Relationships among the Stem, Aboveground and Total Biomass across Chinese Forests

Forest biomass plays a key role in the global carbon cycle. In the present study, a general allometric model was derived to predict the relationships among the stem biomass Ms, aboveground biomass MA and total biomass MT, based on previously developed scaling relationships for leaf, stem and root standing biomass. The model predicted complex scaling exponents for MT and/or MA with respect to Ms. Because annual biomass accumulation in the stem, root and branch far exceeded the annual increase in standing leaf biomass, we can predict that MT ∝MA ∝ Ms as a simple result of the model. Although slight variations existed in different phyletic affiliations （i.e. conifers versus angiosperms）, empirical results using Model Type Ⅱ （reduced major axis） regression supported the model＇s predictions. The predictive formulas among stem, aboveground and total biomass were obtained using Model Type I （ordinary least squares） regression to estimate forest biomass. Given the low mean percentage prediction errors for aboveground （and total biomass） based on the stem biomass, the results provided a reasonable method to estimate the biomass of forests at the individual level, which was insensitive to the variation in local environmental conditions （e.g. precipitation, temperature, etc.）.     

真菌和细菌生物量在土壤团聚体中的分布和耕作响应

首次报道亚热带紫色水稻土中土壤真菌和细菌生物量在不同粒径水稳性团聚体中的分布及耕作的影响.实验样品采自16 年的国家紫色土长期定位试验站的垄作免耕(Combining Ridge and No-tillage, NT)、冬水稻田(Flooded Paddy Field, FPF)和常规平作(Conventional Tillage, CT)土壤.表层土样(0～20cm)通过湿筛法分别得到>4.76 mm、2.0～4.76 mm、1.0～2.0 mm、0.25～1.0 mm、0.053～0.25 mm、<0.053mm粒径的土壤团聚体.采用麦角固醇和胞壁酸标记法测定各级团聚体中真菌和细菌的生物量.结果显示在垄作免耕、冬水稻田、常规平作土样中,真菌生物量与细菌生物量在<0.053 mm的粘粒中含量最低;在0.053～0.25 mm的土壤微团聚体中最高;在大于0.25 mm的大团聚体中真菌和细菌生物量随粒径的增大而增多,但细菌和真菌生物量在不同耕作方式的土样中的变化模式有一定的差异.3种耕作方式相比较,垄作免耕的土壤真菌和细菌的生物量在3种耕作方式中最高,冬水稻田次之,常规平作最低.真菌生物量与细菌生物量的比率分布模式在不同耕作方式的土样中差异较大,垄作免耕的真菌生物量与细菌生物量的比率在3种耕作方式中最高,冬水稻田次之,常规平作最低,但除了在0.25～1.0 mm、2.0～4.76 mm的团聚体之间有明显差异外(P＜0.05),其余粒径之间均无明显差异(P＞0.05).这表明土壤真菌生物量和细菌生物量在亚热带紫色水稻土水稳定性团聚体中的分布模式与团聚体的粒径和耕作方式有关,3种耕作方式中垄作免耕对真菌和细菌生物量分布的响应最为明显.     

黑龙江长白山森林生物量的时空变化分析

森林生物量碳储量的空间分布及其变化信息, 对揭示地表空间变化规律及驱动因子、分析评价森林生产力及生态功能具有重要意义。该文以20世纪70年代、80年代、90年代和21世纪初4个时期的遥感数据和同期的森林资源清查样地数据为基础, 应用遥感信息模型, 估算了黑龙江长白山地区的森林生物量, 分析了该地区森林生物量的时空动态变化, 以及森林生物量随高程、坡度和坡向的变化规律。结果表明: 该地区4个时期的森林平均生物量分别为81.56、44.27、48.27和54.82 t·hm^-2。4个时期总的森林生物量分别为5.37 × 10 ⁸、2.83 × 10 ⁸、3.06 × 10 ⁸和3.46 × 10 ⁸ t。20世纪70年代到21世纪初森林平均生物量和总的森林生物量都呈现出先降低后增加的趋势, 呈先下降趋势的主要原因是20世纪70-80年代以森林采伐为主, 后增加趋势的主要原因是实施天然林保护工程起到了很大的作用。该地区4个时期森林生物量随高程、坡度和坡向都表现出一致性的变化规律, 森林生物量随高程和坡度变化都呈先增加后减少的趋势, 导致这一现象的主要原因是, 高程、坡度和坡向变化引起了局地气候条件的变化, 从而直接影响森林生长环境, 造成森林分布的变化。森林生物量在200-400 m高程所占的比例最大, 约为35%, 在坡度5°-15°所占的比例接近50%。森林生物量在南坡和西南坡所占的比例最小, 为7%; 平坡所占的比例最大, 为28%; 南坡次之, 为19%。     

