not significantly different (p > 0.05) and ranged between 1.14 and 1.78 kg N2O-N ha−1 across the 11-month study. The low N dose resulted in significantly lower emissions of N2O of between 0.80 and 0.84 kg N2O-N ha−1, but biochar had no significant effect on net emissions across the season. The lack of impact of biochar on N2O emissions was attributed to the relatively dry conditions over the trial period resulting in nitrification being the most likely N-transformation pathway. During brief episodes of high soil moisture, peak emissions from the biochar plots were lower than from the control or lime treatment, but these differences did not impact on the emission budget over the 11-month sampling campaign.

Subsoil Compaction: The Intensity of Manifestation in Silty Clayey Calcic Pantofluvic Fluvisols of the Iğdır Region (Eastern Turkey)

The formation of compacted subsoil layer under the impact heavy machines is a global problem in soil science, soil physics, and agrotechnology because of the numerous and significant effects on the water, air, and thermal regimes of soils, their permeability for root systems of plants, etc. For recent calcareous alluvial soils (Calcic Fluvisols) in the foothill areas of eastern Turkey, this problem is particularly important, because these soils were formed as a result of floods of the Aras River. These soils represent unconsolidated homogeneous formations and have a compacted horizon at the depth of 30 to 65 cm, which was formed during dozens of years. Its density almost reaches critical values for loamy soils (>1.5 g/cm3), and its penetration resistance is also high: close to 5 MPa. The studied soils are heavy loamy throughout the profile with a predominance of silt fractions (1–3 and 4–6 µm), have a low content of soil organic matter (up to 0.5% in the plow layer). In the layers of 0–30 cm and 70–150 cm, soil density and penetration resistance are not high: 1.3 g/cm3 and 2 MPa, respectively. Such a fast and deeply penetrating soil compaction is associated with the initial loose state of the soils, their heavy texture, and low content of soil organic matter—the main protector from the subsoil compaction. To prevent further development of subsoil compaction, it is recommended to optimize agrogenic loads, stop using heavy machines under conditions of the high soil water content, and to apply organic fertilizers.

Biochar reduces the efficiency of nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) mitigating N2O emissions

Among strategies suggested to decrease agricultural soil N2O losses, the use of nitrification inhibitors such as DMPP (3,4-dimethylpyrazole phosphate) has been proposed. However, the efficiency of DMPP might be affected by soil amendments, such as biochar, which has been shown to reduce N2O emissions. This study evaluated the synergic effect of a woody biochar applied with DMPP on soil N2O emissions. A incubation study was conducted with a silt loam soil and a biochar obtained from Pinus taeda at 500 °C. Two biochar rates (0 and 2% (w/w)) and three different nitrogen treatments (unfertilized, fertilized and fertilized + DMPP) were assayed under two contrasting soil water content levels (40% and 80% of water filled pore space (WFPS)) over a 163 day incubation period. Results showed that DMPP reduced N2O emissions by reducing ammonia-oxidizing bacteria (AOB) populations and promoting the last step of denitrification (measured by the ratio nosZI + nosZII/nirS + nirK genes). Biochar mitigated N2O emissions only at 40% WFPS due to a reduction in AOB population. However, when DMPP was applied to the biochar amended soil, a counteracting effect was observed, since the N2O mitigation induced by DMPP was lower than in control soil, demonstrating that this biochar diminishes the efficiency of the DMPP both at low and high soil water contents.

Biomechanical properties of plant root systems and their ability to stabilize slopes in geohazard-prone regions

