Soil and vegetation seasonal changes in the grazing Andean Mountain grasslands

Andean grasslands ecosystems are fragile environments with rigorous climatologic conditions and low and variable food for the grazing. The Apolobamba area is located in the Bolivian Andean Mountains. Its high grasslands provide a natural habitat for wild and domestic camelids such as vicuna（Vicugna vicugna） and alpaca（Lama pacos）. The botanical diversity plays an essential role in maintaining vital ecosystem functions. The objectives of this research were to determine the seasonal changes in soil properties, to study the vegetation changes during the wet and dry seasons and the influence of soil properties and camelid densities on the vegetation in the Apolobamba grasslands. Four zones with different vicuna populations were selected to be studied. The following soil parameters were determined： total organic carbon, total nitrogen, available phosphorous, cation exchange capacity, exchangeable cations, pH and texture. The vegetation season changes were studied through botanical identification, above-ground biomass, plant cover and species richness. Results showed that some soil properties such as C/N ratio, CEC, silt and clay percentages kept stable against the seasonal changes. Generally, soil nutrients were relatively higher during the dry season in the surface and subsurface. The results did not point out the predominant vegetation growth during the wet season. The seasonal vegetation growth depended on each species. Thegood soil fertility corresponded to the highest plant cover. Soil fertility presented no influence on the above-ground biomass of the collected species. The negative influence of camelid grazing on soil properties could not be assessed. However, overgrazing could affect some plant species. Therefore, protection is needed in order to preserve the biodiversity in the Andean mountain grasslands.     

Organochlorine pesticides in soils from the Issyk-Kul region in the western Tian Shan Mountains,Kyrgyzstan: Implication for spatial distribution,source apportionment and ecological risk assessment

As organchlorine pesticides(OCPs) may be an ecologic threat to mountain environments due to their tendency to deposit and accumulate in mountain regions undergoing long-range air transport, OCPs were analyzed in soils collected from an intermontane basin of the western Tian Shan Mountains, which is the UNESCO protected natural reserve of Issyk-Kul. Total OCP concentrations in the Issyk-Kul region ranged from 4.63 to 414 ng/g dw, of which two extraordinary high OCP concentrations(414 ng/g dw and 213 ng/g dw, respectively) influenced by an abandoned dumping site and urban sewage, respectively, were found. Principal component analysis(PCA) and correlation analysis inferred that the OCP inputs in the east of the Issyk-Kul region were mainly from local endogenous sources, and exogenous input via LRAT processes were prominent in the west and south. Additionally, the isomeric and parent substance/metabolite ratios revealed most pesticides accumulated in this region were from old usage, while DDTs had fresh input because of possibly illegal regional application and a slow degradation from the dumping site. Furthermore, ecological risk assessment revealed that no frequently adverse ecological effects were observed in the Issyk-Kul region, but potential risks on neighbouring organisms induced by p,p'-DDT and γ-HCH in dumping site and urban sewage should be considered when devising an efficient management plan to prevent secondary pollution.     

Impact of grazing on soil,vegetation and ewe production performances in a semi-arid rangeland