Invading Monotypic Stands of Phalaris arundinacea: A Test of Fire, Herbicide, and Woody and Herbaceous Native Plant Groups

Phalaris arundinacea L. is an aggressive species that can dominate wetlands by producing monotypic stands that suppress native vegetation. In this study invasion windows were created for native species in monotypic stands of P. arundinacea with either fire or herbicide. Three native species groups, herbaceous plants, herbaceous seeds, and woody shrubs, were planted into plots burned or treated with herbicide in the early spring. Fire did not create an effective invasion window for native species; there was no difference in P. arundinacea root and shoot biomass or cover between burned and control plots (p≥ 0.998). Herbicide treatment created an invasion window for native species by reducing P. arundinacea root and shoot biomass for two growing seasons, but that invasion window was fast closing by the end of the second growing season because P. arundinacea shoot biomass had nearly reached the shoot biomass levels in the control plots (p= 0.053). Transplant mortality, frost, and animal herbivory prevented the herbaceous species and woody seedlings from becoming fully established in the plots treated with herbicide during the first year of the experiment. Transplanted monocots had a greater survival than dicots. By the second growing season the herbaceous group had the greatest mean areal cover (5%), compared to the woody seedlings (3%) and seed group (0%). Long‐term monitoring of the plots will determine whether the herbaceous transplants will compete effectively with P. arundinacea and whether the woody species will survive, shade the P. arundinacea, and accelerate forest succession.     

南亚热带常绿阔叶林优势种群的生物量与生物量增量

粘木种群的生物量为７０．１４ｔ／ｈｍ２,生物量增量为２．３２ｔｈｍ２ａ－１。其总生物量的９０％以上分布在ｄ≥２０ｃｍ的大树,仅有０．０４％～０．０５％分布在ｄ＜１０ｃｍ的小树。在各器官的分配是：树干为６５％,根为２５％,枝为１１％,而叶仅占有２％。粘木的平均径向增长为０．３５ｃｍ／ａ。应用树干解析法和形率法估算树干的生物量,两者的结果差别不大。但形率法则既省力省时,又较方便。粘木的形率为０．７１。     

基于树木起源、立地分级和龄组的单木生物量模型

以马尾松(Pinus massoniana)和落叶松(Larix)的大样本实测资料为建模样本,以独立抽取的样本为验证样本,把样本按起源、立地和龄组进行分级,采用与材积相容的两种相对生长方程,分普通最小二乘和两种加权最小二乘,对地上部分总生物量、地上各部分生物量和地下生物量进行模型拟合和验证,使用决定系数、均方根误差、总相对误差和估计精度等8项统计量对结果进行分析。结果表明:两个树种地上部分总生物量,立地分类方法,模型的拟合结果和适用性都最优;马尾松VAR模型较优,而落叶松CAR模型较好;两种加权最小二乘方法,在建模样本和验证样本中表现得不一致。在建模样本中,加权回归2(权重函数1/f^0.5)略优于加权回归1(权重函数1/y^0.5),但在验证样本中,加权回归1却明显优于加权回归2。而同时满足建模样本拟合结果最优和验证样本检验结果最优的组合中,只有加权回归1。两个树种地上部分各分量生物量,模型拟合结果和适用性,均为干材最优,树叶最差、树枝和树皮居中,样本分类、模型类型和加权最小二乘方法对干材生物量的影响,规律和地上部分总生物量相同;样本分类、模型类型和加权最小二乘方法的最优组合,用验证样本检验的结果,总相对误差树枝不超过±10.0%,树皮不超过±5.0%,树叶马尾松不超过±30.0%,落叶松不超过±20.0%。两个树种地下部分(根)生物量,样本按龄组分类方法,模型拟合结果最优,与材积相容的模型总体上优于与地上部分总生物量相容模型。     

