沈阳样区土壤与景观关系的研究

土壤是连续分布在地球陆地表面的自然客体,其发生发展与景观密不可分.在野外调查的基础上,对辽宁沈阳样区100个土壤剖面形态特征、颗粒组成、化学特征等进行对比研究,按照《中国土壤系统分类(修订三稿)》的标准,共划分出淋溶土、雏形土与新成土3个土纲和续分的5个亚纲、7个土类、9个亚类、9个土族、14个土系.土壤性质和类型与景观特征有很好的对应关系,土壤性质是地形部位、母质基础、水分状况等景观要素的综合体现,也是长期气候等环境变化与人为活动影响的综合结果.     

菠萝-甘蔗轮作的土壤生态效应

通过2000～2002年进行菠萝-甘蔗轮作田间试验,研究了菠萝、甘蔗轮作对甘蔗土壤生态的影响。结果表明：菠萝甘蔗轮作田与甘蔗连作田比较,能明显地改善土壤的通气和蓄水性,加速速效性养分的释放;增强土壤酶活性;增加土壤微生物总量(一般好气性细菌、真菌、放线菌);有益的氨化细菌和硝化细菌成倍增加,而无益的厌氧性细菌、反硝化细菌则受到抑制;固氮菌数量小且变化不大。菠萝-甘蔗轮作对甘蔗土壤生态环境的改善其实质在于：菠萝、甘蔗轮作后,由于其作物种类的不同导致土壤结构的改善和土壤微生物种类和数量增多,土壤生物活性增强,并导致土壤速效养分的增加。     

Impacts of litter and understory removal on soil properties in a subtropical Acacia mangium plantation in China

In forest ecosystems, the effects of litter or understory on soil properties are far from being fully understood. We conducted a study in a pure Acacia mangium Willd. plantation in southern China, by removing litter or understory or both components and then comparing these treatments with a control (undisturbed), to evaluate their respective effects on soil physical, chemical and biological properties. In addition, a litter decomposition experiment was conducted to understand the effects of understory on litter decomposition. Our data showed that the presence of understory favored litter decomposition to a large extent. In 1 year, 75.2 and 37.2% of litter were decomposed in the control and understory removal treatment (UR), respectively. Litter had a profound significance in retaining soil water and contributing to soil fertility, including organic matter (OM), available phosphorus (P) and alkali-hydrolyzable nitrogen (N), but understory exerted less influence than litter on soil physical and chemical properties. Both litter and understory played an important role in soil biological activity as indicated by microbial biomass carbon (MBC), while there were no significant impacts on soil exchangeable potassium (K) after either or both were removed. Contrary to our hypothesis, the effects of understory or litter removal were not always negative. A significant soil pH increase with litter removal was a positive factor for acid soil in the studied site. Except for soil moisture, significant effects, caused by removal of litter or/and understory, on measured soil chemical characteristics were only observed in the top 10 cm soil layer, but not in the 10–20 cm layer. Soil available P and exchangeable K contents were significantly higher in the rainy season than in the dry season, however, for the other soil properties, not substantially affected by season.     

土壤生态研究的展望

土壤生态研究是从生态学的观点出发,在对土壤的本质属性和独特运动规律作出更好揭示的基础上,阐明土壤作为陆地生态系统和整个生物圈中的中心环节的独特作用和功能,研究建立高生产力和洁净的陆地生态系统所需的优化土壤条件并拟定相应的有效措施,以更好地发挥土壤的生产潜力和改善人类的生存环境。其主要研究内容应包括:土壤肥力与状态因子的关系;土壤库在物质和能量的流动与转化中的作用;土壤生产力;土壤相对平衡地位的建立与保持以及方法学问题。     

