The invertebrate fauna of grassland and its influence on productivity. 1. The composition of the fauna

The invertebrate groups which are of most significance in grassland are briefly reviewed. Factors influencing the abundance and composition of the fauna are considered together with the types of damage caused in grassland, the economic importance of such damage and beneficial effects on soil fertility.     

Soil Microarthropods and Their Relationship to Higher Trophic Levels in the Pedregal de San Angel Ecological Reserve,Mexico

Soil fauna is essential for ecosystem dynamics as it is involved in biogeochemical processes, promotes nutrient availability, and affects the animal communities associated with plants. In this study, we examine the possible relationship between the soil microarthropod community on foliage production and quality of the shrub Pittocaulon praecox. We also examine the arthropods associated to its foliage, particularly the size of the main herbivores and of their natural enemies, at two sites with contrasting vegetation cover and productivity. The diversity of soil microarthropods was assessed from soil samples collected monthly under P. praecox individuals over 13 mo. Specimens collected were identified to species or morphospecies. Shrub foliage productivity was evaluated through the amount of litter produced. Resource quality was assessed by the mean content (percentage by weight) of N, C, S, and P of 30 leaves from each shrub. The mean size of herbivores and their natural enemies were determined by measuring 20 adult specimens of each of the most abundant species. We found a higher species richness of soil microarthropods and foliar arthropods in the open site, although the diversity of foliage arthropods was lower in the closed site. Shrubs growing in the closed site tend to produce more, larger, and nutritionally poorer (lower nitrogen content) leaves than open site. Herbivores and their natural enemies were also larger in the closed site. We found a significant positive relationship between the diversity and species richness of foliar arthropods and the nitrogen content of leaves. In general, species richness and diversity of both the foliar and soil fauna, as well as the size of organisms belonging to higher trophic levels, were affected by vegetation cover and primary productivity at each site. These findings highlight the need to simultaneously consider at least four trophic levels (soil organisms, plants, herbivores, and natural enemies) to better understand the functioning of these systems and their responses to environmental changes.     

槟榔间作香露兜对土壤微生物丰度与多样性的影响

研究槟榔林下间作香露兜对土壤微生物群落丰度及多样性的影响,不仅为维护热区农田土壤健康提供理论依据,还为优化槟榔林下间作香露兜模式提供数据支撑。本研究采用大田试验的方法,选择万宁、琼海和陵水3个地区建立试验样地,每个试验样地分别设置槟榔单作、香露兜单作和槟榔间作香露兜3种种植模式,测定土壤理化性质、养分含量、土壤微生物丰度与多样性等指标,以槟榔和香露兜单作为对照,探究槟榔间作香露兜模式对土壤微生物群落结构的影响。槟榔间作香露兜模式下真菌丰度显著提高,但多样性没有变化,而间作模式下土壤细菌丰度显著低于香露兜单作和槟榔单作;不同地区试验样地的真菌丰度与多样性不存在差异,但细菌丰度与多样性差异显著;土壤细菌丰度和多样性指数与土壤pH、速效钾、土壤容重以及有机质含量之间存在显著正相关关系,与土壤含水量之间呈显著负相关关系。本研究中,槟榔间作香露兜模式通过降低土壤有机质和速效钾等养分含量,抑制土壤细菌群落丰度与多样性。在不同地区或种植模式下,维持较高的土壤养分水平有助于保持土壤微生物群落结构相对稳定以及维护土壤健康。     

粉垄耕作对甘蔗土壤微生物群落的影响

粉垄耕作是一种新型的深耕深松的耕作技术,与常规耕作方式不同,粉垄耕作能增加耕层土壤深度,从而更好地改善土壤结构.为揭示不同耕作方式对甘蔗种植土壤细菌和真菌群落的影响,本研究以粉垄耕作和常规耕作的土壤为研究对象,通过16S rRNA和18S rRNA高通量测序技术分析不同生态位(非根际、根际和根表)土壤的细菌和真菌群落的...     

