Abundance and diversity of small-bird assemblages in the Monte desert, Argentina

Assemblages of small bird species (<90 g body mass) from the Monte desert in Argentina were studied to analyze spatial and temporal variation in abundance and species richness. Mean species richness was higher during breeding season than in non-breeding season. The same pattern was observed in aerial insectivores, while granivores and substrate insectivores did not differ between breeding and non-breeding seasons. Overall bird abundance was similar across seasons. Species richness was positively correlated with bird abundance and negatively correlated with dominance; bird abundance and dominance were not correlated. These patterns could be explained by distinct responses of functional groups of birds; dominant species were granivores in the non-breeding season and aerial insectivores during the breeding season, and bird abundance in functional groups changed according to food supply. Most species are residents or regular migrants, while there are few nomadic and transient species. Predictable annual fluctuations in rainfall and resource availability should favor a migratory strategy more than nomadic movements. Similarly, breeding is strongly seasonal and most species start breeding when the first summer rains have generally not yet fallen. Finally, concordances in assemblage structure at local and regional scale suggest that similar mechanisms are acting on the local bird assemblages across the Monte.     

Spatiotemporal heterogeneity of soil fertility in the Central Monte desert (Argentina)

In arid environments, soil fertility exhibits a high degree of spatial and temporal heterogeneity, which results from high climatic variability seasonally and heterogeneous plant distribution. However, because most desert areas have been altered by human activities, heterogeneous fertility would originate from grazing or logging activities. We evaluated spatial and temporal heterogeneity of soil fertility in cattle-excluded sites under and outside woody plant cover (Prosopis flexuosa and Larrea divaricata), and in sites disturbed by tree removal during wet and dry season in Ñacuñán Biosphere Reserve (Central Monte desert of Argentina). Soil organic matter, fulvic acids, bioavailable organic matter, and nitrate were lower outside plant canopy (8.9 mg g^?1, 0.03 mg g^?1, 8.2 mg g^?1, and 4.17 mg kg^?1, respectively). Total N, humic acids, and abundance of microbial functional groups did not show differences among sites. Most parameters differed between seasons, tending to be higher in the wet season. Overall soils of Ñacuñán Reserve are characterized by: a) more homogenous spatial pattern than expected from woody plant presence; b) very heterogeneous temporal pattern; and c) after two years, tree removal does not seem to induce infertile soil formation.     

不同尺度下交通对空间流动性的影响

交通的变化对社会经济空间组织产生了重大影响。在宏观与微观尺度下,从理论上分析了交通对空间流动性的影响,借鉴物理学中动能与势能转化理论,构建了单一城市的流动性测度方法,并基于ArcGIS软件的空间分析方法,使用2005年、2010年和2015年的电子地图数据和统计数据,以全国285个设区市和典型市域——赣州市为研究区开展了实证研究。结果表明：① 交通流是空间流动性最显性的表现,与时间、空间及距离相互作用,形成特殊的空间组织形式—流动空间。② 不同尺度下交通对空间流动性的影响表现不一：宏观尺度下,交通的改变使区际流动空间得以生成,相互依赖程度也随着流动性的增强而增强,微观尺度下,交通的变化改变了城市内部的空间组织。③ 全国主要设区市陆路交通网密度呈阶梯状分布,中心城市和交通变化量最大的城市流动性最大,交通的变化对设区市的流动有明显的正向带动作用,对市域内人流的迁移与扩散、功能区的范围扩展与方向迁移、精英空间的变化具有较为显著的引导作用。     

Students' familiarity and initial contact with species in the Monte desert (Mendoza,Argentina)

This study investigates how familiarity and initial contact with species can be explained by social-demographic variables in an arid environment of Argentina. Our main objectives were to investigate which species children are familiar with, and analyse the effect of place of residence, sex and age on students' knowledge and initial contact with species. In total, 1746 students between 7 and 18 years old participated in the study, from 25 urban and 19 rural schools. Students were asked to write down ten animals and ten plants, and to indicate where they had seen them for the first time. Children were able to name an important number of species but they were mostly acquainted with exotic ones. Familiarity with species and the use of different sources of information can be explained by interactions between the studied factors, while place of residence was not as significant as we expected. Sex was an important explanatory variable, likely influenced by differences in roles and children activities' preferences. It is necessary to improve the knowledge on native species, particularly those with conservation problems by using information sources close to nature, without neglecting the knowledge of the exotic species that children showed more familiarity from everyday life.     

