贵州省喀斯特地区解决小流域粮食问题途径

俄脚河小流域,因长期掠夺性开发利用,使植被屡遭破坏,生态环境恶化,加上落后的生产方式,造成粮食单产低,粮食产量严重不足,根据小流域的特点,通过科学配置各项治理措施,综合治理和控制水土流失,恢复生态平衡,改善粮食生产的外部生产条件,建设高标准的水平梯田,提高地力,改变传统的耕作制度,控制人口增长,大力推广良种和高产栽培技术,促进粮食的高产、稳产,为喀斯特地区解决粮食问题提供了较好的模式。     

坡地土壤降雨入渗试验装置研究

分析了目前土壤入渗试验装置的优缺点,研制了一套适用于野外坡地土壤入渗产流的试验装置,该装置模拟雨强谱宽广,精度较高,重复性好,误差不大于５．５％,试验结果表明：该装置是研究野外坡地土壤入渗产流产沙较好的工具。     

襄樊地区水土流失成因及对策研究

阐述了襄樊地区水土流失现状及分布,并分析了其形成自然因素和人为因素,其中自然因素包括地形、降水、土壤、风力等因素;人为因素包括植被的破坏、坡耕地的开垦和工程活动的影响,最后,根据该地区自然和社会经济状况,提出了治理对策,为水土保持部门提供参考。     

Cultivation and grazing altered evapotranspiration and dynamics in Inner Mongolia steppes

To examine the effects of cultivation and grazing on evapotranspiration (ET), continuous measurements of ET were conducted over almost two years, from December 2005 to September 2007, using the eddy-covariance technique in two paired ecosystems: a steppe and a cropland in Duolun and a fenced and a degraded steppe in Xilinhot, Inner Mongolia, China. The ET of the four ecosystems approached or exceeded precipitation in both years. During the growing season (May–September), cultivation reduced the ecosystem ET in Duolun by 15% in the wet year (2006) and 7% in the dry year (2007). Grazing reduced the ET of the steppe in Xilinhot by 13% during the growing season of 2006, while there was similar ET between the degraded and fenced steppes in 2007. The low soil moisture in the cropland and the degraded steppe compared with the steppe at each area was the reason for the decrease in ET of the steppe ecosystems. In addition, a shorter growing period during the growing season, due to the changes in type and phenology characteristics of the vegetation associated with cultivation, was suspected for the reduction in ET in Duolun. The low soil moisture, due to the low precipitation in the dry year, limited vegetation growth and decreased canopy surface conductance (g_c), resulting in reduced plant transpiration. In addition, cultivation and grazing increased the sensitivity of ET to soil moisture in the dry year, suggesting that future changes in precipitation would not only affect ET by changing soil moisture directly, but would also influence the relationship between ET and soil moisture.     

Managing intensive and extensive land uses to conserve grassland plants in sub-tropical eucalypt woodlands

We sampled grasslands at 108 sites, representing five combinations of soil disturbance and enrichment that occurred in eucalypt grassy woodlands in eastern Australia. Intensive land use was represented as a combination of cultivation and fertilizer addition. Other disturbances were represented as various combinations of moderate or no soil disturbance and water enrichment or no enrichment. We identified disturbance response groups that were broadly summarized as Generalists, Tolerant species, Specialists and Intolerant species. The exotic component of the grasslands differs from the native in that there were more Intolerant species amongst natives and more Disturbance Specialist species amongst exotics. However, there were strong similarities, with the majority of exotics (66%) and of natives (60%) being either Generalists or Disturbance Tolerators. The evidence from this study suggests that significant expansion of intensive land use in the district, combining cultivation and fertilization, would pose a major threat to grassland vegetation and would threaten 69 of the 121 native species analysed.     

青藏高原高寒草甸土壤有机质、全氮和全磷含量对不同土地利用格局的响应

草地土地利用格局的变化强烈影响着其土壤营养元素的含量与垂直分布。对青藏高原东北隅高寒草甸不同土地利用格局（封育植被、放牧利用和人工种植）下不同深度（0—10cm、10—20cm和20—40cm）的土壤有机质、全氮和全磷含量的对比研究表明：封育植被下土壤营养元素在表层和深层之间有显著差异（P〈0．05）,与土壤深度表现出一定的负线性相关（R2〉0．40,P〈0．05）。放牧利用和人工种植对营养元素在不同土壤层次的分布无显著影响（P均值〉0．05）,前者的有机质和全氮含量与土壤深度略呈负线性,后者则无此关系。放牧利用和人工种植较显著地（P均值〈0．05）降低了土壤表层有机质和全氮的含量,但增加了土壤表层全磷的含量,对土壤深层的影响较小。人工种植对营养元素含量的影响效果略大于放牧利用,但两者差异不显著。     

