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1. chinaXiv:201805.00010 [pdf]

鼎湖山南亚热带常绿阔叶林荷木种群动态变化

陈 青; 李萌姣; 李 瑶; 沈 浩
Subjects: Biology >> Ecology

荷木(Schima superba)是鼎湖山南亚热带常绿阔叶林群落中的优势种,其种群动态变化对于理解南亚热带常绿阔叶林的群落构建机制具有重要意义。本文分析了鼎湖山南亚热带常绿阔叶林20 ha样地中荷木种群在2005~2017年间的动态变化,并从径级和生境两个方面分析了其死亡率的分布特征。结果表明,荷木种群个体数量从2005~2017年呈减少的态势。在径级方面,荷木的死亡率和相对生长率的变化在不同径级区间呈不同变化规律:径级在1~10 cm范围的荷木相对生长率大并迅速下降,死亡率上升且维持在较高水平;径级在10~50 cm范围的荷木随着径级增大,相对生长率减缓,然后下降,而死亡率不断下降;在50 cm以上的径级范围内,荷木相对生长率小、死亡率大。不同生境中,2010年各个生境死亡率相差不大,2015年高海拔生境(高坡、山脊、高谷)死亡率大于低海拔生境(低坡、低谷),2017年则为低海拔生境大于高海拔。荷木的死亡率与土壤中酸碱度呈正相关关系,而与土壤有机质、总氮、总磷、有效钾、有效氮含量呈负相关关系。

submitted time 2018-04-28 From cooperative journals:《广西植物》 Hits1334Downloads733 Comment 0

2. chinaXiv:201805.00011 [pdf]

贵州凯里药市的侗族药用植物

刘思朝; 张贝西; 雷启义; 周江菊; 龙春林
Subjects: Biology >> Botany

凯里药市最初由当地少数民族同胞自发组织,药市中不仅有大量的苗族传统药用植物,侗族传统药用植物也十分丰富,但是目前对该药市交易的侗族药用植物鲜有报道,其丰富的传统知识至今仍不被外界所知。为掌握该药市侗族药用植物的现状,本研究运用民族植物学和植物分类学等方法于2014至2017年对凯里药市交易的侗族药用植物进行了6次详细调查。结果表明:该药市出售的侗族药用植物种类较多,共65科100属111种,以广义百合科Liliaceae植物(6种,5.4 %)为主,其次为伞形科Umbelliferae、菊科Compositae、天南星科Araceae植物(各5种,各占4.5%),苦苣苔科Gesneriaceae(4种,3.6%)。从植物生活型来看,草本占有绝对优势,共88种,占79.3%;用药部位具有多样化,但全草类药材占总数的一半。本研究对药市中侗族和苗族交易的药用植物进行了比较分析,得出凯里药市交易的侗族药材具有独特的地域性和民族性,尤以治疗风湿关节、跌打损伤等常见疾病为主。此外,还对凯里药市的可持续发展提出了建议。

submitted time 2018-04-28 From cooperative journals:《广西植物》 Hits1448Downloads666 Comment 0

3. chinaXiv:201805.00012 [pdf]

桂林岩溶石山檵木群落不同恢复阶段凋落物层酶对凋落物分解的影响

苏静; 马姜明; 覃扬浍; 张雅君; 莫燕华; 秦佳双; 杨栋林
Subjects: Biology >> Ecology

选取桂林岩溶石山檵木群落不同恢复阶段(灌木阶段、乔灌阶段和小乔林阶段)为研究对象,探究檵木群落不同恢复阶段凋落物层酶对凋落物分解速率的影响。结果表明:檵木群落不同恢复阶段凋落物经过1年分解后,3个阶段凋落物剩余率分别为灌木阶段 (59.58%) 、乔灌阶段 (61.79%) 和小乔林阶段 (62.02%) 。檵木群落不同恢复阶段凋落物分解速率随演替的进行而减小。3个不同恢复阶段凋落物层多酚氧化酶、脲酶、蔗糖酶活性均在12月份最低,多酚氧化酶活性均在3月份最高,脲酶和蔗糖酶活性均在6月份最高。3个恢复阶段纤维素酶活性变化规律趋势一致,均在6月份酶活性最高,灌木阶段纤维素酶活性在3月份最低,乔灌阶段和乔林阶段纤维素酶活性均在9月份最低。檵木群落3个不同恢复阶段的凋落物层酶活性在不同时期均表现为:蔗糖酶>脲酶>纤维素酶>多酚氧化酶。檵木群落不同恢复阶段凋落物层酶活性对凋落物分解速率影响不同。相关性分析表明,檵木群落灌木阶段凋落物层蔗糖酶活性与分解速率呈显著正相关(P < 0.05),乔灌阶段脲酶活性与分解速率呈显著正相关(P < 0.05),小乔林阶段各酶活性与分解速率相关不显著。通径分析表明,蔗糖酶、脲酶和多酚氧化酶是影响灌木阶段凋落物分解速率的重要因素。脲酶、纤维素酶和多酚氧化酶是影响乔灌和小乔林阶段分解速率的重要因素。

submitted time 2018-04-28 From cooperative journals:《广西植物》 Hits1231Downloads663 Comment 0

