马尾松-肉桂人工复层林生物量及生产力研究

应用相对生长法和样方收获法研究了广西岑溪市马尾松不同光环境处理下营造的马尾松-肉桂人工复层林的生物量及生产力.结果显示:(1)不同处理中,枯落物层生物量随林分郁闭度的增加而增加,灌木层、草本层生物量则随着林分郁闭度的增加而减少;马尾松-肉桂人工复层林模式下林分的生物量、生产力以及群落总生物量远大于马尾松单层林.(2)不同处理的马尾松-肉桂人工复层林林分净生产量均大于马尾松单层林,且上层林马尾松郁闭度在0.5～0.7条件下与肉桂形成的复层林更有利于提高环境资源的获取能力,其中以马尾松林分郁闭度为0.5、密度781株/hm2以及肉桂密度5 952株/hm2的人工复层林模式的成层性最明显,群落生物量、乔木层生物量、净生产力水平最高,分别达167.64 t/hm2、160.549 t/hm2、9.146 t/(hm2·a),且分别高于马尾松单层林14.9％、18.5％、68.7％,是经济效益和生态效益最理想的复合林模式.研究表明,光环境处理对群落生物量空间分布有显著影响,对林分各器官生物量的分配有较大影响,复层林能提高乔木层生物量在总群落生物量中的分配.人工复层混交林比单层林更有利于提高获取环境资源的能力并增加林分的稳定性.     

不同干扰模式对受害马尾松人工纯林林分结构的影响

在浙江安吉选择松材线虫病危害的马尾松人工纯林,分别进行暂不采伐直至10年后统一伐除受害木的集中干扰、采伐受害松木的适度干扰、采伐受害松木与周边松木及生长势弱松木的强度干扰,探讨不同干扰模式使受害马尾松林恢复健康的可能性.16年后的试验结果表明: 3种模式下受害林分马尾松的重要值为集中干扰>适度干扰>强度干扰,阔叶树的重要值则正好相反;与集中干扰相比,适度和强度干扰后的马尾松、阔叶树的平均胸径分别提高1.2、1.7倍和1.3、1.9倍,平均树高分别提高了1.5、2.0倍和1.2、1.8倍,林分每公顷蓄积量分别是集中干扰样地的5.2和3.8倍;适度和强度干扰的各径阶株数均远高于集中干扰样地,胸径结构近似于反J型曲线,也形成了复层林,物种丰富度和多样性指数均显著高于集中干扰样地,林木个体差异及林分复杂性指数均表现为适度干扰>强度干扰>集中干扰.适度和强度干扰下单层马尾松同龄纯林均演替为复层马尾松-阔叶树混交异龄林.3种模式均是正向阔叶化演替,演替速度为强度干扰>适度干扰>集中干扰.表明适度干扰更有利于病害马尾松林分恢复,间伐马尾松纯林能加快阔叶混交化进程以抵御松材线虫病的入侵.     

马尾松-阔叶树混交异龄林生物量与生产力分配格局

在25年生的马尾松林下分别套种1年生火力楠、闽粤栲、苦槠、格氏栲、青栲和拉氏栲幼苗,经过16a的培育后形成了郁闭的针阔混交异龄林。应用分层平均标准木收获法,建立相对生长方程,对上述6种混交林及马尾松纯林的生物量与生产力分配格局进行了研究。6个混交林的林木总生物量分别为216·41、260·06、221·92、221·65、246·13t/hm2及201·04t/hm2,而马尾松纯林的生物量为204·37t/hm2;其中地上部分占81·4%~83·7%,林分之间差异较小。在混交林中,处于主林层的马尾松生物量占林分总生物量的比例为73·5%~85·4%。在各林分生物量组成中,干材生物量最大,占总生物量的56·4%~64·8%,其它组分所占的比例依次为根(16·3%~18·6%)>枝(9·0%~16·9%)>皮(4·9%~7·3%)>叶(1·1%~4·3%)。生物量的空间结构在马尾松纯林和混交林之间存在明显差异,混交林中0~9m高度的生物量分配比例(67·1%)明显大于马尾松纯林(53·7%);混交林中,在2~3m高度就出现了枝、叶的分布,而马尾松纯林中则出现在13~14m。混交林中,阔叶树根系的生物量主要集中于0~40cm土层,占根系总生物量的74%~99%,60cm以下土层则根系分布很少,而马尾松的根系则主要分布于土壤表层(0~20cm)和60cm以下土层,分别占总生物量的26%和49%。各混交林分的净初级生产力为10·60~15·25t/(hm2·a),而马尾松纯林的生产力仅7·34t/(hm2·a)。林分净初级生产力(NPP)与光合器官/地上部分生物量比(X1)、细根生物量/地下部分生物量比(X2)存在显著的非线形关系:NPP=5·5745+1·1985X1+2·6479X22。在所研究的林分中,细根(d<2mm)生物量占林分总生物量的平均比例为0·2%,但细根生产力占林分净生产力的平均比达2·9%。     