Patterns of diversity of the Monte Desert small mammals across multiple spatial scales

The relationship between spatial scale and biodiversity patterns is a highly debated topic in ecology. We evaluated the partition of small mammal diversity at multiple spatial scales and analyzed protected areas in order to evaluate their role of protecting biodiversity at the regional scale. Diversity of small mammals in the Monte Desert was quantified at the regional biome scale (96,000 km²) (γ) and partitioned at three spatial scales: aridity range (α₃,n = 6,16 000 km²), locality level (α₂,n = 18,2-3 ha), and habitat patch (α₁,n = 51,0.6 ha). We estimated their diversity using an additive approach with three indices (richness, Shannon-Weiner, Simpson). Diversity was higher than expected at the “between aridity range (β₃)” scale, but lower at the “within-habitat scale (α₁)”. Alpha was higher than beta diversity for most spatial scales; and at the regional scale protected areas preserved a higher biodiversity than unprotected ones. Our results are the first to partition the diversity of desert small mammals at multiple spatial scales and to support the hypotheses of an irregular scale dependence of alpha and beta diversity when increasing the spatial scales. They also highlight that a better understanding of biodiversity patterns is gained when several tools are integrated and combined at different spatial scales.     

霍山县县域范围内不同空间尺度下农田土壤有机碳变异分析

基于安徽省霍山县第二次土壤普查数据,提取2005～2008年耕地监测数据资料建成土壤有机碳含量数据库,对耕地监测的有机碳数据按县域内不同空间尺度进行了统计分析。结果表明:20年来该县农田表土有机碳含量明显提高,显示农田土壤的有机碳库积累。县域范围内耕地土壤有机碳含量的不同尺度的变异系数介于4.53%～14.91%。村民组(自然村)单元内变异性最高,有机碳含量乡镇间变异性低于行政村间变异性。因此,从县级尺度的农田土壤碳计量来说,以乡镇尺度采样研究比村级尺度可靠性要高。影响县域内农田土壤有机碳含量与变异的动力因子主要是农业利用和农田基本建设,茶、桑和水稻利用下农田土壤有机碳含量明显较高。     

Range and livestock production in the Monte Desert,Argentina

This article reviews and analyzes the available information on range and livestock production in the Monte Desert. Cow–calf operations, goats for meat, and sheep for wool are the dominant production systems under continuous grazing. Rest-rotational grazing systems improved the efficiency of the current cow–calf production. Forage resources are primarily composed of perennial grasses and woody species. Rain-use efficiency for the total vegetation ranged from 3.9 to 4.8 kg DM ha^?1 year^?1 mm^?1. Carrying capacity showed a broad range: 18.7, 4.5–64.5, and 21.6–89.3 ha AU^?1 in the north, central, and south portions of the Monte, respectively. Mean crude protein (CP) content of grasses varied from 8.4 to 10.3 (wet season) and 7.1–3.7% DM (dry season) in the central west and Patagonia, respectively. Grasses predominated in the cattle diet, while the sheep diet was highly diverse because they ate most of the available plant species, and there was no unanimity as to the fact that goats are strictly browsers. Livestock diseases have lower prevalence indices than those recorded in other areas of the country. The high variability in carrying capacity values could be attributed to differences in rangeland condition and to the different methods used for its estimation. The CP levels in forage could meet cattle requirements provided that a proper-stocking rate were used. The most promising species for land rehabilitation are Opuntia, Atriplex spp., Eragrostis curvula and Cenchrus ciliaris. Priorities for future research should include topics such as assessment of the carrying capacity for most of the areas and nutrient content of the components of livestock diet, the livestock intake values, the economic feasibility of the use of complementary feeds and the development of seeding technology for valuable forage resources as Trichloris crinita, among others.     

