Effects of Prosopis flexuosa on soil properties and the spatial pattern of understorey species in arid Argentina

Abstract. In arid zones dominant woody plants are capable of causing changes in microclimate and soil properties likely to affect species composition, as well as the establishment and spatial distribution of plant species. In North American and European deserts species richness appears to be higher under the canopy of shrubs and trees, in contrast with Chilean deserts where it seems to be lower. Since Prosopis flexuosa (Fabaceae, Mimosoideae) is the most conspicuous tree in the central Monte desert, Argentina, we analysed the effect of this species on the composition and abundance of the shrub and herbaceous layers and on soil properties. We considered two mesohabitats: ‘under P. flexuosa canopy’ and ‘intercanopy areas’. In addition, we analysed the differences between two microhabitats under canopies: ‘northern part of the canopy’ and ‘southern part of the canopy’. Results indicate that species composition and soil properties are affected by both mesohabitats and microhabitats. We found a higher number of shrubs under canopies, whereas that of grasses and perennial forbs increased in intercanopy areas. Concentrations of organic matter, nitrogen, potassium and phosphorus, factors limiting biological productivity in Monte desert soils, were significantly higher under than outside P. flexuosa canopies. Electrical conductivity and concentrations of Na⁺, Ca⁺⁺, Mg⁺⁺ were higher in the northern than in the southern microhabitats. No differences in species richness, evenness or diversity were found between mesohabitats or between microhabitats. We conclude that P. flexuosa modifies the spatial pattern of plant species in the shrub and herbaceous layers and the chemical conditions of the soil, generating spatial heterogeneity on different scales.     

河北省县域农田生态系统供给功能的健康评价

引入"生态系统服务功能"理论,构建县域农田生态系统供给功能健康评价指标——农田生产力稳定系数,该指标被定义为:一定时期内(若干年),县域自然生态系统第一性生产力波动系数与县域农田生态系统第一性生产力波动系数的平均比值;并构建了评价指标与人类福利指标(用县域人均耕地纯收入表征)关系模型,作为评价指标的阈值判定方法。通过河北省136个县的实证研究表明,农田生产力稳定系数对农田生产力稳定性和农田生产力高低具有综合性指示作用;人类社会对生态系统反馈影响的忍受界限对评价指标阈值的确定非常关键;1991—2000年和2001—2009年两个阶段中,河北省县域农田生产力稳定系数整体呈上升趋势,空间格局较为一致,农田生产力稳定系数较低、农田供给功能健康状况较差的县域集中分布在冀北生态脆弱地区;农田生态系统供给功能健康状况与县域贫困状况形成紧密的空间耦合关系。     

贵州茂兰喀斯特的自然森林景观

茂兰位于贵州省东南部,这里有茂密原始的喀斯特森林,它的原生性与其完好的保护状态使之成为极其重要的自然资源,它有独特多样的喀斯特地貌,有种类繁多的动植物类型,这里林木苍翠,山水奇异,是科研与旅游的理想场所。     

福建省灰水足迹时空变化及驱动因素

灰水足迹是稀释水污染物至达标需要的淡水体积,是评价水污染程度与水环境质量的重要方法,对灰水足迹进行核算与分析,可以促进福建省提高水环境质量,构建可持续的水生态环境。借鉴Hoekstra等提出的灰水足迹核算方法,对福建省及各地市2001—2017年的灰水足迹进行核算,对其时空变化特征进行评价并使用对数平均迪式指数分解法(Logarithmic Mean Divisia Index Method, LMDI)模型对灰水足迹变动的驱动因素进行分解。结果表明:a)总氮是决定灰水足迹总量的主要污染物,非点源污染是灰水足迹的最主要来源但占比由68.25%降至63.35%;b)福建省灰水足迹总量降低了9.58%,且各项指标都呈下降趋势,在空间上,灰水足迹总量及剩余灰水足迹东南多西北少,人均灰水足迹及灰水足迹强度东少西多;c)福建省灰水足迹变动的驱动因素中,经济因素是最大正向驱动因素,产生2932.96亿m³的贡献量,技术因素是最大负向驱动因素,产生-2630.31亿m³的贡献量。最后,针对福建省水污染问题提出建议:a)开展非点源污染防治专项;b)加快速度提...     