4. chinaXiv:201804.02356 [pdf]

Some correlations in CLASH clusters

李希国
Subjects: Astronomy >> Galaxy and Cosmology

本文是[1]对冲突簇的延续和推广。我们研究冲突子群中的总、暗物质密度分布和关联。就像我们对纽曼星系团所做的那样。就像Newman星系团一样,我们发现密度分布受重子相互作用和能量的影响很大。角动量通过动态摩擦从重子转移到DM。大星系团的暗物质密度剖面的内斜率通常比纳瓦罗-弗伦克-白剖面内坡,最大值为-0.79,最小值为-0.30.如在Newman星系团的情况下,斜率α之间存在一系列的相关性。暗物质剖面,以及:A.团簇的核心半径;B.有效半径Re;C.最明亮的中央星系(BCG)的质量;D.总重子质量和恒星质量星系团。我们还发现了有效半径与病毒质量之间的关系。簇的结构,它们的总密度和密度分布,以及它们之间的相关性是:在两个阶段的情况下理解。在第一个耗散阶段,BGC形成。在第二耗散相,重子团与DM的相互作用动力摩擦(DF)使DM分布趋于平缓。这两个阶段的最终结果是不同DM分布、内部斜率及几种关联的簇的形成簇的特征量

submitted time 2018-04-25 Hits4344Downloads901 Comment 0

5. chinaXiv:201804.02357 [pdf]

Diet characteristics of wild sheep (Ovis ammon darwini) in the Mengluoke Mountains, Xinjiang, China

LI Bang; XU Wenxuan; David A BLANK; WANG Muyang; YANG Weikang
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

In most arid and semi-arid regions of the world, domestic livestock and native wildlife share pastures, and their competition for forage and habitat is thought to be a serious conservation issue. Moreover, unmanaged grazing by livestock can cause the population decline in wild ungulates. The diet of an animal species is a determining aspect of its ecological niche, and investigating its diet has been one of the initial steps in basic ecology study of a new species. To get an approximate understanding of the interspeci?c food relationships of argali (Ovis ammon darwini) between sexes, and sympatric domestic sheep and goats, we compared the diet compositions and diet-overlaps among these herbivores, i.e., male argali, female argali, domestic sheep, and domestic goats in the Mengluoke Mountains of Xinjiang, China by using micro-histological fecal analysis. Female argali, male argali, domestic sheep and domestic goat primarily consumed forbs (43.31%±4.86%), grass (36.02%±9.32%), forbs (41.01%±9.18%), and forbs (36.22%±10.61%), respectively in warm season. All these animals consumed mostly shrubs (female argali: 36.47%±7.56%; male argali: 47.28%±10.75%; domestic sheep: 40.46%±9.56%; and domestic goats: 42.88%±9.34%, respectively) in cold season. The diet-overlaps were relatively high among all species in cold season with values ranging from 0.88 to 0.94. Furthermore, Schoener’s index measured between each possible pair of 4 herbivores increased from the warm season to the cold season. The results illustrate that the high degree of diet-overlap of argali and domestic livestock (sheep and goat) may pose a threat to the survival of the argali in cold season. From the viewpoint of rangeland management and conservation of the endangered argali, the numbers of domestic sheep and goats should be limited in cold season to reduce food competition.

submitted time 2018-04-24 From cooperative journals:《Journal of Arid Land》 Hits7789Downloads741 Comment 0

6. chinaXiv:201804.02358 [pdf]

Simulating long-term effect of Hyrcanian forest loss on phosphorus loading at the sub-watershed level

RAJAEI, Fatemeh ; SARI, Abbas E ; SALMANMAHINY, Abdolrassoul ; RANDHIR, Timothy O ; DELAVAR, Majid ; BEHROOZ, Reza D ; BAVANI, Alireza M
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Conversion of forest land to farmland in the Hyrcanian forest of northern Iran increases the nutrient input, especially the phosphorus (P) nutrient, thus impacting the water quality. Modeling the effect of forest loss on surface water quality provides valuable information for forest management. This study predicts the future impacts of forest loss between 2010 and 2040 on P loading in the Tajan River watershed at the sub-watershed level. To understand drivers of the land cover, we used Land Change Modeler (LCM) combining with the Soil Water Assessment Tool (SWAT) model to simulate the impacts of land use change on P loading. We characterized priority management areas for locating comprehensive and cost-effective management practices at the sub-watershed level. Results show that agricultural expansion has led to an intense deforestation. During the future period 2010–2040, forest area is expected to decrease by 34,739 hm2. And the areas of pasture and agriculture are expected to increase by 7668 and 27,071 hm2, respectively. In most sub-watersheds, P pollution will be intensified with the increase in deforestation by the year 2040. And the P concentration is expected to increase from 0.08 to 2.30 mg/L in all of sub-watersheds by the year 2040. It should be noted that the phosphorous concentration exceeds the American Public Health Association′s water quality standard of 0.2 mg/L for P in drinking water in both current and future scenarios in the Tajan River watershed. Only 30% of sub-watersheds will comply with the water quality standards by the year 2040. The finding of the present study highlights the importance of conserving forest area to maintain a stable water quality.