贵州普定喀斯特次生林乔灌层地上生物量

生物量是植物群落最重要的特征之一, 也是研究生态系统基本过程和功能的重要参数。我国西南喀斯特山地次生林是退化生态系统恢复过程中的重要阶段, 其生境特殊, 乔灌层种类繁杂且生长形态多样, 物种间体积质量密度差异悬殊, 生物量测定极为困难。所以, 有关其生物量的基础资料极为缺乏。该文根据对普定喀斯特生态站的窄叶石栎(Lithocarpus confinis)+云南鼠刺(Itea yunnanensis)林、圆果化香(Platycarya longipes)+云南鼠刺林、圆果化香+槲栎(Quercus aliena)林3个主要次生森林类型的样地调查资料, 采用样木回归模型法和收获法, 研究了群落乔灌层地上生物量及其分配格局。利用172株样木数据建立了圆果化香、窄叶石栎、云南鼠刺、刺楸(Kalopanax septemlobus)、安顺润楠(Machilus cavaleriei)、槲栎、香叶树(Lindera communis)、川钓樟(Lindera pulcherrima var. hemsleyana)、异叶鼠李(Rhamnus heterophylla)、倒卵叶旌节花(Stachyurus obovatus)、薄叶鼠李(Rhamnus leptophylla)、贵州花椒(Zanthoxylum esquirolii)、竹叶椒(Zanthoxylum planispinum)、铁仔(Myrsine africana)和刺异叶花椒(Zanthoxylum dimorphophyllum var. spinifolium)15个主要树种的分种生物量回归模型。同时, 利用这些样木建立了3个不同胸径(D)组(D＜1 cm、1 cm≤D≤5 cm和D>5 cm)的生物量回归模型。通过进一步分种和分组的计算得出: 这3个次生乔木林的乔灌层地上生物量分别为85.6×10³、65.3×10³和115.2×10³ kg·hm^-2; 层次分配上, 3个样地的乔木层地上生物量占绝对优势, 分别约占乔灌层地上生物量的98.5%、96.6%和99.0%; 径级分配上, 3个样地的生物量主要集中在大径级(D≥10 cm)的个体上; 物种分配上, 3个样地的生物量排序前10位的物种分别约占乔灌层地上生物量的99.3%、97.3%和99.0%, 并集中分配在少量优势树种中。     

Agriculturally induced vegetation change, 1950–1975

Changes in worldwide grain production area are analyzed to assess the impact of major agricultural activity onglobal biomass. During the 26-year study period, nearly 1% of the earth's ice-free land surface was converted to grain production. This increase in agricultural area reduced the planetary biomass; however, it had minimal effect on net primary productivity. Geographically, the overall change caused by increased grain production has been to redistribute the planetary biomass poleward.     

