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  • eDNA监测测序数据分析注释中参考数据库选择、指标阈值选择、目标数据准备的影响——以长江中游鱼类为监测目标

    分类: 生物学 >> 生态学 提交时间: 2024-01-23

    摘要: 在基于宏条形码(meta-barcoding)的eDNA监测技术路径中,eDNA测序数据的分析和注释是决定监测结果判断和评估精确与否甚至准确与否的基础,而参考数据库选择、指标阈值选择、目标数据准备是eDNA测序数据分析和注释中最为关键的3个技术环节。为弄清上述3个技术环节处理方案的影响,本研究以长江中游2组eDNA监测COI基因测序数据为分析对象,针对鱼类的检出做了3组实验来分别检验1)不同参考数据库及物种注释算法对注释结果的影响,2)不同OTU聚类序列相似度和物种注释分类置信度(序列一致性和序列覆盖度)对注释结果的影响,3)目标数据中各物种不同序列丰富度对注释结果的影响。结果显示:1)Blast算法下,3个版本nt库注释出的物种基本一致(72%~78%),2个本地序列参考库注释出的物种也基本一致(91%~96%),这5个序列参考库注释出的物种52%~68%一致;nt库RDP Classifier算法注释出的物种覆盖95%以上Blast算法注释出的物种,并比Blast算法注释出的物种多151%~443%,多出的物种大都是错误注释,本地参考数据库RDP Classifier算法注释出的物种覆盖66%~85%的Blast算法注释出的物种,并存在数条只注释到科属的结果。2)OTU聚类序列相似度阈值,取值0.999比取值0.99获得的OTU多154%~209%,注释到鱼类的OTU多240%~490%;注释分类置信度阈值(Blast算法,序列一致性和序列覆盖度)从0.8到0.99注释获得的物种组成基本(94%以上)一致,物种下的OTU组成也基本(83%以上)一致,注释分类置信度阈值取0.7时注释获得的物种组成、OTU组成和取0.8及以上时注释获得的有较大差异。3)在OTU聚类序列相似度阈值0.999、注释分类置信度阈值0.9时,多序列数据注释所得鱼类物种数、OTU数最多、物种注释正确率最高(达81.49%),分别比单序列数据的多7%、215%和高5%。在具体eDNA测序数据的分析和注释中,可通过建立完善本地参考数据库、优化OTU聚类序列相似度和物种注释分类置信度(序列一致性和序列覆盖度)取值、增加目标数据的丰富度来提高注释结果的准确性,但受制于物种注释算法的局限性,物种注释错误和注释遗漏的问题可能将长期存在,物种注释正确率通常低于85%(基于COI基因的eDNA监测)。

  • Spatiotemporal variations in ecosystem services and their trade-offs and synergies against the background of the gully control and land consolidation project on the Loess Plateau, China

    分类: 生物学 >> 生态学 提交时间: 2024-01-12 合作期刊: 《干旱区科学》

    摘要: Studying the spatiotemporal variations in ecosystem services and their interrelationships on the Loess Plateau against the background of the gully control and land consolidation (GCLC) project has significant implications for ecological protection and quality development of the Yellow River Basin. Therefore, in this study, we took Yan'an City, Shaanxi Province of China, as the study area, selected four typical ecosystem services, including soil conservation service, water yield service, carbon storage service, and habitat quality service, and quantitatively evaluated the spatiotemporal variation characteristics and trade-offs and synergies of ecosystem services from 2010 to 2018 using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) model. We also analysed the relationship between the GCLC project and regional ecosystem service changes in various regions (including 1 city, 2 districts, and 10 counties) of Yan'an City and proposed a coordinated development strategy between the GCLC project and the ecological environment. The results showed that, from 2010 to 2018, soil conservation service decreased by 7.76%, while the other three ecosystem services changed relatively little, with water yield service increasing by 0.56% and carbon storage service and habitat quality service decreasing by 0.16% and 0.14%, respectively. The ecological environment of Yan'an City developed in a balanced way between 2010 and 2018, and the four ecosystem services showed synergistic relationships, among which the synergistic relationships between soil conservation service and water yield service and between carbon storage service and habitat quality service were significant. The GCLC project had a negative impact on the ecosystem services of Yan'an City, and the impact on carbon storage service was more significant. This study provides a theoretical basis for the scientific evaluation of the ecological benefits of the GCLC project and the realization of a win-win situation between food security and ecological security.