Dynamics of soil chemical properties in shifting cultivation systems in the tropics: a meta‐analysis

The forest cultivation system (slash‐and‐burn or shifting cultivation) has contributed to the transformation of social systems since the early Neolithic period. Despite being considered by conservationists and public policymakers as a system of low productivity that generates environmental degradation and contributes to the maintenance of rural poverty, the shifting cultivation system (SCS) is being declared a practice that is highly ecologically and economically efficient. Such dichotomy of opinions is the consequence of the disparate results of studies assessing the effects of SCS on soil properties of rainforests throughout the last three decades. To circumvent this apparent inconsistency, we used a systematic quantitative review method (meta‐analysis), with the objective of integrating and synthesizing the data published in the literature to assess the overall effects of SCS on soil chemical properties. Four variables traditionally assessed in primary studies were chosen for the meta‐analyses: pH, cation exchange capacity (CEC), total carbon (Total C) and total nitrogen (Total N). Our results show that pH values increase under SCS conditions, while Total N and C content are significantly reduced under SCS. No significant impacts are observed on CEC. Our results on pH and CEC support the position from researchers who argue for the sustainability of SCS and highlight the importance of evaluating the soil system as a soil/vegetation complex. Also, our results indicate that soil chemical properties under SCS scenarios are better conserved and more readily recoverable, provided there is a rather longer fallow period than has been traditionally employed.     

Soil desiccation in the Loess Plateau of China

Soil desiccation usually takes place below the depth of soil affected by rainfall infiltration (about 1–3 m) with relatively low water content, and is one kind of particular hydrological phenomena in semi-arid and semi-humid regions of the Loess Plateau in China. This desiccation results from the excessive depletion of deep soil water by artificial vegetation and long-term insufficient rainwater supply, which is difficult to disappear with land use change. Due to the influence of global warming during 1950–2000, large-scale vegetation rehabilitation aggravated water scarcity and led to soil desiccation in the deep soil layer in the Loess Plateau. From southeast to northwest, soil desiccation becomes more intensive with lower water content and bigger range in depth due to drier climate and lower water holding capacity. The range of soil desiccation has a close relationship with root distribution of plant, and its intensity varies with the types and ages of vegetation. The climate drought, soil properties and soil water cycle characteristics might be the precondition for the occurrence of soil desiccation, and artificial vegetation with improper type and exorbitant productivity could have accelerated this process in range and intensity. Soil desiccation has obviously negative effects on water cycle in soils, greatly reduces the anti-drought capacity of plants, and heavily influences the growth and natural succession of vegetation. In order to reduce the range, intensity, and negative effects of soil desiccation, proper types of vegetation should be selected according to rainfall and soil water conditions, and the control of vegetation density and productivity should be considered together with soil-water conservation measures.     

黄土高原半干旱区植被建设的土壤水分效应及其影响因素

 水分是黄土高原半干旱地区植物生长与植被建设的主要限制因子,植被是影响土壤水分最活跃、最积极的因素。为了给黄土高原半干旱区植被的合理经营和今后植被的科学营造及开展植被建设的水文生态效应研究提供参考,从不同植被类型、生长状况与结构,不同植物的耗水特点及影响因素等方面,概述半干旱地区不同植被对土壤水分影响的研究进展。认为:为保证植被建设的可持续,需适度发展植被生产力,合理选择植物类型。在深入研究不同植物需耗水规律的基础上,加强植被生产力与水分利用的结合研究和从景观配置水平研究植被建设对土壤水分环境的影响。     

Soil carbon and related soil properties along a soil type and land‐use intensity gradient,New South Wales,Australia

The aim of this study was to systematically quantify differences in soil carbon and key related soil properties along a replicated land‐use intensity gradient on three soil landscapes in northwest New South Wales, Australia. Our results demonstrate consistent land‐use effects across all soil types where C, N and C:N ratio were in the order woodland > unimproved pasture = improved pasture > cultivation while bulk density broadly showed the reverse pattern. These land‐use effects were largely restricted to the near surface soil layers. Improved pasture was associated with a significant soil acidification, indicating that strategies to increase soil carbon through pasture improvement in these environments might also have associated soil degradation issues. Total soil carbon stocks were significantly larger in woodland soils, across all soil types, compared with the other land‐uses studied. Non‐wooded systems, however, had statistically similar carbon stocks and this pattern persisted whether or not carbon quantity was corrected for equivalent mass. Our results suggest that conversion from cultivation to pasture in this environment would yield between 0.06 and 0.15 t C/ha/yr which is at the lower end of predicted ranges in Australia and well below values measured in other cooler, wetter environments. We estimate that a 10% conversion rate (cultivation to pasture) across NSW would yield around 0.36 Mt CO₂‐e/yr which would contribute little to emission reductions in NSW. We conclude that carbon accumulation in agricultural soils in this environment might be more modest than current predictions suggest and that systematically collected, regionally specific data are required for the vegetation communities and full range of land‐uses before accurate and reliable predictions of soil carbon change can be made across these extensive landscapes.     