中原地区多尺度城乡收入的时空分异

采用Theil、CV、Moran's I及尺度方差等方法,基于分区级、市域级、县级三种尺度分析2000-2012年中原地区城镇人均收入、乡村人均收入和城乡收入比的区域差异及空间特征,从多维视角探索城乡收入区域差异。研究发现:1 2000年以来,城镇人均收入区域差异在三种尺度上均表现逐渐减小趋势;乡村人均收入区域差异均呈现逐渐增大趋势;而城乡收入比区域差异不同尺度演化趋势不同,但总体与乡村人均收入较为相似。2尺度方差分解结果显示:城镇人均收入尺度方差及构成由大到小为县级、市域级、分区级;而乡村人均收入与城乡收入比则分为县级、分区级、市域级。3城乡收入三项指标在不同尺度水平上空间关联格局均表现出总体的稳定性,城镇人均收入、乡村人均收入的显著空间关联类型以显著LL区为主,而城乡收入比显著空间关联类型以HH为主。4 Arc GIS分类中,市域级尺度城乡收入三项指标空间类型呈现明显的分区分布,县级空间格局更为复杂且多呈规模不等的圈层分布特征。通过探索城乡收入时空变化特征及其尺度变化特征,可了解不同尺度城乡差距特征及其尺度效应,为中原地区、中国类似区城乡统筹发展战略的制定提供理论依据。     

Pre- and post-dispersal seed loss and soil seed dynamics of the dominant Bulnesia retama (Zygophyllaceae) shrub in a sandy Monte desert of western Argentina

In deserts and semi-deserts dominant plants seldom rely on a persistent seed bank to ensure their recruitment from sexual reproduction, which is generally based on the seeds produced in the last reproductive event. We studied pre- and post-dispersal seed loss of Bulnesia retama, a dominant shrub of the sandy Monte deserts (western Argentina). We hypothesised that pre- and post-dispersal seed depletion in B. retama regulate soil seed density and in turn decrease soil seed reserves. We also hypothesised that spatial patches induced by standing vegetation and other microsites additionally affect post-dispersal seed loss and soil seed density.We observed that as much as half the total seed production was lost due to pre-dispersal seed predation. Seed dispersal plus predation showed a negative exponential function with 61% of seeds falling during the first 28 days, and 99% after 90 days, when 34% of the seeds remained inside excluded branches. A significant patch effect was observed on soil seed density and seed dynamics, with a greater number of seeds and increased seed depletion rates below B. retama shrubs. However, spatial patches did not affect seed germination although they increased with burial time, from 22% to 70% after 75 and 276 days, respectively. Likewise, a similar trend was found in potential seed germination; seeds collected directly from mother plants had a low germination rate (less than 25%), which increased to 75% after 276 days of soil burial. About 15% of the dispersed seeds should persist to the next rainy season, thus contributing to a low-density but persistent seed bank.The delay in seed germination and temporal decrease in soil seed density that we observed for B. retama suggest that a set of mechanisms have been developed promoting germination events whenever soil water is available, at any moment of the year.     

Overview of the geography of the Monte Desert biome (Argentina)

The compilation of published results on the geography of the Monte Desert biome of Argentina that we present here offers a review of its boundaries and ecotones, and of its biophysical and socio-economic characteristics. In relation to socio-ecological issues, the focus is on a case study in the province of Mendoza. An analysis is presented about the ecological-economic issues and the sustainable investment policies in rangelands of the Patagonian Monte. In addition, this biome is compared with other South American arid biomes and their North American counterparts. We identified some gaps in the current knowledge, especially at a mesoscale level, where studies on Monte borders are deemed necessary as well as explicit boundary criteria for ecosystem differentiation. Also the ecological-economic relations and feedbacks between livestock herbivory, soil erosion and market behaviour should be considered within the framework of wider socio-ecological research.     

不同时间尺度的阿尔泰山北部和南部降水对比研究

常年受到西风影响的阿尔泰山地区,是古气候研究的重点区域之一。利用阿尔泰山北部和南部的11个气象站观测数据和已发表的古气候数据（包括树轮、冰芯和湖芯）,详细对比了不同时间尺度上（季节、年、几十年、百年和千年尺度）阿尔泰山北部和南部的降水变化。结果表明,阿尔泰山北部器测时段降水是逐渐下降的,而阿尔泰山南部降水反而呈现逐渐增加的趋势。这种反相的降水关系也体现在过去200年、过去1000年和全新世时段,说明阿尔泰山北部和南部降水在季节、年、几十年、百年和千年尺度上均存在相反的趋势。不同时间尺度上降水存在的相反关系表明阿尔泰山是一个重要的气候边界。但不同时间尺度上出现相反变化的原因需进一步详细探讨,这不仅有助于了解区域水汽变化的历史,也有助于加深理解欧亚草原丝绸之路文化的演替。     

