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1.
Sensors (Basel) ; 21(11)2021 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-34200346

RESUMO

Increasing temperatures and drought occurrences recently led to soil moisture depletion and increasing tree mortality. In the interest of sustainable forest management, the monitoring of forest soil properties will be of increasing importance in the future. Vis-NIR spectroscopy can be used as fast, non-destructive and cost-efficient method for soil parameter estimations. Microelectromechanical system devices (MEMS) have become available that are suitable for many application fields due to their low cost as well as their small size and weight. We investigated the performance of MEMS spectrometers in the visual and NIR range to estimate forest soil samples total C and N content of Ah and Oh horizons at the lab. The results were compared to a full-range device using PLSR and Cubist regression models at local (2.3 ha, n: Ah = 60, Oh = 50) and regional scale (State of Saxony, Germany, 184,000 km2, n: Ah = 186 and Oh = 176). For each sample, spectral reflectance was collected using MEMS spectrometer in the visual (Hamamatsu C12880MA) and NIR (NeoSpetrac SWS62231) range and using a conventional full range device (Veris Spectrophotometer). Both data sets were split into a calibration (70%) and a validation set (30%) to evaluate prediction power. Models were calibrated for Oh and Ah horizon separately for both data sets. Using the regional data, we also used a combination of both horizons. Our results show that MEMS devices are suitable for C and N prediction of forest topsoil on regional scale. On local scale, only models for the Ah horizon yielded sufficient results. We found moderate and good model results using MEMS devices for Ah horizons at local scale (R2≥ 0.71, RPIQ ≥ 2.41) using Cubist regression. At regional scale, we achieved moderate results for C and N content using data from MEMS devices in Oh (R2≥ 0.57, RPIQ ≥ 2.42) and Ah horizon (R2≥ 0.54, RPIQ ≥2.15). When combining Oh and Ah horizons, we achieved good prediction results using the MEMS sensors and Cubist (R2≥ 0.85, RPIQ ≥ 4.69). For the regional data, models using data derived by the Hamamatsu device in the visual range only were least precise. Combining visual and NIR data derived from MEMS spectrometers did in most cases improve the prediction accuracy. We directly compared our results to models based on data from a conventional full range device. Our results showed that the combination of both MEMS devices can compete with models based on full range spectrometers. MEMS approaches reached between 68% and 105% of the corresponding full ranges devices R2 values. Local models tended to be more accurate than regional approaches for the Ah horizon. Our results suggest that MEMS spectrometers are suitable for forest soil C and N content estimation. They can contribute to improved monitoring in the future as their small size and weight could make in situ measurements feasible.


Assuntos
Sistemas Microeletromecânicos , Poluentes do Solo , Florestas , Alemanha , Solo , Poluentes do Solo/análise
2.
Sensors (Basel) ; 21(12)2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-34201041

RESUMO

Drought is the most severe problem for agricultural production, and the intensity of this problem is increasing in most cultivated areas around the world. Hence improving water productivity is the primary purpose of sustainable agriculture. This study aimed to use cloud IoT solutions to control a modern subsurface irrigation system for improving irrigation management of date palms in arid regions. To achieve this goal, we designed, constructed, and validated the performance of a fully automated controlled subsurface irrigation system (CSIS) to monitor and control the irrigation water amount remotely. The CSIS is based on an autonomous sensors network to instantly collect the climatic parameters and volumetric soil water content in the study area. Therefore, we employed the ThingSpeak cloud platform to host sensor readings, perform algorithmic analysis, instant visualize the live data, create event-based alerts to the user, and send instructions to the IoT devices. The validation of the CSIS proved that automatically irrigating date palm trees controlled by the sensor-based irrigation scheduling (S-BIS) is more efficient than the time-based irrigation scheduling (T-BIS). The S-BIS provided the date palm with the optimum irrigation water amount at the opportune time directly in the functional root zone. Generally, the S-BIS and T-BIS of CSIS reduced the applied irrigation water amount by 64.1% and 61.2%, respectively, compared with traditional surface irrigation (TSI). The total annual amount of applied irrigation water for CSIS with S-BIS method, CSIS with T-BIS method, and TSI was 21.04, 22.76, and 58.71 m3 palm-1, respectively. The water productivity at the CSIS with S-BIS (1.783 kg m-3) and T-BIS (1.44 kg m-3) methods was significantly higher compared to the TSI (0.531 kg m-3). The CSIS with the S-BIS method kept the volumetric water content in the functional root zone next to the field capacity compared to the T-BIS method. The deigned CSIS with the S-BIS method characterized by the positive impact on the irrigation water management and enhancement on fruit yield of the date palm is quite proper for date palm irrigation in the arid regions.