模拟降水变化和土壤施氮对浙江古田山5个树种幼苗生长和生物量的影响

为了探讨古田山地区5个树种—秃瓣杜英(Elaeocarpus glabripetalus)、枫香(Liquidambar formosana)、木荷(Schima superba)、青冈(Cyclobalanopsis glauca)和马尾松(Pinus massoniana)幼苗的生长和生物量及其分配对添加氮肥和减少降水的响应, 在野外设置了双因素氮肥(对照和施氮)和降水(自然降水(对照)和减少降水)控制试验, 氮肥的施入量为10 g·m^-2·a^-1 NH₄NO₃, 分别于每年5月初和7月初各施5 g·m^-2·a^-1, 减少降水处理是减少自然降水的30%。经过3个生长季的处理发现: 1)施氮显著促进了秃瓣杜英、枫香和木荷的苗高和基径的生长, 并且对秃瓣杜英和枫香的促进作用经过1个生长季的处理就表现出来, 而木荷在经过2个生长季后才表现出来; 2)施氮显著促进了秃瓣杜英、枫香和木荷的全株生物量以及各部分生物量的增长, 而只增加了马尾松的侧枝和叶片生物量以及青冈的侧枝生物量; 3) 2个生长季的施氮处理提高了秃瓣杜英和木荷的叶重比以及枫香和青冈的枝重比, 3个生长季的施氮处理促进了秃瓣杜英、枫香和木荷的茎重比以及青冈和马尾松的枝重比, 地上干物质分配比例的增加以地下干物质分配比例减小为代价, 施氮后显著降低了秃瓣杜英、枫香、木荷和青冈的根重比和根冠比; 4) 降水减少30%对各树种的生长均无显著影响。     

A spatial assessment of potential biomass for bioenergy in Australia in 2010, and possible expansion by 2030 and 2050

This paper provides spatial estimates of potentially available biomass for bioenergy in Australia in 2010, 2030 and 2050 (under clearly stated assumptions) for the following biomass sources: crop stubble, native grasses, pulpwood and residues (created either during forest harvesting or wood processing) from plantations and native forests, bagasse, organic municipal solid waste and new short‐rotation tree crops. For each biomass type, we estimated annual potential availability at the finest scale possible with readily accessible data, and then aggregated to make estimates for each of 60 Statistical Divisions (administrative areas) across Australia. The potentially available lignocellulosic biomass is estimated at approximately 80 Mt per year, with the major contributors of crop stubble (27.7 Mt per year), grasses (19.7 Mt per year) and forest plantations (10.9 Mt per year). Over the next 20–40 years, total potentially available biomass could increase to 100–115 Mt per year, with new plantings of short‐rotation trees being the major source of the increase (14.7 Mt per year by 2030 and 29.3 Mt per year by 2050). We exclude oilseeds, algae and ‘regrowth’, that is woody vegetation naturally regenerating on previously cleared land, which may be important in several regions of Australia (Australian Forestry 77 , 2014, 1; Global Change Biology Bioenergy 7 , 2015, 497). We briefly discuss some of the challenges to providing a reliable and sustainable supply of the large amounts of biomass required to build a bioenergy industry of significant scale. More detailed regional analyses, including of the costs of delivered biomass, logistics and economics of harvest, transport and storage, competing markets for biomass and a full assessment of the sustainability of production are needed to underpin investment in specific conversion facilities (e.g. Opportunities for forest bioenergy: An assessment of the environmental and economic opportunities and constraints associated with bioenergy production from biomass resources in two prospective regions of Australia, 2011a).     

Effect of nitrogen addition,form and clipping on competitive interactions between grassland species

Aims Although the effects of N addition on plant biomass are well understood, we know a lot less about the importance of N form even though some studies have shown different impacts from reduced and oxidized forms of N. Furthermore, responses to grazing are likely to interact with the response to N addition. This experiment investigates the interactive effects of N addition and form with clipping on competition between three grassland species.Methods The three species (Anthoxanthum odoratum L., Plantago lanceolata L. and Prunella vulgaris L.) were grown alone and in combination with factorial additions of deionized water, sodium nitrate and ammonium chloride, and a clipping treatment. Above- and belowground biomass was harvested after 4 months.Important findings In monocultures, the results show increases in biomass with N addition, but clipping resulted in fewer changes with species displaying varying degrees of growth compensation. A. odoratum was the strongest competitor when grown with other species. In monocultures without clipping, N form was not important, but in the presence of clipping and in different species combinations, N form became important. Significant two- and three-way interactive effects were observed showing that complex interactions exist between N addition, clipping and species identity. The results have important implications when considering the effects of N deposition.     

