Impacts of ontogenetic and altitudinal changes on morphological traits and biomass allocation patterns of Fritillaria unibracteata

Environmental variations and ontogeny may affect plant morphological traits and biomass allocation patterns that are related to the adjustments of plant ecological strategies. We selected 2-, 3-and 4-year-old Fritillaria unibracteata plants to explore the ontogenetic and altitudinal changes that impact their morphological traits(i.e., plant height, single leaf area,and specific leaf area) and biomass allocations [i.e.,biomass allocations of roots, bulbs, leaves, stems, and flowers] at relatively low altitudinal ranges(3400 m to 3600 m asl) and high altitudinal ranges(3600 m to4000 m asl). Our results indicated that plant height,root biomass allocation, and stem biomass allocation significantly increased during the process of individual growth and development, but single leaf area, specific leaf area, bulb biomass allocation, and leaf biomass allocation showed opposite trends.Furthermore, the impacts of altitudinal changes on morphological traits and biomass allocations had no significant differences at low altitude, except for single leaf area of 2-year-old plants. At high altitude,significantly reduced plant height, single leaf area and leaf biomass allocation for the 2-year-old plants,specific leaf area for the 2-and 4-year-old plants, and stem biomass allocation were found along altitudinal gradients. Significantly increased sexual reproductive allocation and relatively stable single leaf area and leaf biomass allocation were also observed for the 3-and 4-year-old plants. In addition, stable specific leaf area for the 3-year-old plants and root biomass allocation were recorded. These results suggested that the adaptive adjustments of alpine plants, in particular F. unibracteata were simultaneously influenced by altitudinal gradients and ontogeny.

Biomass distribution patterns of ecotones between forest andswamp in Changbai Mountaion

This paper studied the biomass distribution patterns of Lanix olgensis/swamp ecotones and Betula platyphlla/swamp ecotones in Changbai Mountain so as to provide theory foundation for the management of these nature resources, by setting up sample belts, investigating initial data along the environmental gradients change, and establishing regression models. By means of regression models, the biomass of communities, layers, tree species and organs was calculated. In this system, it was found that the community biomass inreased gradually along the environmental gradients change from swamp to forest in Changbai Mountain. Furthermore, the ecotoneal biomass distributed mainly over tree layer. The tree biomass distributed mainly in two or three dominate tree species.

Effects of rainfall patterns on annual plants in Horqin Sandy Land, Inner Mongolia of China

Growth of annual plants in arid environments depends largely on rainfall pulses. An increased understanding of the effects of different rainfall patterns on plant growth is critical to predicting the potential responses of plants to the changes in rainfall regimes, such as rainfall intensity and duration, and length of dry intervals. In this study, we investigated the effects of different rainfall patterns（e.g. small rainfall event with high frequency and large rainfall event with low frequency） on biomass, growth characteristics and vertical distribution of root biomass of annual plants in Horqin Sandy Land, Inner Mongolia of China during the growing season（from May to August） of 2014. Our results showed that the rainfall patterns, independent of total rainfall amount, exerted strong effects on biomass, characteristics of plant growth and vertical distribution of root biomass. Under a constant amount of total rainfall, the aboveground biomass（AGB）, belowground biomass（BGB）, plant cover, plant height, and plant individual and species number increased with an increase in rainfall intensity. Changes in rainfall patterns also altered the percentage contribution of species biomass to the total AGB, and the percentage of BGB at different soil layers to the total BGB. Consequently, our results indicated that increased rainfall intensity in future may increase biomass significantly, and also affect the growth characteristics of annual plants.

