A review： chemical ecology of Ips typographus （Coleoptera, Scolytidae）

Chemical ecology of the spruce bark beetle lps typographus （L.） was reviewed. The outbreak of 1.typographus in central Europe triggered extensive research on chemical ecology, Males initiate host location and produce semiochemicals which attract both males and females, A successful mass attack must first overcome the resistance of the host tree. Pioneer I. typographus evolved to use the resin flow of host trees as kairomones in host location, and synthesized semiochemicals initially to detoxify the resin. If small bark beetle populations infest healthy trees, mass attack is prevented by host resistance, Nine monoterpene alcohols were found in male hind-guts, including cis-verbenol （cV） and 2-methyl-3-buten-2-ol （MB） which are regarded as primary aggregation pheromones, and a low proportion of lpsdienol （ld） which increases attractiveness of cV and MB, Verbenone （Vn） and Ipsenol （le） are anti-aggregation pheromones, that play important roles in adjusting attack density and insect density under the bark. Non-host volatiles are repellent to L typographus, so that beetles do not waste energy boring into non-host trees. The relationship between host resistance, pheromone compounds and behavior, non-host volatiles, bioassays and mass trapping are reviewed, Results of field bioassays stressed that traps baited with specific pheromones could be used as a reasonable protection measure.     

Spatial distribution of Collembola in presence and absence of a predator

Many Collembola species are characterised by an aggregative behaviour, which is closely related to communication and co-ordination between individuals. In spite of a general heavy predation pressure, a large number of Collembola is found in soil suggesting that they have developed defence strategies against predators.

This study investigates changes in spatial structure of gregarious Collembola species in presence of a predator. It is analysed if the gregarious lifestyle of Collembola populations functions as a defence strategy against predation. In presence of a predator distances between individuals in the Collembola species Folsomia candida and Heteromurus tetrophthalmus became closer, reducing the risk of individuals to be captured by predators. On the contrary, Onychiurus sinensis specimens, which were never caught probably because of the extrusion of repelling fluids by means of their pseudocelli, moved away from each another. Besides being a successful chemical defence against predation, repelling fluid secretion may effectively repel conspecifics, thereby keeping individuals at greater distance.     

Erodibility of a soil drainage sequence in the loess uplands of Mississippi

The susceptibility of loess soils in the lower Mississippi to runoff and erosion losses varies as a function of landscape position and mapping units. This study was conducted to determine the effects of soil drainage on physical and chemical properties that influence erodibility through their control of aggregate stability. Soil samples were collected from the A- and B-horizons of the five representative pedons in the Memphis catena whose drainage class varied from well-drained to poorly-drained. The fine earth fraction (< 2 mm) of each soil was characterized for a range of basic soil physical and chemical properties. Additional sub-samples (< 8 mm) were placed in a rainfall simulator pan (0.6 m × 0.6 m test area) and subjected to simulated rainfall at an intensity of 64 mm h^− 1. Soil erodibility was assessed by the use of an aggregation index (AI) computed from water dispersible clay (WDC) relative to total clay contents. The data show that as soil drainage classes became wetter, the percentage of sediment < 53 µm increased with a decrease in soil AI resulting from a loss of Fe, Al, and Si oxide cementing agents. These results suggest that cementing agents responsible for soil aggregate stabilization are mobilized under conditions of relatively low redox potentials which increase soil erodibility.     

二级构筑水平上刺五加种群分布格局的研究

本文研究了刺五加无性系群团在群落中以及无性系小株在无性系内的分布格局,运用聚集强度指数分析了刺五加无性系种群在不同群落中的聚集性程度。     

生态公园营建中农耕文化主题的运用——以重庆白云寨生态示范园为例

解析了生态公园与主题公园的定义、特点、区别,提出在生态公园的营建中植入与特定区域生态资源匹配的文化主题,将使生态公园在生态效益的满足下得到社会效益的认可、经济效益的平衡,使综合效益发展至最佳状态。以重庆白云寨生态示范园的规划设计为例,确定了生态公园与农耕文化结合的定性,提出遵循因地制宜、修正性保护、植物系统构建的原则,并结合地形地势提出多彩森林带、逸云养生苑、湖滨畅想园三大功能分区,详细说明了各特色园区的规划亮点以及预期景观规划效应,希望白云寨生态示范园的营建可带动重庆区域文化价值的大幅度提升。     

A quantification of short-term macroaggregate dynamics: influences of wheat residue input and texture