南方红壤丘陵区土壤细菌对土壤水分和温度的响应差异

红壤丘陵区稻田不同时期进行的水分管理导致土壤水分和温度同时变化,继而影响土壤微生物群落结构,二者对土壤微生物的影响机制目前还不清楚。本研究以中国科学院桃源农业生态实验站长期定位试验的稻田作为研究对象,同时以旱地农田作为对照,利用末端限制性酶切片段长度多态性分析（T-RFLP）和荧光定量PCR（qPCR）方法,研究不同水分管理时期细菌群落结构与丰度的变化特征,进而分析其变化的影响因素,阐明水分和温度的相对贡献。结果表明,稻田土壤细菌受土壤水分状况的显著影响,淹水期土壤细菌群落结构明显区别于其他时期,且淹水期土壤细菌丰度和多样性指数均显著低于晒田期。稻田土壤细菌群落结构和多样性指数均受到土壤含水量和土壤温度的显著影响,但土壤含水量的相关性大于土壤温度。而作为对照的旱地农田土壤含水量在不同时期没有差异,土壤细菌群落结构也没有差异,仅土壤细菌丰度和多样性指数发生一定变化,但这种变化并不与土壤温度呈现相关性。因此,本研究认为,南方丘陵区农田土壤细菌对土壤水分的响应比对土壤温度更敏感。     

有机管理模式对茶园土壤真菌群落结构及功能的影响

以两种不同管理方式（常规和有机种植）和3个坡位（上、中、下坡位）表层土壤（0~20 cm）为研究对象,通过野外调查、高通量测序、功能预测结合分子生态网络分析,研究管理方式和坡位对土壤真菌群落结构、功能特征和共发生网络的影响。研究结果表明,管理方式和坡位对土壤真菌α多样性指数影响不显著,且不存在交互作用。在门水平,管理方式及不同坡位样地的优势真菌均为子囊菌门、担子菌门和被孢霉门,管理方式没有改变土壤优势真菌的种类,但影响其相对丰度。主坐标分析（PCoA）显示,管理模式导致茶园土壤真菌群落组成发生明显改变,常规管理方式下不同坡位之间的土壤真菌群落结构有显著差异（P<0.05）,而有机种植下不同坡位之间无显著差异（P>0.05）。组间群落差异分析（LEfSe）表明,37个差异物种对管理方式非常敏感,不同管理方式富集了不同的真菌类群。共现性网络分析发现,有机茶园土壤真菌网络节点数、平均聚类系数、边数、网络中心性和网络密度均明显高于常规茶园,说明其生态网络结构更为复杂。不同处理茶园土壤真菌以腐生营养型为主（66.67%~70.18%）,有机茶园土壤中内生-垃圾腐生-土壤腐生-未定义腐生真菌、木材腐生真菌和动物病原-内生-植物病原-未定义腐生真菌的丰度显著高于常规茶园,而未定义腐生真菌、植物病原真菌和动物病原-植物病原-未定义腐生真菌的丰度则显著降低。相关性分析和冗余分析结果表明,土壤全磷、有效磷、全钾、有机质、阳离子交换量和pH值是影响茶园土壤真菌群落结构的主要因子。综上所述,有机管理方式对茶园土壤真菌群落结构产生显著影响,提高了土壤有益真菌的数量（被孢霉属）,增强了土壤真菌网络稳定性和抗干扰能力,降低了病原真菌的丰度（如拟盘多毛孢属和假拟盘多毛孢属等）,具有良好的生态环境效应。     