Biomass and net primary productivity of mangrove communities along the Oligohaline zone of Sundarbans, Bangladesh

Background： The article presents the first estimates of biomass and productivity for mangrove forests along the Oligohaline zone of the Sundarbans Reserve Forest （SRF）, Bangladesh. This study was conducted overone year from March 2016 to April 20] 7. Stand structure, above and below-ground biomass changes, and litterfall production were measured within a 2100 m2 sample plot. Methods： All trees in the study plots were numbered and height （H） and diameter at breast height （DBH） were measured. Tree height （H） and DBH for each tree were measured in March 2016 and 2017. We apply the above and belowground biomass equation for estimating the biomass of the mangrove tree species （Chave et al. Oecologia 145：87-99, 2005; Komiyama et al. J Trop Ecol 21：471-477, 2005）. Litterfall was collected using 1-mm mesh litter traps with collection area of 0.42 m2. Net Primary Production （NPP） was estimated by the summation method of Ogawa Primary productivity of Japanese forests： productivity of terrestrial communities, JIBP synthesis （1977） and Matsuura and Kajimoto Carbon dynamics of terrestrial ecosystem： Systems approach to global environment （2013）. Results： Heritiero fomes has maintained its dominance of the stand and also suffered the highest tree mortality （2.4%） in the suppressed crown class. The total above-ground biomass （AGB） and below-ground biomass （BGB） of the studied stand was ]54.8 and 84.2 Mg.ha-1, respectively. Among the total biomass of the trees, 64.8% was allocated to AGB and 35.2% to BGB. In case of species-wise contribution of biomass allocation, Avicennia officinalis showed the highest score and Aglaia cucullota the lowest. Mean annual total litterfall was 10.1 Mg-ha 1.yr-1, with the maximum litterfall in winter or dry season and late summer or rainy season. The mean AGB increment and above-ground net primary productivity （AGNPP） were 7.1 and 17.2 Mg.ha-1.yr-1, respectively. Total net primary productivity （NPP） was estimated to be 21.0 Mg.ha Lyr-1 over the observed period. The results in the Sundarbans mangrove forests exhibited that mangrove communities with similar height and diameter produced different biomass production with the different basal area. The present analysis revealed that the root biomass was large enough and the mean ratio of above-/below-ground biomass was estimated to be 1.84. Conclusions： Mangrove communities growing at the oligohaline zone of the Sundarbans, Bangladesh showed high biomass and net primary production indicating their ecological and conservation significance that may be considered in future decision making process for the area as well as in understanding the role of Sundarbans mangrove forest on mitigating the effect of global warming.

Microorganisms in Small Patterned Ground Features and Adjacent Vegetated Soils along Topographic and Climatic Gradients in the High Arctic, Canada

In this study, we determine differences in total biomass of soil microorganisms and community structure (using the most probable number of bacteria (MPN) and the number of fungal genera) in patterned ground features (PGF) and adjacent vegetated soils (AVS) in mesic sites from three High Arctic islands in order to characterize microbial dynamics as affected by cryoturbation, and a broad bioclimatic gradient. We also characterize total biomass of soil microorganisms and the most probable number of bacteria along a topographic gradient within each bioclimatic subzone to evaluate whether differences in topography lead to differences in microbial dynamics at a smaller scale. We found total microbial biomass C, the most probable number of heterotrophic bacteria, and fungal genera vary along this bioclimatic gradient. Microbial biomass C decreased with increasing latitude. Overall, microbial biomass C, MPN and the number of fungal isolates were higher in AVS than in PGFs. The effects which topographic position had on microbial biomass C varied across the bioclimatic gradient as there was no effect of topographic position in Isachsen (subzone A) and Mould Bay (subzone B), when compared to Green Cabin (subzone C, warmer site).There was no effect of topographic position on MPN counts at Mould Bay and Green Cabin. However, in Isachsen, MPN counts were highest in the wet topographic position as compared to the mesic and dry. In conclusion, PGFs seem to decouple the effect climate that might have on the total biomass of soil microorganisms along the bioclimatic gradient;and influence gets ameliorated as latitude increases. Similarly, the effect of topography on the total microbial biomass is significant at the warmest bioclimatic zone of the gradient. Thus, climate and topographic effects on total microbial biomass increase with warmer climate.