半干旱草原型流域不同时间尺度降水特征分析

基于锡林浩特气象站1960-2015年逐日降水数据,运用M-K法、R/S 法和Morlet 小波法,分析了半干旱草原型流域--锡林河流域近56a不同时间尺度下降水趋势及突变特征、未来变化趋势、降水周期规律的变化情况。结果表明：近56a来锡林河流域年降水量呈下降的趋势,在1974、1980、1989年和1998年发生过4次突变,存在28a的主周期变化。夏季降水特征和年降水特征基本一致,冬季降水量呈显著上升的趋势。汛期8月份降水量呈显著下降的趋势,并在1998年左右发生突变,降水第一主周期在12a处,非汛期11和12月份降水量都呈显著上升的趋势,其中,12月份降水在2000 年左右发生显著突变,这两个月份降水的第一主周期分别是30a和9a。不同时间尺度下降水序列的Hurst指数均>0.5,说明流域降水趋势具有持续性,未来降水趋势与过去保持一致。     

Seed reserves in the central Monte Desert, Argentina: implications for granivory

It has been suggested that lower rates of granivory in South American warm deserts compared to their North American counterparts arose from a reduction of seed reserves in the former owing to the extinction of argyrolagid marsupials. We measured seed reserves in two habitats of the central Monte Desert in an attempt to detect such seed decline, but to no avail. After moderate rainfall, maximum seed standing crops reached 16,000 and 23,000 seeds m⁻²in shrublands and open forests, respectively. Under the canopy of trees and shrubs there were 19,000 and 37,000 seeds m⁻²; whereas in exposed areas there werec. 10,000 seeds m⁻²in both habitats. Seed banks in other South American semi-arid areas showed similar values. Total grass seeds as well as those presumably preferred by ants also seem to be similar in both continents. Hence, granivory in South America, as has been already reported for Australia, is lower than in North America in spite of the great similarity of seed bank sizes. Moreover, argyrolagids were unlikely seed-hoarding granivores, therefore some other reason than argyrolagid extinction should be sought to explain the lack of specialized seed-eating mammals, and the smaller overall seed consumption rates in South American deserts.     

Short- and long-term effects of shrub management on vegetation in the Monte, Argentina

A comparison was made of plant cover, carrying capacity and diversity in areas of Monte vegetation at the Biosphere Reserve of Ñacuñán, Mendoza, Argentina, in 1982, 1984 and 1995. Treatments applied in 1981 were: control (untreated plots), selective hand-cutting, roller-chopping, and root-plowing. By 1995, woody cover was lower in root-plowed plots (27%) than in the others treatments (41–51%), and herbaceous cover was similar in treated (28–39%) and untreated areas (26%). Carrying capacity of treated areas (6–8 ha per Large Stock Unit (LSU)) was higher than in the control areas (12 ha LSU⁻¹). Woody species diversity, quantified by the Shannon index, for both areas was similar in the study period (0·62), except in root-plowed sites in 1982 (0·0) and 1995 (1·3). Herbaceous species diversity was similar on treated (0·81) and untreated sites (1·2) in 1995. We could recommend less drastic treatments to improve carrying capacity.     

宁杭城市多时空尺度居住空间分异与比较

城市居住分异具有社会群体与住宅空间的社会—空间双重属性,已有研究多关注社会经济属性,采用非空间分异指数开展单个城市和较大尺度的实证分析,较难有效反映中国当前城市内部日趋复杂多变、异质破碎的居住分异景观。基于住宅空间视角,采用多群体分异指数、空间分异曲线、指数分解模型与地理探测器等方法,以南京、杭州为案例城市,从街道、街区与网格3个尺度,分析宁杭2009—2018年居住空间分异及其影响因素。研究表明：空间分异指数因考虑到住宅空间位置和邻域环境,可作为对非空间分异指数的一种改进;南京不同住宅类型空间分异程度高于杭州,主要是由城市空间结构差异造成的;居住空间分异是城市社会空间资源非均衡配置的结果,其中“中心位势”和“教育配套”等因素对城市居住空间分异的影响最为显著;宁杭城市居住空间分异的共性与特性并存,揭示出城市比较研究的可行性与必要性。通过创新性探索,为中国城市居住分异研究提供新视角、新方法和新思维。     