Assuntos
Phoeniceae , Irrigação Agrícola , Agricultura , Clima Desértico , Solo , Água
3.
Huan Jing Ke Xue ; 42(7): 3555-3564, 2021 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-34212682

RESUMO

The spatial distribution of fertilization intensity and its influencing factors are significant for the accurate management of fertilization and pollution prevention and control. Previous studies are mostly limited to the discussion of human factors that influences the spatial distribution of fertilization intensity while ignoring natural geographical factors. Based on the chemical fertilizer survey data collected from 23492 sites in Chengdu Plain and combined with Geostatistics analysis and Geographic Information System (GIS) technology, the spatial distribution characteristics and influencing factors of average nitrogen and phosphorus fertilizer application intensity from 2010 to 2015 in this region were explored. The results show that:① the average annual application intensity of nitrogen and phosphorus fertilizer in the study area from 2010 to 2015 is generally in the low and medium risk intensity of 120-360 kg·hm-2 and 60-180 kg·hm-2. The high risk intensity is mainly distributed in the grain (fruit) and vegetable growing areas such as Pidu, Pengzhou, Shifang, Longquanyi and Jintang, while the relatively low value areas are mostly distributed in the south and northeast. ② the nugget coefficients of nitrogen and phosphorus fertilizer application intensities are 66.17% and 41.60%. Their spatial distribution is determined by structural and random factors, showing a moderate spatial autocorrelation. ③ both human and natural factors have significant effects on the application intensity of nitrogen and phosphorus fertilizer. The crop type (fine classification) can explain the spatial variation of nitrogen fertilizer and phosphorus fertilizer respectively by 12.90% and 25.10%, which is the main controlling factor affecting the spatial distribution of nitrogen and phosphorus application intensity; the importance of soil parent material is second only to the planting crop type, and the independent explanation ability of phosphorus application intensity is about 3.6 times higher than that of nitrogen application intensity. When the type of planting crop plays a decisive role, the soil parent material still deeply restricts and affects the spatial distribution of nitrogen and phosphorus fertilizer application intensity in the study area. Therefore, the comprehensive effects of planting crop types and soil parent materials should be considered in fertilization management and environmental risk analysis, and the effects of soil parent material should also be taken into account in the application of phosphate fertilizer.


Assuntos
Fertilizantes , Fósforo , Agricultura , China , Fertilizantes/análise , Nitrogênio/análise , Fósforo/análise , Solo
4.
Talanta ; 233: 122458, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34215099

RESUMO

Poor recovery of phosphorus (P) across natural environment (water, soil, sediment, and biological sources) is causing rapid depletion of phosphate rocks and continuous accumulation of P in natural waters, resulting in deteriorated water quality and aquatic lives. Accurate detection and characterization of various P species using suitable analytical methods provide a comprehensive understanding of the biogeochemical cycle of P and thus help its proper management in the environment. This paper aims to provide a comprehensive review of the analytical methods used for P speciation in natural environment by dividing them into five broad categories (i.e., chemical, biological, molecular, staining microscopy, and sensors) and highlighting the suitability (i.e., targeted species, sample matrix), detection limit, advantages-limitations, and reference studies of all methods under each category. This can be useful in designing studies involving P detection and characterization across environmental matrices by providing insights about a wide range of analytical methods based on the end user application needs of individual studies.


Assuntos
Meio Ambiente , Fósforo , Fosfatos/análise , Solo
5.
Environ Monit Assess ; 193(8): 468, 2021 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-34226956

RESUMO

Bamboos due to high soil water conservation potential are gaining increased attention in plantation programs across the globe. Large-scale plantation of fast-growing bamboo, however, can have important hydrological consequences. The study aims to quantify the eco-hydrological parameters, viz., throughfall (TF), stemflow (SF), and interception (I) in seven important sympodial bamboo species in north western Himalayan foothills of India. The species selected include Bambusa balcooa, Bambusa bambos, Bambusa vulgaris., Bambusa nutans, Dendrocalamus hamiltonii, Dendrocalamus stocksii, and Dendrocalamus strictus. Throughfall versus gross rainfall (GR) relationship in different species indicated high throughfall production during high rainfall events with r2 > 0.90. Average throughfall was lowest (62.1%) in D. hamiltonii and highest in B. vulgaris (74.6%). SF ranged from 1.32% in B. nutans to 3.39% in D. hamiltonii. The correlation coefficient (r) between leaf area index (LAI), number of culms, and crown area with the interception were 0.746, 0.691, and 0.585, respectively. The funneling ratio (F) was highest (27.0) in D. hamiltonii and least in B. nutans. Canopy storage capacity was highest in D. strictus (3.57 mm) and least in D. hamiltonii (1.09 mm). Interception loss was highest (34.4%) in D. hamiltonii and lowest in B. vulgaris (23.5%) and D. strictus (23.6%). Higher interception in bamboos make them suitable for soil conservation, but careful selection of species is required in low rainfall areas.


