微生物群落构建对杉木凋落叶分解及其酶活性的影响

为了分析不同微生物群落构建对于凋落物分解及其相应酶活性的影响，选取从杉木叶分离获得的内生真菌与腐生真菌共同构建五种不同的群落（室内实验）。结果表明：在凋落物分解3个月后，5组群落中，Ao+A群落引起的失重率最为显著，在其分解过程中Af+A群落对于C1酶活影响最为突出；在凋落物分解6个月后，Af+A群落对于凋落物失重率的影响最显著，在凋落物分解过程中Mr+A群落与Lp+A群落分别对过氧化物酶及漆酶酶活性影响最明显。总得来说，微生物群落构建对凋落物分解过程产生了重要影响。     

Sewage sludge processing determines its impact on soil microbial community structure and function

Composting and thermal drying are amongst the most commonly used post-digestion processes for allowing sanitation and biological stabilization of sewage sludge from municipal treatment plants, and making it suitable as soil conditioner for use in agriculture. To assess the impact of sludge-derived materials on soil microbial properties, fresh (LAF), composted (LAC) and thermally dried (LAT) sludge fractions, each resulting from a different post-treatment process of a same aerobically digested sewage sludge, were added at 1% (w/w) application rate on two contrasting (a loam and a loamy sand) soils and incubated under laboratory conditions for 28 days. Soil respiration, microbial ATP content, hydrolytic activities and arginine ammonification rate were monitored throughout the incubation period. Results showed that soil biochemical variables, including the metabolic quotient (qCO₂), were markedly stimulated after sludge application, and the magnitude of this stimulatory effect was dependent on sludge type (precisely LAT > LAF > LAC), but not on soil type. This effect was related to the content of stable organic matter, which was lower in LAT. Genetic fingerprinting by PCR–DGGE revealed that compositional shifts of soil bacterial and, at greater extent, actinobacterial communities were responsive to the amendment with a differing sludge fraction. The observed time-dependent changes in the DGGE profiles of amended soils reflected the microbial turnover dependent on the sludge nutrient input, whereas no indications of adverse effects of sludge-borne contaminants were noted. Our findings indicate that composting rather thermal drying can represent a more appropriate post-digestion process to make sewage sludge suitable for use as soil conditioner in agriculture.     

澳大利亚社区农园的发展及其对我国的启示

在一些发达国家,社区农园向人们提供了接触自然、放松身心的场所,已受到越来越多市民的喜欢。而我国社区农园的发展仍处于探索期,借鉴国外社区农园对于我国社区农园的发展有很大的裨益。对澳大利亚社区花园的发展状况进行了详细介绍。以三个分别位于居住区、校园、公园的社区花园为例,根据案例分析社区农园对孤独人群、老年人、儿童、残疾人这些弱势群体带来的益处,阐明其对人们身心健康的改善以及对社会可持续发展的重大意义。文末根据澳大利亚社区农园发展的成功经验和我国城市发展的现状,提出我国建设社区农园需要面临的挑战。     

湖北省宜都野生楠木资源调查

【目的】了解湖北省宜都市的野生楠木资源分布状况、种群结构及其群落特征。【方法】采用样方法分别在宜都市的王家畈镇、聂家河镇和潘家湾乡对楠木资源分布集中地段进行野外实地调查,并记录其生境条件和群落特征。【结果】调查区内发现野生楠木类植物计264株,楠属植物3种,分别为竹叶楠Phoebe faberi、桢楠P.zhennan、湘楠P.hunanensis;润楠属植物4种,分别为润楠Machilus pingii、宜昌润楠M.ichangensis、华润楠M.chinensis、刨花润楠M.pauhoi,其中华润楠、刨花润楠初步确定为宜都市新分布记录种。楠木较多分布在山地比较潮湿的阴坡,坡度为30°~40°,坡位为中坡位和下坡位,海拔在710 m左右,群落类型为常绿或落叶阔叶林的生境条件下,其楠木类植物群落的维管束植物共有71种,隶属41科60属,以樟科和蔷薇科植物比较多,被子植物中双子叶植物占有绝对的优势,高位芽植物在群落中的比重最大。【结论】该调查区内的润楠属植物种群年龄结构相比楠属更合理,大致呈稳定型,而楠属植物种群年龄结构大致呈衰退型。探讨了样地野生楠木数量及群落结构特征,为其天然林保护及种质资源保存提供理论依据,同时对城市景观树种的配置有着重要意义。     

