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1.
J Environ Manage ; 255: 109925, 2020 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-32063306

RESUMEN

The Bashang Plateau, which is an ecologically fragile agro-pastoral zone in Hebei Province in China, plays an important role in protecting the Beijing-Tianjin-Hebei region from wind and sand erosion. Over the last four decades, it has been the target of extensive afforestation campaigns to promote improved ecosystem services. Though the benefits and costs of afforestation and its effectiveness within forestry have been widely investigated, few studies have focused on local households' willingness to accept (WTA) compensation relating to afforestation policies. Moreover, despite their importance in ensuring effective afforestation policies, the factors influencing WTA values have seldom been examined. We administered a direct questionnaire survey of households on the Bashang Plateau and applied a contingent valuation analysis to estimate their WTA values for compensation associated with ecological protection policies. We obtained 249 valid questionnaires, evidencing a high response rate (92.22%). New indicators of factors influencing respondents' WTA has been conducted including social, economic and ecological aspects, especially the improvement of ecological factors which consists of respondents' perceptions regarding the importance of ES and their satisfaction levels, and other environmental awareness factors. Additionally, in the case where many studies performed only one single regression analysis, this study performed a two-stage regression analysis and compared the results with those obtained using the Tobit model. A reasonable compensation standard facilitates a positive relationship between economic development and protection of natural environments. The findings showed that a certain amount of compensation (approximately 477.91 CNY/mu/year) was likely to prompt households' participation in afforestation projects. Compared with compensation standards for other ecological projects, the reported standard for afforestation projects on the Bashang Plateau is low, indicating that there is room for improvement. High annual household incomes are a key factor influencing households' WTA regarding their participation in afforestation activities. The results also revealed households' environmental awareness. Among respondents who participated in afforestation, those who valued forests for protecting environments and improving ecosystem services opted for lower compensation amounts. Our findings contribute valuable inputs for formulating ecological compensation standards and can serve as a reference for analyses of WTA and factors that drive it in other similar economically backward and ecologically fragile regions.


Asunto(s)
Ecología , Ecosistema , Beijing , China , Conservación de los Recursos Naturales , Bosques
2.
J Environ Manage ; 255: 109831, 2020 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-32063316

RESUMEN

Zostera capensis is a keystone species providing essential ecosystem services to southern African coastal systems. Like most seagrasses globally, Z. capensis is declining and under threat from anthropogenic pressures, and indicators of seagrass health and resilience may be of interest in preventing further declines. As intraspecific diversity is an important component of resilience, we used a pooled RADseq approach to generate genome-wide measures of variation across the entire South African distribution of Z. capensis. Using nucleotide diversity, heterozygosity and allelic richness we tested for associations with fine-scale anthropogenic pressure data compiled by the South African National Biodiversity Assessment using generalised linear models. Increased fishing effort, habitat loss, sand mining and a change in estuary flow dynamics were found to play an important role in decreasing nucleotide diversity and expected heterozygosity, most likely due to the loss of less resilient genotypes as a result of direct physical damage or indirect consequences. As the building block for adaptation, nucleotide diversity is particularly important for resilience. Because of this, as well as the fact that nucleotide diversity displayed the most distinct difference between the west and east coast, and responded most strongly to anthropogenic pressures, we suggest that this may be a useful measure for monitoring genetic or genomic variation. As genomic diversity influences resilience and resistance to disturbances, the remaining diversity in South African seagrass beds urgently needs to be conserved through restoration efforts and careful management of pressures.