福建蜂斗草属（野牡丹科）一新种

描述了中国福建蜂斗草属（野牡丹科）一新种,即三脉蜂斗草(Sonerila trinervis Q.W.Lin)。本新种与直立蜂斗草(Sonerila erecta Jack)相似,区别在于本种的茎圆柱形,无翅,有卷曲的微柔毛;叶面被极细的微柔毛,仅具基部3出脉;花瓣白色,近圆形,直径约2 mm;雄蕊长约2.5 mm,花药长约1 mm,易于区别。     

云南景颇族的体质特征

本文调查了云南景颇族261人（男105人,女156人）。年龄为成年人（男24－60岁,女23－55岁）。主要测量均值与现代中国汉族和云南省各少数民族比较和聚类分析的结果表明,景颇族属黄种人的东亚类型,但也有南亚类型特征表现。体质特征与傣族、哈尼族和彝族接近,与基诺族和布郎族较远。     

Chinese plasma-derived products supply under the lot release management system in 2007–2011

In 2007, the Chinese State Food and Drug Administration (SFDA) implemented a management system for lot release of all plasma-derived products. Since then, there have been only a few systematic studies of the blood supply, which is a concern when considering the small amount of plasma collected per capita (approximately 3 L/1000 people). As a result, there may be a threat to the safety of the available blood supply. In this study, we examined the characteristics of the supply of Chinese plasma-derived products. We investigated the reports of lot-released biological products derived from all 8 national or regional regulatory authorities in China from 2007 to 2011. The market supply characteristics of Chinese plasma-derived products were analyzed by reviewing the changes in supply varieties, the batches of lot-released plasma-derived products and the actual supply. As a result, the national regulatory authorities can more accurately develop a specific understanding of the production and quality management information provided by Chinese plasma product manufacturers. The implementation of the lot release system further ensures the clinical validity of the plasma-derived products in China and improves the safety of using plasma-derived products. This work provides an assessment of the future Chinese market supply of plasma-derived products and can function as a theoretical basis for the establishment of hemovigilance.     

Climate Influences on the Radial Growth of Centrolobium microchaete,a Valuable Timber Species from the Tropical Dry Forests in Bolivia

In this study, we use tree‐ring records to determine the climate factors controlling the growth of Centrolobium microchaete, a high‐value timber species from the tropical dry Chiquitano forest in Bolivia. We present the first tree‐ring chronologies from C. microchaete for Concepción and Santa Mónica, Bolivia. Statistical analyses show that the chronologies are of good quality and have a significant common signal between trees. The growth of C. microchaete is strongly influenced by climatic conditions during late spring–early summer. Abundant precipitations concurrent with below‐average temperatures during this period of the year favor tree growth. Climate variations in late spring–early summer explain >40 percent of the total variance in C. microchaete tree growth during the interval 1943–2005. Minor differences in tree responses to climate recorded between the two stands may reflect differences in the extent of the dry season and in soil water capacity between sites. Although the chronologies cover the past 180 yr, adding samples from older individuals would permit the extension of these records further back in time. The strong climate dependency of tree growth suggests that predicted future climate changes in the region could have a significant influence on C. microchaete tree growth during the 21st century.     

湖南省种子植物3种新记录

报道了湖南省种子植物分布新记录3种,隶属于3科3属,分别为浙江冬青Ilex zhejiangensis C.J.Tsengex S.K.Chen&Y.X.Feng、长匍通泉草Mazus procumbens Hemsl.和纤叶钗子股Luisia hancockii Rolfe。凭证标本均存于中南林业科技大学森林植物标本室(CSFI)。