Controlled grazing is considered a good management strategy to maintain or increase the live weight of livestock and to reduce vegetation degradation of rangelands. The present study investigated soil characteristics, aboveground vegetation biomass dynamics and controlled grazinginduced changes in the live weight of local ewes in the semi-arid rangeland of Ahmadun, Ziarat, Balochistan province of Pakistan. An area of 115 ha was protected from livestock grazing in April 2014. In June 2015, soil characteristics within 0-30 cm depth i.e. soil organic matter (SOM), mineral nitrogen, pH and texture in controlled and uncontrolled grazing sites were assessed. Aboveground vegetation biomass measured in early (June) and late summer (August) in 2015 and 2016. The nutritional value i.e. crude protein, phosphorus (P), neutral detergent fiber (NDF), acid detergent fiber (ADF), calcium (Ca), magnesium (Mg) and potassium (K) of dominant plant species were assessed at the beginning of experiment in 2015. Vegetation cover of controlled and uncontrolled grazing sites was also measured during the two years of the study period using the VegMeasure software. From June to November in 2015 and 2016, controlled and uncontrolled livestock grazing sites were grazed on a daily basis by local ewes with a stocking rate of 2 and 1 head ha-1 respectively. Results reveal that the organic matter contents of coarse-textured, slightly alkaline soil of the study site were in the range of 9.4 - 17.6 g kg-1 soil and showed a strong positive correlation with aboveground vegetation biomass. The biomass of plants was 56.5% and 33% greater at controlled than uncontrolled grazing site in 2015 and 2016 respectively and plant cover was also higher at controlled than uncontrolled grazing site in both years. The nutrient contents were significantly (P<0.05) lower in grasses than shrubs. In both years, the controlled grazing increased the weight gain of ewes about two folds compared to the uncontrolled grazing. The results indicate that controlled grazing improved the vegetation biomass production and small ruminant productivity.     

Multilevel assessment of spatiotemporal variability of vegetation in subtropical mountain-hill region

The complex spatiotemporal vegetation variability in the subtropical mountain-hill region was investigated through a multi-level modeling framework. Three levels - parcel, landscape, and river basin levels- were selected to discover the complex spatiotemporal vegetation variability induced by climatic, geomorphic and anthropogenic processes at different levels. The wavelet transform method was adopted to construct the annual maximum Enhanced Vegetation Index and the amplitude of the annual phenological cycle based on the 16-day time series of a5om Moderate Resolution Imaging Spectroradiometer Enhanced Vegetation Index datasets during 2OOl-2OlO. Results revealed that land use strongly influenced the overall vegetation greenness and magnitude of phenological cycles. Topographic variables also contributed considerably to the models, reflecting the positive influence from altitude and slope. Additionally, climate factors played an important role： precipitation had a considerable positive association with the vegetation greenness, whereas the temperature difference had strong positive influence on the magnitude of vegetation phenology. The multilevel approach leads to a better understanding of the complex interaction of the hierarchical ecosystem, human activities and climate change.     

Lithological indicators of discontinuities in mountain soils rich in calcium carbonate in the Polish Carpathians

Six soils located within the Polish Carpathians,developed on calcium carbonate–rich sedimentary parent materials and representing various reference groups,were investigated in order to detect the lithic discontinuity.We propose using a multidirectional approach to assess the lithic discontinuity in these soils,one that includes grain size distribution,geochemical composition,heavy mineral content and micromorphology,supported by a traditional soil survey.A further aim of this process was to identify the possible admixture of allochthonous material of aeolian origin.The studied soils presented lithic discontinuities mostly at the contact of underlying calcium carbonate–rich coarsegrained slope deposits with the overlaying colluvium layer having a lower content of rock fragments.The significant changes in grain size distribution,especially in the silt and sand content,as well as high Uniformity Values and partially,high Lithological Discontinuity Index values,confirmed the occurrence of a lithic discontinuity in all studied soils.High heterogeneity in the soil profiles was also confirmed by the distribution of the major oxides;however,their distribution did not clearly indicate the lithic discontinuity.The most visible distinctions were noted from CaO content,which resulted from the deposition of carbonate-free materials(aeolian silts)and their mixing with the calcium carbonate–rich parent material.Furthermore,the analysis of heavy mineral content confirmed the allochthonous origin of the upper(and in some cases also the middle)parts of all profiles,which was manifested by the presence of highly weathering-resistant minerals such as zircon,epidote and various types of garnets.The micromorphological features of some of the studied soils showed distinctiveness within the soil profile,manifested by changes in b-fabric pattern,the occurrence and distribution of secondary carbonate and the coarse and fine coarse and fine ratio.Based on the high content of silt within the upper and middle parts of the soils,the content of Hf and Zr,as well as the higher content of weathering-resistant minerals,admixture of aeolian silt could be considered in some of the studied soils,yet with weak character.However,the dominance of minerals typical for metamorphic and igneous rocks suggested that the supply of aeolian silt was associated with loess covers rather than local sedimentary material.     