Vegetation is widely used for reinforcing slopes, and thus controlling shallow landslides, because plant root systems can increase soil shear strength by anchoring soil layers and modifying hydrological characteristics. However, limited information is available regarding the vertical variation of soil reinforcement by roots at the slope scale, and how slope stability is influenced, especially in plantation areas. In this paper we examine the biomechanical effects on slope stability of the roots of Populus tomentosa, Robinia pseudoacacia and Olea europaea in a geohazard-prone region in China. Root density, variation in root area ratio (RAR) with depth, root tensile strength and root peak tensile force are measured, along with calculating the contribution of root cohesion to the factor of safety. The Wu-Waldron model and fiber bundle model are used to estimate static stress and dynamic stress adherence of plant roots to soil during debris flows and landslides, and a two-dimensional finite element model is used to calculate the increase in the factor of safety caused by additional root cohesion. The results show that RAR is higher for P. tomentosa than for R. pseudoacacia and O. europaea. The vertical soil profile of R. pseudoacacia roots has the highest soil water content (7.06%). The additional cohesion provided by R. pseudoacacia roots (10.35–15.12 kPa) is greater than that provided by P. tomentosa roots (6.19–10.26 kPa) and O. europaea roots (2.31–5.06 kPa). The stable area is also larger on a slope planted with R. pseudoacacia compared with the other two species. Young growth roots (8 years) are shown to affect the distribution of soil water and are limited by soil water in the semi-humid region. R. pseudoacacia roots provide significant additional cohesion by both static and dynamic stress for slope stability. This study aims to increase current understanding of the biomechanical properties of plantation species roots and their efficacy in soil reinforcement.

Optimum ridge width and suitable mulching material for sainfoin production with ridge–furrow rainwater harvesting in semiarid regions of China

Ridge-furrow rainwater harvesting (RFRH) with mulch offers farmers means to address drought, water loss, and soil erosion in arid and semiarid regions. Plastic film is widely used as a mulching material for RFRH; however, contamination of arable lands by its residual is a serious concern. We compared various mulches, including a biodegradable film for RFRH planted with sainfoin (Onobrychis viciifolia). A field study was conducted to (1) estimate runoff efficiency from three ridge widths using three different mulching materials; and (2) assess the effects of ridge widths and mulching materials on topsoil temperature, soil water storage, fodder yield, fodder nutrition, and water use efficiency (WUE) of RFRH planted with sainfoin, during 2015 and 2016. The predicted runoff efficiency for MCS30, MCS45, MCS60, BF30, BF45, BF60, PF30, PF45, and PF60 [MCS, BF, and PF are abbreviations for ridges with manually compacted soil, mulched with biodegradable film and with plastic film, respectively, subscripts 30, 45, and 60 refer to ridge widths (cm) all with 60 cm furrow width] was 9.9%, 22.2%, 24.7%, 85.3%, 88.8%, 92.7%, 85.9%, 89.7%, and 93.3%, respectively. The practice of RFRH, especially BF and PF, resulted in increased topsoil temperature at ridge tops and increased soil water content at furrow bottoms but decreased topsoil temperature at furrow bottoms. MCS decreased actual fodder yield, but BF and PF increased actual fodder yield. Compared to flat planting (FP), the decrease of actual fodder yield for MCS30, MCS45, and MCS60 was 7%, 15%, and 18%, respectively, for 2015 and 2016, but the increase of actual fodder yield for BF30, BF45, BF60, PF30, PF45, and PF60 was 10%, 8%, 6%, 15%, 13%, and 8%, respectively. Mean WUE for MCS, BF, and PF was 1.58, 1.64, and 1.70 times greater than that for FP, respectively. High soil water content and high soil temperature in RFRH, especially for BF and PF, resulted in increased crude protein and phosphorus content of the fodder produced but resulted in decreased acid detergent fiber and neutral detergent fiber content of fodder. Mean crude protein content for BF and PF was 1.25 and 1.30 times greater than that for FP, respectively, whereas phosphorus content for BF and PF was 1.37 and 1.32 times greater than that for FP. The optimum ridge width for BF was 35–36 cm, whereas for PF, it was 36–42 cm. The RFRH design should conserve water and improve fodder yields and quality.

EVALUATION OF TOTAL BACTERIA AND PHOSPHATE SOLUBILIZED BACTERIA IN RHIZOSFIRS OF Stylosanthes guianensis, Gliricidia sepium, Bracharia decumbens, AND Pennisetum purpureum AT UPLAND IN RAINY SEASON

