84%氯酯磺草胺水分散性粒剂对大豆后茬作物安全性的田间试验研究

为明确84%氯酯磺草胺水分散性粒剂(豆杰)对后茬作物的安全性,指导该药科学使用,2012年通过田间试验系统研究了84%氯酯磺草胺水分散性粒剂对玉米、向日葵、南瓜、西瓜、烟草等大豆后茬作物生长的影响,以出苗率、株高和鲜重作为指标对84%氯酯磺草胺水分散性粒剂的安全性进行评价。结果显示:84%氯酯磺草胺水分散性粒剂对5种后茬作物均存在药害,西瓜和烟草受害最为明显,施用氯酯磺草胺的土地翌年不宜种植西瓜和烟草。氯酯磺草胺对玉米、向日葵和南瓜在早期也有明显药害,但3种作物耐药性较好,在上年用药量低于63 g/hm2的地块种植3种后茬作物时,作物初期受害后期可完全恢复,但前提是降雨量必须充沛。     

温带森林次生演替过程中土壤微生物多样性研究

利用Biolog研究温带森林次生演替过程中土壤微生物多样性变化,结果表明:就总体AWCD值来看,阔叶林土体土微生物功能多样性较高于原始红松林,而在根际土上反映更加明显,阔叶林红松幼苗根际土AWCD值几乎高出原始红松林25%。而就整体丰富度及多样性指数上来看,原始红松林根际无论在多样性还是丰富度上均占优,但其土体土却均处于最低位置,这表明在原始林中,微生物更加集中于根系附近。通过单个碳源方差分析发现,在原始林中,无论是土体土还是根际土,在对氨基酸类碳源的利用上均有较大优势。这表明在温带森林次生演替过程中土壤微生物多样性确有变化,且主要集中在根际部分。     

Linking Amazonian secondary succession forest growth to soil properties

The Amazon Basin has suffered extensive deforestation in the past 30 years. Deforestation typically leads to changes in climate, biodiversity, hydrological cycle, and soil degradation. Vegetation succession plays an important role in soil restoration through accumulation of vegetation biomass and improved soil/plant interaction. However, relationships between succession and soil properties are not well known. For example, how does vegetation succession affect nutrient accumulation? Which soil factors are important in influencing vegetation growth? What is the best way to evaluate soil fertility in the Amazon basin? This paper focuses on the interrelationships between secondary succession and soil properties. Field soil sample data and vegetation inventory data were collected in two regions of Brazilian Amazonia (Altamira and Bragantina). Soil nutrients and texture were analyzed at successional forest sites. Multiple regression models were used to identify the important soil properties affecting vegetation growth, and a soil evaluation factor (SEF) was developed for evaluating soil fertility in Alfisols, Ultisols, and Oxisols, which differ in the ways they affect vegetation growth. For example, the upper 40 cm of soil is most important for vegetation growth in Alfisols, but in Ultisols and Oxisols deeper horizons significantly influence vegetation growth rates. Accumulation of vegetation biomass increased soil fertility and improved soil physical structure in Alfisols but did not completely compensate for the nutrient losses in Ultisols and Oxisols; however, it significantly reduced the rate of nutrient loss. Copyright © 2002 John Wiley & Sons, Ltd.     

天津市填海造陆区自然植被演替特征及其影响因素

[目的] 探究天津市填海造陆区自然演替特征和影响因素,为填海造陆区生态恢复与重建提供科学依据。[方法] 以天津市不同时期填海造陆区为研究对象,采取野外调查采样、实验室测定与双向指示种分析法(TWINSPAN)、除趋势典范对应分析(detrended correspondence analysis,DCA)、典范对应分析(canonical correspondence analysis,CCA)等分析方法,分析天津市填海造陆区植物群落类型、演替模式和影响因素。[结果] ①天津市填海造陆区自然植被演替序列为：盐地碱蓬群落→芦苇—盐地碱蓬群落→獐毛群落→芦苇群落→柽柳—鹅绒藤群落。随着演替的进行,土壤含盐量逐渐降低,植物种类逐渐增加。②土壤全盐含量、离市区二级道路的距离和离15 m等深线的距离在不同演替阶段间存在显著差异,是天津市填海造陆区自然植被演替的主要影响因子。[结论] 天津市填海造陆区的植被演替受自然和人为因子的共同作用,科学调控环境因子(如土壤全盐含量)可为填海造区植被恢复提供有利环境条件。     

不同氮、磷比施肥对多混盐水池塘浮游植物群落定向演替的影响

研究了在中华绒螯蟹室外育苗土池中,不同N、P比施肥对土池多混盐水体的水化学和浮游植物群落演替、叶绿素a含量和初级生产力的影响,以及浮游动物对浮游植物的下行效应。结果表明,氮是多混盐水体浮游植物生长的主要限制因子。施肥后土池多混盐水体中共检出浮游生物44种,其中浮游植物平均生物量达188.76 mg/L,优势种为湛江等鞭金藻Isochrysis zhanjiangensis;叶绿素a含量为116.96μg/L,施肥后2~3 d叶绿素a含量达到高值,之后开始下降,6~7 d后恢复到原来水平;初级生产力为2.39~12.04 gO2/(m2.d),均值为5.11 g O2/(m2.d),呈低-高-低的变化趋势。     

Rural depopulation and recent landscape changes in a Mediterranean region: Consequences to the breeding avifauna

We studied the vegetational and avifaunistic changes following rural depopulation in an area covering 2,600 ha north of Montpellier (Southern France). The study area is covered by a mosaic of Mediterranean habitats that includes cultivation, grasslands, shrublands, and woodlands and is representative of the natural features present and of the human usage practiced so far in this part of the Mediterranean. We sampled the vegetation and the bird fauna in the same 193 census plots in 1978 and in 1992. At both the habitat and landscape scales the cover of woody plants increased significantly. Open habitats tend to disappear. As a consequence the abundance of open-habitat bird species decreased significantly whereas the abundance of forest birds increased significantly. These changes favor a pool of forest species widespread in western Europe and reduce habitat availability for open habitat and shrubland species. Many of the latter are Mediterranean species whose distribution in Western Europe could become reduced under current landscape dynamics. Our observation of more woodlands and their typical birds and of less open habitats and their associated avifauna is not consistent with the traditional worry shown by the public and the managers about the regression of forests and woodlands in the Northern Mediterranean as a consequence of fire.     

青贮微生物及其对青贮饲料发酵品质影响的研究进展

青贮微生物在饲料发酵过程中起关键作用。无论是牧草表面附着的微生物还是外源添加的微生物菌剂在青贮发酵过程中对青贮微生物的群落结构及其演替过程都起着重要的作用,而青贮发酵过程中微生物的群落结构及其演替过程与代谢产物很大程度上影响着青贮饲料的发酵品质。本文阐述了青贮微生物群落结构,微生物在青贮过程中的演替及其对青贮饲料品质的影响。从目前研究结果来看,不同牧草及同种牧草生长在不同环境中其表面附着微生物存在很大差异。添加乳酸菌对提高青贮品质效果不稳定,还需了解牧草附着微生物特性决定是否需要接种乳酸菌以得到优质青贮饲料。     

穗花杉群落演替研究

采用固定样地的研究方法,对穗花杉Amentotaxus