Osteomalacia as a result of phosphorus deficiency in beef cattle grazing subtropical native pastures in Uruguay

We investigated 2 outbreaks of osteomalacia as a result of phosphorus (P) deficiency in herds of lactating beef cows grazing subtropical native pastures in Uruguay. Cows exhibited pica, difficulty to stand and walk, rib fractures, and body weight loss even with adequate forage availability. Osteopenia and severe osteomalacia were observed on gross and histologic examination. The concentrations of bicarbonate-extractable P in soil (4.0, 4.1 mg P/kg), total P in pasture (0.9, 1.1 g P/kg), inorganic P in serum (1.0, 0.71 mmol P/L), and P in bone (73 mg P/mL) were all low. Although injectable and mineral salt supplements provided additional P in both outbreaks, these supplementary amounts were insufficient to prevent P deficiency. The P ingested by the cows from the pasture and supplements would have provided 20–55% of their daily P requirements of ~21 g P/d. Osteomalacia occurred in cattle at the 2 ranches as a result of severe P deficiency in the soil and forage, and inadequate P supplementation. Following diagnosis, control of P deficiency in beef cattle requires estimation of the amount of pasture P ingested and provision of sufficient additional supplementary P to meet the animals’ requirements.     

西南地区9种乡土杨树的秋季光合特性比较

季节是影响植物光合特性的重要因素之一,而树木秋季光合作用为次年生长储备营养物质,也是林木育种的重要指标。为了解西南地区9种乡土杨树在秋季生长期对光能的利用效率,以收集于西南地区不同海拔的滇杨、大叶杨、藏川杨、德钦杨、昌都杨、康定杨、乡城杨、西南杨和三脉青杨为研究对象,在10月初采用LI-6400便携式光合测定仪对其光合参数进行测定。结果表明:1）滇杨和藏川杨的生长量优于其他树种。2）乡城杨净光合速率（P_n）日变化呈现为不对称的双峰曲线,其他8种杨树均为单峰曲线,但峰值出现的时间不同;而9种杨树的蒸腾速率（T_r）日变化均为单峰曲线,大叶杨Tr峰值出现在12:00,其他8种杨树均在14:00;9种杨树的气孔导度（G_s）、胞间CO₂浓度（C_i）和水分利用率（WUE）日均值均存在极显著差异,昌都杨G_s日均值最大（0.37 mmol·m^-2·s^-1）,康定杨C_i日均值最小（284.222 4 μmol·mol^-1）,且水分利用率（WUE）最高（4.996 6 μmol·mmol^-1）。3）综合4个光合参数,西南杨和康定杨具有较大的后续生长潜力,且康定杨耐旱性较强,而昌都杨和大叶杨耐旱能力较弱。因此,在今后推广应用及经营管理中,需要考虑不同树种对水分需求的差异。     

Utilisation of wood biomass residues from fruit tree branches,evergreen hardwood shrubs and Greek fir wood as raw materials for particleboard production. Part A. Mechanical properties

This paper investigates the potential of utilising wood biomass from fruit tree branches and evergreen hardwood shrubs as raw materials in the production of particleboards when mixed with Greek fir wood particles. The main mechanical properties of the boards made therefrom were determined and compared with those made of typical industrial wood (IW) particles. The highest modulus of rupture and elasticity (30.0 N/mm² and 4330 N/mm², respectively) in bending and screw withdrawal (SW) resistance (127.8 N/mm) were reported for boards made of Greek fir and were downgraded when the fruit tree branches or evergreen hardwood shrub particles also participated. The participation of fruit tree branch particles in proportions higher than 50% improved the internal bond (IB) of fir produced boards, while the highest IB strength (0.95 N/mm²) was reported for boards made of fruit tree branches. Particleboards made of evergreen hardwood shrubs showed inferior mechanical properties compared with those made of IW particles. The latter also showed superior bending strength but inferior SW resistance compared with boards made of fruit tree branches. Hygroscopic and other properties are under determination and will be presented and discussed in the second part of the work.     