Assuntos
Antozoários , Monitoramento Ambiental , Animais , Hidrologia , Índia , Solo
6.
J Environ Sci (China) ; 106: 1-14, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34210425

RESUMO

The synthesis of biological silicon nano-particles (Bio-Si-NPs) is an eco-friendly and low-cost method. There is no study focusing on the effect of Bio-Si-NPs on the plants grown on saline soil contaminated with heavy metals. In this study, an attempt was made to synthesis Bio-Si-NPs using potassium silica florid substrate, and the identified Aspergillus tubingensis AM11 isolate that separated from distribution systems of the potable water. A two-year field trial was conducted to compare the protective effects of Bio-Si-NPs (2.5 and 5.0 mmol/L) and potassium silicate (10 mmol/L) as a foliar spray on the antioxidant defense system, physio-biochemical components, and the contaminants contents of Phaseolus vulgaris L. grown on saline soil contaminated with heavy metals. Our findings showed that all treatments of Bio-Si-NPs and potassium silicate significantly improved plant growth and production, chlorophylls, carotenoids, transpiration rate, net photosynthetic rate, stomatal conductance, membrane stability index, relative water content, free proline, total soluble sugars, N, P, K, Ca2+, K+/Na+, and the activities of peroxidase, catalase, ascorbic peroxidase and superoxide oxide dismutase. Application of Bio-Si-NPs and potassium silicate significantly decreased electrolyte leakage, malondialdehyde, H2O2, O2•-, Na+, Pb, Cd, and Ni in leaves and pods of Phaseolus vulgaris L. compared to control. Bio-Si-NPs were more effective compared to potassium silicate. Application of Bio-Si-NPs at the rate of 5 mmol/L was the recommended treatment to enhance the performance and reduce heavy metals content on plants grown on contaminated saline soils.


Assuntos
Metais Pesados , Nanopartículas , Phaseolus , Poluentes do Solo , Antioxidantes , Aspergillus , Metais Pesados/análise , Silício , Solo , Poluentes do Solo/análise
7.
Ying Yong Sheng Tai Xue Bao ; 32(6): 1919-1927, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212595

RESUMO

Understanding the changes of natural abundance of stable carbon and nitrogen isotopes (δ13C and δ15N) along soil profile is of great importance in revealing the mechanisms of soil carbon and nitrogen cycling in terrestrial ecosystems. Based on a comprehensive review on the distribution of δ13C and δ15N along soil profile, the mechanisms underlying their vertical distribution were mainly introduced here. There were three mechanisms driving the δ13C vertical distribution in soil profile: 1) historical changes of vegetation δ13C value, 2) changes of C3-C4 species dominance in plant communities, 3) accumulation of 13C-enriched microbial-derived carbon during decomposition. The effects of 13C Suess effect on the vertical distribution of δ13C in soil profile were also discussed. There were four mechanisms underlying the vertical distribution of δ15N in soil profile: 1) 15N-depletion gas loss during denitrification, 2) accumulation of 15N-enriched microbial-derived nitrogen during decomposition, 3) accumulation of 15N-encriched mycorrhizal fungi residues in deep soil as a result of transferring 15N-depleted nitrogen compounds to plants by mycorrhizae, 4) intera-ction between soil organic matter and mineral substance. We proposed important concerning points for the future study on vertical distribution of natural abundance of stable carbon and nitrogen isotopes in soil profile.