土壤性状和营养物质对小麦品质的影响

在影响小麦品质的环境因素中，土壤性状和营养物质的影响极为重要。高肥力和较干燥的土壤条件更有利于生产强筋优质小麦，其他土壤性状如土壤质地、性质、结构等也会影响小麦品质。营养物质供应状况影响小麦植株体内的物质代谢，进而影响其品质。氮素是影响小麦品质的最主要因素，施氮量、施氮时期、施氮方式等，均能显著影响小麦品质；磷素和钾素品质效应一般不明显，只有氮、磷、钾适当配比才能有效提高品质；一般条件施用中、微量元素对品质基本无正效应，但缺素或有效含量不足的土壤只有针对性施中、微量元素肥才能保证小麦品质。     

茶园土壤动物群落结构特征研究

采用手捡法和干、湿漏斗法,以相邻人工林地为对照,研究了茶园土壤动物群落结构特征。结果表明:茶园与人工林土壤动物群落结构存在差异,且各类群个数及其所占比例有所不同,Jaccard相似性系数为0.633,Gower系数(Sg)为0.327,土壤动物群落结构表现出较高的异质性;茶园土壤动物的类群数低于人工林,优势类群所占比例却远远高于人工林,总体群落结构较对照人工林单一;土壤动物群落的丰富度、多样性指数、密度-类群指数及分布的均匀性均低于人工林。在凋落物层以下,随着土层的加深,土壤动物类群数、个体数及多样性均呈现出一定的表聚现象,土壤动物蜱螨目/弹尾目(A/C)比值茶园(2.44)大于人工林(2.09),A/C值并未因干扰强度增大而降低,这与凋落物残留量的多少及茶园螨害有关。     

东北黑土区土壤动物对玉米秸秆不同还田方式的响应

秸秆还田是保护东北农田生态系统黑土资源重要的农业管理手段,在应对黑土退化问题上发挥了重要作用。土壤动物是评价农田生态系统质量和土壤环境优劣的重要指标。为深入分析不同秸秆还田方式对东北黑土区农田中土壤动物群落的影响以及对于土壤环境的改良状况,本文综述秸秆直接还田与秸秆间接还田方式下的土壤动物群落组成、多样性以及动态分布特征,总结概括不同还田方式下土壤动物群落特征差异的影响因素。基于目前秸秆还田与土壤动物相关研究过程中存在的问题进行展望,为秸秆还田模式下东北地区的黑土资源保护与农业生态可持续发展提供参考。     

基于宏基因组学方法分析化肥减施对热带地区菜地土壤微生物群落的影响

为了探究化肥减量配施有机肥对热带地区蔬菜轮作土壤细菌、真菌和古菌群落组成和结构的影响,在海南省文昌市开展田间定位试验,采用宏基因组测序技术分析不同施肥方式下土壤细菌、真菌和古菌群落结构和组成的变化特征,并结合土壤理化性质,探究不同施肥处理下驱动细菌、真菌和古菌群落变化的关键土壤环境因子。结果表明：与全量化肥配施有机肥（M100NPK）相比,化肥减量75%配施有机肥（M75NPK）提高了土壤SOM、TN、NH₄⁺-N和NO₃^--N的含量,化肥减量50%配施有机肥（M50NPK）处理提高了土壤TK和AK的含量。3种施肥处理（M50NPK、M75NPK和M100NPK）显著增加了土壤细菌、真菌和古菌群落的丰度。与M100NPK处理相比,M50NPK和M75NPK增加了细菌群落主要优势菌门中变形菌门（Proteobacteria）和酸杆菌门（Acidobacteria）的相对丰度,而降低了放线菌门（Actinobacteria）和绿弯菌门（Chloroflexi）的相对丰度,同时也增加了真菌群落主要优势菌门中担子菌门（Basidiomycota）的相对丰度,降低了子囊菌门（Ascomycota）的相对丰度;古菌群落主要优势菌门中奇古菌门（Thaumarchaeota）的相对丰度在M75NPK处理呈现增加趋势,在M50NPK处理呈现降低趋势。与不施肥（CK）处理相比,M50NPK、M75NPK和M100NPK增加了土壤细菌和真菌的Shannon指数和Ace指数,而降低了土壤细菌和真菌的Simpson指数,同时也增加了土壤古菌的Simpson指数,但降低了土壤古菌的Shannon指数和Ace指数。可是施肥处理之间Alpha多样性均无显著性差异。土壤细菌、真菌和古菌群落结构组成对不同化肥减量配施有机肥的响应无显著性差异。土壤pH、TP、TN、SOM和AK是导致细菌、真菌和古菌群落结构变化的主要驱动因子。研究结果表明,与M75NPK和M100NPK相比,M50NPK不会改变土壤性质、微生物群落多样性和结构,但可降低过量化肥施用可能带来的环境风险。因此,M50NPK是热带地区蔬菜种植的优化施肥方式。     