Phosphate solubilized bacteria is bacteria that useful to solve P bound to be P elements which could be absorped by plant. So, this research is needed to know total population of bacteria and phosphate solubilized bacteria in plants rhizosfer at dry land in rainy season. The research followed aditive linier model with assumption phosphate solubilized bacteria population caused by different of plant species only. Samples taken were consisted of 5 treatments in plants rhizosfer i.e. non rhizosfer (NR), Stylosanthes guianensis (Sg), Gliricidia sepium (Gs), Brachiaria decumbens (Bd), and Pennisetum purpureum (Pp) with 4 replications. Variable observed were Total Plate Count (TPC), total of Phosphate Solublilized Bacteria (PSB), P element (phosphore) ail water content. The research results showed that the TPC of land about 1.06 - 7.12 × 107 cfu/g, PSB about 4.78 - 7.60 × 106 cfu/g. P element at treatment NR was the highest 12,16 ppm. The highest soil water content on the treatment Bd was 4.86%. It can be concluded that TPC and BPF in non rhizosphere and rhizosphere of plants Sg, Gs, Bd and Pp on dry land in the rainy season are different. The content of P elements ranged from 6.14 to 23.07 ppm and the moisture content ranged from 1.68 to 4.86%.&#x0D; Key words: phosphate soluble bacteria, non rhizosfer, rhizosfer

三工河流域琵琶柴群落凋落物对土壤有机碳固定的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 三工河流域琵琶柴群落凋落物对土壤有机碳固定的影响 DOI: 10.5846/stxb201806301443 作者: 作者单位: 贵州大学动物科学学院,中国科学院植物研究所,贵州大学动物科学学院,贵州大学动物科学学院,贵州省草地技术试验推广站,贵州大学动物科学学院,贵州大学 作者简介: 通讯作者: 中图分类号: 基金项目: 贵州省科技厅-贵州大学联合基金项目（黔科合LH字[2017]7288号）；国家自然科学基金青年项目（31700390） Effects of litter on soil organic carbon fixation in Reaumuria soongorica communities in the Sangong River basin Author: Affiliation: College of Animal Science, Guizhou University,,,,,,College of Animal Science, Guizhou 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:土壤有机碳是土壤碳库的重要组成部分，对生态系统生产力和全球碳循环有着重要作用。采用凋落物收集器和DIRT法（添加和去除凋落物法）研究三工河流域两处不同琵琶柴群落凋落物的产量、现存量、凋落物处理对土壤有机碳的影响。结果表明：群落1和群落2的凋落物产量季节变化趋势相同，均呈"N "型变化，在10月份达到最大值，7月或8月份达到次大值。凋落物现存量随季节均呈现" W"型变化，在10月份达到最大值，最大值分别为30.65 g/m2和57.87 g/m2。土壤有机碳随土壤深度的增加均逐渐降低，群落1和群落2分别下降了61.73%-62.39%和18.24%-25.84%。与对照处理相比，去除凋落物处理（NL）的群落1和群落2土壤有机碳分别降低了6.97%和18.38%；添加凋落物处理（DL）的土壤有机碳分别增加了19.64%和13.66%；去除凋落物处理（NL）的群落1和群落2土壤有机碳储量分别为1007.36 kg/hm2和709.30 kg/hm2，添加凋落物处理（DL）的土壤有机碳储量分别为1197.88 kg/hm2和1010.78 kg/hm2。双因素方差分析表明群落1的土层深度和三种处理对土壤有机碳的交互作用不显著，群落2的交互作用显著。回归分析显示：土壤水分、电导率、pH、容重和温度是导致两琵琶柴群落土壤有机碳不同的主要生态因子。相对较高的土壤pH和盐分含量抑制了凋落物的分解，导致凋落物现存量较高、土壤有机碳含量低；相对较高的土壤含水量和较小的容重，有利于土壤生物的活性和土壤有机碳的矿化，导致土壤有机碳含量降低。 Abstract:Soil organic carbon is an important component of the soil carbon pool,and plays a key role in ecosystem productivity and the global carbon cycle. In this research,litter removal and detritus input treatment (DIRT) methods were used to study the litter productivity,litter amount,and effects of different litter treatments on the soil organic carbon in two Reaumuria soongarica communities in the Sangong River Basin. The results showed that the litter productivities of two communities had almost identical seasonal changes;they reached their second-maximum and maximum values in July (August) and October,and both showed "N" distributions. The litter amount also presented similar seasonal change trends;both showed "W" distributions,and reached their maximum values of 30.65 g/m2 and 57.87 g/m2 in October,respectively. The soil organic carbon content gradually reduced with soil depth;Community 1 and Community 2 decreased by 61.73%-62.39% and 18.24%-25.84%,respectively. The average soil organic carbon content of Community 1 and Community 2 was reduced by 6.97% and 18.38% by the litter removal treatment (no litter,NL),and increased by 19.64% and 13.66% by the litter treatment (double litter,DL),respectively. The soil organic carbon storage values of Community 1 and Community 2 were 1007.36 kg/hm2 and 709.30 kg/hm2 after NL treatment,and 1197.88 kg/hm2 and 1010.78 kg/hm2 after DL treatment,respectively. Two-way analysis of variance showed that the interaction of soil organic carbon between the soil depths and three litter treatments was significant in Community 2,but not Community 1. Regression analysis showed that soil properties were determinants of the differences in soil organic carbon between the two communities. The relatively high litter amount and low soil organic carbon content were attributed to the high soil pH and salt content, which inhibited litter decomposition. Otherwise,the relatively high soil water content and low soil bulk density promoted both soil organism activity and soil organic carbon mineralization,which led to the decrease in soil organic carbon content. 参考文献 相似文献 引证文献