Changes in the relationship between species richness and belowground biomass among grassland types and along environmental gradients in Xinjiang, Northwest China

The association between biodiversity and belowground biomass(BGB) remains a central debate in ecology.In this study, we compared the variations in species richness(SR) and BGB as well as their interaction in the top(0–20 cm), middle(20–50 cm) and deep(50–100 cm) soil depths among 8 grassland types(lowland meadow, temperate desert, temperate desert steppe, temperate steppe desert, temperate steppe, temperate meadow steppe, mountain meadow and alpine steppe) and along environmental gradients(elevation, energy condition(annual mean temperature(AMT) and potential evapotranspiration(PET)), and mean annual precipitation(MAP)) based on a 2011–2013 survey of 379 sites in Xinjiang, Northwest China.The SR and BGB varied among the grassland types.The alpine steppe had a medium level of SR but the highest BGB in the top soil depth, whereas the lowland meadow had the lowest SR but the highest BGB in the middle and deep soil depths.The SR and BGB in the different soil depths were tightly associated with elevation, MAP and energy condition;however, the particular forms of trends in SR and BGB depended on environmental factors and soil depths.The relationship between SR and BGB was unimodal in the top soil depth, but SR was positively related with BGB in the middle soil depth.Although elevation, MAP, energy condition and SR had significant effects on BGB, the variations in BGB in the top soil depth were mostly determined by elevation, and those in the middle and deep soil depths were mainly affected by energy condition.These findings highlight the importance of environmental factors in the regulations of SR and BGB as well as their interaction in the grasslands in Xinjiang.

杉木林分密度对套种闽楠树型、光合能力及生物量分配的影响

[目的]通过探讨不同林分密度杉木林下套种闽楠的树型结构、光合作用及生物量分配的适应性变化规律,为杉木近成熟林林分质量精准改造与提升提供科学依据。[方法]选择21年生杉木人工林为研究对象,通过设置375株·hm^(-2)、570株·hm^(-2)、630株·hm^(-2)和810株·hm^(-2)等4个间伐保留密度处理,分别进行林下套种900株·hm^(-2)闽楠形成杉阔复层林,测定分析林下套种5 a后闽楠冠型、侧枝长度、分枝角、叶片形态、叶绿素荧光参数、SPAD值,以及侧枝、茎干和叶片不同器官生物量等主要适应性生长指标的差异,探讨林分密度对林下套种闽楠树冠形态特性、光合能力及生物量分配的影响规律。[结果]低林分密度(375株·hm^(-2)和570株·hm^(-2))杉木下套种的闽楠2级侧枝长、1级和2级侧枝密度大于810株·hm^(-2)林分密度处理。闽楠叶片的叶面积、比叶面积表现出随着杉木林分密度增加而增加,其中,杉木林分密度375株·hm^(-2)的叶面积、比叶面积显著小于杉木林分密度810株·hm^(-2),相差80.97 cm^(2)和10.43 cm^(2)·g-1;810株·hm^(-2)林分密度处理下,闽楠叶片的叶绿素荧光参数和SPAD值均高于375株·hm^(-2)林分密度处理。低林分密度下(375株·hm^(-2)和570株·hm^(-2))套种的闽楠下层树冠叶片、总叶片生物量、以及侧枝和茎干生物量均显著大于810株·hm^(-2)林分密度处理(p<0.05)。375株·hm^(-2)林分密度处理下,闽楠通过增加株高,促进侧枝生物量积累;810株·hm^(-2)林分密度处理下,闽楠减少对株高的投资,从而增加叶片生物量的积累。[结论]在低林分密度(375株·hm^(-2)和570株·hm^(-2))下,林下光照充足有利于闽楠生物量积累,侧枝生长,其生长状况较好;在高林分密度下(630株·hm^(-2)和810株·hm^(-2)),闽楠可通过促使叶片长度变长,增大叶片比叶面积,增加叶片SPAD值,提高光合电子传递速率和光能捕获效率等变化来增强光捕获能力,从而适应光照资源不足的生存环境。