川西林盘植物群落结构历史变化特征分析——以成都市郫都区为例

林盘是川西平原地区一种极具特色的传统农村聚落形态,具有突出的农业文化遗产价值。植被是构成林盘的核心要素,了解植物群落的历史变化过程可以为传统林盘的保护工作提供科学依据。本研究首先通过查阅历史资料掌握传统林盘植物群落的结构特征,然后选取成都市郫都区4个林盘样地和3个灌渠边林地进行植物群落调查,从而比较不同时期林盘植物群落结构。调查结果显示,目前林盘植物群落结构发生的主要变化包括乔木层中的传统优势种杉木、楠木及柏树被黑壳楠取代,林盘植被趋向单一化;竹类的物种丰富度下降明显,竹林退化严重;灌渠林地中桤木及柏树被枫杨和构树取代,竹类基本消失。川西平原地区社会和经济的变迁破坏了传统农业系统中人口、耕地和林盘之间的平衡,从而导致了林盘植被群落结构的改变。     

布氏乳杆菌和甲酸对青藏高原不同物候期燕麦青贮饲料发酵品质和细菌群落的影响

为探讨布氏乳杆菌和甲酸对青藏高原不同物候期燕麦（Avena sativa L.）青贮饲料发酵品质和细菌群落的影响，本试验以开花期、乳熟期和蜡熟期燕麦为原料，设置对照、添加甲酸和添加布氏乳杆菌3个处理，青贮90 d后，测定其营养成分、发酵指标和细菌群落组成。结果表明：布氏乳杆菌和甲酸处理均改变不同物候期燕麦青贮饲料中细菌群落组成（P<0.05），并提高其乳酸细菌相对丰富度；与对照相比，用布氏乳杆菌和甲酸处理不同物候期的燕麦青贮后，蜡熟期的燕麦pH值降低（P<0.05），乙酸均增加9.7%，丙酸分别降低11.6%和8.6%，氨态氮分别降低11.3%和19.2%。综合细菌群落组成、发酵品质和营养成分来看，蜡熟期的燕麦添加布氏乳杆菌和甲酸后，其青贮品质较佳。     

半干旱区农田杂草的生活史对策研究

2008-2009年通过利用当地常见的10种杂草种植于不同处理的农田,研究半干早区农田杂草群落结构以及10种杂草群落组分种对环境因子的响应,结果表明,1)同一物种在不同的气候环境下,可以表现出不同的生活史策略.蝇虫实、田旋花和金荞麦2008年生活史策略分别具有竟争型(C)对策属性、胁迫忍耐型(S)对策属性和中间型(C-...     

Contrasting development of soil microbial community structure under no-tilled perennial and tilled cropping during early pedogenesis of a Mollisol

A range of agricultural practices influence soil microbial communities, such as tillage and organic C inputs, however such effects are largely unknown at the initial stage of soil formation. Using an eight-year field experiment established on exposed parent material (PM) of a Mollisol, our objectives were to: (1) to determine the effects of field management and soil depth on soil microbial community structure; (2) to elucidate shifts in microbial community structure in relation to PM, compared to an arable Mollisol (MO) without organic amendment; and (3) to identify the controlling factors of such changes in microbial community structure. The treatments included two no-tilled soils supporting perennial crops, and four tilled soils under the same cropping system, with or without chemical fertilization and crop residue amendment. Principal component (PC) analysis of phospholipid fatty acid (PLFA) profiles demonstrated that microbial community structures were affected by tillage and/or organic and inorganic inputs via PC1 and by land use and/or soil depth via PC2. All the field treatments were separated by PM into two groups via PC1, the tilled and the no-tilled soils, with the tilled soils more developed towards MO. The tilled soils were separated with respect to MO via PC1 associated with the differences in mineral fertilization and the quality of organic amendments, with the soils without organic amendment being more similar to MO. The separations via PC1 were principally driven by bacteria and associated with soil pH and soil C, N and P. The separations via PC2 were driven by fungi, actinomycetes and Gram (−) bacteria, and associated with soil bulk density. The separations via both PC1 and PC2 were associated with soil aggregate stability and exchangeable K, indicating the effects of weathering and soil aggregation. The results suggest that in spite of the importance of mineral fertilization and organic amendments, tillage and land-use type play a significant role in determining the nature of the development of associated soil microbial community structures at the initial stages of soil formation.