温度和湿度对暖温带落叶阔叶林土壤氮矿化的影响

 更好地了解温度和湿度对土壤氮矿化过程的影响,从而估计森林生态系统土壤有机氮的矿化速率。在实验室条件下,控制土壤的温度与含水量。将不同含水量(0.12、0.20、0.28、0.35、0.40kg·kg-1)的土柱置于5℃、15℃、25℃和35℃条件下培养30d。分析培养前后的NH4+-N和NO3--N含量,确定土壤的净矿化速率和净硝化速率。结果表明：在5～25℃的温度范围内,氮的矿化速率和硝化速率与温度和湿度呈正相关。当温度超过25℃,含水量超过0.20kg·kg-1时,净矿化速率和净硝化速率随着温度和含水量的升高反而降低。温度和湿度对土壤的矿化和硝化过程存在比较明显的交互作用。我们建立了二维的方程(T,θ)来描述温度和湿度对土壤氮矿化速率的影响。暖温带土壤氮矿化的最佳条件是温度22.4℃、含水量0.40kg·kg-1。另外试验过程中,还观察到了比较明显的土壤氨挥发现象。     

土壤温度和湿度对长白松林土壤呼吸速率的影响

2003年6月17日、8月日和10月10日,研究了长白山长白松林地内土壤呼吸速率和断根土壤呼吸速率日变化,并于2004年5～9月对其季节变化进行了测定.结果表明,土壤总呼吸速率和断根土壤呼吸速率的日变化均呈单峰型,峰值一般出现在12:00～14:00,8月份土壤呼吸速率的日变化幅度小于6月份和10月份.土壤总呼吸速率、断根土壤呼吸速率和根系呼吸速率具有明显的季节变化,6～8月份较高,5月份和9月份较低.2004年5～9月份,土壤总呼吸速率、断根土壤呼吸速率和根系呼吸速率的平均值分别为3.12、1.94和1.18 μmolCO₂·m^-2·s^-1,根系呼吸对土壤总呼吸的贡献为26.5%～52.6%.土壤呼吸速率与土壤温度之间呈显著的指数相关,与土壤湿度之间呈线性相关.土壤总呼吸速率、断根土壤呼吸速率和根系呼吸速率的Q10值分别为2.44、2.55和2.27,断根土壤呼吸速率对温度的敏感程度大于土壤总呼吸速率和根系呼吸速率.土壤总呼吸速率对土壤湿度的敏感程度大于根系呼吸,断根土壤呼吸速率对土壤湿度的敏感程度最差.     

Degradation and resilience of soils

Debate on global soil degradation, its extent and agronomic impact, can only be resolved through understanding of the processes and factors leading to establishment of the cause-effect relationships for major soils, ecoregions, and land uses. Systematic evaluation through long-term experimentation is needed for establishing quantitative criteria of (i) soil quality in relation to specific functions; (ii) soil degradation in relation to critical limits of key soil properties and processes; and (iii) soil resilience in relation to the ease of restoration through judicious management and discriminate use of essential input. Quantitative assessment of soil degradation can be obtained by evaluating its impact on productivity for different land uses and management systems. Interdisciplinary research is needed to quantify soil degradation effects on decrease in productivity, reduction in biomass, and decline in environment quality throught pollution and eutrophication of natural waters and emission of radiatively-active gases from terrestrial ecosystems to the atmosphere. Data from long-term field experiments in principal ecoregions are specifically needed to (i) establish relationships between soil quality versus soil degradation and soil quality versus soil resilience; (ii) identify indicators of soil quality and soil resilience; and (iii) establish critical limits of important properties for soil degradation and soil resilience. There is a need to develop and standardize techniques for measuring soil resilience. <br>     

除草剂阿特拉津对土壤脲酶活性的影响

研究了阿特拉津对4种典型施肥处理的土壤脲酶活力的影响。结果表明,处理初期,低浓度阿特拉津对土壤脲酶有一定刺激作用,高浓度处理在整个试验过程中对脲酶有明显抑制作用,阿特拉津对不同肥力土壤中脲酶的影响有明显差异,对照土壤和NPK肥土壤中脲酶活力较低,脲酶受抑制明显,抑制率分别高达30．35％和28．89％;NPK+秸秆和NPK+有机肥土壤的脲酶活力高,脲酶抑制率低,最高抑制率分别为21．35％和16．86％,不同肥力土壤在整个处理过程中,脲酶抑制率均为先逐渐增大到最大值,然后又逐渐降低;高肥力土壤脲酶抑制率最大值出现的时间比低肥力土壤迟,表明高肥力土壤对阿特拉津有较强的耐受能力。     