Asunto(s)
Zosteraceae , Biodiversidad , Ecosistema , Estuarios , Genómica
3.
J Environ Manage ; 255: 109854, 2020 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-32063317

RESUMEN

Traditional reclamation consists of landform reconstruction characterized by uniform topography and linear slopes. Geomorphic reclamation improves on traditional reclamation by recreating heterogeneous landforms that blend into surrounding landscapes. Environmental heterogeneity created by geomorphic design is expected to increase the number of available ecological niches, and thus increase plant species diversity when compared with traditional reclamation practices. We sampled plant communities at two reclaimed surface mines in Wyoming using line-point intercept transects to compare vegetative diversity, composition, and structure between sites reclaimed using geomorphic and traditional methods. Greater species richness and Simpson's diversity were observed in geomorphic reclamation at the first site, but did not differ significantly at the second site, although geomorphic reclamation was more likely to resemble undisturbed controls. Shrub abundance was up to 10 times greater on geomorphic reclamation compared to traditional reclamation. Neither reclamation method achieved levels of vegetative diversity observed on nearby, undisturbed rangeland. Geomorphic methods have potential benefits for restoration of vegetative diversity and foundation species such as Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis). Our results suggest geomorphic reclamation may improve plant community diversity and wildlife habitat as a practical method for landscape-level restoration in post-mining sites.


Asunto(s)
Artemisia , Ecosistema , Wyoming
4.
5.
Science ; 367(6478): 626-627, 2020 02 07.
Artículo en Inglés | MEDLINE | ID: mdl-32029614
6.
J Environ Manage ; 259: 109754, 2020 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-32072949

RESUMEN

The purpose of this paper is to contribute with a tool to guide decision makers with some level of understanding of coastal dynamics as to the most appropriate management measures to adopt. A set of indices for assessing beach-dune systems and their potential for dune restoration are presented. The systems analysed are described using variables related to physical and anthropic factors, and the sites are classified according to the intervention actions required. Fifty beach-dune systems representing the range of types of beaches, the degree of urbanisation, and the dune morphologies found on the Catalan coastline (NE Iberian Peninsula) are sampled. The results show that beaches with the most developed dunes usually have high scores for management and low scores for urbanisation, while the less developed dunes are found on beaches with very low scores for management. Regarding the potential for dune restoration, the beaches are classified into four groups according to the management measures recommended: dune conservation, dune restoration, dune recovery, and renaturalisation of beaches where only incipient dunes can be developed.


Asunto(s)
Ecosistema
7.
BMC Ecol ; 20(1): 6, 2020 02 03.
Artículo en Inglés | MEDLINE | ID: mdl-32013942

RESUMEN

BACKGROUND: Assessing wildlife movements and habitat use is important for species conservation and management and can be informative for understanding population dynamics. The African buffalo (Syncerus caffer) population of Ruaha National Park, Tanzania has been declining, and little was known about the movement, habitat selection, and space use of the population, which is important for understanding possible reasons behind the decline. A total of 12 African buffalo cows from four different herds were collared with satellite transmitters. Movements were assessed over 2 years from 11 animals. RESULTS: The space use of the individual collared buffaloes as an approximation of the 95% home range size estimated using Brownian bridge models, ranged from 73 to 601 km2. The estimated home ranges were larger in the wet season than in the dry season. With the exception of one buffalo all collared animals completed a wet season migration of varying distances. A consistent pattern of seasonal movement was observed with one herd, whereas the other herds did not behave the same way in the two wet seasons that they were tracked. Herd splitting and herd switching occurred on multiple occasions. Buffaloes strongly associated with habitats near the Great Ruaha River in the dry season and had little association to permanent water sources in the wet season. Daily movements averaged 4.6 km (standard deviation, SD = 2.6 km), with the longest distances traveled during November (mean 6.9 km, SD = 3.6 km) at the end of the dry season and beginning of the wet season. The shortest daily distances traveled occurred in the wet season in April-June (mean 3.6 km, SD = 1.6-1.8 km). CONCLUSION: The Great Ruaha River has experienced significant drying in the last decades due to water diversions upstream, which likely has reduced the suitable range for buffaloes. The loss of dry season habitat due to water scarcity has likely contributed to the population decline of the Ruaha buffaloes.