In-situ studies of microzooplankton grazing pressure on phytoplankton in Jiaozhou Bay, China

Preliminary studies on microzooplankton grazing were conducted with dilution method in Jiaozhou Bay from summer 1998 to spring 1999. Four experiments were carried out at St. 5 located at the center of Jiaozhou Bay. Chlorophyll a concentrations were consistently dominated by netphytoplankton (net-, >20μm), except during the autumn 1998 cruise, when they were dominated by nanophytoplankton(nano-, 2–20μm). The contribution of picophytoplankton (pico-, <2μm) to total chlorophyll a concentrations (<200μm) varied considerably between cruises. Instantaneous growth coefficients(u) of phytoplankton varied from 0.098 to 1.947d⁻¹, with mean value of 0.902d⁻¹. Instantaneous coefficients(g) of microzooplankton grazing on phytoplankton ranged from 0.066 to 0.567d⁻¹, mean value of 0.265d⁻¹, which was equivalent to daily lose of 21.9% of the initial standing stock and 58.1% of the daily potential production. Project No KZCX3-SW-214 supported by Chinese Academy of Sciences.     

Soil conservation assessment via climate change and vegetation growth scenarios in the Nile River basin

Soil conservation by vegetation can mitigate soil erosion hazard and prevent reductions in food productivity. However, previous research applies little consideration to the interaction between vegetation and climate change in the estimation of future soil conservation change. Therefore, based on the Revised Universal Soil Loss Equation(RUSLE), Representative Concentration Pathways(RCPs, specifically RCP4.5 and RCP8.5), and the vegetation index and precipitation datasets, we built a multivariate regression equation that considers changes in vegetation growth under climate change scenarios in the context of soil conservation. Using the Nile River basin as a case study, via our established methods, we modelled and projected the impact of vegetation and climate change on future soil conservation between 2020 and 2100, where three main results were obtained:(1) under the scenarios of RCP4.5 and RCP8.5 from 2020 to 2100, soil conservation in the Nile Basin will first increase and then decrease, with its highest value in the years 2060, at 117.72(t ha-1 y-1), and 2070, at 134.39(t ha-1 y-1).(2) Soil conservation under RCP4.5 is lower than that under the RCP8.5 scenario, with a maximum difference of 27(t ha-1 y-1) in 2040 and a minimum difference of 0.2(t ha-1 y-1) in 2100.(3) The vegetation and climate change models in 2100 had soil conservation values of 110.77(t ha-1 y-1) under RCP4.5 and 38.70(t ha-1 y-1) under RCP8.5. In conclusion, although vegetation growth can increase soil conservation in the Nile River basin, the change in precipitation can offset the soil conservation enhanced by vegetation growth.     

Spatial and seasonal dynamics of soil loss ratio in mountain rangelands of south-western Kyrgyzstan

Vegetation cover is the main factor of soil loss prevention. The C-factor of the RUSLE (Revised Universal Soil Loss Equation) was predicted with NDVI, ground data and exponential regression equation for mountain rangelands of Kyrgyzstan. Time series of C-factor, precipitation and temperature were decomposed into seasonal and trend components with STL (seasonal decomposition by loess) to assess their interrelations. C-factor, precipitation and temperature trend components indicated significant lagged correlation, whereas seasonal components indicated more complex relations with climate factors which can be promoting as well as limiting factors for vegetation development, depending on the season. Rainy springs and hot summers may increase soil loss dramatically, whereas warm and dry springs with rainy summers can decrease it. Steep slopes indicated higher soil loss ratio, whereas flat areas were better protected by vegetation.     

