我国3个桉树人工林种植区生产力影响因素

研究影响桉树人工林生产力的主要因素,对于提高桉树人工林生产力以及经营水平和合理利用树种都具有重要的意义。收集我国3个桉树人工林种植区(广东省、广西壮族自治区、云南省)关于生物量与生产力研究中的相关数据,对海拔、林分密度、林龄、年均温和年降水量与乔木层生物量进行了主成分分析与混合模型分析,探究各因素对我国桉树人工林生物量与生产力的影响。结果显示:年均温、年降水量、林龄、海拔和林分密度均是影响广东、广西、云南这3个省(区)桉树人工林生物量的主要因素,其中年降水量对这3个地区桉树人工林的生物量影响极其显著(P0.01),林龄和林分密度对桉树人工林的生物量影响显著(P0.05)。这是因为这3个地区都位于亚热带,温度都属于桉树生长的适宜温度,而这3个地区存在明显的干湿季,降水量在季节和地域上分布不均匀,导致这3个地区年降水量存在较明显的差异。因此,年降水量成为影响这3个地区桉树人工林生物量的关键因素。     

Estimating photosynthetic rate and annual carbon gain in conifers from specific leaf weight and leaf biomass

Summary Canopy photosynthesis is difficult to measure directly or to predict with complex models demanding knowledge of seasonal variation in environmental and physiological properties of the canopy. Trees in particular offer a challenge with their large, aerodynamically rough and seasonally-changing canopy properties. In this paper we assess the possibility of using specific leaf weight to predict seasonal and annual net photosynthetic rate in deciduous (Larix sp.) and evergreen (Picea abies) conifers.Annual photosynthetic rate and specific leaf weight of different positions of the crown in both species were highly correlated (r ²=0.930). Annual carbon uptake by different segments in a mature P. abies crown was closely related to leaf biomass. The relationship was improved by adjusting the leaf biomass of each segment in regard to its specific leaf weight relative to the maximum found in the canopy. The adjustment accounted for associated differences in photosynthetic activity. This combined structural index (leaf biomassxrelative specific leaf weight) could, when calibrated, predict the total annual carbon uptake by different parts of the crown. If direct measurements of photosynthesis are not available, the combined structural index may still serve as a comparative estimator of annual carbon uptake.     

The effect of environmental factors on floating fresh marsh end-of-season biomass

We used both stepwise and quantile regression to determine the sources of environmental variation that explained the observed inter-annual variation in end-of-season freshwater floating marsh aboveground biomass over an 18-year period. The vegetation at our study site had high species diversity with an average of 20 species recorded from 10 0.25 m⁻² plots. However, Panicum hemitomon was clearly the dominant contributing 74% of the total biomass. Only three other species (Solidago sempervirens, Vigna luteola, and Thelypteris palustris) were so common that they were sampled in all years. We expected that the most important factors controlling interannual variation in aboveground biomass are temperature and nitrogen availability. We also expected that nitrogen availability to the plants is affected by water movement through and under the mat driven by precipitation (lower N), evaporation (transportation of higher N waters to roots), and local runoff (higher N). Stepwise regression analysis indicated that P. hemitomon average biomass was negatively related to average water level and positively related to maximum water level and had a curvilinear response with TKN. Using quantile regression the best fit for P. hemitomon maximum-biomass with two parameters was obtained using hot days (positive relationship) and maximum water level (negative relationship). Both analytical methods showed maximum water level (negative relationship) and cold front passage (positive relationship) to be the environmental parameters that best explained interannual variation in S. sempervirens biomass. V. luteola biomass was positively related to temperature. Stepwise regression added chloride concentration as an additional positive parameter explaining V. luteola biomass, while quantile regression identified nitrogen as an important positive parameter. Both analytical methods identified pH, TKN, and water level as environmental parameters that were negatively correlated with T. palustris biomass. The overall negative effect of water level on all species was unexpected in this floating mat system. We initially assumed that higher water levels were due to higher runoff which should have a positive effect on biomass. However, higher water levels may also be related to a higher retention time in this fresh-water tidal system, which decreases water exchange and nutrient replenishment.     