荒漠植物功能性状及其多样性对土壤水盐变化的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 荒漠植物功能性状及其多样性对土壤水盐变化的响应 DOI: 10.5846/stxb201801300253 作者: 作者单位: 绿洲生态教育部重点实验室,绿洲生态教育部重点实验室,绿洲生态教育部重点实验室,新疆大学资源与环境科学学院,绿洲生态教育部重点实验室 作者简介: 通讯作者: 中图分类号: 基金项目: 新疆维吾尔自治区高校科研计划青年教师科研启动基金（XJEDU2016S026）；国家自然科学基金项目（31700354，31560131） Responses of plant functional trait and diversity to soil water and salinity changes in desert ecosystem Author: Affiliation: Xinjiang University,,,,Key Laboratory of Oasis Ecology, Education Ministry Fund Project: The Scientific Research Startup Foundation for young teachers program in Xinjiang Uygur Autonomous Region University(XJEDU2016S026),The National Natural Science Foundation of China(grant no.31700354, 31500343) 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:植物功能性状及其多样性对环境变化的响应研究有助于揭示极端环境下植物适应策略和群落构建机制。通过实地调查和实验分析，研究艾比湖荒漠植物形态、生理和化学等8个功能性状的特征，并从多维性状和一维性状角度揭示功能多样性对土壤水分和盐分变化的响应规律。结果表明：高水盐环境下（SW1），（1）群落加权株高、叶绿素含量（SPAD）及叶片碳（C）和钙（Ca）含量显著高于低水盐环境，叶片氮（N）、磷（P）、硫（S）含量在不同水盐环境间无显著差异。（2）SW1环境下，沿乔木-小乔木-灌木-草本层次，上层生活型植物性状值普遍高于下层植物，其中灌木叶片仅N、钾（K）含量显著高于草本；沿该生活型层次植物性状呈趋同变化。（3）低水盐环境下（SW2），乔木叶片性状差异特征与SW1相似；小乔木叶片C、N含量分别显著高于和低于灌木及草本；相比于草本，灌木SPAD、S含量显著高，K含量显著低，株高、C、N、P含量差异不显著；SW2环境下各生活型植物性状呈趋同变化。（4）SW1环境下多维功能丰富度、功能离散度显著高于SW2环境，但均匀度无显著差异。（5）一维功能均匀度在不同水盐环境间均无显著差异，但化学性状的均匀度总体高于植物株高；高水盐环境下叶片N、S和Ca的功能分异指数显著高于低水盐环境。研究为掌握胁迫环境下的植物适应策略和荒漠植被恢复提供参考。 Abstract:Exploring the response of plant functional trait to environmental variations is essential to elucidate the adaptation mechanism and community assembly of desert plants under extreme environmental conditions, and more importantly to formulate strategies to protect and restore desert ecosystem. However, previous studies are mostly large scale, and only a few studies have focused on the effects of soil water and salinity on desert plant functional trait and diversity at fine scale. It is known that, even at fine scales, environmental variables (e.g., soil variables) can actually be heterogeneous and affect plant. Therefore, in the present study, we aimed to analyze (1) how morphological, physiological, and chemical functional traits of desert plant, and functional richness, evenness, and dispersion indexes respond to varied soil water and salinity and (2) what community assembly process did functional diversity revealed in different soil water and salinity environment? Three transects were set at 5-km intervals perpendicular to the northern bank of the Aqikesu River in the Ebinur Lake Wetland Nature Reserve (ELWNR). At each transect, the soil gradually changed from saline to sandy soil with the increase in distance from the river. Ten to twelve plots (10×10 m2) were set at an interval of 500 m in each transect. A total of 