Effects of field drainage on the growth of herbage and the liveweight gain of grazing beef cattle

A long-term field grazing experiment was begun in 1982 to examine the impact of efficient field drainage on herbage and animal production from swards on an impermeable clay loam in the south-west of England. Drained and undrained lysimeter plots (each of 1 ha) were established on the existing permanent sward and received annual applications of fertilizer N of 200 or 400 kg ha⁻¹. Similar plots were initially ploughed and reseeded with Lolium perenne (cv. Melle), and received fertilizer N at an annual rate of 400 kg ha⁻¹. All plots were continuously stocked by beef cattle and stock numbers were adjusted to maintain a constant sward height and to avoid poaching damage. Results for the first 5 years show that the benefits from drainage were modest and, for beef production, unlikely to pay for its costs over the shorter term. The main benefit was in spring when herbage dry matter yield was 11% greater on the drained plots, but with no significant interaction with fertilizer N level or sward type. This benefit was reduced to 3% on an annual basis, due to the effect of the larger soil water deficits sustained by the drained swards in mid-season. Drainage increased the annual liveweight gain per ha by the grazing cattle by 11%. Possible mechanisms accounting for these effects are discussed in relation to the influences of seasonal patterns of weather.     

INFLUENCE OF SOIL AND MANAGEMENT ON THE BOTANICAL COMPOSITION OF 20-YEARS-OLD RECLAIMED HILL PASTURES IN MID-WALES

The herbage and associated habitat factors of 15- to 20-years-old reclaimed hill pastures were investigated in Mid–Wales. These swards had been reclaimed from natural hill vegetations by ploughing and sowing. The results were examined to determine which habitat factors were associated with sward reversion. Particular emphasis was given to determining how far reversion was under the control of the farmer. On ill-drained soils the swards became heavily infested with Juncus effusus , regardless of management. On well-drained soils reversion was largely prevented by maintaining an adequate stocking rate in summer, coupled with periodic applications of lime and basic slag. Inherent podsols required approximately twice as much lime as inherent brown earths for the equivalent maintenance of soil pH and sward composition.     

THE PERFORMANCE AND SURVIVAL OF CONTRASTING NATURAL POPULATIONS OF WHITE CLOVER WHEN PLANTED INTO AN UPLAND FESTUCA/AGROSTIS SWARD

A technique is described for the assessment of white clover populations implanted as rooted cuttings into an upland Festuca/Agrostis sward.
Five natural populations of white clover, taken from widely different soils and habitat conditions, were tested by this technique on an acid soil, low in calcium and phosphate and just outside the natural limits of clover distribution.
Throughout the experiment, populations from acid upland soils showed a superior performance and a lower percentage mortality than did populations from lowland calcareous soils and from medium-fertility soil at a very high altitude.
After two years, plants of the acidic populations alone remained alive, and of these only 19–25% of the number originally planted.
The order of performance in the natural sward was an almost complete reversal of the order of performance as spaced plants on a high-fertility lowland soil.
The results indicate that the differential response to soil fertility factors, previously shown to exist between natural populations of white clover by soil- and sand-culture techniques and by field fertilizer trials of spaced plants, became even more marked when the plants were subject to competition from native species.
The possibility of breeding white clover varieties adapted to acid upland conditions is discussed, particularly in relation to compatibility with native species.     