Production of Perennial Vegetation in an Oasis-desert Transition Zone in NW China - Allometric Estimation,and Assessment of Flooding and Use Effects

River oases at the southern fringe of the Taklamakan desert in NW China are surrounded by belts of spontaneous vegetation that protect the oases from sand drift. As an important source of forage, fuel and construction wood, this foreland vegetation is also a component part of the agricultural system of the oases but has been, and still is, destroyed through overuse. Within a broader study that aimed to provide a basis for a sustainable management of this foreland vegetation, biomass and production were studied in four vegetation types dominated either by Alhagi sparsifolia, Calligonum caput-medusae, Populus euphratica, or Tamarix ramosissima that were thought to occur under different regimes of natural flooding in the foreland of Qira (Cele) oasis, Xinjiang, NW China. Shoot biomass components were closely correlated to basal area (Calligonum, Populus, Tamarix) or shrub volume and projection area (Alhagi), enabling non-destructive estimation of stand biomass from shoot diameters or shrub dimensions with sufficient precision using allometric regression equations. Relationships between shoot basal area and biomass of the woody species (Calligonum, Populus and Tamarix) agreed with predictions by a theoretical model of plant vascular systems, suggesting that they are determined by hydraulic and mechanical requirements for shoot architecture. Average aboveground biomass densities of typical stands in late summer were 2.97 Mg/ha in Alhagi, 3.6 Mg/ha in a row plantation and 10.9 Mg/ha in homogenous stands of Calligonum, 22–29 Mg/ha in 22 year-old Populus forests and 1.9–3.1 Mg/ha in Tamarix-dominated vegetation. Annual aboveground production including wood and assimilation organs ranged from 2.11 to 11.3 Mg/ha in plantations of Calligonum, 3.17 to 6.12 Mg/ha in Populus, and 1.55 to 1.74 Mg/ha (based on total ground area) or 3.10 to 7.15 Mg/ha (in homogenous stands) in Tamarix. Production of Alhagi is equal to peak biomass. A thinning treatment simulating use by the local population enhanced productivity of Calligonum, Populus and Tamarix. A complete harvest of Alhagi in late August decreased production in the following year. An artificial flood irrigation treatment did not sufficiently increase soil water content except in the uppermost layer and had no clear beneficial effect on growth of the four species and even a negative effect on Alhagi, which was due to increased competition from annual species. As biomass and production with or without artificial irrigation were much higher than values expected for rain-fed desert vegetation at a mean annual precipitation of 35 mm, it is concluded that the existence of all vegetation types studied is probably based on permanent access to groundwater and that natural floods or precipitation do not contribute to their water supply. The effects of agricultural groundwater use in the oasis on groundwater in the foreland of the oasis need further study. Sustainable use of this productive vegetation is possible but requires proper management.     

Evaluation of some common aquatic macrophytes cultivated in enriched water as possible source of protein and biogas

The biomass production of three common aquatic macrophytes,viz. Azolla pinnata, Eichhornia crassipes andHydrilla verticillata, was high at the prevailing environmental conditions and by the enriched water of River Ganga. The biomass production ofAzolla andEichhornia was positively correlated with the orthophosphate phosphorus and nitrate-nitrogen concentrations of the enriched water. The biomass ofAzolla andHydrilla was positively correlated with the electrical conductivity of the water. The average yield of crude protein was highest in Azolla (8,520 kg.ha^–1.yr^–1), and somewhat lower inEichhornia (6,520 kg.ha^–1.yr^–1). The annual biogas production was highest inEichhornia (44,381 litres), and somewhat lower inAzolla (17,186 litres).     

Estimating the Productivity of the Black Sea Bivalve Chamelea gallinafrom the Size and Biomass of Its Populations

Characteristics of annual production based on various mass data (whole animal mass; shell mass; and wet, dry, and ash-free dry soft tissue mass), the P/B coefficient, and specific production were estimated for the bivalve mollusk Chamelea gallinasampled from 21 localities in the northwestern and eastern Black Sea. The annual production correlated with population biomass (r= 0.994) and mean individual mass (r= –0.737), while the P/Bcoefficient depended mainly on mean individual mass (r= –0.719). Estimates of the P/Bcoefficient in Ch. gallinafrom the Black Sea were smaller than those of other marine invertebrates found worldwide with the same energy equivalent. Multiple linear regression equations were calculated for empirical relationships of various characteristics of annual production to the population biomass and mean individual biomass of Ch. gallina.     