32 plots were set across the three transects. The geographic data (longitude, latitude, and altitude), number of species, plant abundance (number of individuals of each species), and height of each individual sampled in each plot were recorded. The chlorophyll content (SPAD) was measured by SPAD502, and soil volumetric water content (SVWC) at a depth of 12 cm was measured by time domain reflectometry before sampling. The leaf and soil samples were then collected for further investigation. Based on the investigation and analysis, responses of one morphological (height), one physiological (SPAD) and six chemical functional traits (leaf carbon (C), nitrogen (N), phosphorus (P), sulfur (S), potassium (K), and calcium (Ca) content), and response of multidimensional and single dimensional functional diversities to soil water and salinity were explored. The results showed the following. (1) The community weighted mean height, SPAD, and leaf C and Ca content in high soil water and salinity sites (SW1) were significantly higher than those in low soil water and salinity sites (SW2). The leaf N, P, and S content had no significant differences across the two sites. (2) In SW1 sites, the plant functional trait differences generally decreased along the tree-small tree-shrub-herb life form level, with only leaf N and K content exhibiting significant difference between shrub and herb. Furthermore, plant functional trait showed convergence along the life form level. (3) In SW2 sites, functional trait differences in trees were similar to those in the SW1; the leaf C and N content were significantly higher than those in shrubs and herbs. Furthermore, the SPAD and leaf S content of shrubs were significantly higher than those in herbs, whilst, the leaf K content of shrubs was lower than that in herbs. The height, and leaf C, N, and P content exhibited no significant differences between shrubs and herbs. The plant functional traits among life forms in SW2 site presented a trend of convergence. (4) The multidimensional functional richness (FAD2) and functional divergence (Rao) in SW1 sites were higher than those in SW2 sites, whilst, the functional evenness showed no difference. (5) All single dimensional functional evenness showed no difference between high and low soil water content and salinity; however, functional evenness of chemical trait was generally higher than that of plant height. Furthermore, functional logarithmic variance (FDvar) of leaf N, S, and Ca in SW1 was significantly higher than that of SW2. The study provides references to understand the adaption mechanism of plants subjected to extreme environments and to recover desert plants. 参考文献 相似文献 引证文献