Studies on the abundance,biomass and vertical distribution of larvae and pupae of black flies (Simuliidae,Diptera) on plants of the Grabia river,Poland

Studies on black flies larvae and pupae on water plants demonstrated an abundance, often exceeding 100 000 individuals per m², in the lotic region of the Grabia river. The biomass of larvae and pupae on water plants constitutes occasionally over 90% of the biomass of all water invertebrates. Aquatic larval stages of Simuliidae occupy preferentially most superficially located plant parts.     

Biomass estimation models and allocation patterns of 14 shrub species in Mountain Luya,Shanxi, China

Aims Shrub species have evolved specific strategies to regulate biomass allocation among various organs or between above- and belowground biomass and shrub biomass model is an important approach to estimate biomass allocation among different shrub species. This study was designed to establish the optimal estimation models for each organ (leaf, stem, and root), aboveground and total biomass of 14 common shrub species in Mountain Luya, Shanxi Province, China. Furthermore, we explored biomass allocation characteristics of these shrub species by using the index of leaf biomass fraction (leaf to total biomass), stem biomass fraction (stem to total biomass), root biomass fraction (root to total biomass), and root to shoot mass ratio (R/S) (belowground to aboveground biomass).
Methods We used plant height, basal diameter, canopy diameter and their combination as variables to establish the optimal biomass estimation models for each shrub species. In addition, we used the ratios of leaf, stem, root to total biomass, and belowground to aboveground biomass to explore the difference of biomass allocation patterns of 14 shrub species.
Important findings Most of biomass estimation models could be well expressed by the exponential and linear functions. Biomass for shorter shrub species with more stems could be better estimated by canopy area; biomass for taller shrub species with less stems could be better estimated by the sum of the square of total base diameter multiply stem height; and biomass for the rest shrub species could be better estimated by canopy volume. The averaged value for these shrub species was 0.61, 0.17, 0.48, and 0.35 for R/S, leaf biomass fraction, stem biomass fraction, and root biomass fraction, respectively. Except for leaf biomass fraction, R/S, stem biomass fraction, and root biomass fraction for shrubs with thorn was significantly greater than that for shrubs without thorn.     

全球森林土壤微生物生物量碳氮磷化学计量的季节动态

土壤微生物生物量在森林生态系统中充当具有生物活性的养分积累和储存库。土壤微生物转化有机质为植物提供可利用养分, 与植物的相互作用维系着陆地生态系统的生态功能。同时, 土壤微生物也与植物争夺营养元素, 在季节交替过程和植物的生长周期中呈现出复杂的互利-竞争关系。综合全球数据对温带、亚热带和热带森林土壤微生物生物量碳(C)、氮(N)、磷(P)含量及其化学计量比值的季节动态进行分析, 发现温带和亚热带森林的土壤微生物生物量C、N、P含量均呈现夏季低、冬季高的格局。热带森林四季的土壤微生物生物量C、N、P含量都低于温带和亚热带森林, 且热带森林土壤微生物生物量C含量、N含量在秋季相对最低, 土壤微生物生物量P含量四季都相对恒定。温带森林的土壤微生物生物量C:N在春季显著高于其他两个森林类型; 热带森林的土壤微生物生物量C:N在秋季显著高于其他2个森林类型。温带森林土壤微生物生物量N:P和C:P在四季都保持相对恒定, 而热带森林土壤微生物生物量N:P和C:P在夏季高于其他3个季节。阔叶树的土壤微生物生物量C含量、N含量、N:P、C:P在四季都显著高于针叶树; 而针叶树的土壤微生物生物量P含量在四季都显著高于阔叶树。在春季和冬季时, 土壤微生物生物量C:N在阔叶树和针叶树之间都没有显著差异; 但是在夏季和秋季, 针叶树的土壤微生物生物量C:N显著高于阔叶树。对于土壤微生物生物量的变化来说, 森林类型是主要的显著影响因子, 季节不是显著影响因子, 暗示土壤微生物生物量的季节波动是随着植物其内在固有的周期变化而变化。植物和土壤微生物密切作用表现出来的对养分的不同步吸收是保留养分和维持生态功能的一种权衡机制。     