submitted time 2018-04-24 From cooperative journals:《Journal of Arid Land》 Hits1778Downloads675 Comment 0

7. chinaXiv:201804.02359 [pdf]

Effect of water deficiency on relationships between metabolism, physiology, biomass, and yield of upland cotton (Gossypium hirsutum L.)

BOZOROV, Tohir A ; USMANOV, Rustam M ; YANG, Honglan; HAMDULLAEV, Shukhrat A ; MUSAYEV, Sardorbek ; SHAVKIEV, Jaloliddin ; NABIEV, Saidgani ; ZHANG, Daoyuan; ABDULLAEV, Alisher A
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Drought is a common abiotic stress that considerably limits crop production. The objective of this study is to explore the influence of water deficiency on the yield, physiologic and metabolomic attributes in upland cotton cultivars (Gossypium hirsutum L). Cotton cultivars, 'Ishonch' and 'Tashkent-6' were selected to study the relationships among their physiologic, metabolomic and yield attributes during water deficiency. Deficit irrigation was designed by modifying the traditional watering protocol to reduce water use. Results indicate that cotton cultivars respond differently to water deficit stress. Water deficit significantly influenced plant height, the number of internodes, and sympodial branches in both cultivars. However, yield components such as the number of bolls, boll seed, lint mass, and individual plant yield were significantly reduced only in 'Tashkent-6'. The leaf area decreased and the specific leaf weight increased in 'Ishonch' under deficit irrigation conditions. However, 'Tashkent-6' demonstrated significant water loss compared to 'Ishonch', and both cultivars showed reduced transpiration rates. Untargeted metabolite profiles of leaves showed clear separation in 'Ishonch', but not in 'Tashkent-6' under deficit irrigation compared to full irrigation. The individual metabolites such as proline and galactinol showed strong association with yield under water deficit stress. Moreover, this study indicates that leaf area and transpiration intensity influence yield during water deficiency. In summary, the correlation among morpho-physiologic, metabolic, and yield components significantly varied between the two cultivars under water deficiency. The flowering stage was sensitive to water stress for both cultivars. The direct relationship between physiology, metabolism, and yield may be a useful selection criterion for determining candidate parents for cotton drought tolerance breeding.

submitted time 2018-04-24 From cooperative journals:《Journal of Arid Land》 Hits1732Downloads708 Comment 0

8. chinaXiv:201804.02360 [pdf]

Growth and sustainability of Suaeda salsa in the Lop Nur, China

LI, Congjuan; LIU, Ran; WANG, Shijie; SUN, Yongqiang; LI, Shengyu; ZHANG, Heng; GAO, Jie; DANG, Yanxi; ZHANG, Lili
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Extremely saline soils are very harsh environments for the growth and survival of most plant species, however, halophytes can grow well. The underlying mechanism of halophyte to resist high saline is not well understood by us. This study was conducted at the potash mine near the Lop Nur, China, where the effects of the halophyte Suaeda salsa L. on the saline-alkaline soils and its growth and sustainability were investigated. Four plots (in which the salt encrustation layers were removed), with different soil treatments were evaluated: (1) undisturbed soil, with no additional treatment (T1); (2) the slag soil zone, in which a 40-cm layer of slag was placed on the undisturbed soil surface (T2); (3) slag+sandy soil, in which a 20-cm layer of slag was placed in the lower layer and 20 cm of sandy soil, taken from an area about 70 km away from Lop Nur potash mine, where Tamarix species were growing, was placed in the upper layer (T3); and (4) a 40-cm sandy soil layer taken from the area where Tamarix species were growing was placed on undisturbed soil (T4). Soil nutrient contents increased in the four treatments, but salt content only decreased in the T1 treatment. Salt content in the T4 treatment increased over the two-year period, which may be partly attributed to salt deposition from wind-blown dust within the mine and salt accumulation within the surface soil (0–20 cm) in response to high evaporative demands. The S. salsa plants exhibited greater improvements in growth under the T4 treatment than under the T1, T2, and T3 treatments, which demonstrated that low levels of salinity are beneficial for the growth of this species. The T1 treatment was sustainable because of its low cost and superior soil improvement characteristics. Therefore, S. salsa plants not only reduced soil salinity and increased soil nutrient levels, but also ameliorated the plant growth environment, which would be beneficial for both the ecological restoration of the Lop Nur area and similar areas throughout the world.