南极冰间湖浮游植物生物量和生物生产力时空特征及影响因素研究进展

南极冰间湖在气候变化中和生态系统环境中扮演着重要角色。本文通过回顾南极罗斯海、阿蒙森海、松岛和默茨等4个冰间湖浮游植物生物量和生产力的时空分布特征和变化规律、物理环境参数和气候模态对冰间湖中叶绿素a和浮游植物水华开始及持续时间的影响,得出以下几点结论:(1)罗斯海冰间湖是南极近海生物生产力最高的区域,占南大洋总生产力的28%;阿蒙森海和松岛冰间湖在37个南极冰间湖生态系统中单位面积的生产力最高;默茨冰间湖浮游植物生物量年际变化明显。(2)海冰密集度、风速和云量等物理参数与浮游植物生物量变化密切相关,其相关关系的季节性和地域特征明显。海冰密集度主要通过改变冰间湖开放水域的面积来影响可到达海表的光合有效辐射;风速通过影响水体的垂直混合强度来改变营养盐及浮游植物的垂向输运;云量对冰间湖生态系统的影响是可见光强度及紫外线辐射量之间平衡的结果。(3)在部分冰间湖,浮游植物生物量的年际变化同调控南半球高纬度气候的主要模态,如南半球环状模和半年振荡等存在显著相关性。未来工作可结合长期卫星遥感观测、现场观测和数值模拟,进一步开展气候模态对冰间湖浮游植物生物量年际变化的物理-生态耦合机制、冰间湖生态系统生产力各个尺度变异规律和机制等的深入探究,从而更好地认知极地关键海区的生物地球化学循环过程及其气候效应。

大豆玉米复合种植模式中2种作物的互作关系

定量化探索中国北方在平水年下,不同大豆玉米复合种植模式的种间竞争与种间互惠关系,以期为旱作条件下选择合理的牧草种植模式提供理论依据。试验选用我国中南部春播区推荐的作物品种大豆铁丰31和玉米强盛199,在旱作区域开展不同大豆玉米带状复合种植模式的大田栽培试验,采用完全随机区组设计4种大豆玉米带状复合种植模式,同时以大豆与玉米清种作为对照,测定不同种植模式下的生物量、邻体效应指数(RII),比较不同种植模式下大豆和玉米的互作关系。结果显示,大豆RII为-0.28~0.13,玉米RII为-0.28~0.12。在6行大豆3行玉米(S6M3)复合种植模式下,大豆和玉米的生物量较清种对照分别增加了28.95%和27.79%,且高于其他复合种植模式下作物生物量;大豆和玉米的RII分别为0.13和0.12,二者存在正相互作用。综上,在与试验区年降雨量相差不明显的旱作区域,选择S6M3复合种植模式有望提高青贮饲料产量。

不同更新方式对雷州半岛尾细桉生长及生物量分配特征的影响

为准确认识更新方式对桉树人工林生长及生物量的影响,进而为不同培育目标桉树更新方式的筛选提供理论依据和数据支持,文章以相同林龄梯度的尾细桉植苗林和萌芽林为研究对象,探讨两种更新方式对生长和生物量分配特征的影响。结果表明:萌芽林前期胸径和树高显著大于植苗林,但增长速率的下降幅度大于植苗林,胸径在5年生时以及树高在7年生时两种更新方式之间已无显著差异。两种更新方式之间尾细桉各器官的生物量分配随林龄变化存在显著差异,但这种差异主要体现在树干和树根上。两种更新方式下的尾细桉各器官生物量均随着林龄的增大呈极显著的线性增加,但增长速率表现为萌芽林小于植苗林。萌芽林各器官的生物量显著大于植苗林的优势平均可维持到5年生,之后两种更新方式之间各器官生物量基本无差异,但从增长速率的趋势来看,植苗更新在生长后期的生长潜力要高于萌芽更新。因此,在桉树栽培实践中,可根据不同的培育目标选择不同的更新方式以获得最大的效益,以培育短轮伐期为主的尾细桉人工林利用萌芽更新的方式造林;而以培育大径材为目标的尾细桉人工林可利用植苗更新的方式造林。

