On the Biomass of Four Major Tree Species in Vegetation Restoration Pattern Area of Beichuan Nature Reserve

Yonglin FENG，Jinliang SHEN，Jianshe ZHANG，Dongzhou DENG，Wen SHAO，Gang WANG，Zhipeng SUN，Chunying SU，Gang WANG*

1.Sichuan Agricultural University，Chengdu 611130，China；

2.Sichuan Academy of Forestry，Chengdu 610081，China

On the Biomass of Four Major Tree Species in Vegetation Restoration Pattern Area of Beichuan Nature Reserve

Yonglin FENG1*，Jinliang SHEN1*，Jianshe ZHANG1，Dongzhou DENG2，Wen SHAO1，Gang WANG1，Zhipeng SUN1，Chunying SU1，Gang WANG1**

1.Sichuan Agricultural University，Chengdu 611130，China；

2.Sichuan Academy of Forestry，Chengdu 610081，China

In the experiment，by taking Quercus engleriana Seem.，Betula albosinensisBurk.，Abiesfaxoniana Rehd.and Fargesia rufa Yi，in the vegetation restoration pattern area of Beichuan Nature Reserve as the research objects，the study on the biomass models，the biomass distribution law of single plant and the growth rule of every organ of the four tree species was made.The results indicated that in the compositions of all of the species，the proportion of trunk biomass was the highest，while that of trunk biomass was the lowest，the proportions of branch and root biomasses varied depending on species；in the comparison of correlativity between the proportions of biomasses of all nutrition organs and biomass of single plant，the relations were generally significant，the tree trunks were positively related while the roots were negatively related；the proportion of trunk biomass of all species was significantly and negatively related to the proportions of leaf and branch biomasses，while the biomass of leaves was significantly and positively related to the biomass of branches.

Beichuan Nature Reserve；Biomass；Regression model；Allocation pro-portion

V egetative biomass not only di-rectly reflects the growth con-ditions of the vegetation and the change of the habitat，but also re-flects the resource utilization capacity of the vegetation，thus it is the impor-tant indicative character of the prop-erty and state of forest ecosystem，and also the important way of deeply understanding the change rule of for est ecosystem［1-2］.The forest land re-source of Beichuan Nature Reserve was damaged to a certain extent at the "5.12"earthquake，thereby causing the decline of vegetation ecosystem function within the local scope of the protection zone，and the deterioration of regional ecological regime，as well as the severe damage of the habitats of wild animals and plants.After the earthquake，related departments de- signed four kinds of vegetation restoration patterns，including Quercus engleriana Seem.，Betula albosinensis Burk.，Abies faxoniana Rehd. and Fargesia rufa Yi，taking the exist-ing vegetation form of Beichuan Na-ture Reserve as the model，without in-troducing alien species，based on the site conditions of damaged forests，and giving full consideration to the ecological characteristics of tree species and the suitable scope of alti-tude.Based on this，this experiment took the above tree species as the studying objects，and studied the biomass models of the tree species and biomass distribution rule of single plant，so as to provide some basic da-ta and theoretical bases as well as beneficial reference proposals for the restoration and protection of the vege-tation of Beichuan Nature Reserve.

General Situation of Study Areas

BeichuanNatureReserve（30°14′-32°14′N，103°44′-104°42′E）is locat-ed in Beichuan County of Mianyang City with hilly territory，ravines cross-bar，high terrain of the northwest and low terrain of the southeast，and the al-titude is 540-4 769 m.Annual average temperature here is 15.6℃，annual average frost-free days are 244-282 d，annualaverageprecipitationis1399.11 mm，and annual average sunshine hours are 931.1-1 111.5 h.There are rich forest and water resources；in ge-ographical distribution，it has the char-acteristics of complex forest composi-tion，wide varieties and abundant types，etc.

Research Methods

The arrangement of sample plot

The sample-plot survey was car-ried out during July and October in 2013；taking Q.engleriana，B.albosinensis，A.faxoniana and F.rufa in the vegetation restoration pattern area of Beichuan Nature Reserve as the research objects，and based on field survey，the forest lands unaffected or less affected by earthquake with rela-tively tidy forest form and relatively in-tact terrain were selected；in the distri-bution areas of the four vegetation types，the sample plots with 20 m×20 m in area were randomly set upward a-long the elevation （the sample plot of F.rufa was 2 m×2 m），then the basic information of forest stand was sur-veyed，and the site factors including elevation and gradient were recorded. In the sample plot，the tree layer was surveyed，and each tree with the height≥1.3 m was surveyed，then the factors including tree name，tree height，diameteratbreastheight， numberand canopydensitywere recorded.The basic information of sample plots was in Table 1.

The collection and measurement of biomass

Every tree of the sample plot was measured，and the model trees were determined according to average di-ameter at breast height and average stand height，then a certain number of model trees were cut for analyzing，in-cluding 20 Q.engleriana，20 B.albosinensis，20 A.faxoniana and 30 F.rufa，in order to build the biomass mod-els and carry out model test.

（1）Stem analysis.Analytic trees were selected and their growing envi-ronment was recorded，then the stem analysis was carried out taking 2.0 m as a fragment，the fresh weight of the disk and the whole bole were mea-sured on the spot and the samples were taken.

（2）The measurement of branch andleafbiomassesusing sample branch evaluation.The branches with average diameter and average length were selected from the whole branch，then the fresh weight of branches and leaves was measured on the spot，af-ter that，the samples were taken.