submitted time 2018-04-24 From cooperative journals:《Journal of Arid Land》 Hits1905Downloads661 Comment 0

9. chinaXiv:201804.02361 [pdf]

Grazing exclusion-induced shifts, the relative importance of environmental filtering, biotic interactions and dispersal limitation in shaping desert steppe communities, northern China

WANG Xing; SONG Naiping; YANG Xinguo; WANG Lei; CHEN Lin
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Grazing exclusion is one of the most efficient approaches to restore degraded grassland but may negatively affects the recovery of species diversity. Changes in plant species diversity should be a consequence of the ecological assembly process. Local community assembly is influenced by environmental filtering, biotic interactions, and dispersal. However, how these factors potentially contribute to changes to species diversity is poorly understood, especially in harsh environments. In this study, two management sites within a Stipa breviflora desert steppe community (typical natural steppe) were selected in northern China. In one of the two management sites, grazing has been excluded since 2010 and in the other with open grazing by sheep. In August 2016, three plots were established and 100 sampling units were created within each plot in a 5 m×5 m area at the two management sites. To assess the effects of grazing exclusion on S. breviflora steppe, we analyzed the vegetation biomass, species diversity, soil organic carbon, and soil particle size distribution using paired T-tests. In addition, variation partitioning was applied to determine the relative importance of environmental filtering and dispersal limitation. Null mode analysis was used to quantify the influence of biotic interactions in conjunction with EcoSim niche overlap and co-occurrence values. Our results demonstrated that (1) species diversity significantly decreased and the main improvements in soil quality occurred in the topsoil 0–10 cm after the grazing exclusion; (2) environmental filtering was important for community assembly between grazed and fenced grassland and this appears particularly true for soil particle size distribution, which may be well correlated with soil hydrological processes; and (3) however, competitive exclusion may play a significant role within the exclusion. The multiple pathways of assembly may collectively determine negative effects on the restoration of species diversity. Therefore, designers should be aware of the risk of reducing grazing exclusion-induced species diversity and account for manipulating processes. This in turn will reduce dominant species and promote environmental heterogeneity to maximize species diversity in semi-arid regions.

submitted time 2018-04-24 From cooperative journals:《Journal of Arid Land》 Hits1673Downloads644 Comment 0

10. chinaXiv:201804.02343 [pdf]

Variations of precipitation characteristics during the period 1960–2014 in the Source Region of the Yellow River, China

IQBAL, Mudassar ; WEN, Jun; WANG, Shaoping; TIAN, Hui; ADNAN, Muhammad
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Precipitation, a natural feature of weather systems in the Earth, is vitally important for the environment of any region. Under global climate change condition, the characteristics of precipitation have changed as a consequence of enhanced global hydrological cycle. The source region of the Yellow River (SRYR), locating within the Qinghai-Tibet Plateau, is sensitive to the global climate change due to its complex orography and fragile ecosystem. To understand the precipitation characteristics and its impacts on the environment in the region, we studied the characteristics of rainy days and precipitation amount of different precipitation classes, such as light (0–5 and 5–10 mm), moderate (10–15, 15–20 and 20–25 mm) and heavy (≥25 mm) rains by analyzing the precipitation data of typical meteorological stations in the SRYR during the period 1961–2014, as well as the trends of persistent rainfall events and drought events. Results showed that annual average precipitation in this area had a non-significant (P>0.05) increasing trend, and 82.5% of the precipitation occurred from May to September. Rainy days of the 0–5 mm precipitation class significantly decreased, whereas the rainy days of 5–10, 10–15, and 20–25 mm precipitation classes increased and that of ≥25 mm precipitation class decreased insignificantly. The persistent rainfall events of 1- or 2-day and more than 2-day showed an increasing trend, with the 1- or 2-day events being more frequent. Meanwhile, the number of short drought periods (≤10 days) increased while long drought periods (>10 days) decreased. Since the 0–5 mm precipitation class had a huge impact on the grasslands productivity; the 5–10, 10–15, and 20–25 mm precipitation classes had positive effects on vegetation which rely on the deep soil water through moving nutrients and water into the root zone of these vegetation or through the plant-microbe interactions; the ≥25 mm precipitation class contributed to the floods; and more persistent rainfall events and fewer long drought events inferred positive effects on agriculture. Thus, these results indicate grassland degradation, less risk of floods, and the upgrading impact of climate change on agriculture. This study may provide scientific knowledge for policymakers to sustain the eco-environmental resources in the SYSR.

submitted time 2018-04-24 From cooperative journals:《Journal of Arid Land》 Hits1899Downloads742 Comment 0

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