大气氮沉降对云南亚热带森林地表草本层植物生长的影响

[目的]研究不同浓度大气氮沉降条件下云南亚热带常绿阔叶林生态系统地表草本层植被的生长情况,探讨大气氮沉降对森林生态系统植被组成和结构功能的影响。[方法]以云南亚热带常绿阔叶林生态系统为研究对象,设置0、1、5、10、15和30 g/(m^(2)·a)共6个施氮梯度,采用每30 d 1次林冠下人工喷施的方式对野外样地连续进行2年施氮处理,观察2年后试验样地内地表草本层植被的多样性、丰富度、株高和生物量等生长特征。[结果]随着施氮浓度的增大,植物丰富度、株高和生物量也逐渐增大,在年均30 g/(m^(2)·a)浓度梯度样地中,上述各项数据均达到最大值;而植物多样性则在5 g/(m^(2)·a)浓度梯度样地中达到最大值,为(13±3)种/m^(2)。植物地上部生物量占其总生物量比重较大,为(0.69±0.06)~(0.77±0.09),且呈随着施氮浓度的增大而逐渐降低趋势;植物地下部生物量占其总生物量比重相对较小,为(0.23±0.03)~(0.32±0.04),且呈随着施氮浓度增大而逐渐增加的趋势。[结论]证明了大量大气氮沉降对森林生态系统植物物种多样性的消极影响,明确了不同浓度大气氮沉降对地表草本层植物地上部和地下部之间生物量分配规律的影响,为受大气氮沉降干扰严重的森林生态系统的科学管理及合理开发利用提供理论依据和实际参考。

小尺度高寒湿地放牧干扰格局——以纳帕海湿地为例

高寒湿地放牧干扰强烈,是其生态系统退化的主因。湿地植被生物量空间格局不仅能够反映自然因素的作用,也能够体现地域放牧等人类活动的主要特征,因此常作为表征放牧干扰格局的主要度量方法。但尺度效应导致的植被生物量影响要素在不同空间尺度下存在较大差异,尤其是针对面积为几十至几百km^(2)范围的小尺度高寒湿地而言,自然因素和放牧等人为干扰对其植被地上生物量的共同作用特征仍不明确,缺乏针对该类型湿地的合理评估模式。以滇西北国际重要湿地纳帕海为例,在排除其它人为干扰的条件下,通过植被地上生物量的空间异质性特征来表征其放牧干扰格局,并以该案例为基础提出一种小尺度高寒湿地放牧干扰格局评估模式。研究尝试基于详细地面植被调查,获得潜在植被地上生物量,利用调查同时期高分定量遥感方法(法国PLEIADES卫星数据结合实测植被地上生物量建模)获得实际植被地上生物量,并使用潜在与实际植被地上生物量之差的空间异质性特征表示纳帕海湿地放牧干扰格局。该评估模式可以有效减少对于小尺度湿地放牧干扰数据的依赖,同时减少牛羊马等大牲畜散养带来的空间分布随机性。研究结果显示纳帕海湿地放牧干扰对湿地植被地上生物量的影响严重,影响比例约为93.5%。研究发现水文等自然因素和放牧等人为干扰分别决定纳帕海湿地植被地上生物量的上限和下限,并基于此提出四方面干扰调控策略。

准噶尔盆地东南缘不同生境条件下梭梭群落结构特征研究

在新疆准噶尔盆地东南缘,以平缓低洼地、平缓沙地、半流动沙丘等3种不同生境类型上的天然梭梭群落为研究对象,从物种结构、物种多样性、生物量以及梭梭天然更新幼苗幼树种群分布格局等方面,研究不同生境条件下梭梭群落的结构特征.结果表明,以平缓低洼地上梭梭群落的植物种类最丰富,其次是平缓沙地,半流动沙丘上的植物种类最少.3种生境类型上群落中的植物种类分别为16种、15种和12种;梭梭天然更新幼苗幼树以半流动沙丘上的梭梭群落为最多,达6687株·hm-2,但幼苗幼树在梭梭群落内分布不均匀,平缓低洼地上梭梭群落内的幼苗幼树比半流动沙丘上的略少,为5799株·hm-2,但幼苗幼树在梭梭群落内分布均匀,总体评价以平缓低洼地上梭梭群落的天然更新最好;平缓低洼地上梭梭群落的总生物量为19.39t·hm-2,平缓沙地上为9.32t·hm-2,半流动沙丘上为6.69t·hm-2;不同生境类型上梭梭群落天然更新幼苗幼树的分布格局均为聚集分布.平缓低洼地地面固定,土壤水分和肥力较好,比较适宜梭梭林木生长和梭梭群落的发育,平缓沙地和半流动沙丘的地面容易产生风蚀,土壤水分和肥力较差,生境条件比较严酷.