海岛植物不同演替阶段植物功能性状与环境因子的变化规律

PDF HTML阅读 XML下载 导出引用 引用提醒 海岛植物不同演替阶段植物功能性状与环境因子的变化规律 DOI: 10.5846/stxb201807051468 作者: 作者单位: 福建农林大学,福建农林大学,福建农林大学,云南大学,福建农林大学 作者简介: 通讯作者: 中图分类号: 基金项目: 福建省自然科学基金面上项目（2018J01699）；国家自然科学基金项目（31800401）；福建省教育厅科技项目（JAT170198） Summary of changes in plant functional traits and environmental factors in different successional stages of island plants Author: Affiliation: Fujian Agriculture and Forestry University,Fujian Agriculture and Forestry University,Fujian Agriculture and Forestry University,,Fujian Agriculture and Forestry University Fund Project: 省、部研究计划基金, 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:植物功能性状与环境之间的关系是功能性状研究的重点，环境因子驱使植物功能性状发生变化，进而推动群落发生演替。以平潭岛4个不同演替阶段的森林植被（灌草丛、针叶林、针阔混交林、常绿阔叶林）为研究对象，结合不同群落演替阶段的物种特征和群落结构，分析海岛不同演替阶段茎、叶功能性状的变化规律，以及功能性状与环境因子的关系。结果表明：（1）随着演替的进行，土壤养分和水分逐渐增加，土壤pH逐渐下降。比叶面积（SLA）、叶片氮含量（LNC）、叶片磷含量（LPC）、茎氮含量（SNC）、茎磷含量（SPC）下降后上升，叶厚度（LT）、叶片碳含量（LCC）、茎碳含量（SCC）与之相反，叶干物质含量（LDMC）、茎组织密度（STD）逐渐上升。（2）冗余分析表明，演替早期植物主要分布在土壤pH、容重高的贫瘠环境，拥有较高SLA、SNC、SPC、LPC的性状组合；演替后期植物主要分布在土壤养分和水分高的肥沃环境，拥有较高的STD、LDMC、LCC、LNC的性状组合。其中，土壤有机质和全氮含量是影响海岛植物演替过程中功能性状变化的关键环境因子。研究海岛植物功能性状与环境之间的关系随演替的变化规律，探讨各演替阶段功能性状和环境特征，以及功能性状如何响应环境变化。旨在为今后选择合适的树种进行海岛植被修复和重建提供依据。 Abstract:The relationship between plant functional traits and environment is the focus of functional traits research. Environmental factors drive the changes in plant functional traits, which in turn promote community succession. Based on the forest vegetation of four different succession stages (shrub-grassland, coniferous forest, mixed wood, and broadleaf forest) in Pingtan Island, this study combined the species characteristics and community structure of different community successional stages. We analyzed the changes in stem and leaf functional traits in different succession stages of island plants. Moreover, we explored the relationship between plant functional traits and environmental factors. The results showed the following. (1) With progress in succession, soil nutrient and water content gradually increased and the soil pH gradually decreased. The specific leaf area (SLA), leaf nitrogen content (LNC), leaf phosphorus content (LPC), stem nitrogen content (SNC), and stem phosphorus content (SPC) decreased initially, and then increased, Meanwhile, the leaf thickness (LT), leaf carbon content (LCC), and stem carbon content (SCC) increased initially, and then decreased. The leaf dry matter content (LDMC) and stem tissue density (STD) gradually increased. (2) The redundancy analysis showed that the early succession plants were mainly distributed in barren environments with high soil pH and high bulk density, and they presented higher SLA, SNC, SPC, and LPC. Plants in the late succession stages were mainly distributed in fertile environments with high soil nutrient and water content, and they presented higher STD, LDMC, LCC, and LNC. Therefore, soil organic matter and total nitrogen are the important environmental factors that affect the functional traits of island plants succession. We studied the relationship between plant functional traits and environment along with the changes in succession, understood the functional traits and environmental characteristics of each succession stage, and revealed how plant functional traits adapted to the environmental changes. The study provides the basis for the selection of suitable tree species for island vegetation restoration and reconstruction in the future. 参考文献 相似文献 引证文献

How do Soil Moisture and Vegetation Covers Influence Soil Temperature in Drylands of Mediterranean Regions?

Interactions between land and atmosphere directly influence hydrometeorological processes and, therefore, the local climate. However, because of heterogeneity of vegetation covers these feedbacks can change over small areas, becoming more complex. This study aims to define how the interactions between soil moisture and vegetation covers influence soil temperatures in very water-limited environments. In order to do that, soil water content and soil temperature were continuously monitored with a frequency of 30 min over two and half hydrological years, using capacitance and temperature sensors that were located in open grasslands and below tree canopies. The study was carried out on three study areas located in drylands of Mediterranean climate. Results highlighted the importance of soil moisture and vegetation cover in modifying soil temperatures. During daytime and with low soil moisture conditions, daily maximum soil temperatures were, on average, 7.1 °C lower below tree canopies than in the air, whereas they were 4.2 °C higher in grasslands than in the air. As soil wetness decreased, soil temperature increased, although this effect was significantly weaker below tree canopies than in grasslands. Both high soil water content and the effect of shading were reflected in a decrease of maximum soil temperatures and of their daily amplitudes. Statistical analysis emphasized the influence of soil temperature on soil water reduction, regardless of vegetation cover. If soil moisture deficits become more frequent due to climate change, variations in soil temperature could increase, affecting hydrometeorological processes and local climate.