辽宁省人工林樟子松径向生长对水热梯度变化的响应

基于树轮年代学的理论和方法,建立辽宁地区人工林樟子松年轮宽度年表网络,研究人工林樟子松树木年轮生长变化,探讨樟子松生长与气候变化的关系以及其对水热梯度变化的响应规律。结果表明,研究区各采样点人工林樟子松的径向生长变化呈现较为一致的显著下降趋势(P0.05),并且下降趋势由西北至东南降低。空间上水平上,研究区樟子松的径向生长与研究区降水和相对湿度的空间梯度变化吻合(P0.05),均呈西北至东南增加的特点;各采样点樟子松年轮宽度变化的平均敏感度与降水量、相对湿度显著负相关关系(P0.05),但与温度的正相关关系不显著。各样点樟子松径向生长与月降雨量和月平均相对湿度多呈正相关关系,与月平均温度多呈负相关关系,进一步表明区域水分因子对人工林樟子松生长的限制作用明显。     

Biomass structure of exotic invasive plant Galinsona parviflora

Galinsona parviflora (Asteraceae) is a widespread annual weed that is invasive, colonizing new ground where it is able to persist. We studied the biomass structure of the G. parviflora population at the module level by using the methods of field plot investigation and weighing at 10 sample plots. Modular biomass was calculated and used for analysis of relationships between various modules. The results show that there was a positive correlation between plant height and modular biomass, between stem biomass and root biomass, stem biomass and capitulum biomass, aboveground biomass and underground biomass, and lastly, stem biomass and leaf biomass. The preferred model which measured all the relationships was a power function model with absolute coefficients (R²) ranging from 0.6303 to 0.9782. __________ Translated from Chinese Journal of Applied Ecology, 2006, 17(12): 2283–2286 [译自: 应用生态学报]     

Distribution and production ofChironomus salinarius (Diptera: Chironomidae) in a shallow coastal lagoon in the Bay of Cádiz

The abundance, generation time and production ofChironomus salinarius larvae in a lagoon fish-pond system in the Bay of Cádiz were studied by taking monthly samples at 3 sites during 1991 and 1992. Numerical abundance and biomass of larvae showed considerable spatial, seasonal and interannual variation (ANCOVAs,P<0.001). The maximum mean annual density was 7048 larvae m^–2, and corresponded to a biomass of 3.08 g dry weight (DW) m^–2. It was recorded at the site with the lowest rate of water renewal. Seasonal patterns were similar at all sites, with main annual peaks of abundance and biomass in autumn-early winter. Chironomid density was positively related to the biomass of benthic macroalgae (P<0.001). The population studied was multivoltine with a probable average of five generations per year, with overlapping cohorts and a predominance of third- and fourth-instar larvae. Estimates of annual production ranged between 72.2 g DW m^–2 yr^–1 at the site with the lowest rate of water renewal in 1991 and 0.1 g DW m^–2 yr^–1 at the site with the highest rate of water renewal in 1992. Mean annual production and the production/biomass ratio for the system was estimated to be 16.8 g DW m^–2 yr^–1 and 12.7, respectively. Possible factors leading to the observed density fluctuations are discussed, as well as possible sources of error in production estimates.     

巨桉连栽对土壤微生物生物量和数量的影响

为探讨巨桉连栽对土壤微生物生物量和数量的影响,采用时空互换法,研究了马尾松(Pinus massoniana)林和不同连栽代次的巨桉(Eucalyptus grandis)人工林的微生物生物量、数量与土壤理化性质的关系。结果表明,巨桉一代林的土壤微生物生物量碳、生物量氮和土壤真菌、细菌数量与马尾松林的差异不显著,放线菌数量则显著增加。随巨桉连栽代次增加,土壤微生物生物量碳、生物量氮和土壤细菌、放线菌、真菌数量均递减。回归分析表明,土壤全磷能独立解释微生物生物量氮、细菌和真菌数量71.7%、86.1%和63.0%的变异,与总孔隙度共同解释微生物生物量碳87.9%的变异,与全氮共同解释放线菌数量89.6%的变异。可见,土壤全磷较大程度解释了微生物的变化。     