黑土坡耕地土壤有机质与生产力的空间关系

[目的]从田块尺度上揭示黑土坡耕地生产力与土壤有机质和全氮的空间关系,为坡耕地水土流失的治理和农业生产提供参考。[方法]利用经典统计学和地统计学的方法对典型黑土区坡耕地大豆产量与土壤有机质、全氮、海拔高度的空间关系进行分析。[结果]坡耕地大豆产量、土壤有机质和全氮含量存在较大变异,分别为0.05~0.26g/kg,19.27~52.64g/kg和0.95~2.38g/kg,但大豆产量与土壤有机质和全氮之间不存在显著的空间相关关系,与海拔高度之间存在负相关,但不显著。土壤有机质和土壤全氮之间存在极显著相关关系。[结论]坡耕地生产力受地形、地下水位、成土过程等结构性因子的影响约占2/3,受人类耕作、施肥、种植作物的影响只占1/3。水土流失是造成黑土农田生产力降低的主要因素。     

Changes in soil properties and site productivity caused by red alder

Red alder (Alnus rubra Bong.) is well recognized as an effective host plant for the symbiotic fixation of N. While this fixation process leads to the rapid accumulation of N within the ecosystem, it also enhances nutrient accumulation in biomass and soil organic matter and increases nitrification and cation leaching. We hypothesized that changes in soil properties resulting from these processes would decrease site productivity for second rotation red alder. Adjacent stands of 55 yr old alder and Douglas fir (Pseudotsuga menziesii (Mirb.] Franco) were studied at the Thompson Research Center on the Cedar River Watershed in western Washington, USA.The presence of red alder caused the following soil changes: decreased soil solution pH, increased CEC, increased exchangeable acidity accompanied by a decreased soil pH and base saturation. This decreased soil and soil solution pH resulted in increased A1 concentration in the soil solution and on exchange sites as well as decreased P availability. To determine the effect of these changes on the productivity of the 2nd rotation alder forest, a species conversion experiment was initiated 5 yr ago. Results from this conversion study clearly indicated that the first rotation red alder forest has caused a relative decrease in the productivity of the second rotation red alder plantation. Compared to the growth of red alder on the former Douglas fir site, the second rotation red alder on the former red alder site exhibited 339 less height growth and 759, less aboveground biomass accumulation after 5 yr. Future research will focus on identifying those factors causing this lower productivity including P availability, soil acidity and Al toxicity, cation availability, and competition with other vegetation.     

Changes in soil properties and site productivity caused by red alder

Red alder (Alnus rubra Bong.) is well recognized as an effective host plant for the symbiotic fixation of N. While this fixation process leads to the rapid accumulation of N within the ecosystem, it also enhances nutrient accumulation in biomass and soil organic matter and increases nitrification and cation leaching. We hypothesized that changes in soil properties resulting from these processes would decrease site productivity for second rotation red alder. Adjacent stands of 55 yr old alder and Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) were studied at the Thompson Research Center on the Cedar River Watershed in western Washington, USA. The presence of red alder oaused the following soil changes: decreased soil solution pH, increased CEC, increased exchangeable acidity accompanied by a decreased soil pH and base saturation. This decreased soil and soil solution pH resulted in increased A1 concentration in the soil solution and on exchange sites as well as decreased P availability. To determine the effect of these changes on the productivity of the 2nd rotation alder forest, a species conversion experiment was initiated 5 yr ago. Results from this conversion study clearly indicated that the first rotation red alder forest has caused a relative decrease in the productivity of the second rotation red alder plantation. Compared to the growth of red alder on the former Douglas fir site, the second rotation red alder on the former red alder site exhibited 33% less height growth and 75% less aboveground biomass accumulation after 5 yr. Future research will focus on identifying those factors causing this lower productivity including P availability, soil acidity and Al toxicity, cation availability, and competition with other vegetation.     