土壤生态研究的展望

土壤生态研究是从生态学的观点出发,在对土壤的本质属性和独特运动规律作出更好揭示的基础上,阐明土壤作为陆地生态系统和整个生物圈中的中心环节的独特作用和功能,研究建立高生产力和洁净的陆地生态系统所需的优化土壤条件并拟定相应的有效措施,以更好地发挥土壤的生产潜力和改善人类的生存环境。其主要研究内容应包括:土壤肥力与状态因子的关系;土壤库在物质和能量的流动与转化中的作用;土壤生产力;土壤相对平衡地位的建立与保持以及方法学问题。     

发生分类半淋溶土在中国土壤系统分类中的归属特征

利用最新建立的1∶100万中国土壤数据库,研究了我国发生分类半淋溶土在中国土壤系统分类的归属及其在中国土壤系统分类下的空间和数量特征.结果表明,我国发生分类半淋溶土总面积为427 843.1 km²,可参比归属于中国土壤系统分类中的4个土纲,即淋溶土、雏形土、均腐土、人为土,分别占发生分类半淋溶土总面积的51.3%、35.2%、10.7%和2.8%,其中包含了系统分类的22个土类和38个亚类.对发生分类某一类型土壤分属于系统分类不同类型的面积比例及其标准偏差的分析表明,土壤参比归属的单元级别越低,越易于参比和把握.研究结果对于土壤类型的正确参比、中国土壤系统分类的应用具有很好的参考价值.     

Distribution of ectomycorrhizal and pathogenic fungi in soil along a vegetational change from Japanese black pine (Pinus thunbergii) to black locust (Robinia pseudoacacia)

The nitrogen-fixing tree black locust (Robinia pseudoacacia L.) seems to affect ectomycorrhizal (ECM) colonization and disease severity of Japanese black pine (Pinus thunbergii Parl.) seedlings. We examined the effect of black locust on the distribution of ECM and pathogenic fungi in soil. DNA was extracted from soil at depths of 0–5 and 5–10 cm, collected from the border between a Japanese black pine- and a black locust-dominated forest, and the distribution of these fungi was investigated by denaturing gradient gel electrophoresis. The effect of soil nutrition and pH on fungal distribution was also examined. Tomentella sp. 1 and Tomentella sp. 2 were not detected from some subplots in the Japanese black pine-dominated forest. Ectomycorrhizas formed by Tomentella spp. were dominant in black locust-dominated subplots and very little in the Japanese black pine-dominated forest. Therefore, the distribution may be influenced by the distribution of inoculum potential, although we could not detect significant relationships between the distribution of Tomentella spp. on pine seedlings and in soils. The other ECM fungi were detected in soils in subplots where the ECM fungi was not detected on pine seedlings, and there was no significant correlation between the distribution of the ECM fungi on pine seedlings and in soils. Therefore, inoculum potential seemed to not always influence the ECM community on roots. The distribution of Lactarius quieticolor and Tomentella sp. 2 in soil at a depth of 0–5 cm positively correlated with soil phosphate (soil P) and that of Tomentella sp. 2 also positively correlated with soil nitrogen (soil N). These results suggest the possibility that the distribution of inoculum potential of the ECM fungi was affected by soil N and soil P. Although the mortality of the pine seedlings was higher in the black locust-dominated area than in the Japanese black pine-dominated area, a pathogenic fungus of pine seedlings, Cylindrocladium pacificum, was detected in soil at depths of 0–5 and 5–10 cm from both these areas. This indicates that the disease severity of pine seedlings in this study was influenced by environmental conditions rather than the distribution of inoculum potential.     