Assuntos
Carbono , Solo , Isótopos de Carbono/análise , Ecossistema , Nitrogênio/análise , Isótopos de Nitrogênio
8.
Ying Yong Sheng Tai Xue Bao ; 32(6): 1928-1934, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212596

RESUMO

Water cycle in the soil-plant-atmosphere continuum (SPAC) is an important research topic in hydrology and ecology. The differences in the composition of hydrogen and oxygen stable isotopes in different water bodies can indicate water cycle process. Based on the measurements of isotopic compositions in precipitation, soil water, and plant water, we analyzed water isotope evolution in a SPAC system located in a subtropical evergreen broad-leaved forest in Chengdu Plain. The different interface processes of regional water cycle was revealed. The results showed that the local meteoric water line (LMWL) equation was δD=7.13 δ18O+2.35 (R2=0.99), and the soil evaporation line (SEL) equation was δD=6.98δ18O-0.32 (R2=0.92). In the water transportation process of precipitation-soil water-plant water, hydrogen and oxygen isotopes were gradually enriched. The δ18O in water of the surface soil layer (0-35 cm) was sensitive to precipitation input, as it was directly affected by precipitation. In contrast, the δ18O in water of the middle and deep layers (35-100 cm) was relatively stable. The isotopes of plant xylem water were slightly more enriched than those of soil water, indicating the possibility of slight evaporation or transpiration through phloem or bark in plant water transportation. The estimation of plant water intake from different soil layers was performed by direct correlation method. Cinnamomum camphora mainly used water from the middle layer, Broussonetia papyrifera mainly used that from the surface layer, and Parathelypteris glanduligera tended to use surface soil water and precipitation intercepted by plants because of the shallow root system. Compared with P. glanduligera, C. camphora and B. papyrifera experienced stronger water evaporation and the isotopes were influenced by more intense dynamic fractionation.


Assuntos
Hidrogênio , Solo , Atmosfera , Florestas , Oxigênio , Isótopos de Oxigênio/análise , Água
9.
Ying Yong Sheng Tai Xue Bao ; 32(6): 1935-1942, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212597

RESUMO

To clarify the changes of water sources for Caragana intermedia plantations at different ages (4, 9, 17 and 31 years) in response to rainfall in the Gonghe Basin of Qinghai Province, China, we used the stable isotope technique to identify δ2H and δ18O compositions of soil water, xylem water, groundwater, and rain water before and after rainfalls. The proportions of different water sources were calculated by the Iso-Source model. The results showed that the δ2H and δ18O compositions of the shallow soil layer (0-40 cm) of all plantations responded significantly to the precipitation. The isotopic values of plant xylem water, soil water, and groundwater of each plantation were spotted on the lower right of the local meteoric water line (LMWL) either before or after rainfall, with lower intercepts and slopes than LMWL and the global meteoric water line (GMWL). The isotopic compositions of xylem water and soil water of C. intermedia plantations were closer to LMWL after rainfall. The 4- and 9-year-old C. intermedia plantations mainly used shallow soil water, the 17-year-old plantation mainly used middle layer soil water (40-90 cm), and the 31-year-old plantation primarily use deep soil water before rainfall. After rainfall, the shallow soil layer became sources of water absorption for all plantations. The utilization proportions of groundwater for all plantations were only 1.8%-11.9%. In general, water sources of different aged C. intermedia plantations showed similar responses to rainfall, by primarily absorbing the shallow soil water supplied by rainfall and reducing the use of groundwater.


Assuntos
Caragana , China , Chuva , Areia , Solo , Água
10.
Ying Yong Sheng Tai Xue Bao ; 32(6): 1943-1950, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212598

RESUMO

In the areas with seasonal drought, water is the key factor affecting plant growth and development. Based on long-term continuous observation data, it is of great significance to explore plant water use patterns for vegetation construction in areas with seasonal drought. Taking Platycladus orientalis in Beijing mountainous area as the research object, stable hydrogen and oxygen isotope technique was applied to measure the isotopic composition of water from the soil, plant branches, and precipitation from 2012 to 2017. The relative contribution of soil water from different soil layers to P. orientalis was quantified by the MixSIAR model. The results showed that soil water in the deep layer (40-100 cm) was more stable than that in the shallow layer (0-40 cm). The variation of soil water content and water isotope values in the shallow layer were more obvious due to the effects of evaporation and precipitation. P. orientalis mainly absorbed stable deep soil water, with a relative contribution rate of 55.7%. In the dry season, with the decreases of soil water content, the absorption depth of plants to soil water gradually shifted to the shallow layer. Under conditions of moist, natural condition, mild drought and moderate drought, the relative contribution rates of deep soil water were 59.8%, 57.9%, 54.6%, 52.7%, respectively. To maintain higher transpiration in the wet season, P. orientalis relied more on deep soil water under mild and moderate drought conditions than in the dry season. Under the conditions of moist, natural condition, mild drought and moderate drought, the relative contribution rates of deep soil water were 58.9%, 57.6%, 56.4%, and 57.1%, respectively. The adaptive characteristic of P. orientalis, which adjusts the depth of root water absorption according to soil moisture condition, is of great significance for tree species selection in ecological afforestation and long-term management planning in areas with seasonal drought.


