吴旗县不同植被类型土壤干层特征分析

吴旗县位于黄土高原暖温带半干旱地区,由于降雨量较少以及地表的蒸发和植物的蒸腾,使土壤水亏损严重,部分植被下的土壤中出现了土壤干层。为了系统比较不同植被类型下土壤干层特点,通过对吴旗不同植被0～9.0m土壤水分的实地测量和分析,得出以下结论:除农地外,其它植被类型下都不同程度的存在着土壤干层,干层严重程度,林地大于灌木林地,灌木林地大于草地;草地存在临时干层和永久干层,永久干层深度可以达到4.0m。测量当时,灌木林没有临时干层,存在永久干层,深度3.0～8.4m;杏树林不存在临时干层,油松林临时干层则很严重,杏树林和油松林永久干层深度分别在8.0m和9.0m以上。临时干层的出现取决于降水的补充,因此可能与采样时间有关。通过对吴旗县土壤干层的分析可以为进一步研究土壤干层和植被建设提供借鉴。     

陕北黄土丘陵沟壑区植被恢复与重建技术对策

对黄土丘陵沟壑区植被性质、土壤基质旱化、植被恢复和重建途径等理论及实践问题进行了详细论述,提出应采用集雨造林和径流林业技术,利用地带性林草种类,仿拟自然演替规律恢复和重建森林植被群落,构建"乔灌草"配置合理的稳定森林生态体系的思路和对策.     

矿区复垦土壤接种丛枝菌根对玉米生长及营养吸收的影响

采用盆栽试验方法,研究了不同培养基质条件(10cm土5cm尾矿、8cm土7cm尾矿、5cm土10cm尾矿)下,接种丛枝菌根真菌和不接种丛枝菌根真菌(对照)两种处理对玉米生物量及植株中营养元素吸收的影响。结果表明,无论接种与否,植株的生物量都随覆土厚度增大而增大;与非菌根植物相比,接种菌根真菌的植株可以吸收更多的营养元素,而向地上部运移的Na较少,抑制了植株积累过量的Na盐;地上部Zn和Cu的含量受接种菌根的影响不大,而接种菌根降低了地上部Mn的含量。植株生物量及其植株体内的营养元素含量,接种菌根真菌后,覆土少的(覆5cm厚的土壤于10cm厚的尾矿上)相应高于不接种且覆土厚(覆10cm厚的土壤于5cm厚的尾矿上)的,说明接种菌根可以抵消由于覆土少而导致的植株生物量降低,并且对尾矿充填复垦土壤的植被重建具有重要作用。     

庐山杉木林与黄山松林的土壤层水源涵养能力和土壤侵蚀敏感性探究

森林的水土保持效益包含水源涵养能力和土壤的侵蚀敏感性,为探讨基于坡面尺度林分因子对水土流失的影响,进一步揭示森林植被的水土保持效益机制,采用环刀法、EPIC模型等分别计算黄山松林、杉木林的水源涵养能力和土壤侵蚀因子.结果表明:(1)黄山松林的土壤容重在垂直剖面无明显差异,变化范围为0.66～1.10 g/cm3;杉木林...     

木屑复合基质在樱桃番茄上的栽培效果初报

利用来源广泛且成本低廉的木屑作为主要成分制成不同复合基质,研究其理化性质及其栽培樱桃番茄的效果。结果表明,以木屑为主要成分制成的复合基质在总孔隙度、通气孔隙度、田间持水量及pH等理化性质方面优于以泥炭为主要成分的复合基质（60%泥炭＋20%细沙＋20%珍珠岩）,其中以复合基质（60%木屑＋40%煤炉渣）综合性状表现最优,另外其在栽培樱桃番茄过程中的保水保肥能力也最强,产量表现也最佳,比对照增产30.3%,并且果实在VC、可溶性固形物、可溶性糖、还原糖等品质指标上与对照无显著差异,是栽培樱桃番茄较理想的复合基质。     

一种南方小花蝽产卵基质的高效利用方法

南方小花蝽(Orius strigicollis)是一类应用前景广阔的捕食性天敌。以芸豆豆荚作为南方小花蝽的产卵基质,研究了南方小花蝽在该产卵基质上产卵部位选择的偏好性,并以此为基础探讨了一种该产卵基质的高效利用方法。结果表明,90%以上的南方小花蝽卵被产在豆荚的荚缝线处,而且50%以上的卵被产在豆尖的荚缝处。斜45°切取豆荚的豆尖部分,并对切口处进行上蜡包裹,放置5 d切口处密封性仍保持完好,荚果保持新鲜,并且不影响卵的孵化。研究明确了该产卵基质高效利用方法的可行性,能为后期南方小花蝽室内扩繁和产品创制提供科学依据。     