  • Response of ecosystem carbon storage to land use change from 1985 to 2050 in the Ningxia Section of Yellow River Basin, China

    分类: 生物学 >> 生态学 提交时间: 2024-01-12 合作期刊: 《干旱区科学》

    摘要: Regional sustainable development necessitates a holistic understanding of spatiotemporal variations in ecosystem carbon storage (ECS), particularly in ecologically sensitive areas with arid and semi-arid climate. In this study, we calculated the ECS in the Ningxia Section of Yellow River Basin, China from 1985 to 2020 using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model based on land use data. We further predicted the spatial distribution of ECS in 2050 under four land use scenarios: natural development scenario (NDS), ecological protection scenario (EPS), cultivated land protection scenario (CPS), and urban development scenario (UDS) using the patch-generating land use simulation (PLUS) model, and quantified the influences of natural and human factors on the spatial differentiation of ECS using the geographical detector (Geodetector). Results showed that the total ECS of the study area initially increased from 1985 until reaching a peak at 402.36×106 t in 2010, followed by a decreasing trend to 2050. The spatial distribution of ECS was characterized by high values in the eastern and southern parts of the study area, and low values in the western and northern parts. Between 1985 and 2020, land use changes occurred mainly through the expansion of cultivated land, woodland, and construction land at the expense of unused land. The total ECS in 2050 under different land use scenarios (ranked as EPS>CPS>NDS>UDS) would be lower than that in 2020. Nighttime light was the largest contributor to the spatial differentiation of ECS, with soil type and annual mean temperature being the major natural driving factors. Findings of this study could provide guidance on the ecological construction and high-quality development in arid and semi-arid areas.
     

  • Spatiotemporal changes of gross primary productivity and its response to drought in the Mongolian Plateau under climate change

    分类: 生物学 >> 生态学 提交时间: 2024-01-12 合作期刊: 《干旱区科学》

    摘要: Gross primary productivity (GPP) of vegetation is an important constituent of the terrestrial carbon sinks and is significantly influenced by drought. Understanding the impact of droughts on different types of vegetation GPP provides insight into the spatiotemporal variation of terrestrial carbon sinks, aiding efforts to mitigate the detrimental effects of climate change. In this study, we utilized the precipitation and temperature data from the Climatic Research Unit, the standardized precipitation evapotranspiration index (SPEI), the standardized precipitation index (SPI), and the simulated vegetation GPP using the eddy covariance-light use efficiency (EC-LUE) model to analyze the spatiotemporal change of GPP and its response to different drought indices in the Mongolian Plateau during 1982–2018. The main findings indicated that vegetation GPP decreased in 50.53% of the plateau, mainly in its northern and northeastern parts, while it increased in the remaining 49.47% area. Specifically, meadow steppe (78.92%) and deciduous forest (79.46%) witnessed a significant decrease in vegetation GPP, while alpine steppe (75.08%), cropland (76.27%), and sandy vegetation (87.88%) recovered well. Warming aridification areas accounted for 71.39% of the affected areas, while 28.53% of the areas underwent severe aridification, mainly located in the south and central regions. Notably, the warming aridification areas of desert steppe (92.68%) and sandy vegetation (90.24%) were significant. Climate warming was found to amplify the sensitivity of coniferous forest, deciduous forest, meadow steppe, and alpine steppe GPP to drought. Additionally, the drought sensitivity of vegetation GPP in the Mongolian Plateau gradually decreased as altitude increased. The cumulative effect of drought on vegetation GPP persisted for 3.00–8.00 months. The findings of this study will improve the understanding of how drought influences vegetation in arid and semi-arid areas.
     

  • Soil seed bank is affected by transferred soil thickness and properties in the reclaimed coal mine in the Qilian Mountains, China

    分类: 生物学 >> 生态学 提交时间: 2023-12-20 合作期刊: 《干旱区科学》

    摘要: Reclamation of lands abandoned after mining in mountain areas is critical to erosion control, safety from landslides, and ecological protection of mountain ecosystems. However, little is known about alpine coal mine reclamation using the soil seed bank as a potential source for revegetation. We collected samples of persistent soil seed bank for germination experiments from nine reclaimed sites with different soil cover thicknesses and from six control sites in the Qilian Mountains of China. Soil properties of each site were determined (including soil water content, soil available potassium, soil available phosphorus, soil total nitrogen, pH, soil organic matter, soil total phosphorus, and soil total potassium, and soil alkali-hydrolyzable nitrogen), and the relationships of the characteristics of the soil seed bank with soil cover thickness and soil properties were examined. The results showed that the density, number of species, and diversity of the topsoil seed bank were significantly correlated with soil cover thickness, and all increased with the increment of soil cover thickness. Soil cover thickness controlled the soil seed bank by influencing soil properties. With the increase in soil cover thickness, soil properties (e.g., soil organic matter, soil total nitrogen, etc.) content increased while soil pH decreased. The soil seed bank had the potential to restored the pre-mining habitat at reclaimed sites with approximately 20-cm soil cover thickness. Soil properties of reclaimed sites were lower than that of natural sites. The relationship between the soil seed bank and soil cover thickness determined in this study provides a foundation for improving reclamation measures used in coal mines, as well as for the management and monitoring of reclaimed areas.
     