Assuntos
Secas , Árvores , Pequim , Estações do Ano , Solo , Água
11.
Ying Yong Sheng Tai Xue Bao ; 32(6): 1980-1988, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212602

RESUMO

We examined the characteristics of water use in typical tree species of arbor and shrub in Hunshandake Sandy Land, Populus cathayana and Salix gordejevii, in the different seasons, with the aim to provide theoretical basis for the structural optimization of the artificial shelterbelt. Samples of precipitation, soil water, groundwater and stem water of the two vegetation were collected, and their distribution characteristics of δD-δ18O were analyzed by hydrogen and oxygen stable isotope technology. The contribution rate of these potential water source to the arbor and shrub species were calculated using multi-source linear mixing model. The precipitation equation line in the study area was δD=7.84δ18O+9.12, while soil moisture lines in the dry and wet season were δD=3.56δ18O-41.28 and δD=4.30δ18O-42.02, respectively. The δD-δ18O of soil water and stem water in the two seasons were lower than the precipitation δD-δ18O, indicating that both of them were strongly affected by the evaporation. Soil water contents in the shallow layer were strongly affected by rainfall and evaporation, with substantial fluctuation. With the increases of soil depth, soil water content tended to be stable, and the hydrogen and oxygen isotope in each soil layer showed significant differences. In the dry season, P. cathayana mainly utilized soil water in 0-40 cm and 120-200 cm layers, with contribution rates of 50.2% and 31.5%, respectively. S. gordejevii mainly absorbed soil water in 20-40 cm and 60-100 cm layers, and the contribution rates were 53.2% and 22.9%, respectively. In the wet season, the greatest contribution of soil water to P. cathayana was mainly in the 0-40 cm soil layer, accounting for 72.8%. S. gordejevii was mainly in the 0-20 cm soil water, evenly utilized the deeper soil water and groundwater. Due to the differences in root depth and distribution of the arbor and shrub, their water use strategies differed in different seasons, which was conducive to the stability of the shelterbelt community and tree species coexistence in Hunshandake Sandy Land. We proposed that the mixed planting species with different root depth should be considered in the future planting of artificial shelterbelt, which would help rationally utilize water resources and maintain the stability of sandy land ecosystem.


Assuntos
Ecossistema , Solo , China , Isótopos de Oxigênio/análise , Água
12.
Ying Yong Sheng Tai Xue Bao ; 32(6): 1989-1997, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212603

RESUMO

Gaseous nitrogen (N) emission [nitric oxide (NO), nitrous oxide (N2O), and nitrogen (N2)] is an important pathway of soil N loss. Nitrification and denitrification are the main processes of gaseous N production in soil. However, the contribution of heterotrophic nitrification, co-denitrification, and anammox to gaseous N production remains uncertain. In a laboratory soil incubation experiment, we used the 15N labelling and pairing technique, combining the nitrification inhibitor dicyandiamide (DCD), to quantify the contribution of different microbial processes to soil NO, N2O and N2 production under anaerobic conditions. The results showed that after 24 h anaerobic incubation, the highest total 15N recovery of three gases occurred at 65% water filled pore space (WFPS), accounting for 20.0% of total added 15N. Denitrification contributed 49.9%-94.1%, 29.0%-84.7%, and 58.2%-85.8% to the production of NO, N2O and N2 respectively, suggesting that denitrification was the predominant process of those three N gases emission. Heterotrophic nitrification was an important pathway of NO and N2O production, particularly at conditions with low soil water content (10% WFPS), with its contribution to those two N gases production being 50.1% and 42.8%, respectively. Co-denitrification contributed 10.6%-30.7% of N2O production. For N2 production, the total contribution of co-denitrification and anammox was 14.2%-41.8%. The role of co-denitrification can not be ignored for N2O and N2 production. Our results demonstrated that the 15N labelling and pairing technique is a promising tool to quantify the contribution of different microbial processes to gaseous N loss.