Asunto(s)
Búfalos , Parques Recreativos , Animales , Bovinos , Ecosistema , Femenino , Estaciones del Año , Tanzanía
8.
BMC Ecol ; 20(1): 7, 2020 02 06.
Artículo en Inglés | MEDLINE | ID: mdl-32028944

RESUMEN

BACKGROUND: Spartina alterniflora is an invasive plant on the coast of China that replaces native vegetation and has a serious negative impact on local ecosystems. Monitoring the spatial distribution of S. alterniflora and its changes over time can reveal its expansion mechanism, which is crucial for the management of coastal ecosystems. The purpose of this study was to map the distribution of S. alterniflora in Zhejiang Province from 1985 to 2015 using a time series of Landsat TM/OLI images and analyze the temporal and spatial patterns of expansion of this species. RESULTS: After analyzing the distribution of coastal vegetation, the vegetation index was calculated based on Landsat images for 4 years (1985, 1995, 2005 and 2015). According to a threshold determined based on expert knowledge, the distribution of S. alterniflora in Zhejiang Province was extracted, and the temporal and spatial changes in the distribution of S. alterniflora were analyzed. The classification accuracy was 90.3%. S. alterniflora has expanded rapidly in recent decades after being introduced into southern Zhejiang. Between 1985 and 2015, S. alterniflora increased its area of distribution by 10,000 hm2, and it replaced native vegetation to become the most abundant halophyte in tidal flats. Overall, S. alterniflora expanded from south to north over the decades of the study, and the fastest expansion rate was 463.64 hm2/year, which occurred between 1995 and 2005. S. alterniflora was widely distributed in the tidal flats of bays and estuaries and expanded outward as sediment accumulated. CONCLUSIONS: This study reveals the changes over time in S. alterniflora cover in Zhejiang and can contribute to the control and management of this invasive plant.


Asunto(s)
Ecosistema , Humedales , China , Especies Introducidas , Poaceae
10.
Ambio ; 49(3): 666-677, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31955396

RESUMEN

Vegetation change has consequences for terrestrial ecosystem structure and functioning and may involve climate feedbacks. Hence, when monitoring ecosystem states and changes thereof, the vegetation is often a primary monitoring target. Here, we summarize current understanding of vegetation change in the High Arctic-the World's most rapidly warming region-in the context of ecosystem monitoring. To foster development of deployable monitoring strategies, we categorize different kinds of drivers (disturbances or stresses) of vegetation change either as pulse (i.e. drivers that occur as sudden and short events, though their effects may be long lasting) or press (i.e. drivers where change in conditions remains in place for a prolonged period, or slowly increases in pressure). To account for the great heterogeneity in vegetation responses to climate change and other drivers, we stress the need for increased use of ecosystem-specific conceptual models to guide monitoring and ecological studies in the Arctic. We discuss a conceptual model with three hypothesized alternative vegetation states characterized by mosses, herbaceous plants, and bare ground patches, respectively. We use moss-graminoid tundra of Svalbard as a case study to discuss the documented and potential impacts of different drivers on the possible transitions between those states. Our current understanding points to likely additive effects of herbivores and a warming climate, driving this ecosystem from a moss-dominated state with cool soils, shallow active layer and slow nutrient cycling to an ecosystem with warmer soil, deeper permafrost thaw, and faster nutrient cycling. Herbaceous-dominated vegetation and (patchy) bare ground would present two states in response to those drivers. Conceptual models are an operational tool to focus monitoring efforts towards management needs and identify the most pressing scientific questions. We promote greater use of conceptual models in conjunction with a state-and-transition framework in monitoring to ensure fit for purpose approaches. Defined expectations of the focal systems' responses to different drivers also facilitate linking local and regional monitoring efforts to international initiatives, such as the Circumpolar Biodiversity Monitoring Program.