茶园昆虫群落多样性和时间格局分析

为明确茶园害虫群落多样性、优势种与昆虫群落的时间格局,对山东省代表性茶园的主要害虫及天敌群落特征进行研究.通过目测法、黄板法、扫网法以及室内观察法,进行害虫和天敌的种类鉴定以及数量统计,共发现害虫(包括害螨)27种,天敌(包括蜘蛛)15种.茶园的主要优势种害虫有黑刺粉虱、小贯松村叶蝉、茶蚜、绿盲蝽与茶黄蓟马.主要优势天...     

玉米秸秆还田对盐碱地土壤细菌多样性的影响

以通辽典型的盐碱地玉米田为研究对象,在玉米吐丝期利用高通量测序技术对盐碱地土壤细菌进行测序,结合相关生物信息学分析,研究未开垦盐碱地(ZH1)、非盐碱地连作玉米田(ZH2)和玉米秸秆还田盐碱地种植玉米田(ZH3)3个处理下耕层土壤细菌群落丰富度、多样性和群落结构的变化。结果表明,3个处理土壤细菌群落结构和丰度差异大,已知菌属中鞘氨醇单胞菌属(Sphingomonas)和pontibacter是ZH1与ZH3的优势菌属;ZH2的优势菌属为链霉菌属(Streptomyces)、鞘氨醇单胞菌属和类诺卡氏属(Nocardioides)。玉米秸秆还田对盐碱地土壤细菌多样性的影响较大,细菌菌群Alpha及样品群落组成丰度分析可知,两年玉米秸秆还田盐碱地土壤细菌多样性和物种丰度与未开垦盐碱地比较均有所上升,并出现能降解有机物料和农药的功能菌属。     

河西绿洲灌区连作玉米根际土壤真菌群落结构特征

为探究连作对玉米根际土壤真菌群落特征的影响，采用高通量测序技术分析轮作1年和连作5年、11年、25年和50年的玉米根际土壤真菌菌群落结构特征。结果表明，子囊菌门(Ascomycota)、被孢霉门(Mortierellomycota)、球囊菌门(Glomeromycota)和担子菌门(Basidiomycota)4个门为真菌优势类群，占所有真菌的90%左右。在属分类水平下镰孢菌属(Fusarium)在连作11年的玉米根际土壤中丰度最高，为56%；在连作5年的玉米根际土壤中丰度最低，为6%。不同连作年限下玉米根际土壤中的主要功能真菌依次为植物病原/腐生/共生过渡型菌(Pathogen-Saprotroph-Symbiotroph)、腐生/共生过渡型菌(Saprotroph-Symbiotroph)、植物病原菌/腐生菌过渡型(Pathotroph-Saprotroph)、腐生菌(Saprotrophs)、共生菌(Symbiotroph)、植物病原菌(Pathotroph)和植物病原菌/腐生菌过渡型(Pathotroph-Saprotroph)，连作50年的玉米根际土壤中的功能真菌丰度最低，连作5年的根际土壤中功能真菌丰度最高。     

Comparative effects of pesticides,fenitrothion and fipronil,applied as ultra-low volume formulations for locust control,on non-target invertebrate assemblages in Mitchell grass plains of south-west Queensland,Australia

