Assessing regional differences in predation of endangered species: Implications from Texas populations of the endangered star cactus (Astrophytum asterias)

Understanding threats to endangered species is one of the most critical components of implementing a successful recovery plan. For the endangered star cactus Astrophytum asterias, both mammalian and insect herbivory have been documented as a major threat to populations in Mexico. Herein, we focus on populations of A. asterias in Texas, examining how mortality threats differ from populations found in Mexico as well as among sites within Texas. Our study supports insect and mammalian herbivory as a major threat to A. asterias in Texas, with reductions in population sizes ranging between 16 and 54%. However, our study highlights that both regional and local differences can influence rates of mortality even in a range-restricted species such as A. asterias and highlights the need to assess threats at both of these levels for effective development and implementation of endangered species recovery plans.     

Dynamic Parameters of Plant Communities Partially Reflect the Soil Quality Improvement in Eco‐Reclamation Area of an Opencast Coal Mine

The influence of soil physicochemical properties and the relationship between the plant community and edaphic factors have been studied through monitoring the community dynamic parameters and analyzing the soil properties from four plant plots at the Pingshuo opencast coal mine eco‐reclamation area. The results are obtained as follows: (1) the law of the quantity variation of total N and available K is affected by the different kinds of plant configuration mode. It is Robinia pseudoacacia + Pinus tabuliformis (SIV) > R. pseudoacacia (SV) > R. pseudoacacia + P. tabuliformis (SI) > R. pseudoacacia + Ulmus pumila + Ailanthus altissima (SIII). The quantity is close to or exceeds the level of the original geomorphology. The average content of available N has the following order: SIV > SI > SIII > SV; the average content of available P SV > SIII > SIV > SI, both are far below the level of the original geomorphology; pH SIV < SIII < SI < SV; bulk density SI < SIV < SV < SIII, moisture content SIV > SIII > SI > SV; in the soil layer of 20–40 cm, except the available P, other physicochemical factors are in accordance with the factors of the surface soil; (2) the population average density, height and diameter at breast height (DBH) have no obvious relevance with the average density of the stumpage; (3) the average density, height, and DBH of R. pseudoacacia are closely related to pH and the content of available N and available P and all the index can be fitted by the equation of linear regression of the edaphic factors mentioned above. The principal component analysis shows that the magnitude of the impacts of three kinds of edaphic factors on the R. pseudoacacia population has the following order: pH > available N > available P. The average density of U. pumila is closely related to the moisture content of the soil. This regression model can be used to direct the cultivation and propagation of R. pseudoacacia and U. pumila population at the mine eco‐reclamation area.     

The effects of precipitation timing on sagebrush steppe vegetation

Changes in precipitation patterns and inputs have the potential to cause major changes in productivity, composition, and diversity of terrestrial plant communities. Vegetation response to altered timing of precipitation was assessed during a 7-year experiment in an Artemisia tridentata spp. wyomingensis community in the northern Great Basin, USA. Four permanent rainout shelters excluded natural rainfall, with seasonal distribution of precipitation controlled with the use of an overhead sprinkler system. Precipitation treatments under each shelter were WINTER, SPRING, and CURRENT. The WINTER treatment received 80% of its water between October and March; in the SPRING treatment 80% of total water was applied between April and July; and the CURRENT treatment received precipitation matching the site's long-term (50 years) distribution pattern. A CONTROL treatment, placed outside each shelter replicate, received natural precipitation inputs. CURRENT, WINTER, and CONTROL treatments had similar in soil water-content patterns and thus, there were few consistent differences in vegetation response. The SPRING treatment resulted in more bare-ground and lower plant productivity compared to other shelter treatments. This result contrasted with our initial hypothesis that shallower-rooted grasses would gain a competitive advantage over shrubs if precipitation was shifted from winter to spring. Our results also demonstrated the resilience of these communities to climate perturbation as many of the vegetation shifts did not begin until the fourth year after treatments were applied.     

Acacia exchanges: Wattles, thorn trees, and the study of plant movements

Plants are frequently moved around the world, creating new regional landscapes and environmental imaginaries. Building on previous work in environmental history and geography, we develop a three-part approach to analyzing plant movements and apply it to trees from the Acacia genus (sens. lat.) exchanged between Australia and the rest of the world. First, we investigate the agents, circuits, and frequencies of acacia movements, including transoceanic transfers, regional diffusion, and ecological dispersal. Second, we trace bundles of knowledge or technology that accompany the acacias, highlighting how they help shape regional biogeographies. Finally, we analyze how different societies, with distinct economies, politics, and environmental sensibilities, receive introduced plants. This approach allows us to see transferred plants as active agents in region-forming processes, and to avoid normative tropes like ‘miracle plants’ or ‘alien invasives’. The highlighted species include Acacia colei, Acacia melanoxylon, Acacia mearnsii, Acacia farnesiana, Acacia nilotica, Acacia mangium, and their close relatives.     