  • Effects of degradation and species composition on soil seed density in the alpine grasslands, China

    分类: 生物学 >> 生态学 提交时间: 2023-12-20 合作期刊: 《干旱区科学》

    摘要: Grassland degradation can alter the structure and function of ecosystem and soil seed bank. Therefore, estimating the role of soil seed bank in vegetation regeneration of degraded grasslands is crucial. We selected grasslands with three levels of degradation, namely non-degraded (ND), mildly degraded (MD), and heavily degraded (HD) to analyze the effect of grassland degradation on soil seed bank, as well as the role of soil seed bank on vegetation regeneration of the alpine grasslands, China. Soil samples from each level were collected in May, before seedling emergence, in August, after completion of transient seed bank germination, and in December, after seed dispersal, to determine the seed density and species composition through germination experiment. Result showed that a total of 35 plant species was identified, including 15 species observed in both soil seed bank and above-ground vegetation. A total of 19, 15, and 14 species of soil seed bank were identified in December, May, and August, respectively. The most abundant species in soil seed bank were Compositae (5 species), followed by Poaceae (4 species), and Cyperaceae (3 species). Degradation level has no significant impact on species richness and Shannon- Wiener index of soil seed bank. In addition, sampling month and grassland degradation affected soil seed bank density, in which December>May>August, and ND>MD>HD, indicating that density of transient seed bank was greater than persistent seed bank. Soil seed bank density of surface layer (0–5 cm) accounting for 42%–72% of the total density, which was significantly higher than that of deep layer (5–10 cm). Similarity of species composition between vegetation and soil seed bank was low, and it increased with degradation level (ranged from 0.14 to 0.69). We concluded that grassland degradation affects soil seed bank density more than species diversity, and soil seed bank contributed slightly to vegetation regeneration of degraded alpine grassland. Therefore, it is unlikely that degraded alpine meadow can be restored solely through soil seed bank.
     

  • Effects of dieback on the vegetative, chemical, and physiological status of mangrove forests, Iran

    分类: 生物学 >> 生态学 提交时间: 2023-11-13 合作期刊: 《干旱区科学》

    摘要: Mangrove forests are valuable resources in tropical and subtropical regions, which have been faced dieback due to various human activities including rapid expansion of shrimp farming, urban development, and pollution, as well as natural factors such as rising sea level, increasing air temperature, drought, and sharp decrease in rainfall. However, the mechanisms of dieback of mangrove forests are not well understood. Therefore, this research aimed to assess the vegetative, chemical, and physiological status of grey mangrove (Avicennia marina (Forsk.) Vierh.) forests at different intensities of dieback in the Hormozgan Province, Iran. A total of 40 plots categorized into four dieback intensities (severe, medium, low, and control) were randomly selected for monitoring, and various parameters related to vegetative, chemical, and physiological status of grey mangrove forests were examined. The results revealed that the control group had the highest tree density, seedling density, vitality levels, aerial root density, and aerial root height. Generally, as dieback severity increased, a decrease in demographic and vegetative parameters of trees and seedlings was observed in the dieback treatments. The amounts of heavy metals (lead, cadmium, and nickel) in the sediment, roots, and leaves of grey mangrove trees at different dieback levels indicated that lead levels were the highest in the sediment, roots, and leaves in the severe dieback treatment. At the same time, the control had the lowest values. Cadmium concentrations in the sediment followed the pattern of severe dieback>moderate dieback>low dieback>control with no significant differences in the roots and leaves. Nickel amounts in all three parts, i.e., sediment, roots, and leaves showed the highest levels in the severe dieback treatment. Furthermore, metal level analysis in the organs of grey mangrove trees at different dieback levels revealed that lead and nickel were more abundant in the root organ compared with the leaves. In contrast, the leaf organ exhibited the highest cadmium levels. Dieback significantly impacted water electrical conductivity (EC), soil organic carbon (SOC), and chlorophyll a, b, and total chlorophyll contents, with the highest values observed in the severe dieback treatment. However, no significant differences were observed in acidity and carotenoid levels. In conclusion, sediment erosion and heavy metal accumulation were critical contributors to dieback of grey mangrove trees, affecting their physiological, vegetative, and plant production characteristics. As the ability of these plants to rehabilitate has diminished, effective management planning is imperative in dieback-affected areas.
     