Asunto(s)
Ecosistema , Tundra , Regiones Árticas , Cambio Climático , Suelo , Svalbard
11.
Ambio ; 49(3): 655-665, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31955398

RESUMEN

The Arctic is undergoing biological and environmental changes, and a coordinated effort to monitor is critical to detect these changes. The Circumpolar Biodiversity Monitoring Programme (CBMP) of the Arctic Council biodiversity working group, Conservation of Arctic Flora and Fauna (CAFF), has developed pan-Arctic biodiversity monitoring plans that aims to improve the ability to detect and report on long-term changes. Whilst introducing this special issue, this paper also presents the making of the terrestrial monitoring plan and discusses how the plan follows the steps required for an adaptive and ecosystem-based monitoring programme. In this article, we discuss how data on key findings can be used to inform circumpolar and global assessments, including the State of the Arctic Terrestrial Biodiversity Report, which will be the first terrestrial assessment made by the CBMP. Key findings, advice for future monitoring and lessons learned will be used in planning next steps of pan-Arctic coordinated monitoring.


Asunto(s)
Ecosistema , Monitoreo del Ambiente , Regiones Árticas , Biodiversidad
12.
Ambio ; 49(3): 833-847, 2020 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-31955399

RESUMEN

This review provides a synopsis of the main findings of individual papers in the special issue Terrestrial Biodiversity in a Rapidly Changing Arctic. The special issue was developed to inform the State of the Arctic Terrestrial Biodiversity Report developed by the Circumpolar Biodiversity Monitoring Program (CBMP) of the Conservation of Arctic Flora and Fauna (CAFF), Arctic Council working group. Salient points about the status and trends of Arctic biodiversity and biodiversity monitoring are organized by taxonomic groups: (1) vegetation, (2) invertebrates, (3) mammals, and (4) birds. This is followed by a discussion about commonalities across the collection of papers, for example, that heterogeneity was a predominant pattern of change particularly when assessing global trends for Arctic terrestrial biodiversity. Finally, the need for a comprehensive, integrated, ecosystem-based monitoring program, coupled with targeted research projects deciphering causal patterns, is discussed.


Asunto(s)
Biodiversidad , Ecosistema , Animales , Regiones Árticas , Aves , Invertebrados
13.
Ying Yong Sheng Tai Xue Bao ; 31(1): 1-8, 2020 Jan.
Artículo en Chino | MEDLINE | ID: mdl-31957374

RESUMEN

Endangered plant species are an important part of global biodiversity. To understand the competition patterns and mechanisms of endangered tree species from plant growth forms in the middle subtropical forest ecosystems, we examined the differences in intra- and inter-specific competitions between Toona ciliate var. pubescens (an intolerant of shade, deciduous species) and Taxus chinensis var. mairei (a tolerant of shade, evergreen species) in the Jiulingshan National Nature Reserve, Jiangxi Province. The results showed that intra-specific competition was dominant in the T. ciliate var. pubescens population, accounting for 66.4% of the total competition intensity. In contrary, the competitive intensity of T. chinensis var. mairei was dominated by the inter-specific competition, which accounted for 68.7% of the total competition intensity. The intra- and inter-specific competition intensity of both species decreased gradually with increasing tree diameter, indicating that competitive pressure was prevalent in small trees. T. ciliate var. pubescens was mainly affected by self-thinning due to intra-specific competition, whereas T. chinensis var. mairei was dominated by alien-thinning due to inter-specific competition. The small individuals of both species could develop into mature stage only after experiencing intense competitive selection during stand regeneration. Considering the substantial difference in the sources of competition pressures, different biodiversity conservation measures should be taken for the two endangered species with contrasting growth forms in the middle subtropical regions.


