兰州北山不同植被土壤可培养微生物丰度变化特征及影响因素

以黄土高原中部的兰州北山为对象,通过野外取样和室内分析,动态监测黄土高原半干旱区两种人工林地生态系统的微生物类群分布规律.结果表明：试验区环境因子差异较大,林地土壤含水量、有机碳、全氮均高于荒地.全磷随植被类型变化差异不显著,随季节变化差异显著.土壤温度夏季 > 秋季 > 春季 > 冬季,土壤容重与有机碳、全氮含量呈显著负相关.不同植被类型土壤微生物丰度四季变化趋势为：细菌 > 放线菌 > 真菌的分布规律.微生物类群总数整体表现为林地高于荒地.回归分析显示：土壤pH值与细菌数量、放线菌数量及微生物总数均呈显著正相关（P < 0.05）,而与真菌呈显著负相关（P < 0.05）;土壤容重与真菌数量呈显著负相关（P < 0.05）;土壤温度与细菌、真菌及微生物总数均表现出显著正相关（P < 0.05）.通径分析表明,pH值对细菌数量的直接通径系数最大,容重对真菌数量的直接通径系数最大,土壤含水量对放线菌数量直接通径系数最大.研究显示,兰州北山植被恢复区土壤的有机碳、全氮、全磷等林地高于荒地,表明植被恢复对微生物的数量与种类有影响,且混交林的造林方式适宜兰州北植被恢复.     

Distribution and transportation of mercury from glacier to lake in the Qiangyong Glacier Basin, southern Tibetan Plateau, China

The Tibetan Plateau is home to the largest aggregate of glaciers outside the Polar Regions and is a source of fresh water to 1.4 billion people. Yet little is known about the transportation and cycling of Hg in high-elevation glacier basins on Tibetan Plateau. In this study, surface snow,glacier melting stream water and lake water samples were collected from the Qiangyong Glacier Basin. The spatiotemporal distribution and transportation of Hg from glacier to lake were investigated. Significant diurnal variations of dissolved Hg(DHg) concentrations were observed in the river water, with low concentrations in the morning(8:00 am–14:00 pm) and high concentrations in the afternoon(16:00 pm–20:00 pm). The DHg concentrations were exponentially correlated with runoff, which indicated that runoff was the dominant factor affecting DHg concentrations in the river water. Moreover, significant decreases of Hg were observed during transportation from glacier to lake. DHg adsorption onto particulates followed by the sedimentation of particulate-bound Hg(PHg) could be possible as an important Hg removal mechanism during the transportation process. Significant decreases in Hg concentrations were observed downstream of Xiao Qiangyong Lake, which indicated that the high-elevation lake system could significantly affect the distribution and transportation of Hg in the Qiangyong Glacier Basin.     

Techno-environmental risks and ecological modernisation in “double-risk” societies: reconceptualising Ulrich Beck’s risk society thesis

By utilising a relatively underused framework developed by Maurie J. Cohen (1997. Risk society and ecological modernisation alternative visions for post-industrial nations. Futures, 29 (2), 105–119), this theoretical paper joins two of the most debated theories of environmental politics – ecological modernisation (EM) and Ulrich Beck’s risk society thesis – into a unified framework and problematises some of their implicit assumptions to theoretically introduce the notion of a “double-risk” society. In addition, it explains the differences between the traditional “Risk Society” theorised by the German sociologist Ulrich Beck and the newly introduced concept of a “double-risk” society. The arguments put forward in this paper provide some fresh perspectives facilitating the study of the techno-environmental risks and other ecological problems faced by “double-risk” societies. Theoretically, this paper adds to both EM theory and the risk society thesis as the generalisability of their existing versions is limited precisely because they fail to address some important social changes at the global structural level.     

Application of compost of two-phase olive mill waste on olive grove: Effects on soil,olive fruit and olive oil quality

Composting is a method for preparing organic fertilizers that represents a suitable management option for the recycling of two-phase olive mill waste (TPOMW) in agriculture. Four different composts were prepared by mixing TPOMW with different agro-industrial by-products (olive pruning, sheep manure and horse manure), which were used either as bulking agents or as N sources. The mature composts were added during six consecutive years to a typical “Picual” olive tree grove in the Jaén province (Spain). The effects of compost addition on soil characteristics, crop yield and nutritional status and also the quality of the olive oil were evaluated at the end of the experiment and compared to a control treated only with mineral fertilization. The most important effects on soil characteristics included a significant increase in the availability of N, P, K and an increase of soil organic matter content. The application of TPOMW compost produced a significant increase in olive oil content in the fruit. The compost amended plots had a 15% higher olive oil content than those treatment with inorganic fertilization. These organics amendments maintained the composition and quality of the olive oil.     

Soil effects of six different two-species litter mixtures that include Ulmus pumila

The tree species that contribute to decomposed leaf litter can have important effects on soil properties and thus nutrient cycling and interactions between tree species. We examined ground leaf litter and soil mixtures consisting of leaves from Ulmus pumila (Up) combined individually with leaves from one of six other species: Betula platyphylla (Bp), Quercus liaotungensis (Ql), Salix matsudana (Sm), Hippophae rhamnoides (Hr), Caragana microphylla (Cm), and Amorpha fruticosa (Af). The soil–litter mixtures were incubated for 120 days to analyse the effects of their decomposition on soil properties and to determine the interactions between the different types of litter within each mixture. The decomposed litter mixtures were composed of Up combined with Sm- or Hr-improved soil fertility relative to the pure Up mixture, but the decomposed litter mixtures were composed of Up combined with Cm-, Af-, or Ql-diminished soil properties. Three leaf mixture treatments, namely Up?×?Bp, Up?×?Sm, and Up?×?Hr, exhibited synergistic effects on soil properties (i.e. soil properties exceeding the predicted values); however, three other treatments, namely Up?×?Ql, Up?×?Cm, and Up?×?Af, exhibited antagonistic effects (i.e. properties below the predicted values). Therefore, litter from Bp, Sm, or Hr should be mixed with Up to improve soil fertility and production in plantations.     