Cattle grazing effects on annual plants assemblages in the Central Monte Desert,Argentina

Plant assemblages' dynamics have been studied to evaluate the influence of different environmental factors. The aim of our work was to assess the effect of a disturbance in the form of livestock grazing on annual plants, in a South American desert. We tested the exclusion of cattle grazing by comparing the composition of annual plants in three major vegetation types within a MaB Reserve in the Monte Desert of Argentina, with those of an adjacent grazed field. Sampling was conducted in two consecutive years that differed in precipitation. We established three sampling sites within each vegetation type at the reserve and the grazed field. Transects were set to assess plant cover, abundance, and richness. Theoretically, changes in diversity are explained by changes in one of its components: species richness. Species richness of annual plants was not different between the grazed and ungrazed sites. However, plant cover and diversity were lower in grazed sites, whereas abundance increased. Owing to a strong species-specific effect, we propose that it is evenness the main parameter involved in diversity dynamics in the heterogeneous vegetation mosaic of the Monte desert. Finally, vegetation types (spatial heterogeneity) and rainfall regime (temporal heterogeneity) greatly interacted with grazing effects. We endorse the idea that rapid responses of annual plant assemblages to changes in rainfall conditions coupled with herbivore control, might result in a restoration pathway for degraded arid landscapes.     

Plant impacts on nitrogen and carbon cycling in the Monte Phytogeographical Province,Argentina

In arid and semiarid ecosystems, primary productivity and nutrient cycling are directly related to the amount and seasonal distribution of precipitation. However, depending on morphological, phenological, physiological, and biochemical traits, plants may influence the quality and quantity of organic matter inputs to the soil and thus the biomass and activity of the soil biota responsible for carbon and nitrogen dynamics. In this paper, we review the available knowledge on plant functional traits and their impacts on ecosystem processes such as N and C cycling throughout the Monte Phytogeographical Province. We address the mechanisms of N conservation, the quantity and quality of leaf litterfall and root traits of the dominant plant life forms and their effects on decomposition processes, soil organic matter accretion, and soil-N immobilization and mineralization. We conclude that plant functional traits affect ecosystem processes in the Monte Phytogeographical Province since the chemistry of senesced leaves and root biomass exerts an important control on organic matter decomposition and N availability in soil.     

基于MODIS数据不同荒漠植被指数的空间变化研究--以新疆三工河流域为例

通过对三工河流域的实例研究,探讨了干旱区不同下垫面荒漠植被指数的空问变化规律。采用植被信号／土壤噪音对15个植物样方数据进行对比分析,探讨了三工河流域荒漠植被指数的梯度变化及适宜性。结果表明：扇缘溢出带植被指数值最高,其次是山前丘陵带和固定沙丘,较真实地反映出了三工河流域荒漠植被的梯度变化规律;扇缘溢出带的EVI值要比NDVI值离散程度小,趋势平稳,在扇缘溢出带用EVI能更好地反映植被生长状况;山前丘陵带的NDVI值要比EVI值均匀,山前丘陵区用NDVI这一植被指数较好,扇缘溢出带和固定沙丘区用EVI要比用NDVI好。     

基于不同尺度的中国运动健身场所空间差异及影响因素研究

运动健身场所是开展全民健身运动的重要推手,探明运动健身场所的区域差异及影响因素对推动运动健身场所的建设、推进“健康中国”战略有重要作用。从省级、城市群以及地级市3个尺度出发,运用总体分异测度指数(Global differentiation index,GDI)、Moran’s I指数、热点分析探讨运动健身场所的空间差异,采用Pearson相关系数、灰色关联度以及地理探测器等方法分析运动健身场所分布的影响因素。结果表明:(1)运动健身场所数量与每万人拥有运动健身场所数量主要集中分布于东部地区,而西部地区除成都、重庆外,其余省区均分布较少。(2)运动健身场所数量与每万人拥有运动健身场所数量的GDI随着尺度的缩小而扩大,城市群尺度中,优化提升类差异最大,而发展壮大类差异最小。(3)经济总量和人口数量是运动健身场所集中的重要驱动因素,人口数量与城镇人口占比的交互作用最强。在城市群尺度上,受教育程度和城市规模大小是运动场所的重要影响因素。而在地级市尺度上,建成区面积占辖区面积比重对运动健身场所的影响更为显著。