Effects and mechanisms of erosion control techniques on stairstep cut-slopes

Many erosion control techniques, such as stone pitching, concrete revetment, and geotextile covering, have been effective at protecting cut slopes along roads or railways. However, these methods are expensive and hard to operate for high stairstep cut-slopes. To investigate the efficiency of several easily implemented and low-cost techniques, five plots with different treatments were built on stairstep cut-slopes. The five treatments consisted of vegetation coverage on platforms, counter-slope on platforms, upslope drainage, a control check (CK), and a comprehensive treatment of the first three techniques. During nineteen recorded rainfall events from June 2015 to August 2016, the runoff and sediment amount of each plot was measured. Soil water content and shear strength of the 2-m depth profile at each plot after the occurrence of rainfall and evapotranspiration were also investigated. The results indicated that runoff and the sediment amount from the five plots increased with an increase in rainfall amount with a threshold of 5 mm rainfall to produce sediment loss. Compared with the CK, the comprehensive and upslope drainage treatments had a larger reduction in runoff and sediment amount than those of the vegetation and counter-slope treatments. After either rainfall or evapotranspiration, the vegetation and comprehensive treatments had the highest soil water content, and the upslope drainage treatment had the lowest soil water content. The infiltration capacity followed the order of upslope drainage < CK < counter-slope < vegetation < comprehensive treatment. The shear strength of soil logarithmically decreased with soil water content in the five plots, and a critical water content of 12% determined the rate of change for shear strength. Finally, the upslope drainage technique was determined as the preferred recommendation to protect high stairstep cut-slopes.

Surface-deformation monitoring in the permafrost regions over the Tibetan Plateau, using Sentinel-1 data

Differential Interferometric Synthetic Aperture Radar (D-InSAR) has been widely used to measure surface deformation over the Tibetan Plateau. However, the accuracy and applicability of the D-InSAR method are not well estimated due to the lack of in-situ validation. In this paper, we mapped the seasonal and long-term displacement of Tanggula (TGL) and Liangdaohe (LDH) permafrost regions with a stack of Sentinel-1 acquisitions using the Small Baseline Subset InSAR (SBAS-InSAR) method. In the TGL region, with its dry soils and sparse vegetation, the InSAR-derived surface-deformation trend was consistent with ground-based leveling results; long-term changes of the active layer showed a settlement rate of around 1 to 3 mm/a due to the melting of ground ice, indicating a degrading permafrost in this area. Around half of the deformation was picked up on monitoring, in contrast with in-situ measurements in LDH, implying that the D-InSAR method remarkably underestimated the surface-deformation. This phenomenon may be induced by the large soil-water content, high vegetation coverage, or a combination of these two factors in this region. This study demonstrates that surface deformation could be mapped accurately for a specific region with Sentinel-1 C-band data, such as in the TGL region. Moreover, although the D-InSAR technology provides an efficient solution for broad surface-deformation monitoring in permafrost regions, it shows a poor performance in the region with high soil-water content and dense vegetation coverage.

Investigating plant root effects on soil electrical conductivity: An integrated field monitoring and statistical modelling approach

AbstractPlants have been shown to affect soil water content and temperature. Previous studies were conducted mainly in forestry and agricultural soils, where conditions of soil and vegetation are different from those in an urban landscape. In an urban landscape, the influence of plant roots on electrical conductivity, soil water content and temperature is still not clear. This study aims to investigate the effects of soil water content and temperature on electrical conductivity in vegetated soils through an integrated field monitoring and computational modelling approach. A new relationship between soil electrical conductivity and water content as well as temperature is proposed. Field monitoring was conducted in both vegetated (tree species) and bare soils. The monitoring included measurements of soil water content, soil temperature and soil electrical conductivity. This was followed by response surface regression modelling. Measured results show that soil temperature at shallow depths was lower in vegetated soil than that in the bare soil. This observation was also consistent with the higher soil water content and hence, higher electrical conductivity under tree canopy. The model developed could predict nonlinear relationships between electrical conductivity and soil temperature and water content. Uncertainty analysis indicated normal distribution for electrical conductivity under variation of soil temperature and water content. © 2018 John Wiley &amp; Sons, Ltd.