Asunto(s)
Taxus , Animales , China , Ecología , Ecosistema , Especies en Peligro de Extinción
14.
Ying Yong Sheng Tai Xue Bao ; 31(1): 72-82, 2020 Jan.
Artículo en Chino | MEDLINE | ID: mdl-31957382

RESUMEN

Photosynthetically active radiation (PAR) is a key environmental factor affecting the change of net ecosystem exchange (NEE) during the daytime. However, the coordinate system of PAR measured by horizontal radiometers over sloping terrain does not match that of NEE after tilt-corrected of the ultrasonic anemometer. Using the temperate deciduous broad-leaved forest at the Maoershan site with an average slope of 9° and a azimuth of 296° as a case, we investigated the diurnal variations in NEE and its driving factors in the growing season (May to September) of 2016. We assessed the differences in estimating light response parameters and the explanations of NEE by other environmental factors between the PAR measured by horizontal and slope-parallel radiometers. The results showed that the diurnal change of NEE in each month of the growing season presented a morning-afternoon asymmetrically unimodal curve: the value was negative (net carbon absorption) about 2.5 h after sunrise, reached the peak around 12:00, then approached zero again at two hours before sunset. The daily net uptake maximized in July and minimized in May. During the whole growing season, the time-lag and difference in the PAR measured by the horizontal versus slope-parallel radiometers led to that the PAR values measured by the horizontal radiometer increased photosynthetic quantum yield (α) and daytime respiration rate (Rd) by 13.3% and 11.5%, respectively, and decreased the maximum photosynthetic efficiency (Amax) by 7.7%. The light response curves of NEE were asymmetrical in the morning and afternoon, with Rd and Amax in the afternoon being greater than that in the morning. Weather conditions affected light response parameters: on cloudy days, Amax was higher than that in sunny days, the α and Rd were lower versus those in sunny days for most conditions. However, the monthly Amax and Rd were generally higher for horizontally measured PAR than for slope-parallelly measured PAR, especially for Amax in the cloudy afternoon. The radiometer-orientation affected the explanation of daytime NEE by air temperature (Ta) and vapor pressure deficit (VPD). The correlation of NEE residual based on the slope-parallel radiometer with Ta and VPD (r ranged: 0.013 to 0.197, 0.098 to 0.224) was tighter than that based on the horizontal radiometer (r ranged: 0.082 to 0.219, 0.162 to 0.282) when the negative correlations with Ta for September was excluded. Our results indicated that the measurements of PAR on the inclined terrains could cause errors in the environmental interpretations of NEE. Such findings had implications for the radiometric measurement of mountain vegetation and the reasonable interpretation of carbon exchange in terrestrial ecosystems.


Asunto(s)
Carbono , Ecosistema , Dióxido de Carbono , China , Bosques , Fotosíntesis , Estaciones del Año
15.
Ying Yong Sheng Tai Xue Bao ; 31(1): 83-88, 2020 Jan.
Artículo en Chino | MEDLINE | ID: mdl-31957383

RESUMEN

The perennial clonal grasses rely mainly on vegetative reproduction to achieve continuous regeneration. Buds and juvenile tillers formed by buds are potential populations for vegetative reproduction. We compared the composition and size of potential population of Leymus chinensis in the enclosure meadow, long-term mowing meadow, enclosing sand-covered meadow, and forest-grassland, with excavation sampling by unit area and using vegetative reproduction generations to classify the age of tillers, rhizomes and various types of buds and juvenile tillers. The results showed that at the end of the growing season, potential population of L. chinensis was composed of rhizome buds and buds of tiller growing upwards at different ages, as well as juvenile tillers on the tillers and rhizomes. Across the four habitats, the potential population of tillers of L. chinensis was composed of 3-4 age classes, and the rhizomes' potential population consisted of four age classes, of which the potential population formed by rhizomes accounted for 68.3% of the total potential population. The potential population produced by 1st age class tillers and rhizomes accounted for 60.2% of the total, which was the main part of the potential population composition and the main source of population renewal. The potential population of tillers was the most abundant in long-term mowing meadow. The potential population of rhizomes was the most abundant in enclosing sand-covered meadow. The vegetative fertility of tillers and rhizomes was the highest in young age. The vegetative fertility of rhizomes was 10.0 times as that of tillers, which dominated the vegetative reproduction of L. chinensis. The potential population composition of L. chinensis varied greatly across different habitats, reflecting the divergent adaptation to habitat variation.