Seasonality,abundance, and biomass of bacteria in a southwestern reservoir

The seasonality, abundance, and biomass of planktonic bacteria was investigated in a south temperate zone reservoir. Epilimnetic samples were collected periodically throughout 1983 from 5 locations within Lake Arlington, TX. Total bacteria were determined from epifluorescence microscopy and averaged 1.1 × 10¹³ cells m^–3 of water. Planktobacteria accounted for 85% of total cell counts and 73% of total bacterial biomass. Cell volumes were substantially larger in winter than in summer and were negatively correlated with temperature. Cell volumes ranged from 0.076 to 0.330 µm³ and averaged 0.160 µm³. The average biovolume corresponded to a sphere 0.670 µm in diameter. Bacterial biomass was high, averaging 172 mg C m^–3 of water and reached seasonal maximum during winter months. Correlation analysis (simple linear and multiple linear) revealed that approximately 50% of the variation in bacterial biomass could be accounted for by variation in temperature and dissolved organic carbon.     

Relationships among salinity, egg size, embryonic development, and larval biomass in the estuarine crab Chasmagnathus granulata Dana, 1851

We studied interrelationships between initial egg size and biomass, duration of embryogenesis at different salinities, and initial larval biomass in an estuarine crab, Chasmagnathus granulata. Ovigerous females were maintained at three different salinities (15‰, 20‰ and 32‰); initial egg size (mean diameter), biomass (dry weight, carbon and nitrogen) as well as changes in egg size, embryonic development duration, and initial larval biomass were measured.

Initial egg size varied significantly among broods from different females maintained under identical environmental conditions. Eggs from females maintained at 15‰ had on average higher biomass and larger diameter. We hypothesise that this is a plastic response to salinity, which may have an adaptive value, i.e. it may increase the survivorship during postembryonic development. The degree of change in egg diameter during the embryonic development depended on salinity: eggs in a late developmental stage were at 15‰ significantly larger and had smaller increment than those incubated at higher salinities. Development duration was longer at 15‰, but this was significant only for the intermediate embryonic stages. Initial larval biomass depended on initial egg size and on biomass loss during embryogenesis. Larvae with high initial biomass originated either from those eggs that had, already from egg laying, a high initial biomass (reflecting individual variability under identical conditions), or from those developing at a high salinity (32‰), where embryonic biomass losses were generally minimum. Our results show that both individual variability in the provisioning of eggs with yolk and the salinity prevailing during the embryonic development are important factors causing variability in the initial larval biomass of C. granulata, and thus, in early larval survival and growth.     

The role of environmental, root, and microbial biomass characteristics in soil respiration in temperate secondary forests of Northeast China

For secondary forests, the major forest resources in China (accounting for more than 50% of the national total), soil respiration (R _S) and the relationship between R _S and various biotic/abiotic factors are poorly understood. The objectives of the present study were to examine seasonal variations in soil respiration during the growing season, and to explore the factors affecting the variation in soil respiration rates for three forest types (Mongolian oak, Manchurian walnut and mixed forests) of temperate secondary forest in Northeast China. The results showed that (1) the maximum total R _S rate occurred in July, following a bell-shaped curve with season, (2) for all forest types, the total R _S was significantly influenced by soil temperature (P < 0.01), and did not significantly correlate with soil moisture, (3) compared with fine root biomass, coarse root biomass was more closely related with the root respiration in mixed forest (R ² = 0.711, P = 0.017) and in Manchurian walnut forest (R ² = 0.768, P = 0.010), and (4) microbial biomass carbon (MBC) and nitrogen were significantly correlated with heterotrophic R _S in Mongolian oak forest (R ² = 0.664, P = 0.026; R ² = 0.784, P = 0.008, respectively) and in mixed forest (R ² = 0.918, P = 0.001; R ² = 0.967, P = 0.001, respectively). We can conclude that in temperate secondary forests: (1) the R _S rate and the relationships between R _S and abiotic/biotic factors change greatly with forest types, and (2) R _S is strongly influenced by soil temperature, MBC, microbial biomass nitrogen and coarse root biomass in temperate secondary forests.     