Assuntos
Óxido Nitroso , Solo , Anaerobiose , Desnitrificação , Gases , Nitrificação , Nitrogênio/análise , Óxido Nitroso/análise
13.
Ying Yong Sheng Tai Xue Bao ; 32(6): 1998-2006, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212604

RESUMO

Losses of organic matter in agricultural watersheds result in eutrophication and land degra-dation, which not only threaten water quality and food security, but also lead to environmental problems such as the greenhouse gases emission. We used 13C, 15N and C/N as fingerprint markers to trace the sources of sedimentary organic matter at the outlet in the Nanyue small watershed. We analyzed the spatial distribution in watershed sedimentary organic matter and soils of typical land use types, including forest, paddy field, and vegetable fields. The Bayesian stable isotope mixing model was used to quantitatively estimate the contribution of different sources. The results showed that there was significant spatial variation of δ13C. The δ13C of sediment organic matter (-22.6‰±0.53‰) and forest soil (-23.13‰±1.71‰) was significantly higher than that of paddy soil (-25.24‰±1.4‰). The differences of δ15N among the sources were not significant, with sediment having the maximum (4.37±0.83)‰ and forest soil having the minimum (2.38±1.97)‰. Forest soil had the highest C/N of 16.66±7.18, while paddy soil had the lowest C/N of 11.95±0.92. The results of the Bayesian stable isotope mixture model showed that the contribution rates of forest land, paddy fields and vegetable fields to the organic matter deposited at the outlet in the watershed were 19.6%, 15.7%, and 64.7%, respectively. Paddy filed and vegetable field had a combined contribution rate of 80.4%. It was concluded that, soils of agricultural land were the main sources of organic matter deposited in the Nanyue small watershed, and that nutrient loss in the watershed would be effectively controlled by optimizing farmland management.


Assuntos
Monitoramento Ambiental , Solo , Agricultura , Teorema de Bayes , Eutrofização
14.
Ying Yong Sheng Tai Xue Bao ; 32(6): 2045-2052, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212610

RESUMO

We investigated the effects of warming on soil nitrogen cycling process in alpine scrub ecosystem, with an in-situ simulated warming experiment at Sibiraea angustata alpine scrubland on the eastern Qinghai-Tibet Plateau, China. We examined the responses of soil nitrogen transformation rate to warming in three critical periods (the early, late, and non-growing seasons). The results showed that warming increased soil temperature by 1.2 ℃, but decreased soil moisture by 2.5%. The soil net nitrogen mineralization rates (i.e., ammonification and nitrification) in the growing season were significantly higher than those in the non-growing season. The rates of soil net nitrogen fixation in the non-growing season were significantly higher than that in the growing season. Soil nitrification was the major process of soil nitrogen transformation in the early growing season, while soil ammonification was the major one in the late growing season and non-growing season. The effects of experimental warming on soil nitrogen transformation differed among those three periods. Experimental warming significantly increased soil net ammonification, nitrification, nitrogen mine-ralization and fixation in the early growing season, and enhanced soil net nitrification and nitrogen mineralization in the non-growing season. However, warming significantly decreased soil net nitrification, nitrogen mineralization and fixation in the late growing season and soil net ammonification in the non-growing season. Moreover, warming did not affect soil net nitrogen fixation rates in the non-growing season and soil net nitrification rates in the late growing season. Future climate warming would significantly change soil nitrogen transformation by accelerating soil nitrogen cycling in the alpine scrub ecosystem on the eastern Qinghai-Tibet Plateau.


Assuntos
Nitrogênio , Solo , China , Ecossistema , Tibet
15.
Ying Yong Sheng Tai Xue Bao ; 32(6): 2079-2088, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212614

RESUMO

The sandy-hilly region of northwest Shanxi is a typical fragile agro-pastoral ecotone in north China. With the artificial Caragana korshinskii at 0 (the uncultivated land), 6, 12, 18, 40 and 50 years-old in the typical sandy-hilly region of northwest Shanxi as the subjects, we investigated soil moisture, aboveground and belowground biomass, individual morphological characteristics, growth, reproduction, and photosynthetic physiological characteristics of different-aged C. korshinskii, with the aim to evaluate the long-term growth and reproductive dynamic characteristics of artificial C. korshinskii. The results showed that soil moisture was significantly affected by stand ages. Soil moisture was low under the 6-year-old C. korshinskii plantation. During 6-18 years-old, soil moisture increased due to the increased crown width and reduced the near-surface wind speed, solar radiation, and soil water evaporation. During 18-50 years-old, soil moisture decreased sharply due to higher biomass and plant transpiration of C. korshinskii, and soil moisture was reduced to the lowest level of 11.1%. C. korshinskii mainly developed underground root system during 6-18 years-old, and changed to the aboveground biomass accumulation in 18-40 years-old. At the 40-year-old stand, biomass reached to the highest level with the greatest crown width and plant height. During 40-50 years-old, crown width and plant height decreased significantly, while the growth began to degrade. Photosynthetic capacity (chlorophyll a, b, carotenoid and total chlorophyll content) gra-dually decreased with the increases of planting ages, especially after 18 years-old. The quantity and quality of C. korshinskii seeds increased from 6 to 40 years-old, reached the maximum at 40 years-old stand, and began to decrease after 50 years-old. In the later growth period (30-40 years-old), more seeds with small individual weight were produced compared with early period (6-12 years-old). The germination test showed that small seeds had higher germination rate than the large ones under the same stand age, suggesting a shift of reproduction strategy. After 50 years-old, both of the growth and reproduction of C. korshinskii degenerated, and the plantation began to degrade.