  • Evaluation of restoration success in arid rangelands of Iran based on the variation of ecosystem services

    分类: 生物学 >> 生态学 提交时间: 2023-11-13 合作期刊: 《干旱区科学》

    摘要: The plantation of non-native species is one of the most expensive ecological restoration measures in arid and semi-arid areas, while its impacts on local communities are largely ignored. This study assessed the rate of change and the dynamic degree of the economic values of ecosystem services related to local conservation (water yield, stocking rate and aesthetic value) and preserving the future (carbon sequestration, soil protection, soil stability and habitat provision) to determine the restoration success of the plantation of non-native species Haloxylon ammodendron (C.A.Mey.) Bunge ex Fenzl (15- and 30-year-old) in parts of arid rangelands of Bardsir region, Kerman Province, Iran. We investigated the impacts of the two plantations on the seven ecosystem services and ecosystem structures (horizontal and vertical structures, vegetation composition and species diversity) based on field sampling and measurements at four sampling sites (i.e., control, degraded, and 15- and 30-year-old plantation sites) in spring and summer of 2022. The restoration success of the plantation of non-native species was then examined by assessing the rate of change and the dynamic degree of the total economic value of all ecosystem services as well as the rate of change and the dynamic degree of the economic values of ecosystem services for the two groups (local conservation and preserving the future). Although the plantation of non-native species H. ammodendron enormously improved the vertical and horizontal structures of ecosystems, it failed to increase species diversity and richness fully. Further, despite the plantation of non-native species H. ammodendron had significantly increased the economic values of all ecosystem services, it was only quite successful in restoring carbon sequestration. Path analysis showed that plantation age had a significant impact on restoration success directly and indirectly (through changing ecosystem structures and services). The dynamic degree of the economic values of ecosystem services related to local conservation and preserving the future at the 15- and 30-year-old plantation sites indicated that the two plantations successfully restored the ecosystem services related to preserving the future. The presented method can help managers select the best restoration practices and predict their ecological-social success, especially for the plantation of high-risk non-native species in arid and semi-arid areas.
     

  • Temporal and spatial responses of ecological resilience to climate change and human activities in the economic belt on the northern slope of the Tianshan Mountains, China

    分类: 生物学 >> 生态学 提交时间: 2023-10-17 合作期刊: 《干旱区科学》

    摘要: In the Anthropocene era, human activities have become increasingly complex and diversified. The natural ecosystems need higher ecological resilience to ensure regional sustainable development due to rapid urbanization and industrialization as well as other intensified human activities, especially in arid and semi-arid areas. In the study, we chose the economic belt on the northern slope of the Tianshan Mountains (EBNSTM) in Xinjiang Uygur Autonomous Region of China as a case study. By collecting geographic data and statistical data from 2010 and 2020, we constructed an ecological resilience assessment model based on the ecosystem habitat quality (EHQ), ecosystem landscape stability (ELS), and ecosystem service value (ESV). Further, we analyzed the temporal and spatial variation characteristics of ecological resilience in the EBNSTM from 2010 to 2020 by spatial autocorrelation analysis, and explored its responses to climate change and human activities using the geographically weighted regression (GWR) model. The results showed that the ecological resilience of the EBNSTM was at a low level and increased from 0.2732 to 0.2773 during 2010–2020. The spatial autocorrelation analysis of ecological resilience exhibited a spatial heterogeneity characteristic of "high in the western region and low in the eastern region", and the spatial clustering trend was enhanced during the study period. Desert, Gobi and rapidly urbanized areas showed low level of ecological resilience, and oasis and mountain areas exhibited high level of ecological resilience. Climate factors had an important impact on ecological resilience. Specifically, average annual temperature and annual precipitation were the key climate factors that improved ecological resilience, while average annual evapotranspiration was the main factor that blocked ecological resilience. Among the human activity factors, the distance from the main road showed a negative correlation with ecological resilience. Both night light index and PM2.5 concentration were negatively correlated with ecological resilience in the areas with better ecological conditions, whereas in the areas with poorer ecological conditions, the correlations were positive. The research findings could provide a scientific reference for protecting the ecological environment and promoting the harmony and stability of the human-land relationship in arid and semi-arid areas.
     

  • Response of soil respiration to short-term changes in precipitation and nitrogen addition in a desert steppe