黑龙江省东部地区红松人工中幼龄林生物量研究

运用非线性联立方程组建模理论建立红松立木相容性生物量模型,然后利用模型计算出人工红松各个样地林木各器官和样地总生物量。以林分年龄、林分平均胸径、林分密度等因素为制约条件,讨论分析林分生物量在林木各器官之间的分配规律,并且探究林分年龄、林木大小和林分密度的变化对林分生物量的影响。结果表明:幼龄红松人工林林分生物量与平均胸径成正相关关系;林分密度对林分生物量影响较大,并且随着密度的增大而增大,且最适合的林分密度范围是1 000~1 400株·ha-1;红松人工幼、中龄林林分生物量各器官分配规律相同,表现为树干树根树枝树叶,地上生物量占林分生物量79%左右;林分地上和地下生物量大概呈3.8∶1的比例。     

广西黄冕林场次生常绿阔叶林生物量及净第一性生产力

应用相对生长法和样方收获法,测定了广西黄冕林场天然次生常绿阔叶林的地上、地下生物量及林分净第一性生产力．阔叶林总生物量为99．96t·hm^-2,其中地上部分占69．41％,地下部分(根系)占30．59％．林分叶面积指数为6．50．全林净第一性生产力为24．65t·hm^-2·年^-1,其中地上部分占44．54％。根系占55．46％．     

林窗模型BKPF模拟红松针阔叶混交林群落对气候变化的潜在反应

用森林动态模型ＢＫ荭松针阔叶混交林群落在气候变化和ＣＯ２倍增后的反应得出,在气候变化５０ａ后现存的天然红松林林木总株数减少２０％以上,地上部分生物量将减少９０％以上,蒙古栎的生物量占锯林分的５７％以上,林分生产力与现在气候条件下比较接近,略高４％,但主要以蒙古栎、山杨、白桦为主,林分叶面积指数大幅度减少。     

马尾松与湿地松人工林生物量动态及养分循环特征

对乡土树种马尾松和引进外来树种湿地松人工林的生物量动态变化、养分积累与分配以及养分循环特征进行比较 ,结果表明 :在林分生长发育早期 ,马尾松生长慢 ,而湿地松生长快 ,生长发育后期马尾松生长速度比湿地松快。马尾松人工林生物量的数量成熟年龄为 36 a,采伐利用时的最大生物量为 4 34t/ hm2 ;湿地松的为 2 6 a,采伐利用时的最大生物量为 338t/ hm2。湿地松人工林各器官和总的养分积累量均高于马尾松 ,其中养分的总积累量是马尾松的 2倍多 ,树干高达 5倍多。在采伐利用时 ,不管是全树利用还是仅利用干材 ,同马尾松相比 ,湿地松林将带走更多的养分 ,对地力的养分消耗量更大。同时 ,湿地松林养分循环速率低 ,周转时间长 ,需要的养分多 ,比马尾松林维持地力的能力差。因此 ,在湿地松人工林的经营管理过程 ,更应处理好养地与用地之间的关系 ,否则会造成林地生产力的下降     