Asunto(s)
Ecosistema , Poaceae , China , Reproducción , Estaciones del Año
16.
Ying Yong Sheng Tai Xue Bao ; 31(1): 89-96, 2020 Jan.
Artículo en Chino | MEDLINE | ID: mdl-31957384

RESUMEN

Prediction of the potential distribution of species based on the data of its current distribution in combination with climatic variables is important for understanding species evolution and reasonable conservation. Based on 220 distribution sites in China and 12 low-correlation climatic variables, we analyzed the potential distribution of Paris verticillata at present and future (2050s and 2070s) using the MaxEnt model and ArcGIS program. Further, we analyzed the dominant driving factors for its geographic distribution. The results showed that the area under the curve indices (AUC) was 0.940, with high prediction accuracy. The potential suitable regions of P. verticillata were mainly distributed in the Greater Xing'an Mountains, the Xiao Xing'an Mountains, the Changbai Mountains, the Qinling-Daba Mountains, Hebei, Shanxi and north Shandong under current climate scenario. Those regions accounted for 18.1% of the total suitable area in the country, of which the highly suitable areas accounted for 7.0% and the lowly suitable area 11.1%. The total suitable areas of P. verticillata in the 2050s and 2070s would decline under the climate change scenarios of RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5. The highly suitable area would decline, but the lowly suitable area would increase. With the global climate change, both the range and the geometric center of its distribution would gradually spread to higher altitude in the northeast. The cumulative contributions of four dominant factors reached as high as 89.2%, namely, precipitation of wettest month, mean annual temperature, isothermality, and precipitation of January. Their appropriate ranges were 100-275 mm, -0.1-16 ℃, 21-35 and 3-14 mm, respectively.


Asunto(s)
Cambio Climático , Ecosistema , China , Predicción , Temperatura Ambiental
17.
Ying Yong Sheng Tai Xue Bao ; 31(1): 208-218, 2020 Jan.
Artículo en Chino | MEDLINE | ID: mdl-31957398

RESUMEN

The rational delimitation of urban development boundary plays an important role in guiding the orderly growth of urban space and ensure proper environment health of urban space. In this study, we evaluated the ecological sensitivity of Nanchang City from four aspects (soil erosion, habitat, geological disaster and water resource) and simulated urban expansion in 2020 based on CA-Markov and land use data in 2000, 2010 and 2015. Spatial decision-making analysis of the two aspects was carried out in combination to the future development of the study area. We proposed a new method of delimitating urban development boundary integrating environmental protection and urban development through the dynamic coordination of both aspects. The results showed that ecological sensitivity of Nanchang City was moderate. The scale of urban construction land based on CA Markov simulation was 1239.67 km2, which slightly exceeded the planned construction land target (1201.65 km2). When the dynamic adjustment was done by superimposing the ecological sensitivity evaluation results with the expansion simulation results, the adjusted construction land scale of Nanchang City was 1193.15 km2, which met the planned requirement. Consideration of the coordination of protection and development could not only protect the ecological space, but also help to guide the orderly growth of urban space and ensure the healthy development of urban space, and thus was an important way to achieve a win-win situation between rational urban development and ecological protection.


Asunto(s)
Ecología , Remodelación Urbana , China , Ciudades , Conservación de los Recursos Naturales , Ecosistema
18.
Ying Yong Sheng Tai Xue Bao ; 31(1): 219-229, 2020 Jan.
Artículo en Chino | MEDLINE | ID: mdl-31957399