Soil structure and soil aggregation play an important role in an array of processes such as soil erodibility, organic matter protection and soil fertility. Modeling attempts of these processes would benefit substantially from including soil structural parameters such as soil aggregation. However, quantitative data on soil structural dynamics is lacking. Therefore, we conducted short-term (3 weeks) incubations to acquire necessary soil structural parameters for modeling purposes. Prior to incubation, all structures >53 μm were destroyed from three soils with varying texture but under similar management. Five different amounts of wheat residue, ranging from 0 to 3 wt%, were added to each of these soils. After 3 weeks, samples were analyzed for large water-stable macroaggregates (>2000 μm) using a wet sieving method and for fungal growth using epifluorescence microscopy. Aggregate formation increased linearly with increasing amounts of residue at a rate of 12.0±1.24 g aggregates g⁻¹ residue added. We found no differences in aggregate formation among the three soils, even though the equilibrium level of macroaggregates differed in the field. While amounts of water-stable macroaggregates in the sandy loam and the silt loam soil corresponded well with fungal lengths, this was not the case for the silty clay loam soil. This suggests that fungi are less important in aggregate formation in more clayey soils. Cumulative respiration correlated well (r=0.89-0.91) with water-stable macroaggregates for all three soils. A model assuming an aggregate formation rate proportional to the respiration rate was very successful in fitting the measured aggregate amounts. This model predicted about 65% of the changes in aggregation when different amounts were added, and about 85% of the changes in aggregation over time. This model yielded a macroaggregate turnover time of 40-60 days. The quantitative results presented here can directly be incorporated into models describing and predicting soil aggregate dynamics, as a determining factor for physical protection of organic matter within a soil.     

Influence of FGD Gypsum on the Properties of a Highly Erodible Soil under Conservation Tillage

Surface application of agricultural lime and fertilizers in no-till (NT) systems can be inadequate because of the excess time required for slowly soluble lime to improve soil aggregation such that water and nutrients move more rapidly into and down the soil profile. This study used fluidized gas desulfurization (FGD) gypsum as an alternative to lime because of its greater solubility and calcium (Ca) and sulfur (S) contents. Gypsum was applied to NT cotton (Gossypium hirsutum L.) plots at rates of 0, 2.24, 4.48, and 6.72 Mg ha^?1 for 3 years. After 1 year, Ca, S, and soil aggregation increased significantly (P ≤ 0.05) while exchangeable aluminum (Al) activities were reduced. These results indicate that FGD gypsum can increase NT cotton yields by increasing infiltration and soil water contents, reducing runoff, ameliorating exchangeable Al problems, and by providing a readily available source of S, a limiting nutrient in many cotton soils.     

Nested spatial biodiversity patterns of nematode genera in a New Zealand forest and pasture soil

Biodiversity has a spatial dimension, which we estimated by examining generic turnover (beta diversity) of nematodes in adjacent forest and pasture sites. Dissimilarity was estimated in small and intermediate scale transects, the distribution of sampling points being determined by spatial simulated annealing. On an average, the forest yielded fewer nematodes per 24 mm dia 0-10 cm deep core than did pasture (435 vs 2818) but more genera (23.7 vs 19.1). Dissimilarity analysis suggests generic turnover is higher in forest than pasture, at both scales. At the small scale both communities have comparable dissimilarities up to 0.6 m, but only in forest does increasing distance increase dissimilarity. At the intermediate scale no spatial structure was apparent in the pasture nematode community, but in forest dissimilarity increased with distance, with no plateau. Quantifying the difference in spatial patterns between ecosystems illustrates the utility of geostatistical methods for addressing soil biodiversity.     

稻瘿蚊对水稻为害空间格局和抽样技术初步研究

本文应用10个聚集度指标分析了不同时期稻瘿蚊为害株的空间格局,用Fuzzy聚类分析法测定空间格局的时序状态,并对田间抽样技术进行了探讨.结果表明:田间受害株密度不超过3株/丛时,受害株的空间格局是聚集型的;超过3株/丛时,则为均匀型的;受害株分布的基本成分是个体群,基本成分的分布是聚集型的;不同时期的为害株的空间格局可归纳为低密度前期和高密度后期两大类;田间的最适抽样部位是水稻的分蘖株;为害株的Iwao和改进的Iwao序贯抽样模型分别是: T′_0(n)=0.15n+t·(0.18n)~(1/2);T″_0(n)=0.15n-t·(0.18n)~(1/2) 和T′_0(n)=0.15n+t·(0.1342n)~(1/2);T″_0(n)=0.15n-t·(0.1342n)~(1/2)式中,T′_0(n),T″_0(n)分别为序贯抽样过程中累计标葱数的上限和下限;n为序贯抽样数;t为在给定的显著性水平下的t分布值.