近自然化改造对马尾松和杉木人工林生物量及其分配的影响

近自然化改造作为森林新增碳汇的最有希望的选择之一,将如何通过改变林分结构影响林分生物量和生产力进而影响林分固碳能力和潜力目前尚不清楚,因此,了解近自然化改造对人工林生物量及其分配的影响,对人工林生态系统碳管理具有重要意义。以马尾松近自然化改造林(P(CN))、马尾松未改造纯林(P(CK))、杉木近自然改造林(C(CN))和杉木未改造纯林(C(CK))4种人工林为研究对象,采用样方调查和生物量实测的方法,分析4种林分生物量差异,旨在揭示近自然化改造对马尾松和杉木人工林生物量及其分配的影响。结果表明:马尾松杉木人工林近自然化改造通过调整林分结构显著提升马尾松和杉木人工林生物量和生产力,8a后马尾松和杉木林分生物量分别增加46.71%和37.24%。乔木层生物量在林分生物量总量中占主导地位(95.48%-98.82%),并对林分生态系统总生物量变化起决定性作用。林分生物量和生产力的增加主要因为近自然化改造改变了林分群落结构,进而提高了乔木层生产力。研究结果表明,合理的经营措施不仅可以改善林分结构,提升林分生产力,并可为增强植被固碳能力创造有利条件。     

江西千烟洲不同恢复途径下白栎种群生物量

利用不同自变量和函数，建立白栎枝条和单株地上各器官的生物量模型，选择其中的最佳模型估算了千烟洲人工造林和自然封育两种恢复途径下白栎种群地上生物量及其年增长量，并利用地上生物量和地下生物量的线性关系，估算了白栎种群地下生物量及其年增长量.结果表明:模拟白栎枝条和单株地上各器官生物量的最佳函数均为幂函数，而最佳自变量分别为d²l和D²H.白栎种群各器官生物量和总生物量均为天然次生林大于人工湿地松林.次生林中白栎种群地上和地下生物量分别为3.592和1.723 t·hm^-2，其中树干生物量>枝生物量>叶生物量；湿地松林中白栎种群地上和地下生物量分别为0.666和0.462 t·hm^-2，其中树干生物量>叶生物量>枝生物量.2004—2006年，两种恢复途径下白栎种群地上、地下及总生物量的年增长量均逐年增加.其中地上生物量年增长量占总年增长量的比重呈逐年升高趋势，湿地松林中由54.35%增至62.20%，次生林中由67.27%增至68.94%.与次生林相比，湿地松林中白栎种群各器官生物量年增长量较小，但其相对增长速率较快.     

基于年轮分析的不同恢复途径下森林乔木层生物量和蓄积量的动态变化

 基于树木年轮学与标准地调查法, 研究了川西亚高山林区3种恢复森林类型生物量、蓄积量及生产力动态变化特征, 旨在尝试年轮学在森林生长过程反演中的运用, 并探索不同恢复模式下森林生物量和蓄积量的动态变化。结果表明, 不同恢复类型发育至20年以后, 均进入生长加速期, 平均胸径间差异逐渐显著, 人工云杉(Picea asperata)林胸径增长最快, 明显高于天然恢复的次生桦木(Betula spp.)林和次生针阔混交林。在恢复过程中, 次生针阔混交林一直保持最高的林分平均地上生物量与林分蓄积量, 其地上平均生物量一直显著高于人工云杉林(p < 0.05), 在20年以后显著高于次生桦木林(p < 0.05)。与人工云杉林相比, 次生桦木林在25年前具有相对较高的生物量, 而在25年之后则低于人工云杉林。在0–20年桦木林林分蓄积量略高于云杉林, 而20年以后, 云杉林蓄积量则超过桦木林。不同恢复类型的生产力大小对比显示, 30年之前, 次生针阔混交林>次生桦木林>人工云杉林, 30年之后, 针阔混交林生产力仍然最高, 而人工云杉林则超过次生桦木林。川西林区次生针阔混交林恢复模式在生物量和蓄积量积累方面均具有显著优势。     

高原鼢鼠对高寒草甸植被特征及生产力的影响

本研究结果表明,高原鼢鼠栖息10年的斑块,植物群落的物种数减少,植物物种多样性指数下降,地上、地下总生物量显降低,单子叶和可利用双子叶植物生物量极显减少,但不可利用双子叶植物生物量显增加。高原鼢鼠去除5年后,斑块内植物群落的单子叶植物物种数增加,而双子叶植物下降,植物群落物种多样性指数下降,地上、地下总生物量显增加,单子叶和可利用双子叶植物生物量增加极显,不可利用双子叶植物生物量显降低。高原鼢鼠栖息10年的斑块,净初级生产量较未栖息地区减少68.98%。高原鼢鼠去除5年后,净初级生产量增加,但仅达到未栖息地区的58.69%。     