RESUMEN

Using Landsat 5/TM and Landsat 8/OLI images in 2000 and 2017, based on remote sensing ecological index (RSEI) model, combined with meteorological observation data and socio-economic data in Nanjing from 2000 to 2017, we analyzed and evaluated the ecological environment changes and the characteristic ecological areas in Nanjing. The results showed that the average RSEI of Nanjing decreased from 0.626 to 0.618 during 2000-2017. The RSEI values could be divided into five grades: bad, poor, fair, good and excellent. The proportion of area above good grade decreased from 61.0% to 57.1%, while that below poor grade increased slightly. Compared with 2000, the proportion of areas with improved ecological environment quality was 34.5%, 34.7% area had deteriorated, and 30.8% area remained unchanged in 2017. Among them, the ecological quality of main urban area had significantly improved, and the area with improved ecological quality exceeded that of deterioration. The ecological quality of new urban area and suburbs had deteriorated. The area with poor ecological environment exceeded the area of improvement. Among the three ecological protection areas, the ecological quality of Zijin Mountain was significantly better than that of Laoshan Mountain and Jiangxinzhou. The urbanization rate was negatively correlated with RSEI, with a correlation coefficient of -0.91. The urbanization process would have negative impacts on the ecological environment in general. However, strict protection and management measures could maintain the good ecological environment even improve it.


Asunto(s)
Ecosistema , Urbanización , China , Monitoreo del Ambiente , Tecnología de Sensores Remotos
19.
Ying Yong Sheng Tai Xue Bao ; 31(1): 239-248, 2020 Jan.
Artículo en Chino | MEDLINE | ID: mdl-31957401

RESUMEN

With Tongxin, Xiji, and Longde counties in the mountainous area of southern Ningxia as the research area, we used extended-exergy analysis (EEA) to compare their ecological efficiency driving mechanism in 2008-2017 to explore the causes of their variation in ecological degradation. The results showed that the overall difference of ecological efficiency in the three counties was significant during the study period. The ecological efficiency of Tongxin was low, with large inter-annual variation. The ecological efficiency of Xiji was stable, and the overall efficiency of Longde was the highest. The difference of exergy scale was small among the three counties. The exergy proportion in the economic sectors was not coordinated, which were dominated by agricultural and residential sectors. The economic sectors presented significant capital-pull-type and labor-intensive characteristics, indicating the driving force for ecological degradation mainly came from agricultural production and residents' lives in underdeveloped regions. The system's internal exergy conversion rate and the external energy exchange rate of the three counties were extremely low, constituting a simple network circulation path with high input, low storage, low opening and low conversion, which weakened the endogenous development of social economic subsystem and threatened the fragile ecosystem.


Asunto(s)
Ecología , Ecosistema , Agricultura , China , Eficiencia
20.
Ying Yong Sheng Tai Xue Bao ; 31(1): 249-258, 2020 Jan.
Artículo en Chino | MEDLINE | ID: mdl-31957402

RESUMEN

Stellera chamaejasme is one of the most serious weeds in Qinhai-Tibetan Plateau, the rapid expansion of which exerts an increasing effect on the alpine meadow ecosystem. With high-throughput sequencing technology, geostatistics and GIS method, the spatial heterogeneity of soil fungal diversity in Stellera occurrence area and the spatial correlation between Stellera coverage and soil fungal diversity were investigated in a typical degraded alpine meadow of the Qilian Mountain. Compared to no-Stellera area, the fungi richness in Stellera area decreased, the dominance increased, and the α-diversity reduced. The difference of fungal species composition enhanced and ß-diversity significantly increased. The spatial pattern of soil fungal diversity was affected by the invasion of Stellera, resulting in higher fragmentation in occurrence area. Spatial heterogeneity of species composition increased remarkably, and spatial stability of α-diversity and ß-diversity decreased. The portion of positive correlation and negative correlation interlaced, indicating no clear spatial correlation between Stellera coverage and soil fungal diversity. Our results indicate that the spatial pattern of soil fungal diversity was affected by the interaction of soil and vegetation in Stellera invaded meadows.


Asunto(s)
Suelo , Thymelaeaceae , Ecosistema , Hongos , Pradera , Microbiología del Suelo
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