Assuntos
Caragana , Adolescente , Adulto , Idoso , Criança , China , Clorofila A , Humanos , Pessoa de Meia-Idade , Reprodução , Solo , Água/análise , Adulto Jovem
16.
Ying Yong Sheng Tai Xue Bao ; 32(6): 2107-2118, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212617

RESUMO

Epikarst is the core area of karst critical zone, with important hydrologic regulation and storage function. However, the effects of karst development degree on hydrologic characteristics of epikasrt is still unclear. We used geophysical exploration and hydrogeological techniques, combined with the dynamic monitoring of moisture and water levels, to quantify the karst development degrees and their hydrologic characteristics on slope lands. We analyzed the responses of soil-epikarst systems to rainfall. Results showed that geophysical exploration technology could be well applied to the detection of surface-subsurface structures in the karst areas. The average thickness of soil and surface karst zone on the slope was less than 0.63 m and 2.60 m, respectively. The slopes of strong-karstification characterized by high apparent resistivity, well-developed joint fractures, and strong permeability (0.73 m·d-1). Such a result indicated that epikarst could regulate precipitation. The responses of soil moisture had a larger rainfall threshold (>20.50 mm·d-1) and the water level was determined by rainfall amount. In contrast, the slope with weak-karstification had low apparent resistivity and weak permeability (0.07 m·d-1). Moisture and water level were sensitive to rainfall. Karst channels were developed locally at 240-300 cm with a permeability coefficient of up to 432 mm·d-1. Obvious preferential flow was observed in extreme rainfall events on this slope, which could induce flood disaster in the adjacent depression. Our results would provide scientific basis for further research on water resources regulation, management, and eco-hydrology in karst areas of southwest China.


Assuntos
Hidrologia , Solo , Carbonato de Cálcio , China , Monitoramento Ambiental , Magnésio
17.
Ying Yong Sheng Tai Xue Bao ; 32(6): 2138-2146, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212620

RESUMO

We investigated the plant species richness both in cespitose Carex mires (C. schmidtii, C. meyeriana) and non-cespitose Carex mire (C. lasiocarpa) in Changbai Mountain. A total of 83 species (36 families, 59 genuses) was recorded in three sites. Among which, 71 species occurred in the C. meyeriana site, 61 species in the C. schmidtii site, and 26 species in the C. lasiocarpa site. The total species number and species richness in the two cespitose Carex mires were much higher than that in the non-cespitose Carex mire, while those on tussocks were much higher than between tussocks in the two cespitose Carex mires. Plant species richness on tussocks was positively related to the height, basal circumference and surface area of the tussocks, suggesting that tussocks were important for plant species diversity in Carex mires. Results of the canonical correspondence analysis indicated that the differences in soil water content, nutrient (soil organic carbon, total N, total P and C/N), and litter layer depth were the main factors influencing the differences of plant community composition on tussocks and between-tussocks. In the cespitose Carex mires, the hummock-hollow microtopography could foster high diversity by increasing surface area and creating multiple micro-habitats. Given its function in maintaining high species diversity, cespitose Carex could be a preferred species for vegetation restoration in degraded peat mires.


Assuntos
Carex (Planta) , Carbono , China , Humanos , Solo , Áreas Alagadas
18.
Ying Yong Sheng Tai Xue Bao ; 32(6): 2147-2157, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212621

RESUMO

Information on the spatial distribution of soil microbial communities on the Tibetan Pla-teau is critical for in-depth understanding the important roles of microbes in typical alpine ecosystems. In this study, 16S rDNA Illumina Miseq sequencing was used to analyze the variations in bacterial community composition and functional potentials in soils sampled from four elevations on Mount Segrila, Tibet, and the driving environmental factors. Results showed that richness and Shannon diversity index of soil bacteria significantly decreased with increasing altitude. The relative abundances of Acidobacteria, Chloroflexi, Gemmatimonadetes, and Nitrospirae significantly increased, whereas that of Proteobacteria, Actinobacteria and Bacteroidetes significantly decreased with increasing altitude. In KEGG pathway (level Ⅱ), the relative abundance of genes related to membrane transport and the metabolism of amino acids, lipids, terpenoids and polyketones was significantly lower at high elevations. In contrast, genes related to carbohydrates metabolism, signal transduction, replication and repair and enzyme family were more abundant at high altitudes. Soil bacterial community composition and predicted functions were significantly affected by vegetation types and soil properties, with soil pH being the key driver. There were significant correlations between the abundances of predicted functions and bacterial taxa, such as Acitnobacteria, Bacteroidetes, and Fibrobacteres. The dissimilarity in the composition of KEGG pathway genes along the elevational gradient (ß-diversity) showed a significantly positive correlation with the dissimilarity in bacterial community structure, indicating that there was a strong relationship between microbial community composition and potential functionality.