Substrate selection by subyearling European river lampreys (Lampetra fluviatilis) and older larvae (Lampetra spp)

More information on the habitat requirements of lamprey is needed to improve measures aiming at rehabilitation of lamprey populations. Knowledge on habitat requirements of subyearling lampreys is especially scarce. We studied substrate selection by subyearling lamprey during the first three months after hatching using aquarium experiments. Differences in substrate selection by different‐sized larvae older than one year and the substrate depth selection by large larvae were also studied. Prolarvae of an average total length (TL) of 6.9 mm actively selected substrates with existing holes. When lampreys reached TL of over 8.0 mm, they started to select substrates which enabled them to construct a burrow. Lampreys of that size avoided coarse sand and gravel without fine material. Natural gravel with fine material was a frequently selected burrowing substrate during the 10‐week experiment suggesting its importance for subyearling lampreys. Substrates where very fine sand prevailed were the most selected soft sediments by subyearling larvae. Larvae older than one year did not select clay as a burrowing substrate. Medium (TL 70–98 mm) and large (TL 110–146 mm) larvae preferred coarse organic matter to fine sand. Larvae older than one year (TL 80–110 mm) preferred the thickest layer of soft substrate (10 cm) available to thinner layers.     

穴施不同定植基质对黄瓜生长和产量的影响

以黄瓜(Cucumis sativus L.)为试材,研究施用不同定植基质对黄瓜生长和产量的影响。结果表明,定植基质的容重、通气孔隙、持水孔隙、电导率等理化性质均显著优于对照,施用定植基质缩短了黄瓜幼苗的缓苗期,提高了缓苗率,促进了定植后黄瓜的生长,并且单株前期产量有所提高;其中高浓度营养液浸泡0.8%丙烯酰胺-丙烯酸钾共聚交联物处理对黄瓜生长的促进效果最明显,定植20 d和50 d后,黄瓜的株高、茎粗、叶色指数、地上部鲜重和干重(定植20 d)、根体积(定植50 d)、地下部鲜重和干重均显著高于对照,单株前期产量比对照提高13.2%。表明应用定植基质可以通过增加黄瓜根际的通气性改善根际营养,缩短黄瓜缓苗期,提高缓苗率,促进营养生长和生殖生长,从而提高产量。     

Soil organic matter and the extracellular microbial matrix show contrasting responses to C and N availability

An emerging paradigm in soil science suggests microbes can perform ‘N mining’ from recalcitrant soil organic matter (SOM) in conditions of low N availability. However, this requires the production of extracellular structures rich in N (including enzymes and structural components) and thus defies stoichiometric expectation. We set out to extract newly synthesised peptides from the extracellular matrix in soil and compare the amino acid (AA) profiles, N incorporation and AA dynamics in response to labile inputs of contrasting C/N ratio. Glycerol was added both with and without an inorganic source of N (10% ¹⁵N labelled NH₄NO₃) to a soil already containing a large pool of refractory SOM and incubated for 10 days. The resulting total soil peptide (TSP) and extracellular pools were compared using colorimetric methods, gas chromatography, and isotope ratio mass spectrometry. N isotope compositions showed that the extracellular polymeric substance (EPS) contained a greater proportion of products formed de novo than did TSP, with hydrophobic EPS-AAs (leucine, isoleucine, phenylalanine, hydroxyproline and tyrosine) deriving substantially more N from the inorganic source provided. Quantitative comparison between extracts showed that the EPS contained greater relative proportions of alanine, glycine, proline, phenylalanine and tyrosine. The greatest increases in EPS-peptide and EPS-polysaccharide concentrations occurred at the highest C/N ratios. All EPS-AAs responded similarly to treatment whereas the responses of TSP were more complex. The results suggest that extracellular investment of N (as EPS peptides) is a microbial survival mechanism in conditions of low N/high C which, from an evolutionary perspective, must ultimately lead to the tendency for increased N returns to the microbial biomass. A conceptual model is proposed that describes the dynamics of the extracellular matrix in response to the C/N ratio of labile inputs.