    分类: 生物学 >> 生态学 提交时间: 2023-10-17 合作期刊: 《干旱区科学》

    摘要:  Changes in precipitation and nitrogen (N) addition may significantly affect the processes of soil carbon (C) cycle in terrestrial ecosystems, such as soil respiration. However, relatively few studies have investigated the effects of changes in precipitation and N addition on soil respiration in the upper soil layer in desert steppes. In this study, we conducted a control experiment that involved a field simulation from July 2020 to December 2021 in a desert steppe in Yanchi County, China. Specifically, we measured soil parameters including soil temperature, soil moisture, total nitrogen (TN), soil organic carbon (SOC), soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), and contents of soil microorganisms including bacteria, fungi, actinomyces, and protozoa, and determined the components of soil respiration including soil respiration with litter (RS+L), soil respiration without litter (RS), and litter respiration (RL) under short-term changes in precipitation (control, increased precipitation by 30%, and decreased precipitation by 30%) and N addition (0.0 and 10.0 g/(m2–a)) treatments. Our results indicated that short-term changes in precipitation and N addition had substantial positive effects on the contents of TN, SOC, and SMBC, as well as the contents of soil actinomyces and protozoa. In addition, N addition significantly enhanced the rates of RS+L and RS by 4.8% and 8.0% (P<0.05), respectively. The increase in precipitation markedly increased the rates of RS+L and RS by 2.3% (P<0.05) and 5.7% (P<0.001), respectively. The decrease in precipitation significantly increased the rates of RS+L and RS by 12.9% (P<0.05) and 23.4% (P<0.001), respectively. In contrast, short-term changes in precipitation and N addition had no significant effects on RL rate (P>0.05). The mean RL/RS+L value observed under all treatments was 27.63%, which suggested that RL is an important component of soil respiration in the desert steppe ecosystems. The results also showed that short-term changes in precipitation and N addition had significant interactive effects on the rates of RS+L, RS, and RL (P<0.001). In addition, soil temperature was the most important abiotic factor that affected the rates of RS+L, RS, and RL. Results of the correlation analysis demonstrated that the rates of RS+L, RS, and RL were closely related to soil temperature, soil moisture, TN, SOC, and the contents of soil microorganisms, and the structural equation model revealed that SOC and SMBC are the key factors influencing the rates of RS+L, RS, and RL. This study provides further insights into the characteristics of soil C emissions in desert steppe ecosystems in the context of climate change, which can be used as a reference for future related studies.
     

  • 南非如何发展旅游业

    分类: 地球科学 >> 地理学 分类: 生物学 >> 生态学 分类: 法学 >> 民商法学 分类: 管理学 >> 部门经济管理 分类: 其他 >> 综合 提交时间: 2023-10-06

    摘要: 目的/意义 南非是世界知名的“旅游天堂”。对南非如何发展旅游业进行专题研究,能够为我国提供有益借鉴。 方法/过程 本文主要基于国外研究资料,运用文献研究方法,对南非发展旅游业的经验进行了总结。 结果/结论 在发展旅游业上,南非主要有五方面成功经验:一是对旅游业高度重视,采取了包括制定《旅游法》、出台旅游业发展战略和规划、成立南非旅游部和南非旅游局等在内的一系列举措;二是积极提升软硬件设施;三是努力实现旅游产品的多样化;四是践行“负责任旅游”理念;五是大力发展国内旅游业。

  • 鄯善库木塔格沙漠北缘细菌群落结构特征及影响因素

    分类: 生物学 >> 生态学 提交时间: 2023-08-26 合作期刊: 《干旱区研究》

    摘要: 鄯善库木塔格沙漠是一个与城市相连的沙漠,蕴含着丰富独特的微生物菌株资源。为了探究鄯善库木塔格沙漠的微生物群落结构以及其与环境因子之间的关系,采集了鄯善库木塔格沙漠北缘4个样点的表层(0~5 cm)和深层(45~50 cm)的沙土样本,并测定了其含水量(WC)、pH、总碳(TC)、总氮(TN)、总有机碳(TOC)和电导率(EC);利用高通量测序技术,研究不同采样点、不同深度沙土样本的细菌群落结构;运用Spearman相关性分析环境因子和细菌群落结构之间的相关性,探讨影响细菌群落结构的主要因素。结果表明:鄯善库木塔格沙漠北缘沙土样本呈碱性;门水平上的优势菌是放线菌(Actinobacteria)、厚壁菌(Firmicutes)和变形菌(Proteobacteria),属水平上的优势菌是unclassified_f__Micrococcaceae、Bacillus、Sphingomonas、Escherichia-Shigella。PCoA分析表明,鄯善库木塔格沙漠北缘不同样点之间的细菌群落结构存在显著差异(P<0.05);表层和深层样本的物种多样性没有显著差异。RDA分析表明,WC、TC、TN和pH显著影响表层样本的细菌群落结构(P<0.05),TOC含量显著影响深层样本的细菌群落结构(P<0.05)。本研究为后期鄯善库木塔格沙漠及相似生境中微生物资源的发掘提供了理论依据。

