Geospatial Assessment of Grazing Regime Shifts and Sociopolitical Changes in a Mongolian Rangeland

Drastic changes have occurred in Mongolia’s grazing land management over the last two decades, but their effects on rangelands are ambiguous. Temporal trends in Mongolia’s rangeland condition have not been well documented relative to the effects of long-term management changes. This study examined changes in grazing land use and rangeland biomass associated with the transition from the socialist collective to the current management systems in the Tsahiriin tal area of northern Mongolia. Grazing lands in Tsahiriin tal that were formerly managed by the socialist collective are now used by numerous nomadic households with their privately owned herds, although the lands remain publicly owned. Grazing pressure has more than tripled and herd distribution has changed from a few spatially clustered large herds of sheep to numerous smaller herds of multiple species. Landsat image–derived normalized-difference vegetation index estimates suggest that rangeland biomass significantly decreased (P < 0.001) from the collective to the postcollective periods. The observed decrease was significantly correlated with changes in the grazing management system and increased stocking density (P < 0.001), even when potential climate-induced changes were considered. Furthermore, field- and Satellite Pour l’Observation de la Terre imagery–based rangeland assessments in 2007 and 2008 indicate that current rangeland biomass is low. Spatial pattern analyses show that the low biomass is uniform throughout the study site. The observed decrease in rangeland biomass might be further accelerated if current grazing land use continues with no formal rangeland management institution or organized, well-structured efforts by the local herding households.     

山东番茄细菌性疮痂病研究：病原鉴定及品种抗病性测定

１９９３－１９９５年从本省济南、泰安、新泰、青岛等１３县（市）调查采集的番茄茄疮病病叶和病果上分离得到６０个细菌菌株，经致病性测定、均能产生典型的疮痂病症状，各菌株间致病力有一定差异。结果表明，该病菌为油菜黄单胞杆菌疱斑致病变种：Ｘａｎｔｈｏｍｏｎａｓｃａｍｐｅｒｓｔｒｉｓｐｖ．ｖｅｓｉｃａｔｏｒｉａ（Ｄｏｉｄｇｅ１９２０）Ｄｙｅ１９７８。从本省收集２５个品种（系），进行抗病性测定，没有一个免疫的     

Energetics of large fullerenes: balls, tubes, and capsules

First-principles calculations were performed to compare the energies of 29 different fullerene structures, with mass number from 60 to 240, and of eight nonhelical graphite tubes of different radii. A quantity called the planarity, which indicates the completeness of the pi-bonding, is the single most important parameter determining the energetics of these structures. Empirical equations were constructed for the energies of nonhelical tubes and for those fullerene structures that may be described as balls or capsules. For a given mass number, bail-shaped fullerenes are energetically favored over capsular (tube-like) fullerenes.     

Characterizing Western Juniper Expansion via a Fusion of Landsat 5 Thematic Mapper and Lidar Data

Juniper encroachment into shrub steppe and grassland systems is one of the most prominent changes occurring in rangelands of western North America. Most studies on juniper change are conducted over small areas, although encroachment is occurring across large regions. Development of image-based methods to assess juniper encroachment over large areas would facilitate rapid monitoring and identification of priority areas for juniper management. In this study, we fused Landsat 5 Thematic Mapper and Light Detection and Ranging (lidar)–based juniper classifications to evaluate juniper expansion patterns in the Reynolds Creek Experimental Watershed of southwestern Idaho. Lidar applications for characterizing juniper encroachment attributes at finer scales were also explored. The fusion-based juniper classification model performed well (83% overall accuracy). A comparison of the resulting juniper presence/absence map to a 1965 vegetation cover map indicated 85% juniper expansion, which was consistent with tree-ring data. Comparisons of current and previous canopy-cover estimates also indicated an increase in juniper density within the historically mapped juniper distribution. Percent canopy cover of juniper varied significantly with land-cover types highlighting areas where intensive juniper management might be prioritized.