Impacts of primary deforestation upon limestone slopes in northern Vancouver Island, British Columbia

Effects of deforestation upon slopes in limestones and in volcanic rocks in the Benson River valley, northern Vancouver Island, have been investigated quantitatively. Postlogging soil erosion and vegetal regeneration success were assessed by measuring soil depth, percent bare rock and moss cover, and the numbers and diversity of trees, shrubs, and plants on 25 sampling sites, each containing ten measuring quadrats selected at random. Sixteen sites were on the Quatsino Formation, a well-karstified limestone, and nine on the Karmutsen Formation of basaltic lavas. Eight sites were of virgin forest, 16 were logged between 1970 and 1983, and one (on limestone) was logged in 1911. Both bedrock types were significantly affected by the cutting. There was greater loss of soil and an increase in bare rock on the limestones. Erosion was increased significantly by burning on the limestones but not on the volcanics. Within-group comparisons on the limestones determined that steeper slopes and harder burned areas suffered the most and are slowest to regenerate. Volume of timber on the 1911 site was 19 percent of that in similar uncut forest sites. It appears that complete recovery on the barren limestone slopes will require at least some centuries.     

城镇增长下的收缩：以武汉为例

首先从人口、经济、用地3个维度综合考察武汉市增长与收缩的全貌,并采用县区及街道2个尺度的数据定量描述了武汉市增长与收缩的特征与空间格局,发现武汉市下辖青山区、硚口区、汉阳区和蔡甸区存在局部较严重的收缩现象,空间上形成集聚,形态上呈“穿孔式”。进一步以青山区为案例,着重从资本视角探讨发生局部收缩的内在机制,发现其存在老龄化、少子化趋势,但局部收缩的主因是资本从产业部门的“逃逸”。     

岱海地区近400年来的"尘暴"事件——来自岱海沉积物粒度的证据

根据高分辨率的岱海沉积物粒度分布的中值粒径和粗颗粒含量,结合区域降水、历史记载资料,重建了内蒙古岱海地区近４００年来发生的尘暴事件。结果表明,尘暴事件是受冬、夏季风的相对强弱制约的,大量尘暴事件频发于小冰期干冷的气候条件下,表现为中值粒径大,粗颗粒含量高,在转暖的现代气候下,尘暴事件很少,中值粒径也随之降低,但是近十几年尘暴事件又呈上升趋势,部分可能与人类活动造成的土地荒漠化有关。     

Microseismicity and faulting geometry in the Gulf of Corinth (Greece)

During the summer of 1993, a network of seismological stations was installed over a period of 7 weeks around the eastern Gulf of Corinth where a sequence of strong earthquakes occurred during 1981. Seismicity lies between the Alepohori fault dipping north and the Kaparelli fault dipping south and is related to both of these antithetic faults. Focal mechanisms show normal faulting with the active fault plane dipping at about 45° for both faults. The aftershocks of the 1981 earthquake sequence recorded by King et al . (1985 ) were processed again and show similar results. In contrast, the observations collected near the western end of the Gulf of Corinth during an experiment conducted in 1991 ( Rigo et al . 1996 ), and during the aftershock studies of the 1992 Galaxidi and the 1995 Aigion earthquakes ( Hatzfeld et al . 1996 ; Bernard et al . 1997 ) show seismicity dipping at a very low angle (about 15°) northwards and normal faulting mechanisms with the active fault plane dipping northwards at about 30°. We suggest that the 8–12 km deep seismicity in the west is probably related to the seismic–aseismic transition and not to a possible almost horizontal active fault dipping north as previously proposed. The difference in the seismicity and focal mechanisms between east and west of the Gulf could be related to the difference in the recent extension rate between the western Gulf of Corinth and the eastern Gulf of Corinth, which rotated the faults dipping originally at 45° (as in the east of the Gulf) to 30° (as in the west of the Gulf).     

Simulation and projection of climate change using CMIP6 Muti-models in the Belt and Road Region