黄土丘陵小流域沟坡水热条件及其生态修复初探

在黄土丘陵沟壑区,沟坡是小流域尺度上水土流失最为活跃的部分,对其水热条件的了解是进行综合治理的基础。论文以黄土丘陵区甘肃定西安家沟小流域为例,观测了沟坡不同地形部位和植被类型土壤水分季节动态和剖面变化特征,同时观测了光照、大气湿度、温度和风速等小气候条件,并探讨了沟坡生态修复方式。结论与建议如下。①历次取样中,0～100cm平均土壤水分均以沟道灌木林地最高,沟坡中的阳坡和阴坡的草地和灌木林地次之,梁峁坡农地最低,且6种类型样地间有显著差异(P<0.01);对于相同的植被类型来说,阳坡的林草植被土壤水分均要小于阴坡,但没有显著差异(P>0.05);而在同一坡向,草地的土壤水分要显著高于灌木林地(P<0.01);和梁峁坡农地的土壤水分季节变化特征相比,沟坡植被土壤水分的季节变化不明显。②对于梁峁坡农地和阴坡的灌木林地来说,土壤水分在剖面内随着深度变化平缓,而其它4种类型样地土壤水分在剖面内随着深度呈增加的趋势。对于这6种类型样地,土壤水分剖面差异格局与0～100cm平均含水量相似;且随着深度的增加,6种类型样地间土壤水分的差异性增大。③对于梁峁坡和沟坡来说,4～5月份风速均是观测期内最大的,但沟坡风速要小于梁峁坡坡面;在观测期内,高湿期出现在5月,且沟坡大气相对湿度高于梁峁坡;和     

黄土丘陵小流域土地利用的时空分布及其与地形因子的关系

采用航片解读、实地调查、土地规划和基于GIS的统计分析相结合的方法,从土地利用面积和地形分布格局的变化分析入手,研究了黄土丘陵小流域土地利用的时空分布格局及其影响因子。研究结果表明,黄土丘陵区大南沟小流域的土地利用变化可以分成两个阶段,第一阶段从1975、1998年到25°退耕,林地/灌木地面积增加,荒草地、休闲地和耕地的面积减少,果园/经济林地的面积变化不明显;第二阶段即3种土地利用规划方案,包括25°、20°和15°退耕方案,林地/灌木地和荒草地的面积保持不变,耕地和休闲地逐渐被果园/经济林地所替代。汇总与相关分析表明,这5种土地利用类型的地形分布格局也发生相应的变化。研究指出,近20年来,大南沟小流域土地利用格局日趋优化,3种土地利用规划方案体现了土地持续利用的生态、经济和社会效益,具有很强的操作性。     

植被对黄土高原沟壑区坡地土壤有机碳的影响

选取高原沟壑区王东沟流域内典型的治理坡段,研究不同植被条件下土壤有机碳、氮的含量变化和坡面分布特征。结果表明:与荒草(白羊草)群落相比,油松群落条件下,土壤有机碳含量提高9.3%(P>0.05),而果园土壤有机碳含量降低40.1%(P<0.05)。沙棘、侧柏和刺槐群落下,土壤有机碳含量虽低于荒草群落,但尚未达到显著水平(P>0.05)。果园和刺槐群落下坡面有机碳变化趋势不明显;杏树群落下表现为坡中部含量高,上部和下部低;白羊草群落下坡面有机碳含量从上到下逐渐增加。不同植被条件下土壤全氮与土壤有机碳存在极显著(R²=0.925)的相关关系。     

Formation Process and Amelioration of the Loess Plateau in China

Abstract

Based on the formation process of the Loess Plateau, the characteristics comparison between loess and ancient soil and the located materials of spore- pollen, ancient stone artifact, history, geography and soil erosion, the analysis reveals that the present state serious soil erosion in Loess Plateau, instead of being a natural geologic course, is a consequence of destruction of vegetation, irrational land utilization and the direct destruction of soil permeability and anti-erosion ability, esp. anti-scourability. The water and soil conservation measures, with the twenty-eight-word amelioration principle as the core, are the basis for exploiting and improving water and soil resources of the Loess Plateau so as to harness the Huanghe (the Yellow River).     

基于FY2C卫星数据的藏北高原降水估算研究

如何确切的掌握降水的时空分布,对区域气候、水文和生态应用等至关重要。以藏北高原典型区为研究区,在大量地面实况降水观测数据与对长时间序列FY 2C 影像光谱特征和云图特征分析的基础上,获取卫星降水模拟参数特征集以刻画云降水的发生与发展过程,选用最值归一化方法对不同量纲云图特征参数进行归一化处理。构建基于三层前向型反向传播神经网络的卫星降水估算模型,用于该地域降水估算,并采用多指标体系分析模型的降水模拟精度。结果表明：静止气象卫星红外波段能较精确地揭示云的降水机理,较高时间分辨率遥感图像可以监测云图的变化细节,并获取能够反映云图降水特征的降水模拟参数;人工神经网络能较好地刻画该地域卫星降水特征的非线性规律;三层前向型反向传播神经网络卫星降水估算模型的估算结果与雨量计实测值间的相关性可以达到0.57。模型估算结果系统性的低估偏小,预示着对该地域弱降水强度将有较好的指示性