Effect of forest canopy composition on soil nutrients and dynamics of the understorey: mixed canopies serve neither vascular nor bryophyte strata

Question: The effect of overstorey composition on above‐ground dynamics of understorey vegetation is poorly understood. This study examines the understorey biomass, production and turnover rates of vascular and non‐vascular plants along a conifer–broadleaf gradient of resource availability and heterogeneity. Location: Canadian boreal forests of northwest Quebec and Ontario. Methods: We sampled mature stands containing various proportions of black spruce (Picea mariana (Mill.) BSP), trembling aspen (Populus tremuloides Michx.) and jack pine (Pinus banksiana Lamb.). Above‐ground biomass of the understorey vegetation was assessed through harvesting; annual growth rates were calculated as the differences between biomass in 2007 and 2008, as estimated by allometric relationships, and turnover rates were estimated as net primary production divided by the biomass in 2007. Results: Higher aspen presence, linked to greater nutrient availability in the forest floor, was generally associated with higher vascular biomass and production in the understorey. This effect was less pronounced in sites of high intrinsic fertility. In contrast, bryophyte biomass was positively associated with conifer abundance, particularly in wet sites of the Quebec study area. Non‐linear responses resulted in total understorey biomass being lower under mixed canopies than under pure aspen or pure conifer canopies. Turnover rates did not differ with overstorey composition. Conclusions: While resource availability is a main driver of understorey productivity, resources as drivers appear to differ with differences in understorey strata components, i.e. vascular versus non‐vascular plants. Resource heterogeneity induced by a mixed canopy had overall negative effects on understorey above‐ground productivity, as this productivity seemed to rely on species adapted to the specific conditions induced by a pure canopy.     

Stability of ecosystem properties in response to above-ground functional group richness and composition

While there has been a rapidly increasing research effort focused on understanding whether and how composition and richness of species and functional groups may determine ecosystem properties, much remains unknown about how these community attributes affect the dynamic properties of ecosystems. We conducted an experiment in 540 mini‐ecosystems in glasshouse conditions, using an experimental design previously shown to be appropriate for testing for functional group richness and composition effects in ecosystems. Artificial communities representing 12 different above‐ground community structures were assembled. These included treatments consisting of monoculture and two‐ and four‐species mixtures from a pool of four plant species; each plant species represented a different functional group. Additional treatments included two herbivore species, either singly or in mixture, and with or without top predators. These experimental units were then either subjected to an experimentally imposed disturbance (drought) for 40 d or left undisturbed. Community composition and drought both had important effects on plant productivity and biomass, and on several below‐ground chemical and biological properties, including those linked to the functioning of the decomposer subsystem. Many of these compositional effects were due to effects both of plant and of herbivore species. Plant functional group richness also exerted positive effects on plant biomass and productivity, but not on any of the below‐ground properties. Above‐ground composition also had important effects on the response of below‐ground properties to drought and thus influenced ecosystem stability (resistance); effects of composition on drought resistance of above‐ground plant response variables and soil chemical properties were weaker and less consistent. Despite the positive effects of plant functional group richness on some ecosystem properties, there was no effect of richness on the resistance of any of the ecosystem properties we considered. Although herbivores had detectable effects on the resistance of some ecosystem properties, there were no effects of the mixed herbivore species treatment on resistance relative to the single species herbivore treatments. Increasing above‐ground food chain length from zero to three trophic levels did not have any consistent effect on the stability of ecosystem properties. There was no evidence of either above‐ground composition or functional group richness affecting the recovery rate of ecosystem properties from drought and hence ecosystem resilience. Our data collectively point to the role of composition (identity of functional group), but not functional group richness, in determining the stability (resistance to disturbance) of ecosystem properties, and indicates that the nature of the above‐ground community can be an important determinant of the consistency of delivery of ecosystem services.     