Effects of long-term grazing exclusion on vegetation structure,soil water holding capacity,carbon and nitrogen sequestration capacity in an alpine meadow on the Tibetan Plateau

Grazing exclusion is one of the primary management practices used to restore degraded grasslands on the Tibetan Plateau. However, to date,the effects of long-term grazing exclusion measures on the process of restoring degraded alpine meadows have not been evaluated. In this study, moderately degraded plots, in which the vegetation coverage was approximately 65% and the dominant plant species was Potentilla anserina L, with grazing exclusion for 2 to 23 years, were selected in alpine meadows of H...     

The lateral pressure coefficient at rest of expansive soils in landfill at various vertical stresses and moisture contents

When expansive soils in the original location are artificially transferred to landfill in different seasons, and subject to engineering activities afterwards, the corresponding deformation and stability of retaining structures become unpredictable.This necessitates the determination of lateral pressure coefficient at rest(k0 value) for expansive soils in landfill. Considering compaction, excavation of expansive soils, as well as construction of landfill in different seasons, series of stepwise l...     

Plant diversity as a good indicator of vegetation stability in a typical plateau wetland

Biotic indicators have been widely used to monitor wetland health. However, few studies have explicitly evaluated if plant diversity could serve as a useful community-level indicator of wetland stability, especially when wetlands are confronted with anthropogenic perturbations. Based on three-year record of wetland plant species abundance in Napahai plateau wetland, Shangri-la under the influence of varying anthropogenic perturbation types, our study tests the impact of such perturbations on plant richness and the relationship between ecosystem temporal stability and plant richness, and further assesses the effectiveness of using plant diversity indicator to probe ecosystem temporal stability of Napahai plateau wetland and the potential mechanisms. The results showed that anthropogenic perturbations could have contributed significantly to realistic variation in plant diversity, and further demonstrated that ecosystem temporal stability was positively related to realistic variation in plant diversity. In particular, communities with high levels of diversity might have better capacity to dampen perturbation impacts than communities with low levels of diversity, and statistical averaging could have played an important role in causing greater stability in more diverse communities. Also, asynchrony might have a stabilizing effect on community stability, and diversity could have stabilized communities through both species asynchrony and population stability propagation. Therefore, our results suggest that plant diversity could be used as a useful indicator of the stability conditions of plateau wetland ecosystems confronted with anthropogenic perturbations, and the preservation of plant communities at sufficient abundance and diversity is necessary for maintaining healthy plateau wetlands and for sustaining their essential ecosystem functions and services.     

Sedimentary ladderane core lipids as potential indicators of hypoxia in the East China Sea

Anammox (anaerobic ammonium oxidation) is an important process in many suboxic to anoxic marine environments for converting fixed nitrogen to N₂, and has a major impact on the marine nitrogen cycle. Ladderane core lipids have been utilized as an indicator of the contribution of anammox to the marine nitrogen cycles. However, such studies have not been reported for the China seas and little is known about the importance of anammox within the nitrogen cycle of these marginal seas. In the research reported here, the ladderane core lipid contents of 17 surface sediment samples from the East China Sea are reported, and their spatial distribution is investigated. C₁₈ -[5]-ladderane FAME, C₂₀-[5]-ladderane FAME and C₂₀-[3]-ladderane FAME have all been detected, suggesting that the anammox bacteria are widely present within the study area. The total contents of the three ladderane lipids (ΣFAMEs) range from 24–355 ng/g (weight of dry sediments), with higher contents occurring in the Minzhe Mud Zone and broadly coincident with the spatial distribution of hypoxia. It is suggested that the sedimentary ladderane core lipids are mainly produced in the water column and their sedimentary contents can be used as indicators of water column hypoxia.     