  • 天山南坡山前荒漠草地植物群落分布对环境因子的响应——以拜城县为例

    分类: 生物学 >> 生态学 提交时间: 2023-08-26 合作期刊: 《干旱区研究》

    摘要: 为探明天山南坡拜城县山前荒漠草地植物群落分布对地形与土壤因子的响应,本研究选取了拜城山前荒漠草地典型区域进行调查,采用优势度法和典范对应分析(Canonical correspondence analysis,CCA)法,研究山地荒漠草地植物群落分布与地形和土壤因子之间的关系。结果表明:(1)不同调查样点灌木层和草本层物种多样性存在差异,东坡调查样点Shannon-Wiener指数、Pielou指数和Simpson指数均表现为灌木大于草本,西坡和北坡调查样点Shannon-Wiener指数、Pielou指数和Simpson指数均表现为草本大于灌木;(2)典范对应分析法分析结果表明,地形因子对植物群落的影响大小顺序为:坡向(SA)>坡度(SG)>坡位(SP),土壤因子对植物群落的影响大小为:30~100 cm土层土壤水分(SMC-2)>土壤总孔隙度(STP)>0~30 cm土层土壤水分(SMC-1)。地形和土壤因子对不同植物群落的形成具有一定的筛选作用,30~100 cm土层土壤水分和坡向是影响天山南坡拜城县山前荒漠草地植物群落分布的关键因子。

  • 人类活动对额尔齐斯河流域碳储量的影响

    分类: 生物学 >> 生态学 提交时间: 2023-08-26 合作期刊: 《干旱区研究》

    摘要: 基于阿尔泰山额尔齐斯河流域2000—2020年土地利用数据,运用InVEST模型,模拟并分析了不同时期该流域碳储量空间分布,并探讨了人类活动对碳储量空间分布的影响。研究表明:(1)流域内土地利用类型以草地和未利用地为主,2000—2020年土地利用格局发生明显改变,耕地和城乡、工矿、居民用地分别增加2619.35 km2和186.68 km2;草地和水域分别增加4725.13 km2和33.47 km2;林地和未利用地分别减少2328.88 km2和5237.76 km2。(2)研究期间,流域内碳储量空间分布格局较为相似且呈现带状分布,高值区分布在高海拔地区,低值区分布在低海拔地区,2000年、2005年、2010年、2015年和2020年流域内碳储量总量分别为641.60 Tg、645.78 Tg、646.83 Tg、650.28 Tg和665.91 Tg,其年增长率为0.95%,呈现上升趋势。(3)流域内碳储量减少或增加的区域呈现点状分布,2000—2020年碳储量的增加量大于减少量,因此,额尔齐斯河流域的固碳能力呈上升趋势。

  • 沙封区农户生计资本对生计策略选择敏感性影响——以临泽县为例

    分类: 生物学 >> 生态学 提交时间: 2023-08-26 合作期刊: 《干旱区研究》

    摘要: 沙化土地封禁保护区(沙封区)是我国对暂不具备治理条件和不宜开发的连片沙化土地,通过封禁等方法预防土地沙化,恢复区域植被,维护生态安全,促进经济和社会可持续发展的重要手段。农户作为沙封区活动的主体,沙封区的建设对当地农户生计产生影响,为探究该区域生计资本对生计策略选择的影响。本文采用参与式农村评估法(PRA)以沙化土地封禁保护区张掖市临泽县为例,在SLA(Sustainable Livelihoods Approach)可持续分析框架基础上结合二元Logistic回归模型,分析农户生计资本对生计策略的敏感性影响。结果表明:(1)自然和人力资本显著影响纯农型生计策略的选择,物质和社会资本对农户选择兼农型生计策略的影响显著,而金融资本是农户选择非农型生计策略最主要的影响因素。(2)农户生计资本的储量影响农户对不同类型生计策略的选择,储量越多,选择的敏感性越强。(3)不同类型农户对调整现有生计策略的意愿存在较大差异,68%的纯农型和56%的兼农型农户希望调整现有的生计策略;但63%的非农户无调整现有生计策略的意愿。该结果对提高沙封区农户生计和生态安全,促进社会经济可持续发展提供重要理论依据。

  • 面向SDGs的塔里木河流域农业灰水足迹分析

    分类: 生物学 >> 生态学 提交时间: 2023-08-26 合作期刊: 《干旱区研究》

    摘要: 塔里木河流域地处西北干旱区是新疆重要的农牧资源交错带,研究该流域农业面源污染对促进流域农业绿色可持续发展具有重要意义。本文在灰水足迹理论的基础上,引入中国可持续发展评价指标,计算2006—2020年塔里木河流域农业灰水足迹、农业灰水足迹强度和农业灰水足迹效率,基于SDGs可持续发展框架分析其时空格局变化特征。结果表明:(1)2006年以来,塔里木河流域农业灰水足迹整体处于下降趋势,由2006年的6.95×1010 m3(最高值)降至2017年的3.96×1010 m3(最低值),畜牧业灰水足迹在流域农业灰水足迹中年均占比为91.3%,是流域农业灰水足迹的主要来源。喀什地区对流域农业灰水足迹贡献率最高。(2)塔里木河流域农业灰水足迹强度由2006年的4.48×104 m3·hm-2下降至2017年的1.68×104 m3·hm-2,下降幅度为62.5%。2012年后,和田地区、喀什地区与克州农业面源污染下降幅度较为明显。(3)塔里木河流域农业灰水足迹效率由2006年的0.6元·m-3上升为2019年4.03元·m-3。2012—2020年塔里木河流域农业灰水足迹效率有一定程度的提升,不发达地区数量有所下降。为此,推进农区农牧耦合发展,调整畜禽养殖结构,提高畜禽粪便的资源化是塔里木河流域水环境改善关注的重点。