Assuntos
Microbiologia do Solo , Solo , Bactérias/genética , China , RNA Ribossômico 16S , Tibet
19.
Ying Yong Sheng Tai Xue Bao ; 32(6): 2199-2208, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212626

RESUMO

Soil microorganism was the engine of the migration and transformation of biological elements in the soil-plant system of wetland ecosystems. Exploring the relationship between plant community, soil properties, and spatial structure with soil microorganisms is the key to maintain the health and stability of wetlands. In order to examine the effects of plant community, soil properties, and spatial structure on the bacterial community in wetlands, we used two-way indicator species analysis (TWINSPAN) to classify plant communities from 35 samples collected in Bitahai Wetland. We measured microbial community composition at the surface soil of the samples using high-throughput sequencing technology, and analyzed the relationship among plant community, soil pro-perties and spatial structure with bacterial community. The results showed that plant communities could classified into three different types by TWINSPAN. The physiognomy and structure of plant communities in same community type were relatively consistent. We found that quantitative classification had good applicability in vegetation classification of plateau wetland ecosystem. Acidobacteriota (21.0%), Chloroflexi (15.5%), Proteobacteria (15.3%) and Bacteroidetes (10.1%) had higher population densities (≥10%) in Bitahai Wetland. Analysis of similarities (ANOSIM) showed that different plant community types differed significantly in bacterial community composition, suggesting that plant communities could affect bacterial community. Cano-nical correspondence analysis (CCA) results showed that plant diversity, soil water content (SWC), pH, iron (Fe) and spatial structure were the dominated factors that significantly affecting bacterial community. The variance partitioning analysis (VPA) results showed that bacterial community was affected by single environment factors and their interactions. Our results highlighted that bacterial community is shaped by plant community, soil properties and spatial structure, with their effects being indivisible.


Assuntos
Solo , Áreas Alagadas , Bactérias , China , Microbiologia do Solo
20.
Ying Yong Sheng Tai Xue Bao ; 32(6): 2209-2216, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34212627

RESUMO

The abundance of denitrifying functional genes plays a key role in driving the soil nitrous oxide (N2O) emission potential. Nitrite reductase genes (nirK and nirS) and nitrous oxide reductase genes (nosZ I and nosZ II) are the dominant denitrifying funtional genes. In this study, real-time quantitative PCR was conducted to evaluate the effects of 32-year imbalanced fertilization and lime and gypsum additions on the abundances of nirK, nirS, nosZ I and nosZ II genes in an Ultisol at Yingtan, Jiangxi Province. We further explored the underlying driving factors. The results showed that, compared with the balanced fertilization treatment, fertilization without phosphorus (P) signifi-cantly decreased the abundances of nirK, nirS, nosZ I and nosZ II genes. Fertilization without nitrogen (N) significantly reduced the abundances of nirK, nosZ I and nosZ II, but did not affect the abundance of nirS. Fertilization without potassium (K) did not affect the abundances of all denitri-fying functional genes. Results of stepwise regression analysis and random forest analysis showed that soil pH was a key environmental factor affecting the abundances of nosZ I and nosZ II. The application of lime or lime + gypsum significantly increased soil pH, which subsequently increased the abundances of nosZ II and nosZ II/nosZ I by 150%-231% and 127%-155%, respectively. Our results suggested that application of lime or lime + gypsum favored nosZ II more than nosZ I in upland Ultisols, which might enhance the relative importance of nosZ II in N2O reduction. Overall, fertilization without P would reduce denitrifying gene abundances, while the application of lime or lime + gypsum enriched nosZ II and increased ratio of nosZ II/nosZ I, which might be beneficial for reducing N2O emission potential in the Ultisols.


Assuntos
Sulfato de Cálcio , Microbiologia do Solo , Compostos de Cálcio , China , Desnitrificação , Fertilização , Óxido Nitroso/análise , Óxidos , Solo
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