黄花草木樨改良盐碱土的试验研究

在调查陕北地区不同地域作物(谷子)、人工草灌(苜蓿与柠条)和天然草地(退耕地)的生产力,土壤水分及耕层养分的基础上,对比研究了不同类型植物生产力的差异,并分析了引起差异的原因及限制生产力提高的因素。结果表明,作物地(谷子)生产力占据明显优势,但稳定性较差;人工草灌(苜蓿与柠条)及天然草地的生产力较谷子低;天然草地群落的生产力、稳定性、物种丰度指数和土壤养分含量均较优越。指出除水分不足是限制不同植物生产力发挥的主要因素外,土壤养分含量低和缺乏管理也是限制植物生产力提高的重要因素。同时指出,为达到正确评价不同类型植物的生产力和长期适应性,为该地区大范围植被建设提供依据和参考,应设立定位或半定位研究点进行长期测定与研究。     

The impact of land‐cover change on soil properties in northern Ghana

Effects of changes in land‐cover on soil quality parameters in an area in northern Ghana were studied. Land‐cover changes were derived from maps of the study area for 1984, 1992 and 1999. There were no significant differences between properties of soils under natural vegetation and soils put under cultivation from 1992, but permanently cultivated soils (1984–1999) showed significantly lower physical and chemical soil properties. Soils recently opened up since 1992 for cultivation in the last seven years (i.e. 1992–1999) were found to manifest significantly higher contents of organic C, N, Ca, Mg and ECEC than those under permanent cultivation, suggesting that continuous cropping is responsible for deterioration in soil quality. Minimum organic C contents necessary to meet critical levels of selected soil quality parameters were estimated. The organic C content of recently cultivated soils would need to be increased by about 7 t ha⁻ to replenish soil nutrient capital. This calls for a strategy to synchronize organic matter management with inorganic fertilizer application. Further research is also needed to develop farming systems that conserve organic matter and also improve the quality of organic matter in the study area. Copyright © 2004 John Wiley & Sons, Ltd.     

广西喀斯特地区植被演替对土壤质量的影响

以植被演替空间序列代替时间序列的方法,在野外选取广西喀斯特地区4个主要植物群落演替阶段即草地、灌草地、灌丛、乔林的典型样地,对土壤物理、化学和生物学性状进行了比较研究,以探讨植被演替对土壤质量的影响。结果表明：不同的植被演替导致了土壤物理、化学和生物学性质的显著差异。随演替的正向进行,土壤综合肥力指标值（Q I）呈增长趋势,其土壤质量综合指数分别为：草地（0.09）、灌草地（0.16）、灌丛（0.61）、乔林（0.89）。自然植被的正向演替是提高土壤质量的有效途径。导致草地和灌草地土壤质量相对较低的主要因素是植物生产力较低,土壤养分积累较少,土壤有机质等养分含量较低,土壤微生物数量较少,土壤酶活较低。土壤微生物数量结合土壤酶是反映土壤生物学活性和土壤质量的较好指标。     

广西喀斯特地区植被演替对土壤质量的影响

以植被演替空间序列代替时间序列的方法,在野外选取广西喀斯特地区4个主要植物群落演替阶段即草地、灌草地、灌丛、乔林的典型样地,对土壤物理、化学和生物学性状进行了比较研究,以探讨植被演替对土壤质量的影响。结果表明:不同的植被演替导致了土壤物理、化学和生物学性质的显著差异。随演替的正向进行,土壤综合肥力指标值(Q I)呈增长趋势,其土壤质量综合指数分别为:草地(0.09)、灌草地(0.16)、灌丛(0.61)、乔林(0.89)。自然植被的正向演替是提高土壤质量的有效途径。导致草地和灌草地土壤质量相对较低的主要因素是植物生产力较低,土壤养分积累较少,土壤有机质等养分含量较低,土壤微生物数量较少,土壤酶活较低。土壤微生物数量结合土壤酶是反映土壤生物学活性和土壤质量的较好指标。     

辽东山区柞蚕场土壤侵蚀研究

辽宁省东部山区现有柞蚕场面积74．5万hm^2，由于近年来过度开发，管理粗放，造成土壤侵蚀加剧，生产力下降。为更好治理柞蚕场，了解掌握其土壤侵蚀程度和规律，结合全省土壤侵蚀研究，通过野外模拟降雨试验，着重对不同降雨、坡度、雨前土壤含水量和植被盖度条件下柞蚕场的土壤侵规律，进行了较为系统的研究，得出4因子与土壤侵蚀之关系，为有的放矢地采取相应的治理管护措施，提供了一套科学的基础依据。     

红壤丘陵区水土流失过程及综合治理技术

根据试验结果 ,分析了红壤丘陵区水土流失和养分损失的过程和动态变化以及在不同耕作轮作措施下的变异特征 ,提出了水土流失区综合治理的技术措施。东南红壤丘陵区水土流失的面积约占土地总面积的 2 1.5 %。水土流失量的年际间差异非常大 ,达 18～ 2 0倍 ,季节间的变化则主要受降雨分布、植被覆盖及人为活动的影响 ,保护性耕作可以明显减少水土流失和养分损失量。采用综合治理技术 ,创造合适的水分和养分条件 ,是快速恢复水土流失区的植被和土壤肥力的有效措施。