乡土果树南酸枣在城市绿化中的应用

南酸枣是优良的林果药兼用型乡土树种,具有广阔的城市栽培前景。文章对其生物学特性以及城市中栽培的价值、形式、技术等方面进行了简要探讨。     

Nearshore fish assemblages associated with introduced predatory fishes in lakes

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Persistence of native fishes in small streams of the urbanized San Francisco Estuary,California: acknowledging the role of urban streams in native fish conservation

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Genetic identification of native populations of fluvial white-spotted charr <Emphasis Type="Italic">Salvelinus leucomaenis</Emphasis> in the upper Tone River drainage

ABSTRACT:   Stocking of exogenous, hatchery-reared white-spotted charr Salvelinus leucomaenis has been conducted throughout much of their range in Honshu Island, Japan, to increase angling opportunities. Although the native charr populations are thought to have declined because of hybridization with introduced fish, their distribution and genetic status have been uncertain. Fine population structures of charr in the upper Tone River drainage were examined using mitochondrial DNA and microsatellite analyses so as to clarify the presence of native populations. One common mtDNA haplotype was detected in all populations in the Ohashi River and Watarase River, and four and one tributary populations were monomorphic for such haplotypes, respectively. However, several haplotypes, considered to have originated from stocked hatchery fish, were observed in the stocked and the remaining populations. Judging from the genetic integrity over a fine geographic scale, the former were considered as indicative of native populations and the latter as admixtures with hatchery fish. Comparisons of genetic diversity, deviations from the Hardy–Weinberg equilibrium, principal component analysis, and relatedness estimations based on microsatellite DNA can also provide evidence for distinguishing native populations from those influenced by hatchery fish.     

Plant Diversity and Vegetation Structure in Encroached and Non-encroached Areas of Borana Rangelands： The Case of Hallona and Medhacho Pastoralist Associations

The Borana rangelands are important areas of cattle production in Ethiopia. However, these rangelands are threatened by the increasing changes in the natural vegetation from grass and forbs dominated into unpalatable bushy woody vegetation resulting in the loss of some of the highly desirable grass species. This study was conducted to assess the impacts of bush encroachment on the biodiversity, structure and cover of the native vegetation in bush encroached and non-encroached sites. Vegetation data were collected from both sites by laying quadrate plots along transects using a systematic sampling method. According to the results, higher number of species was recorded in the non-encroached sites than that in the encroached sites. The diversity indices for the non-encroached and the encroached sites were 3.16 and 2.67, respectively. The abundance and cover analysis indicated that there was high density and cover of herbaceous species in the non-encroached site. There was a significantly higher density of woody species cover in the encroached site. Generally, the bush encroachment in the Borana rangelands has hampered the diversity of the native vegetation, particularly the grasses and forbs and reduced the ground cover, exposing large parts of the rangelands for soil erosion and other degradation process.     

Carbon and Nitrogen Contents in Typical Plants and Soil Profiles in Yanqi Basin of Northwest China

Carbon and nitrogen are the most important elements in the terrestrial ecosystem. Studying carbon and nitrogen distributions in plant and soil is important for our understanding of the ecosystem dynamics and carbon cycle on arid lands. A study was conducted in a typical arid area, the Yanqi Basin, Northwest China. Carbon and nitrogen distributions in plant tissues and soil profiles were determined at 21 sites with typical native plants and crops. Our results indicated that carbon content was similar between crops and native plants, and the average carbon contents in aboveground （42.4%） and belowground （42.8%） tissues were almost the same. Average nitrogen contents in crops were nearly the same （~0.7%） in aboveground and belowground tissues whereas mean nitrogen content was approximately 100% higher in aboveground （2.2%） than in belowground （1.2%） tissues for native species. Soil organic carbon （SOC） and total nitrogen （TN） in cropland （9.4 and 0.9 g kg^-1） were significantly higher than those in native land （6.2 and 0.7 g kg^-1）. Multiple regression analyses indicated that carbon content in belowground tissue and nitrogen content in aboveground tissue were key factors connecting plant and soil in native land. However, there was no significant relationship for carbon or nitrogen between soil and crop, which might reflect human disturbance, such as plowing and applications of various organic materials.     

长三角城市乡土树种的天然林木群落分析与应用

长三角城市群园林绿化程度很高,但一些城市仍缺少乡土树种特色,危及生态系统稳定。长三角地跨北、中两个亚热带,有三类林木群落组成,即含有常绿阔叶树种的落叶阔叶林、落叶常绿阔叶混交林、常绿阔叶林。长三角范围乡土树种丰富,城市绿化以乡土树种为主,应大力推广应用。