Comparative analysis of mixing distribution in aerobic stirred bioreactor for simulated yeasts and fungus broths

The study on mixing distribution for an aerobic stirred bioreactor and simulated (solutions of carboxymethylcellulose sodium salt), yeasts (S. cerevisiae) and fungus (P. chrysogenum pellets and free mycelia) broths indicated the significant variation of mixing time on the bioreactor height. The experiments suggested the possibility to reach a uniform mixing in whole bulk of the real broths for a certain value of rotation speed or biomass concentration domain. For S. cerevisiae broths the optimum rotation speed increased to 500 rpm with the biomass accumulation from 40 to 150 g/l d.w. Irrespective of their morphology, for fungus cultures the existence of optimum rotation speed (500 rpm) has been recorded only for biomass concentration below 24 g/l d.w. The influence of aeration rate depends on the apparent viscosity/biomass concentration and on the impellers and sparger positions. By increasing the apparent viscosity for simulated broths, or biomass amount for real broths, the shape of the curves describing the mixing time variation is significantly changed for all the considered positions. The intensification of the aeration induced the increase of mixing time, which reached a maximum value, decreasing then, due to the flooding phenomena. This variation became more pronounced at higher viscosities for simulated broths, at higher yeasts concentration, and at lower pellets or filamentous fungus concentration, respectively. By means of the experimental data and using MATLAB software, some mathematical correlations for mixing time have been proposed for each broth and considered position inside the bioreactor. These equations offer a good agreement with the experiment, the maximum deviation being ±7.3% for S. cerevisiae broths.     

长白山原始林红松径向生长及林分碳汇潜力

长白山地处温带针阔混交林的中心地带,其植物生长对气候变化反映较为敏感。运用树木年代学的基本原理与方法,以该区保存完好的地带性顶级群落阔叶红松林为研究对象,探讨了红松(Pinus koraiensis)径向生长对气候变化的响应,以期揭示全球气候变化对阔叶红松林及红松树木生长的影响。以长白山自然保护区北坡为研究地点,建立红松树轮年表,计算年均生物量生长量,与逐月各气候因子进行相关和响应函数分析,以期揭示红松径向生长与气候变化的关系。同时利用多元逐步回归分析方法分别建立了红松树轮指数、年均生物量生长量与主要气候因子的模拟回归方程。主要结论如下:(1)长白山红松年表特征分析表明其生长对气候变化敏感,适用于进行树轮气候学分析;(2)红松径向生长受当年生长季前期温度影响较大;(3)温度是限制红松径向生长的主要因子,气候变暖将促进红松的径向生长;(4)目前林分单位面积地上生物量为310.88t/hm~2,单位面积林分生物量生长量约为5.077t hm~(-2)a~(-1),即每公顷每年固碳约2.539t,表明该地区老龄阔叶红松林仍具有较强的固碳能力。     

Tree growth,mortality, and above-ground biomass accumulation in a holm oak forest under a five-year experimental field drought

A holm oak forest was exposed to an experimental drought during 5 years to elucidate the growth responses of the dominant species Quercus ilex, Arbutus unedo and Phillyrea latifolia. Soil water availability was partially reduced, about 15% as predicted for this area for the next decades by GCM and ecophysiological models, by plastic strips intercepting rainfall and by ditch exclusion of water runoff. The stem diameter increment was highly correlated with annual rainfall in all species, and drought treatment strongly reduced the diameter increment of Q. ilex (41%) and specially of A. unedo (63%), the species showing higher growth rates. Stem mortality rates were highly correlated with previous stem density, but drought treatment increased mortality rates in all species. Q. ilex showed the highest mortality rates (9% and 18% in control and drought plots, respectively), and P. latifolia experienced the lowest mortality rates (1% and 3% in control and drought plots, respectively). Drought strongly reduced the increment of live aboveground biomass during these 5 years (83%). A. unedo and Q. ilex experienced a high reduction in biomass increment by drought, whereas P. latifolia biomass increment was insensitive to drought. The different sensitivity to drought of the dominant species of the holm oak forest may be very important determining their future development and distribution in a drier environment as expected in Mediterranean areas for the next decades. These drier conditions could thus have strong effects on structure (species composition) and functioning (carbon uptake and biomass accumulation) of these Mediterranean forests.     