河流性湿地公园植物景观设计初探——以陕西千湖国家湿地公园为例

以河流性湿地陕西千湖国家湿地公园为例,介绍了湿地公园植物景观配置中存在的问题,阐明了公园植物景观设计的原则。介绍了保护保育区、科普宣教展示区和湿地休闲区植物景观规划设计方法,以期为湿地公园植物的保护与恢复、植物景观规划营建提供有益的参考。     

Characteristics of selenium migration in soil–plant system of East Meshchera and Transbaikalia

Herein some results of comparative researches to determine the parameters of selenium migration in meadow biogeocenoses of East Meshchera and East Transbaikalia are presented. The parameters of selenium mobility in soils (i.e., the element total content, plant-accumulation coefficient (Kb) and/or mobile form ratio) in Urov biogeochemical provinces of the East Transbaikalia are quite comparable to the element migration parameters found in selenium-deficient landscapes of the same area. Selenium mobility indices and ecological status are significantly higher for meadow biogeocenoses of the East Meshchera (Moscow Region) and also for limestone soils.     

Selenium levels in Lebanese environment

Very limited research has been conducted on selenium (Se) in Lebanese soils and forage crops but no work has been done on Se in water and locally produced vegetables and grains. This research was conducted in order to quantify Se levels and its availability in agricultural soils, vegetables and grains in Lebanon. Sixty-six (66) soil samples were collected from 33 selected sites in Lebanon: the Bekaa Valley, coastal and mountainous regions. Thirteen (13) different plant types (86 samples) were sampled from the same locations. Also, 13 spring water and 10 bottled water samples were collected. Soil samples were analyzed for their physical and chemical properties. Selenium was extracted from soils with: deionized–distilled water (Soluble-Se), KH₂PO₄-0.1 M (MKP-Se) and concentrated (HNO₃ + HCl) mixture (acid-Se). Plant Se was extracted by acid digestion on a hotplate. Selenium concentrations were measured by the inductively coupled plasma-mass spectrophotometer (ICP-MS). The values of Soluble-Se, MKP-Se and acid-Se ranged between 47 and 142, 147 and 400, and 1749 and 4713 μg/kg, respectively, with average values of 95, 306, and 3118 μg/kg and at a ratio of 1:3:30. Thus, Se extracted with deionized–distilled water is a good indicator for Se availability in the studied soils. The average Se concentration in plants was in the following order: radish > lettuce > cucumber > cabbage > parsley > alfalfa > onion (leaves) > broccoli > tomato > mint > chickpeas > wheat > onion (bulbs). The Se levels in water samples were in the safe range (less than 50 μg/L) and ranged between 2.14 and 17.6 μg/L. The levels of Se in the three soil extractants were positively correlated with each other and with organic matter content, salinity and phosphorus (P). Selenium levels in plant samples were positively correlated at a 0.01 significance level with clay and P content.     

植物生长调节剂对几种饵料微藻的影响

本文研究三种植物生长调节剂对4种饵料微藻的生长、叶绿素含量、细胞大小、干重及氨基酸含量的影响;结果表明:丰产素,2,4—D对叉鞭金藻,青岛大扁藻有显著的促进生长作用,尤其是在低温下也能有效地促进其生长,并能保持其营养价值。     

海洋细菌B-9987 胞外代谢产物的纯化及抑菌机理初探

由渤海海泥中分离得到 30 0株菌株 ,从中筛选获得海洋生境芽孢杆菌B 9987菌株 ,其胞外物质经乙醚萃取、硅胶G薄层层析、官能团显色反应及紫外扫描 ,测其组分 ;以不同浓度B 9987菌株的抑菌液测定对植物病原真菌的抑制效果。结果表明 ,B 9987菌株的胞外抑菌物质可能是酚类化合物 ;该物质对植物病原真菌茄交镰孢菌、大丽轮枝菌、黄枝孢菌、立枯丝核菌的抑制作用 ,主要是造成真菌孢子或菌丝末端膨大成球状 ,继而胞壁崩解 ,原生质外泄。对尖刀镰孢菌和莴苣霜霉菌的抑制作用 ,则表现为孢子萌发率降低和菌丝长度明显变短。该抑菌物质可望开发为农用抗生素     

Karstification at Beşkonak dam site and reservoir area,southern Turkey

Bekonak dam and hydroelectric power plant are planned to be constructed on the Köprüçay river, 40 km east of the Antalya city. In the dam site and reservoir area, Köprüçay Conglomerates of Miocene age and the Bekonak Formation (sandstone-claystone) alternating with each other crop out vertically. Köprüçay conglomerates, with the components of limestone fragments and carbonate texture, are karstic and permeable, whereas the Bekonak Formation is impermeable. At the northern edge of the reservoir area, the Olukköprü karst springs discharge at a minimum of 30 m³/s. These springs discharge mainly through vertical and subvertical joint systems. Intensive superficial karstification developed along the joint systems and the terrane reveals columns of rocks, called fairy chimneys. Olukköprü springs represent the discharge point for a large and continuous system of underground solution cavities. In the Köprüçay basin, there are numerous karstic features within the conglomerates. Within the reservoir area, Kuruköprü cave, with a length of 530 m, is an example of these caves developed within the conglomerates. In some parts of the reservoir area, where the groundwater level is lower than the surface-river elevation, a highly developed karstification zone is present within the fluctuation range of groundwater between depths of 40 and 50 m. The above-mentioned Kuruköprü cave is an active cave developed in the dam site and its vicinity. The solution conduits developed along the system of mostly vertical fractures and joints are interconnected, thus giving rise to a three-dimensional conduit network. On the other hand, a majority of these conduits have clay and calcite filling materials. Karstification in the dam site varies with depth exponentially. Data suggest that karstification has a vertical extention as deep as –220 m.