呼伦贝尔草原生物量变化及其与环境因子的关系

根据呼伦贝尔草原大范围草地生物量的调查和实验数据,分析了该地区草地生物量的动态变化规律及其与环境因子的关系。结果表明,沿着环境梯度,不同区域草地生物量差异显著,其变化与水分、温度变化关系不显著,与0～20cm土层的土壤有机碳含量呈正相关,而与土壤容重呈负相关。逐步多元回归表明,土壤有机碳是制约生物量变化的主要因素,可能是当地草地利用方式使土壤养分成为制约草地植物生长的限制因子,从而影响草地生物量。

紫椴生物量分配格局及异速生长方程

紫椴是东北地区阔叶红松林中重要的阔叶树种,采用整株收获法分析39株紫椴地上、地下生物量分配格局。根据胸径(DBH)大小将紫椴划分为3个等级:小树(1 cm≤DBH<10 cm)、中树(10 cm≤DBH<20 cm)和大树(DBH≥20 cm)。以不同高度处树干直径作为自变量建立紫椴各器官生物量异速生长模型。结果显示:1)随着径级的增加,紫椴干、根生物量比例先增加后减小而树冠生物量比例先减小后增加,但不同径级间差异不显著;2)不同径级紫椴枝、叶生物量均位于树冠中下层;3)紫椴地上、地下生物量之间呈显著线性相关(P<0.001),拟合线性方程斜率为0.31;4)胸径和树高与地上竞争强度均呈显著的指数相关(P<0.001),地上竞争强度并没有影响树冠比例、茎叶比和根冠比,但与树高胸径比成幂相关(P<0.05);5)综合考虑模型的可解释量及回归系数显著性可知,胸径是预测紫椴不同器官生物量的最可靠变量。更准确地估测紫椴各器官生物量需要针对不同生长阶段或不同径级建立相应的生物量方程。

林窗对川西亚高山岷江冷杉幼苗生物量及其分配格局的影响

采用样带法调查了川西亚高山原始岷江冷杉林林窗和林冠下岷江冷杉幼苗(H≤100cm)的密度、高度、基径和各构件生物量,分析了各构件生物量间的相关性.结果表明:林窗与林冠下幼苗密度分别为12903和2017株.hm-2;平均高度分别是26.6和24.3cm,差异显著;平均基径分别为4.97和5.13mm,差异不显著.林窗内各龄级幼苗的生物量与林冠下同龄级幼苗的生物量之间差异不显著.林窗对不同龄级幼苗各构件生物量积累的影响不同,林窗内幼苗枝干生物量比在12年达到最大(1.54),随后其比值维持在0.69左右;林冠下幼苗在15年后(含15年),枝条生物量大于主干生物量.生长在林窗和林冠环境的幼苗单株总生物量、叶生物量、茎生物量、地上生物量和根生物量与幼苗基径的平方(D2)和苗高(H)的乘积有显著的线性关系.林窗与林冠下幼苗各构件生物量之间有显著的正相关关系.

华北落叶松人工林生物量及其分配模式

植物生物量及其分配模式是全球碳循环研究的重要内容之一。为提高我国不同尺度森林生物量碳的估算和模型模拟等的准确性,该文采用标准木法研究了华北落叶松人工林典型分布区(关帝山、五台山中山和亚高山、五台山山间盆地、塞罕坝林区)的单木生物量相对生长模型、林分生物量及其分配模式的动态变化。结果表明:①林分生物量随林龄的增加而增加,但不同分布区林分生物量的生长过程存在有一定的差异。林龄较小时各区林分生物量的差别很小,但随着林龄的增加各区之间的差异逐渐变大。在五台山中山和亚高山,林分生物量在林龄25年左右时基本达到稳定,而五台山山间盆地则在林龄35年左右时才基本达到稳定,并且这两个分布区的最大林分生物量都小于关帝山和塞罕坝。②不同分布区生物量的分配模式存在一定的差异。干生物量的比例在关帝山和塞罕坝间无显著性差异(P>0.05),都明显大于五台山(P<0.05),其中五台山中山和亚高山干生物量所占的比例最小。各区枝生物量所占的比例均有显著差异(P<0.05),叶生物量所占的比例却无明显差异(P>0.05)。除五台山山间盆地外,其余3个分布区干生物量的比例与林龄、胸径和蓄积量等林分指标呈极显著正相关(P<0.01),枝和叶生物量的比例与这些指标呈极显著负相关(P<0.01),而且都以指数形式趋于稳定值,但根生物量的比例却与这些指标大多无明显相关性(P>0.05)。