Thinning effects on walnut stem and crown diameter growth and fruiting in the walnut-fruit forests of Kyrgyzstan

The walnut-fruit forests (Juglans regia L.) in southern Kyrgyzstan are considered to be biodiversity hotspots and of considerable economic and ecological importance to local populations. The fruiting ability and stability of these forests are, however, decreasing because of infrequent silvicultural interventions and non-existent natural regeneration. Continuous inventories and walnut harvest measurements were carried out on 18 trial and control plots over the course of 13 year. Results showed that i) thinning had a positive influence on diameter at breast height (dbh) increase, ii) dbh growth and crown area increases are strongly and positively correlated, iii) large crowns enhanced the production of fruits, and iv) temperature conditions had a major influence on the production of fruits. The above-mentioned points are particularly relevant for young plantations but are also valid for relatively old plantations (> 50 years). We conclude that regular thinning substantially improves diameter growth, fruit production and ability of trees to withstand wind and snow damage in both young stands and in older walnut-fruit forests.     

Compound-specific isotopes of fatty acids as indicators of trophic interactions in the East China Sea ecosystem

The composition and compound-specific isotopes of fatty acids were studied within food webs in the East China Sea.Lipid-normalized stable carbon isotopes of total organic carbon had a good correlation with trophic level.Variations in fatty acid compositions among different species were observed but were unclear.Different dietary structures could be traced from molecular isotopes of selected fatty acids in the Shiba shrimp(Matapenaeus joyneri),the coastal mud shrimp(Solenocera crassicomis) and the northern Maoxia shrimp(Acetes chinensis).Both M.joyneri and S.crassicomis are mainly benthos feeders,while A.chinensis is a pelagic species,although they have a similar fatty acid composition.There was a good correlation for isotopes of arachidonic acid(C20:4n6;ARA) and docosahexaenoic acid(C22:6n3;DHA)among pelagic species from higher trophic levels.The isotopic compositions of DHA in benthic species were more negative than those of pelagic species at the same trophic level.The fact that the diet of benthic species contains more degraded items,the carbon isotopes of which are derived from a large biochemical fraction,may be the reason for this variation.A comparative study of benthic and pelagic species demonstrated the different carbon sources in potential food items and the presence of a more complex system at the watersediment interface.     

海南岛北部种植园土壤中多环芳烃的质量分数、来源及生态风险

海南岛是我国主要的热带农作物种植基地,对海南岛种植园土壤污染物评估具有重要意义。对海南岛北部种植园土壤中的16种多环芳烃（PAHs）质量分数、来源及生态风险进行评估。使用气相色谱-质谱联用技术对咖啡、香蕉、山药、甘蔗、橙子、百香果和石榴种植园中100件表层土壤样品进行PAHs质量分数测定。结果表明,研究区种植园土壤平均∑₁₆PAHs为37.6 ng/g,低于我国土壤背景值和荷兰无污染土壤限值（< 200 ng/g）。三环、四环和五环PAHs为主要组成成分,分别占据∑₁₆PAHs质量分数的25.8%,26.8%和23.5%。源识别显示,种植园内PAHs主要来自机动车尾气排放,部分来自石油产品的泄露及煤和生物质的低温燃烧。生态风险评价结果显示,等效毒性当量∑₁₆BaP_eq低于国家标准,表明土壤中PAHs污染物水平处于可接受范围。      

Diagnostic model construction and example analysis of habitat degradation in enclosed bay: II. spatiotemporal variations in habitat degradation in Sansha Bay

The process of habitat degradation varies in habitat type and driving force which shows certain spatial and temporal heterogeneity on regional scales. In the present study, a new diagnostic model for enclosed bay habitat degradation was established, with which the spatial and temporal variation patterns of habitat degradation during 1991–2012 in Sansha Bay, Fujian, China was investigated. The results show that anthropogenic disturbance is the major controlling factor for the habitat degradation in large temporal heterogeneity in the bay. On the other hand, the habitat degradation experienced signifi cant spatial variations among six sub-bays. Under the joint action of temporal and spatial heterogeneity, the degradation trend in growing scale shows a more signifi cant correlation with the distribution of local leading industries along shorelines. Therefore, we quantifi ed the main characters of habitat degradation in Sansha Bay, and have understood the relationship between the status of habitats spatio-temporal variation value and the main controlling factor leading to the changes. However, a defi ciency of this research is the lack of or inaccessible to the detailed data, which shall be better solved in the future study for accessing more data from more sources.     