Climate condition over a region is mostly determined by the changes in precipitation, temperature and evaporation as the key climate variables. The countries belong to the Belt and Road region are subjected to face strong changes in future climate. In this paper, we used five global climate models from the latest Sixth Phase of Coupled Model Intercomparison Project (CMIP6) to evaluate future climate changes under seven combined scenarios of the Shared Socioeconomic Pathways and the Representative Concentration Pathways (SSP1-1.9, SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP4-3.4, SSP4-6.0 and SSP5-8.5) across the Belt and Road region. This study focuses on undertaking a climate change assessment in terms of future changes in precipitation, air temperature and actual evaporation for the three distinct periods as near-term period (2021-2040), mid-term period (2041-2060) and long-term period (2081-2100). To discern spatial structure, K?ppen-Geiger Climate Classification method has been used in this study. In relative terms, the results indicate an evidence of increasing tendency in all the studied variables, where significant changes are anticipated mostly in the long-term period. In addition to, though it is projected to increase under all the SSP-RCP scenarios, greater increases will be happened under higher emission scenarios (SSP5-8.5 and SSP3-7.0). For temperature, robust increases in annual mean temperature is found to be 5.2 °C under SSP3-7.0, and highest 7.0 °C under SSP5-8.5 scenario relative to present day. The northern part especially Cold and Polar region will be even more warmer (+6.1 °C) in the long-term (2081-2100) period under SSP5-8.5. Similarly, at the end of the twenty-first century, annual mean precipitation is inclined to increase largely with a rate of 2.1% and 2.8% per decade under SSP3-7.0 and SSP5-8.5 respectively. Spatial distribution demonstrates that the largest precipitation increases are to be pronounced in the Polar and Arid regions. Precipitation is projected to increase with response to increasing warming most of the regions. Finally, the actual evaporation is projected to increase significantly with rate of 20.3% under SSP3-7.0 and greatest 27.0% for SSP5-8.5 by the end of the century. It is important to note that the changes in evaporation respond to global mean temperature rise consistently in terms of similar spatial pattern for all the scenarios where stronger increase found in the Cold and Polar regions. The increase in precipitation is overruled by enhanced evaporation over the region. However, this study reveals that the CMIP6 models can simulate temperature better than precipitation over the Belt and Road region. Findings of this study could be the reliable basis for initiating policies against further climate induced impacts in the regional scale.     

荒漠土壤微生物群落结构特征研究进展

荒漠生态系统占地球陆地面积三分之一,是地球化学循环中的重要部分。荒漠干旱高温、缺乏植被、UV辐射强,曾被认为是没有生命的地方。然而在这恶劣环境中却蕴含有大量的微生物资源,尤其是荒漠土壤富集了大量微生物。微生物参与和主导整个荒漠生态系统地球生物化学循环,对于调节重要生态过程、修复和稳定荒漠生态系统起到重要作用,对其的研究生态学意义突出。本文综述了国内外对荒漠土壤微生物群落结构特征、群落功能多样性以及微生物群落、微生物与植物、微生物与环境之间相互关系的研究现状,旨在充分了解荒漠土壤微生物多样性研究,总结对荒漠微生物生态认识的不足,为荒漠微生物生态研究方向提供参考。     

南方冬小麦三叶——抽穗期干物重与叶面积动态耦合计算探讨

根据实测资料,尝试性地提出了一种南方麦区冬小麦三叶到抽穗期的干物重与叶面积动态的耦合计算方法,经检验效果尚好。另外,初值灵敏度试验表明苗期生长状况的优劣对于其后生育阶段的干物重与叶面积动态影响似乎不大。     

Influence of fines content on the anti-frost properties of coarse-grained soil

This paper aims to determine the optimal fines content of coarse-grained soil required to simultaneously achieve weaker frost susceptibility and better bearing capacity. We studied the frost susceptibility and strength properties of coarse-grained soil by means of frost heaving tests and static triaxial tests, and the results are as follows:(1) the freezing temperature of coarse-grained soil decreased gradually and then leveled off with incremental increases in the percent content of fines; (2) the fines content proved to be an important factor influencing the frost heave susceptibility and strength properties of coarse-grained soil. With incremental increases in the percent content of fines, the frost heave ratio increased gradually and the cohesion function of fines effectively enhanced the shear strength of coarse-grained soil before freeze-thaw, but the frost susceptibility of fines weakened the shear strength of coarse-grained soil after freeze-thaw; (3) with increasing numbers of freeze-thaw cycles,the shear strength of coarse-grained soil decreased and then stabilized after the ninth freeze-thaw cycle, and therefore the mechanical indexes of the ninth freeze-thaw cycle are recommended for the engineering design values; and (4) considering frost susceptibility and strength properties as a whole, the optimal fines content of 5% is recommended for railway subgrade coarse-grained soil fillings in frozen regions.     

The 3D simulation and optimized management model of groundwater systems based on eco-environmental water demand

Through the study of mutual process between groundwater systems and eco-environmental water demand, the eco-environmental water demand is brought into groundwater systems model as the important water consumption item and unification of groundwater’s economic, environmental and ecological functions were taken into account. Based on eco-environmental water demand at Da’an in Jilin province, a three-dimensional simulation and optimized management model of groundwater systems was established. All water balance components of groundwater systems in 1998 and 1999 were simulated with this model and the best optimal exploitation scheme of groundwater systems in 2000 was determined, so that groundwater resource was efficiently utilized and good economic, ecologic and social benefits were obtained.