  • 油蒿与沙柳灌木地藓结皮发育差异研究

    分类: 生物学 >> 生态学 提交时间: 2023-08-25 合作期刊: 《干旱区研究》

    摘要: 针对毛乌素沙地油蒿灌木地的藓结皮发育总是明显优于沙柳灌木地的现象,基于两类灌木地的土壤性状、藓结皮发育指标的观测分析,结合两类灌木不同器官浸提液对藓结皮发育的化感试验,揭示造成两类灌木地中藓结皮发育差异巨大的原因。结果显示:(1)两类灌木地藓结皮的盖度存在显著差异(P<0.05),灌木地藓结皮的总盖度及冠层下、冠层间盖度均表现为:油蒿>沙柳,且油蒿灌木地的藓结皮总盖度及冠层下、冠层间的藓结皮盖度分别为沙柳灌木地相应藓结皮盖度的1.6倍、2.9倍和1.1倍;(2)Pearson相关分析显示,冠层下藓结皮盖度与土壤含水率显著正相关、厚度与粉粒含量显著正相关;冠层间藓结皮盖度与土壤含水率、黏粒含量显著正相关(P<0.05)。油蒿灌木地较高的土壤含水率和黏粒、粉粒含量明显促进了藓结皮的发育;(3)化感试验表明,油蒿、沙柳的根、茎、叶水浸提液均抑制了藓结皮的发育,即化感综合效应(SE)均为负值。其中,0.2 g·mL-1沙柳叶水浸提液的化感抑制作用最强,SE为-0.95,抑制作用显著高于油蒿叶(SE为-0.65)(P<0.05)。表明油蒿灌木地较高的土壤含水率、黏粒和粉粒含量,以及沙柳叶对藓结皮显著的化感抑制作用,共同导致油蒿灌木地藓结皮的发育状况优于沙柳地。

  • Effects of nitrogen and phosphorus additions on soil microbial community structure and ecological processes in the farmland of Chinese Loess Plateau

    分类: 生物学 >> 生态学 提交时间: 2023-08-15 合作期刊: 《干旱区科学》

    摘要: Microorganisms regulate the responses of terrestrial ecosystems to anthropogenic nutrient inputs. The escalation of anthropogenic activities has resulted in a rise in the primary terrestrial constraining elements, namely nitrogen (N) and phosphorus (P). Nevertheless, the specific mechanisms governing the influence of soil microbial community structure and ecological processes in ecologically vulnerable and delicate semi-arid loess agroecosystems remain inadequately understood. Therefore, we explored the effects of different N and P additions on soil microbial community structure and its associated ecological processes in the farmland of Chinese Loess Plateau based on a 36-a long-term experiment. Nine fertilization treatments with complete interactions of high, medium, and low N and P gradients were set up. Soil physical and chemical properties, along with the microbial community structure were measured in this study. Additionally, relevant ecological processes such as microbial biomass, respiration, N mineralization, and enzyme activity were quantified. To elucidate the relationships between these variables, we examined correlation-mediated processes using statistical techniques, including redundancy analysis (RDA) and structural equation modeling (SEM). The results showed that the addition of N alone had a detrimental effect on soil microbial biomass, mineralized N accumulation, and β-1,4-glucosidase activity. Conversely, the addition of P exhibited an opposing effect, leading to positive influences on these soil parameters. The interactive addition of N and P significantly changed the microbial community structure, increasing microbial activity (microbial biomass and soil respiration), but decreasing the accumulation of mineralized N. Among them, N24P12 treatment showed the greatest increase in the soil nutrient content and respiration. N12P12 treatment increased the overall enzyme activity and total phospholipid fatty acid (PLFA) content by 70.93%. N and P nutrient contents of the soil dominate the microbial community structure and the corresponding changes in hydrolytic enzymes. Soil microbial biomass, respiration, and overall enzyme activity are driven by mineralized N. Our study provides a theoretical basis for exploring energy conversion processes of soil microbial community and environmental sustainability under long-term N and P additions in semi-arid loess areas.