The effect of an aerial application of two broad-spectrum insecticides, the organophosphorus compound, fenitrothion, and the phenyl pyrazole pesticide, fipronil, on non-target invertebrates was investigated during Australian plague locust (Chortoicetes terminifera, (Walker, 1870)) control operations on a Mitchell grass (Astrebla spp.) plain in south-western Queensland, Australia, between 2002 and 2004. The invertebrate assemblages were monitored using yellow pan and Malaise traps to target flying invertebrates and pitfall traps to target ground-dwelling invertebrates, sampled immediately before spraying and then at 3, 7, 39, 79, 189 and 414 days after spraying. Both pesticides caused significant changes to invertebrate community composition immediately after spraying, largely due to changes in the abundance of Orthoptera, Collembola and Formicidae. The richness and abundance of invertebrates in Malaise and yellow pan traps did not differ significantly with pesticide application although significant changes in assemblage composition persisted for up to 79 days. Although not statistically significant, the richness and abundance of invertebrates in pitfall traps declined at sprayed sites after treatment, relative to controls. Assemblage composition in pitfall traps at sprayed sites was significantly different from that in the control sites and these differences persisted for up to 189 days post-spray. Prolonged drought across the study site is likely to have affected the recovery of invertebrate populations and a return to pre-spray abundances did not occur until after heavy rain fell approximately one year after the commencement of the study. The controlling influence of climatic conditions on recovery of non-target arthropod populations after exposure to pesticides therefore has implications for risk assessments for the use of pesticides in arid environments.     

改善磷矿粉肥效方法研究进展

磷矿对农业生产有着重要的意义,不同品位的磷矿粉其经济适用性和农学利用效率不同。影响磷矿粉肥效的因素主要有：磷矿粉自身的物理化学性质、土壤性质、植物种类、气候因素和管理措施等。本文简要总结了改善磷矿粉肥效的方法,主要包括生物学方法、化学方法和物理方法,以期为磷矿粉的合理利用提供参考。     

不同品种香蕉种植地土壤微生物多样性及其对土壤理化性质的响应

本研究以广西不同品种香蕉种植地土壤微生物为研究对象,利用扩增子测序技术、Spearman相关性分析、RDA分析等方法对土壤微生物丰度与多样性进行测定分析,阐述了香蕉及种植地土壤理化性质对土壤微生物丰度与多样性的影响。结果表明：香蕉土壤细菌样品OTU总量与真菌样品OTU总量比率大约是2∶1;香蕉枯萎病病原菌所在属Fusarium占属水平丰度5.132%~55.132%;Spearman相关性分析显示Fusarium与土壤理化性质无显著相关;真菌的丰度与多样性比细菌更易受到土壤的理化性质与营养元素的影响,单一土壤理化性质无法显著影响土壤微生物的群落结构和物种组成;土壤真菌在一定程度上体现香蕉品种的抗病性程度。     

The invertebrate fauna of grassland and its influence on productivity. III. Effects on soil fertility and plant growth

The effects of grassland invertebrates on organic matter decomposition, soil fertility and plant growth are reviewed. Their role as primary decomposers is limited because of relatively low rates of metabolic and enzymatic activity compared with microorganisms. However, they greatly facilitate decomposition by fragmenting and incorporating litter into the soil and by stimulating microbial activity. Earthworms are the main litter consumers in productive temperate grasslands and termites in the tropics, while the activities of dung beetles, dipterous larvae and earthworms are essential for efficient dung decomposition. Earthworms and microbial-feeding invertebrates facilitate mineralization and release into the soil solution of plant nutrients. Earthworms have a major influence on soil structure through burrowing, soil ingestion and mixing and they significantly increase plant growth.
Herbivorous invertebrates at non-outbreak densities normally consume less than 10% of net primary production in grassland, but consumption bears little relationship to overall effects on productivity. These depend on factors such as the nature of the damage caused and regrowth potential, tolerance for damage and effects on animal production at the time of attack. Sap feeding insects may cause wilting and reduced growth and selective feeding on preferred species can alter botanical composition, while aphid-transmitted virus disease can depress yield. On the positive side, low levels of herbivory can stimulate growth, weed feeding insects may limit the distribution of pasture weeds, while the role of flower-visiting insects can be important in the pollination of legume seed crops. Pest management approaches incorporating biological control, alteration of botanical composition, adjustment of stocking densities and accurately timed insecticidal applications offer prospects for the control of recurring pests such as grass grub and porina in New Zealand.