太湖沉积物微生物生物量及其与碳、氮、磷的相关性

对太湖沉积物中微生物生物量碳(MBc)、氮(MBN)、磷(MBp),以及沉积物总有机碳(TOC)、总氮(TN)、总磷(TP)进行测定并进行相关性分析,揭示太湖沉积物微生物对太湖沉积物营养盐的响应及反馈特征.结果表明:沉积物微生物生物量(MB)在湖体沿岸地区大于湖心区,平均值为184.66 mg·kg-1,MBc在西部沿岸区以及竺山湾和梅梁湾区域较高,平均值为127.57 mg·kg-1;MBN在梅梁湾、贡湖部分区域以及靠近梅梁湾和贡湖的湖心区域和东部沿岸区较高,平均值为19.25 mg·kg-1;MBp在东部沿岸区及其附近的湖心区最高,平均值为19.09 mg·kg-1;沉积物TOC高值区(≥2.30 g· kg-1)主要集中在竺山湾、西部沿岸区、梅梁湾、贡湖地区,平均值为1.59 g·kg-1;沉积物TN高值区(≥0.30g· kg-1)主要集中在贡湖、梅梁湾、竺山湾部分地区以及西部沿岸区,平均值为0.21 g·kg-1;沉积物TP高值区(≥1.20g·kg-1)主要集中在东部沿岸区以及湖心部分区域,平均值为0.55 g·kg-1;太湖沉积物TOC/TN在7～19,平均值为8.97,表明太湖沉积物中的有机质具有明显的双重来源,其中陆源有机质主要集中在西部沿岸区;太湖沉积物MB与沉积物TOC和TN呈显著正相关,与沉积物TP相关性不显著;沉积物MBc/MBN与沉积物TOC/TN显著相关.太湖沉积物微生物主要受沉积物TOC、TN影响,且沉积物TOC/TN的变化显著影响微生物群落结构.     

Adult activity and oviposition of corn rootworms,Diabrotica spp. (Coleoptera: Chrysomelidae), in Miscanthus,corn and switchgrass

The ability of the biomass crop Miscanthus (Miscanthus × giganteus Greef and Deuter ex Hodkinson and Renvoize) to support larval development for both United States and European populations of the western corn rootworm, Diabrotica virgifera virgifera LeConte, suggests an avenue for interactions with corn (Zea mays L.). To provide context to survival of D. v. virgifera on Miscanthus, adult activity and oviposition of Diabrotica spp. were monitored in central Illinois in 2010–2011 in Miscanthus, corn and switchgrass (Panicum virgatum L.). For D. v. virgifera, vial traps within corn plots captured 3–10 times as many adults as in Miscanthus or switchgrass, while soil samples showed females laid approximately 10 times as many eggs in corn as in the perennial grasses. Adult southern corn rootworms, Diabrotica undecimpunctata howardi Barber, were the most abundant species in 2010 and clearly preferred switchgrass as an adult habitat, with vial traps in switchgrass capturing 5–10 times as many D. u. howardi as those in corn or Miscanthus. Based on the small production areas for Miscanthus and switchgrass (and low use of both by D. v. virgifera), it seems likely that there are no current impacts of these perennial grasses on pest status of Diabrotica spp. in corn or other crops. However, adaptations by Diabrotica spp. to pest management practices suggest they could be a source for interactions between biomass and food or feed crops. Early‐season soil samples did not recover eggs of D. u. howardi, but their use of switchgrass as an adult habitat suggests additional research in areas where switchgrass may be grown near peanuts, alfalfa or other hosts may be needed. Also, investigation of other candidate bioenergy crops known to support Diabrotica spp. larval development is needed to better understand the possible effects of a changing agricultural landscape on corn rootworms.