The distribution of submerged aquatic macrophyte biomass in a eutrophic stream,Badfish Creek: the effect of environment

The distribution of biomass of the macrophyte community in Badfish Creek was examined in three sections (A–C) totaling ten kilometers. Biomass samples were taken in a stratified-random manner, with sediment characteristics, depth, current velocity and incident light measured at each site to correlate individual biomass samples with environmental factors. Total community biomass decreased in the downstream section (C), with the biomass ofElodea canadensis decreasing abruptly below section A. The only environmental factors which were correlated with the decrease in macrophyte community biomass, especially that ofPotamogeton pectinatus, in section C was the increase in substrate heterogeneity and sand substrates which lacked surface gravel. The change in substrate was related to channelization. Considering the stream as a whole, the biomass of the dominant species,Potamogeton pectinatus, was correlated with incident light. Other species present wereCeratophyllum demersum andCladophora glomerata. Analysis of riparian vegetation type indicates that tree cover significantly reduced macrophyte biomass by incident light reduction.     

Ribosomal DNA variation and its phylogenetic implication in the genusBrachypodium (Poaceae)

The structure of ribosomal DNA ofBrachypodium and several other grass species was investigated using a heterologous rDNA probe from wheat. Several different rDNA families were present among perennial and annual species within the genus. In contrast to the annual species the perennial species exhibited a very low degree of repeat length variation. An extra Eco RI site and a Hin dIII site were observed in the IGS, which distinguishedBrachypodium from other grass genera. The restriction fragment length polymorphism and length variation of the repeat units have taxonomic value withinBrachypodium and are correlated with the classification ofBrachypodium derived from other data.     

Cytotaxonomy and breeding system of the genusBiscutella (Cruciferae)

Chromosome counts were determined for 46 populations ofBiscutella representing 28 taxa. The genus was found to contain diploid taxa with 2n = 12, 16 and 18, tetraploid taxa with 2n = 36 and hexaploid taxa having 2n = 54.B. laevigata L. s. l. consists of diploid and tetraploid populations which are poorly differentiated morphologically. TetraploidB. laevigata s. l. and hexaploidB. variegata Boiss. & Reuter (s. l.) are characterized by chromosomal instability. The variation in chromosome numbers and the occurrence of polyploidy is discussed in relation to the taxonomy of the genus. An investigation of the breeding system showed that most of the annual species were self-compatible and partly inbreeding and most of the perennial species self-incompatible and, therefore, outbreeding, while one annual species,B. cichoriifolia Loisel., showed both systems.     

不同混交比例对杉木和大叶榉幼苗功能性状的影响

了解林木功能性状在不同培育模式下的变异和关联,对揭示林木生态适应性及其生态功能具有重要意义。选取了亚热带地区两种常见人工林树种杉木、大叶榉幼苗为研究对象,设置4种不同栽培模式的盆栽试验：单一杉木（4C）,单一大叶榉（4Z）和杉木、大榉树3种混栽模式（1C3Z、2C2Z、3C1Z）,研究不同混交比例对其叶、茎、根功能性状的影响。结果表明：（1）杉木总叶面积、叶干物质含量、净光合速率、蒸腾速率和气孔导度在混栽模式下显著减小,而比叶面积显著增大;根长和比根长在不同处理间无显著差异;叶、茎、根生物量和单株总生物量在混栽模式下显著低于4C处理,不同混栽模式之间差异不显著。（2）大叶榉单叶面积在3C1Z处理下最高,总叶面积随大叶榉在树种组成中所占比例的降低而逐渐增大,比叶面积在不同处理间无显著差异,叶干物质含量、净光合速率、蒸腾速率和气孔导度均在2C2Z处理下最大,而瞬时水分利用效率在2C2Z处理下最小;根长在3C1Z处理下显著增大,比根长在不同处理间无显著差异;叶、茎、根生物量和单株总生物量随大叶榉在树种组成中所占比例的降低而逐渐增大。综合来看,杉木和大叶榉混合处理中杉木种间竞争大于种内竞争,而大叶榉相反;随杉木在混栽处理中比例减少,其主要通过增加比叶面积,提高净光合速率,减少茎生物量积累来适应种间竞争关系;而大叶榉随其在混栽处理中比例的减少,显著增加叶面积和根长来提高资源利用率,减少地下资源分配,提高地上茎生物量积累。因此,树种混交比例将显著影响林木功能性状及其生物量积累,选择适宜混交比例对混交林可持续经营具有重要意义。     