连作对三七种子萌发及种苗生长的影响

为进一步明确三七的连作效应,以不同种植年限及不同空间分布的土壤为栽培基质,研究了连作对三七种子萌发及种苗生长的影响。结果表明:连作使三七种子萌发的最大速度增加,种子的发芽势变化不大,而发芽率、发芽指数和快速发芽期则呈明显降低或变短的趋势;与根区外土相比,根区土和根区下土使三七种子的发芽势、发芽率和发芽指数显著降低,对种子萌发的最大速度也有降低的作用;种植1年三七的土壤(1年土)对后茬三七种苗的生长并无明显障碍效应,2年土比3年土具有更强的抑制三七种苗生长的作用。连作对三七种子萌发及种苗生长均会产生明显的障碍效应,自毒作用可能只是造成三七连作障碍的原因之一。     

半干旱地区天然草地灌丛化与土壤异质性关系研究进展

 回顾了半干旱地区天然草地灌丛化的成因和机理、灌丛化导致草地土壤水分和养分空间异质性及其对生态系统生物地球化学过程的影响,以及土壤异质性与土地退化关系等方面的研究进展,周期性气候干旱和过度放牧是天然草地灌丛化的主要原因,伴随灌木入侵而出现的草地土壤水分和养分的空间异质性,是造成生态系统水分和养分流失,以及土壤加速侵蚀的原因之一。因此,半干旱地区天然草地的灌丛化应得到一定的控制,使群落中灌丛保持适宜的密度,以避免生态系统水分和养分的损失。     

非饱和土壤水力参数的模型及确定方法

土壤水力参数的选取和确定是土壤中水分运动和污染物迁移预测的基础,本文在国内外研究成果的基础上,综述了土壤水力参数的模型(土壤水分特征曲线模型、土壤导水率模型)及其直接测定法和间接推求法,并比较了土壤水力参数的模型及确定方法的适用性与局限性,以便为生态环境建设和农业可持续发展研究中土壤水力参数的选取提供依据。     

干旱区绿洲-荒漠过渡带灌丛土壤属性研究

以天山北坡绿洲 荒漠过渡带为研究区,选择3种类型的灌丛并采集不同位置和深度的灌丛土壤样品进行分析,研究灌丛土壤资源的聚集效应.结果表明,干旱区绿洲 荒漠过渡带不同类型灌丛对土壤粒度分布的影响不显著,土壤以砂和粉砂为主,红柳＋裸地灌丛土壤粒度分布的聚集效应明显;灌丛土壤有机质、全氮和速效钾含量在冠幅下最高,其次为灌丛间低矮植物下,灌丛间裸地最低,呈现出明显的“肥岛”现象;不同灌丛类型和采样位置对土壤盐分离子和总盐含量的变化影响显著,且不同灌丛土壤资源的聚集效应各异;导致不同类型灌丛土壤资源富集率不同的原因有气候因素、灌木分布的土壤环境、灌丛高度和冠幅、灌丛间有无低矮植物等.     

不同土壤类型和肥力玉米地土壤养分根际效应研究

采集吉林省玉米植株及土壤样品,研究不同土壤类型和肥力,玉米不同品种和生育时期土壤－植物系统根际养分动态变化及植物吸收的相互关系,结果表明,玉米地土壤ＮＨ＾＋４－Ｎ、ＮＯ＾－３－Ｎ在根际富集,其变化主要与化肥供应有关,高肥力土壤根际有效磷亏缺,种植密度越大,根际亏缺率超大;低肥力土壤则有效磷在根际略高。高肥力土壤有效钾较高,根际有效钾富集也更明显,茎叶、根对养分的吸收量顺序为：Ｎ     