草原黑蘑(Agaricus arvensis)圈对牧草生产的影响

在黑蘑圈上、圈内及圈外分别作测产样方,分析它们之间的差异。结果表明：黑蘑圈可极显著地提高群落地上生物量。其中对羊草(Leymus chinensis)的影响较大,圈上羊草的 生物量和密度均明显高于圈内、圈外;对其它植物的影响不明显。黑蘑圈可增强植物的吸水力和储水力。     

草原蘑菇圈对牧草长势影响的初步分析

在白蘑,黄蘑圈上,圈内及圈外分别作测产样方,分析它们之间的差异。结果表明：白蘑,黄蘑圈均可极显著地提高群落地上生物量。其对羊草的影响较显著,圈上羊草的生物量,株高,密度及单株重均明显高于对圈内,圈外;对黄囊苔草和其它植物的影响不明显。白蘑圈对羊草的影响较黄蘑圈小。     

Biomass, productivity and density of the seagrass Thalassia testudinum at three sites in Cahuita National Park, Costa Rica

The basic ecology of seagrass beds was investigated by comparing biomass, productivity and density of Thalassia testudinum (turtle grass) at three sites: Puerto Vargas, Punta Cahuita and Rio Perezoso, in Cahuita National Park, Limón, Costa Rica, over a two month period (March-April 1999). Above ground biomass, density, and productivity were highest in the Puerto Vargas site while Punta Cahuita had the least non-green above ground biomass was significantly lower in total biomass than Puerto Vargas. Punta Cahuita was distinguished by the largest grain size, a very hard substrate, and shallower water. Rio Perezoso, on the other hand, had extremely fine sediment and lower salinity, while Puerto Vargas was intermediate both in sediment size and environmental conditions. It appears, therefore, that higher biomass and productivity result from a combination of moderate environmental characteristics and an intermediate sediment size.     

Models of underlying autotrophic biomass dynamics fit to daily river ecosystem productivity estimates improve understanding of ecosystem disturbance and resilience

Directly observing autotrophic biomass at ecologically relevant frequencies is difficult in many ecosystems, hampering our ability to predict productivity through time. Since disturbances can impart distinct reductions in river productivity through time by modifying underlying standing stocks of biomass, mechanistic models fit to productivity time series can infer underlying biomass dynamics. We incorporated biomass dynamics into a river ecosystem productivity model for six rivers to identify disturbance flow thresholds and understand the resilience of primary producers. The magnitude of flood necessary to disturb biomass and thereby reduce ecosystem productivity was consistently lower than the more commonly used disturbance flow threshold of the flood magnitude necessary to mobilize river bed sediment. The estimated daily maximum percent increase in biomass (a proxy for resilience) ranged from 5% to 42% across rivers. Our latent biomass model improves understanding of disturbance thresholds and recovery patterns of autotrophic biomass within river ecosystems.     

A regional‐scale consideration of the effects of species richness on above‐ground biomass in temperate natural grasslands of China

Question: Can species richness be a predictor for above‐ground biomass in natural grasslands at a regional scale? Location: A total of 647 sites across temperate natural grasslands of northern China. Methods: Structural equation modelling (SEM) was used to examine the effect of species richness on above‐ground biomass. Asymptotically distribution‐free estimation was selected for parameter estimation. The SEM process was performed at five sample sizes (n=50, 100, 200, 300 and 647). Spatial structure in the original data was examined by calculating Moran's I. Results: SEM run at n=647 revealed a positive effect of species richness on above‐ground biomass after controlling for the influences of bioclimatic factors and grazing. At the four reduced sample size levels, the positive effect held true for most cases in 400 observations (>92%). Conclusions: Contrary to observations in previous studies in natural grasslands, our data showed a positive effect of species richness on above‐ground biomass. This suggests that, as a short‐term effect of diversity on productivity, niche complementarity among coexisting species tends to be an important process in arid and semi‐arid natural grasslands. We hold that biodiversity conservation is among the fundamental approaches required to maintain productivity of grasslands in arid and semi‐arid areas.     

浙江次生青冈林林木层的生物量模型及其分析

 笔者用收获法对浙江建德山区的天然次生青冈常绿阔叶林群落的第一性生产力进行了研究。本文报道了林木层样木的生物量优化回归模型,并对模型进行了分析、检验和估算。结果表明,立木各器官变量之间存在着很好的相对生长关系;进行分层次、种类(组分)和自变量的模型选优是十分必要的;各种模型都有较高的精度,可以对该群落的生物量作出有效的估计;种间模型的有效组合适用于亚乔木层的种类和乔木层的伴生种类;种类(组分)间的模型差异与它们在群落中所处的地位或所起作用密切相关;净第一性生产力在各器宫中的分配比例是植物群落结构与功能在种间关系、生态位分化和种群动态特征上的综合反映。