Effects of vegetation restoration on soil organic carbon in China: A meta-analysis

Vegetation restoration has been proposed as an effective method for increasing both plant biomass and soil carbon(C) stocks. In this study, 204 publications(733 observations) were analyzed, focusing on the effects of vegetation restoration on soil organic carbon(SOC) in China. The results showed that SOC was increased by 45.33%, 24.43%, 30.29% and 27.98% at soil depths of 0–20 cm, 20–40 cm, 40–60 cm and 60 cm after vegetation restoration, respectively. Restoration from both cropland and non-cropland increased the SOC content. The conversion of non-cropland was more efficient in SOC accumulation than the conversion of cropland did, especially in 40 cm layers. In addition, the conversion to planted forest led to greater SOC accumulation than that to other land use did. Conversion period and initial SOC content extended more influence on soil C accumulation as the main factors after vegetation restoration than temperature and precipitation did. The SOC content significantly increased with restoration period after long-term vegetation restoration( 40 yr), indicating a large potential for further accumulation of carbon in the soil, which could mitigate climate change in the near future.     

Land degradation and management of red beds in China:Two case studies

Red beds cover approximately 9.5% of China, and are home to approximately 144 million people. In total, 83% of these lands are distributed in humid regions making it an important part of research on red bed soil erosion in China in these areas. This paper presents the main types of land degradation in red bed landscapes and the status of current soil erosion in a typical red bed basin, the Nanxiong Basin located in the north of Guangdong Province, China, and establishes the connection between management strategies and regional economic development in humid red bed regions of China. The soil erosive modulus was calculated in the Nanxiong Basin by using RUSLE(The Revised Universal Soil Loss Equation). The results of overlapping analyses demonstrated that appropriate measures, such as the Return Farmland to Forests initiative, should be taken at the junction of central red bed areas and mountainous areas in order to mitigate current soil erosion. Two examples are presented to demonstrate this: the tourism development in Mt. Danxiashan, a noted scenic mountainous area near Nanxiong Basin, and the land degradation mitigation in the Nanxiong Basin. Both examples promote local economic growth while simultaneously protecting the environment. A.stakeholder‘ strategy is pursued at Mt. Danxiashan,which can help residents to understand their positive effects on the environment as well as increase theirincome. The second example, in Nanxiong City,showcases how local farmers became stakeholders by implementing contract responsibility and self-support systems for economic forests and terraced land in the 1980s.     

SEFIDROOD RIVER SUB-WATERSHED-DAM-ESTUARY AND DEGRADATION MODEL： A HOLISTIC APPROACH IN IRAN

The major concern of this article is to address the shortcoming and outgoing effects of the human activities on the landscape patterns and their consequences in the Sefidrood River watershed in Iran. A flow of data includes three inputs; each of them belongs to one part of three zones of a fluvial system. The three parts of the Sefidrood River fluvial system include Zone 1, a sub-watershed as degradation modeling site, Zone 2, Sefidrood Dam asdam site, and Zone 3, 17kin away from the Sefidrood River path to the Caspian Sea as ending point site. The degra-dation model in the Zone 1 provides a suitable mean for decision support system to decrease the human impacts oneach small district. The maximum number for degradation coefficient belongs to the small district with the highest physiographic density, relatively cumulative activities, and a lower figure for the habitat vulnerability. The human degradation impact were not limited to the upstream. The investigation to the Sefidrood Dam and ending point of the Sefidrood River depicts that sedimentation continues as a significant visual impact in the Sefidrood Dam reservoir and the estuary.