土壤有机质概念和分组技术研究进展

土壤有机质一直是土壤学研究领域的重点,在过去的50年里,对土壤质量可持续性观念的增强和寻找快速判断人为因素对土壤质量影响方向指标的强烈愿望导致了土壤有机质的研究重点发生了急剧变化：对农业措施反映慢的土壤腐殖质类物质的研究正在退出土壤有机质研究领域,而侧重点逐渐转向了土壤中未受微生物作用或正在受微生物降解的有机残体;也出现了新的土壤有机质研究概念和对应测试手段：土壤有机质的比重分组、与有机质结合的土壤颗粒大小分组、土壤团聚体中的POM和iPOM以及土壤水溶性有机质和微生物体C等概念和测试手段被相继提了出来,土壤有机质的研究重点正在从土壤微生物的作用产物(腐殖质)向土壤微生物作用前的、具有部分生物活性的有机质(轻组有机质、砂粒组和粗粉砂粒组中的有机质、POM和iPOM)和完全具有生物活性的有机质(微生物体C和水溶性有机质)转移,这一过程与土壤有机质概念的拓展密不可分。     

Modeling WEPP erodibility parameters in calcareous soils in northwest Iran

Modeling soil detachment rates at the regional scale is important for better understanding of the processes of erosion and the development of erosion models. Soil erodibility is an important factor for predicting soil loss, but its direct measurement at the watershed scale is difficult, time-consuming and costly. This study used stepwise multiple-linear regression (MLR) and artificial neural networks (ANNs) to model Water Erosion Prediction Project (WEPP) soil erodibility parameters, including the baseline inter-rill erodibility (K_ib), baseline rill erodibility (K_rb) and critical shear stress (τ_cb) of cropland conditions in calcareous soils of northwest Iran. Simulated inter-rill and rill erosion experiments were conducted at 100 locations with three replications. K_ib, K_rb and τ_cb and basic soil properties were measured at each location. Auxiliary variables related to soil erodibility were derived from a Landsat 7 satellite image and a 30 m × 30 m digital elevation model (DEM). MLR and ANN models were employed to predict K_ib, K_rb and τ_cb using two groups of input variables: i) more easily measurable basic soil properties (pedo-transfer functions (PTFs)) and ii) more easily measurable basic soil properties and auxiliary data (soil spatial prediction functions (SSPFs)). The results indicated that the WEPP models performed poorly in comparison to the derived models. PTFs and SSPFs generated from ANN models provided more reliable predictions than the MLR models. ANN-based SSPF models yielded the best results (with the highest R² and lowest RMSE values) for predicting Kib and Krb. ANN-based PTF model performed reasonably well for predicting τ_cb. These results show that information from terrain attributes and remote sensing data are potential auxiliary variables for improving prediction of soil erodibility parameters.     

Vertical rooting patterns of mature Quercus trees growing on different soil types in northern Germany

At two different sites in northern Germany, the vertical distribution patterns of roots with diameters of up to 10 mm were investigated with the trench profile wall technique beneath mature trees of Quercus petraea (Matt.) Liebl. growing on clayey (cambi-stagnic gleysol) or sandy soil (dystric cambisol). The rooting patterns were related to soil bulk density, maximum plant-available soil water and soil chemistry, and were compared with the rooting pattern of Q. petraea growing on a silty soil on limestone (luvisol) and with that of Q. robur L. growing on clayey loam (stagnic cambisol). All three Q. petraea sites differed in their vertical rooting pattern, as was indicated by significant differences in the parameter which was calculated from the cumulative root fraction (Y) for the cumulative rooting depth (d; Y=1–^d). At the clayey site, a relatively large fraction of roots was found in deeper soil layers (highest value); whereas, at the silty site, the rooting pattern was most superficial (lowest value). No significant difference in the vertical rooting pattern was observed between Q. petraea and Q. robur growing on clayey soil. The soil-area related biomasses of living roots did not differ between the clayey and the sandy site of Q. petraea.Comparisons of the rooting patterns with soil water relations and soil chemistry lead to the hypothesis that under the climatic conditions of Central Europe, the vertical root distribution of Q. petraea is more influenced by the availability of nutrients, especially that of nitrogen, than by the amounts of plant-available soil water.