Invasion of a Habitat-Forming Seaweed: Effects on Associated Biota

Fucus evanescens is a brown alga of arctic origin that has invaded European coasts. The epiphytic community of F. evanescens in southern Sweden was compared with that of the native Fucus vesiculosus, to examine to what extent an invading seaweed can modify local biodiversity. F. evanescens was much less fouled than F. vesiculosus, supporting both less biomass and fewer species of epiphytes. Multivariate analysis of the most common epiphyte taxa showed that the epiphytic community composition of F. evanescens was not entirely separated from that of F. vesiculosus, but host species contributed significantly to explain the variation in community composition. The biomass of free-living invertebrates was also lower on F. evanescens, although the pattern differed between taxonomic groups. While the biomass of amphipods was lower on F. evanescens, there was no significant difference in biomass of isopods or gastropods between the Fucus species. The good correlation between biomass of epiphytes and free-living animals suggests that the epiphytes play an important role in providing a suitable habitat for many species of free-living epifauna. The study shows that the invasion of F. evanescens affects the environmental conditions for many species associated with the Fucus community but that the direct effect on biodiversity is probably low.     

三峡库区消落带落羽杉与立柳林土壤微生物生物量碳氮磷动态变化

为探究库区消落带人工乔木植被恢复重建后土壤质量及肥力的变化特征,于2016年6月(T_1)、2016年9月(T_2)、2017年6月(T_3)及2017年9月(T_4)选择165—175 m高程落羽杉与立柳土壤为研究对象,并以裸地作为对照,测定土壤微生物生物量碳、氮、磷和相关理化性质。结果表明:(1)经历水淹(T_2—T_3)会使土壤微生物生物量处于较低水平,落干期(T_1—T_2、T_3—T_4)落羽杉与立柳人工植被恢复生长能显著提高土壤微生物生物量,对土壤微生物恢复具有重要意义。(2)落羽杉与立柳土壤微生物生物量碳、氮占土壤有机碳、全氮百分比在4个时期均显著高于裸地,表明落羽杉与立柳土壤微生物对土壤碳、氮库的贡献大于裸地;落羽杉土壤微生物生物量磷及其占全磷百分比在T_1和T_3处于极低水平,T_2和T_4处于较高水平,应注意磷元素的迁移。(3)土壤微生物生物量碳、氮、磷与土壤有机碳和全氮有极显著相关性,与土壤pH值呈不同程度的负相关。在三峡库区消落带进行落羽杉与立柳乔木植被恢复重建能显著提高土壤微生物生物量及土壤肥力,进一步证实开展科学的植被修复与重建值得提倡和肯定。     

Population niche structure

Summary The response of twenty maternal families of the annual Abutilon theophrasti to two resource gradients, nutrient and light, was investigated. The structure of the population niche for both biomass and reproductive output was found to be quite different on the two gradients. On the light gradient there was a great diversity of responses among the families while on the nutrient gradient the families responded in a similar manner. On both gradients the plants showed a significant genotype/environment interaction. Three strategies for the production of seed variation have been proposed-all offspring are adapted to the same restricted environment, each offspring of an individual is adapted to a particular environment somewhat different thant that of its siblings, and all the offspring are able to grow in a wide range of environments. We found evidence for all three of these strategies amongst the families. The range of responses seen amongst families (of the same species) in this study was as broad as that found in previous studies among species of the old field annual community to which Abutilon theophrasti belongs. This has significant implications to the nature of competitive interactions and to the evolution of differential resource use in plant populations.