臭冷杉生物量分配格局及异速生长模型

臭冷杉是长白山阔叶红松林中重要针叶树种,采用整株收获法分析21株臭冷杉地上地下生物量分配格局。在枝条水平上采用样枝直径(BD)、样枝长度(BL)、样枝所在轮生枝位置(WP)建立活枝、针叶生物量异速生长模型,在植株水平上采用胸径(DBH)、树高(H)、年龄(Age)、树冠长度(CL)、树冠比率(CR)、南北向冠幅(CW1)、东西向冠幅(CW2)等变量建立树干木质、树皮、活枝、针叶、粗根及整株生物量模型。并利用逐步线性回归法获得不同器官生物量最优模型。结果表明:(1)活枝生物量主要集中在树冠中下层,针叶生物量集中在树冠中层。树冠中层和下层枝叶生物量无显著差异(P>0.05);(2)21株臭冷杉地上生物量和地下生物量变动范围分别为1.026—506.047 kg/株和0.241—112.000 kg/株。粗根、活枝、针叶、树干木质、树皮及枯枝生物量占整株生物量的相对比例分别为18.68%、18.39%、12.02%、39.29%、8.70%和2.92%;(3)地上生物量与地下生物量呈显著线性相关(P<0.001),拟合线性方程斜率为0.23;(4)枝条水平上,活枝生物量模型解释量超过95%,平均预测误差小于30%。与单变量(BD)活枝生物量模型相比,2变量(BD、BL)和3变量(BD、BL、WP)模型解释量分别提高1.2%和2.0%,平均预测误差分别下降6.26%和9.27%。针叶生物量相对较难预测,模型解释量仅为82.7%,平均预测误差接近50%,模型中增加BL和WP变量并未提高针叶生物量的预测精度。活枝生物量与BD、BL、WP正相关,针叶生物量与BD正相关,与BL、WP负相关;(5)植株水平上,基于胸径的单变量模型可解释量大于90%,增加树高变量未能显著提高生物量模型的预测精度。年龄决定了臭冷杉的树干生物量,忽视年龄变量将会产生生物量预测误差。树冠特征是影响枝叶生物量预测精度的重要变量。综合考虑模型的可解释量及回归系数显著性可知,胸径是预测臭冷杉不同器官生物量的可靠变量。

四季竹立竹地上现存生物量分配及其与构件因子关系

通过对四季竹立竹构件因子和地上生物量的调查,分析了立竹地上现存生物量分配格局及立竹构件因子与构件生物量的关系。结果表明:地上现存生物量分配格局1年生立竹为竹秆>竹叶>竹枝,2年生立竹为竹叶>竹秆>竹枝,2年生立竹竹秆和竹叶生物量分配比例较1年生立竹分别极显著减少和增加,而竹枝生物量分配比例不同年龄立竹间无显著变化。2年生立竹各构件因子与构件生物量间大多呈显著或极显著相关,立竹全高、枝下高、枝盘数是立竹胸径的从属因子,立竹胸径对立竹构件生物量和地上部分总生物量起着决定作用,两者具有极显著的三次曲线函数关系。四季竹在资源分配时对竹叶构件的倾斜有利于种群对已占领生境的巩固和新生境的开拓。

金露梅灌丛地下生物量形成规律的研究

对金露梅灌丛地下生物量形成规律的研究结果表明 :金露梅灌丛地下生物量具有“V”字形季节变化规律和明显的垂直分布特征 ;金露梅灌丛死根和活根的生物量变化有显著的季节变化规律 ;金露梅灌丛草场地下生物量的周转值为 35 .72 % ,地下净生产量为 12 0 6 .4 g/ m2 ;金露梅灌丛地下生物量与地上生物量、总生物量的比值接近于生长季始末时最大 ;