  • Long-term light grazing does not change soil organic carbon stability and stock in biocrust layer in the hilly regions of drylands

    分类: 生物学 >> 生态学 提交时间: 2023-08-15 合作期刊: 《干旱区科学》

    摘要: Livestock grazing is the most extensive land use in global drylands and one of the most extensive stressors of biological soil crusts (biocrusts). Despite widespread concern about the importance of biocrusts for global carbon (C) cycling, little is known about whether and how long-term grazing alters soil organic carbon (SOC) stability and stock in the biocrust layer. To assess the responses of SOC stability and stock in the biocrust layer to grazing, from June to September 2020, we carried out a large scale field survey in the restored grasslands under long-term grazing with different grazing intensities (represented by the number of goat dung per square meter) and in the grasslands strictly excluded from grazing in four regions (Dingbian County, Shenmu City, Guyuan City and Ansai District) along precipitation gradient in the hilly Loess Plateau, China. In total, 51 representative grassland sites were identified as the study sampling sites in this study, including 11 sites in Guyuan City, 16 sites in Dingbian County, 15 sites in Shenmu City and 9 sites in Ansai District. Combined with extensive laboratory analysis and statistical analysis, at each sampling site, we obtained data on biocrust attributes (cover, community structure, biomass and thickness), soil physical-chemical properties (soil porosity and soil carbon-to-nitrogen ratio (C/N ratio)), and environmental factors (mean annual precipitation, mean annual temperature, altitude, plant cover, litter cover, soil particle-size distribution (the ratio of soil clay and silt content to sand content)), SOC stability index (SI) and SOC stock (SOCS) in the biocrust layer, to conduct this study. Our results revealed that grazing did not change total biocrust cover but markedly altered biocrust community structure by reducing plant cover, with a considerable increase in the relative cover of cyanobacteria (23.1%) while a decrease in the relative cover of mosses (42.2%). Soil porosity and soil C/N ratio in the biocrust layer under grazing decreased significantly by 4.1%–7.2% and 7.2%–13.3%, respectively, compared with those under grazing exclusion. The shifted biocrust community structure ultimately resulted in an average reduction of 15.5% in SOCS in the biocrust layer under grazing. However, compared with higher grazing (intensity of more than 10.00 goat dung/m2), light grazing (intensity of 0.00–10.00 goat dung/m2 or approximately 1.20–2.60 goat/(hm2•a)) had no adverse effect on SOCS. SOC stability in the biocrust layer remained unchanged under long-term grazing due to the offset between the positive effect of the decreased soil porosity and the negative effect of the decreased soil C/N ratio on the SOC resistance to decomposition. Mean annual precipitation and soil particle-size distribution also regulated SOC stability indirectly by influencing soil porosity through plant cover and biocrust community structure. These findings suggest that proper grazing might not increase the CO2 release potential or adversely affect SOCS in the biocrust layer. This research provides some guidance for proper grazing management in the sustainable utilization of grassland resources and C sequestration in biocrusts in the hilly regions of drylands.
     

  • 青藏高原沙柳河流域自然径流驱动的流域生物信息流量化特征——以环境微生物为指标

    分类: 生物学 >> 生态学 提交时间: 2023-07-06

    摘要: 物质流、能量流、信息流是生态系统过程研究中的三大主题。然而,在流域生态学研究中,有关信息流的研究一直缺位。为了推动流域信息流研究,从生物信息流切入,提出“流域生物信息流”概念,将其定义为“生物信息依托于流域生态系统过程在不同空间和系统之间进行传递、交流、作用、反馈的路径、过程与控制”,并将其研究内容拟定为主要关注于水陆间、干支流间、上下游间、不同生态斑块间的流域生物信息流及其周期性节律和趋势性变迁,以及地貌、水文、人类活动等对这些生物信息流的影响等。然后,以青藏高原上青海湖重要入湖河流——沙柳河的河流水体微生物和岸带土壤微生物为研究对象,利用环境DNA技术,对沙柳河流域的自然径流驱动的流域生物信息流进行量化研究。结果表明(1)岸带土壤到水体的流域生物信息流主要由地表表面流、地下潜流等驱动,并受环境过滤效应影响,其输移效率降雨天约为62.76%、晴天约为44.16%,其中输移能力降雨天约为68.49%、晴天约为56.82%,环境过滤效应降雨天约为8.38%、晴天约为22.28%;(2)水体上游到下游的流域生物信息流主要由河川径流驱动,并受衰减效应影响,其基础综合输移效率约为97.41%/km,其中径流输移能力约为99.42%/km,无效流域生物信息流占比约为43.46%,无效流域生物信息流的半衰距离约为14.52 km;(3)降雨通过增加地表表面流等的冲蚀搬运能力并削弱环境过滤效应,促使岸带土壤到水体的流域生物信息流输移能力和输移效率增大;(4)流域生物信息流的输入在一定程度上增加了输入地的可检出生物多样性,但这种增加对于流水生态系统来讲是非累积的。