（3）Themeasurementofroot biomassusing excavation method. The roots were excavated from differ-ent directions and layers （0-30 cm，below 30 cm）and divided into 4 types，namely fine roots（d＜1.0 cm），middle roots（1.0 cm＜d＜2.0 cm），large roots（d＞2.0 cm）and root pocket［3］，then weighing according to the classifica-tion，after that，each sample was got.

（4）The overground part of F.rufa was measured using"harvest meth-od"［4］，and"excavation method"was used for the underground part，the fresh weight of the bole，branch，leaf and root system was measured on the spot，then the samples were taken respectively.

In the end，all samples were taken back to the lab and put into 85℃oven until drying to constant quality，then the moisture content of each sample was obtained，and based on the fresh weight，the dry weight of each organ and part was got.

Table 1 The basic information of sample plots

Results and Analyses

The establishment of relative growth equation

In recentyears，the biomass models usually used have been：linear model（y=a+bx），polynomial model（y= a+bx+cx2），non-linear model（y=axb），etc.When establishing the model，tree height（H），diameter at breast height（D）and the combination（D2H）were re-spectively taken as independent vari-ables，so as to establish the biomass models of the three types；then the precision and the complexity of the fit-ted equation were analyzed and com-pared，so as to finally determine the biomass models of each organ and in-dividual tree of four tree species.The basic information was in Table 2.

The distribution law of individual biomass

Tree species have theirown growth characteristics，the biomasses of vegetative organs of different tree species have different proportions and orders.As shown in Table 3，the biomass proportions of different vege-tative organs of Q.engleriana fol-lowed the sequence of trunk＞branch＞root＞leaf，and that of B.albo-sinensis，A.faxoniana and F.rufa was trunk＞root＞branch＞leaf.Tree trunk has a very important role in supporting the tree body，thus after many years of ac-cumulation，its biomass has a relative-ly high proportion；leaf will fall in the process of growth，thus its biomass has a relatively small proportion；there-fore，the proportion of trunk biomass of individual plant was the highest，and that of leaves was the lowest.

Table 2 The biomass models of the four tree species

For the same vegetative organ，the proportion of biomass of different tree species also has greater differ-ences.The proportions of trunk and root biomasses of A.faxoniana were the highest，and the proportions of branch and leaf biomasses in Q.engleriana and B.albo-sinensis were the highest.Therefore，the proportion of trunk biomass of coniferous species was higher than that of deciduous species，and the proportion of branch biomass of deciduous species was higher than that of coniferous species，this may be caused by more obvious trunks of coniferous species and more branches of deciduous species.

The growth rhythm of vegetative organs

The allocation pattern between vegetative organs and individual biomass Generally speaking，with the growth of tree height and diameter at breast height，the biomass of indi-vidual tree would increase，and the biomass of each organ would also in-crease［5-6］.However，there were not detailed studies on the change of the proportion of organ biomass in individ-ual biomass；the change of the pro-portion of organ biomass can reflect the growth rate of the organ in the growth process，and also contribute to understanding the dynamic change of the distributive law of individual biomass.

Table 3 The biomasses of vegetative organs of the four tree species

Table 4 Correlation coefficients between organ biomass percent allocation and the biomass of individual tree of different tree species

The analysis results were shown in Table 4.From each organ of view，the proportions oftrunk and leaf biomasses of Q.engleriana were sig-nificantly and positively correlated with individual biomass，but the proportions of branch and root biomasses had not significant relationship with individual biomass.The proportion of each organ biomass of B.albo-sinensis all had sig-nificant relationship with individual biomass，in which trunk and branch biomasses had positive correlation with individual biomass，and leaf and root biomasses had negative correla-tion with that.The proportion of trunk biomass of A.faxoniana was signifi-cantly correlated with individual biomass，while the proportions of branch，leaf and root biomasses hadnot significant relationship with individ-ual biomass.The proportion of bam-boo trunk biomass of F.rufa was sig-nificantly and positively correlated with individual biomass，but the proportions of bamboo branches，bamboo leaves and bamboo roots were significantly and negatively correlated with individ-ual biomass.

Table 5 Correlation coefficients of organ biomass percent allocation for different tree species

As a whole，with the growth of trees，the proportions of trunks of Q.engleriana，B.albo-sinensis，A.faxoniana and F.rufa would increase while the proportion of roots would de-crease，the proportions of branches and leaves would be different with dif-ferent tree species.The growth rates of the four tree species were different，the organ biomasses of B.albo-sinensis and F.rufa had significant relation-ship with individual biomass，showing better growth rhythm.

The growth rhythm of each vegeta-tive organ The correlation among the proportion of each organ biomass can fully reflect the internal dynamic of treesin the growth process.The statistic of correlation coefficients of organ biomass percent allocation for different tree species was in Table 5.It can be seen that the proportion of trunk biomass of each tree species had significantly negative correlation with branch and leaf biomasses，while there was significantly positive corre-lation between branch biomass and leaf biomass，that was，when the pro-portion of trunk biomass increased，the proportions of branch and leaf biomasses would decrease obviously；when the proportion of branch biomass increased，the proportion of leaf biomass would increase.Other organs also had certain correlation，but the rule was not obvious.

From tree species，the proportion of each organ biomass of A.faxoniana had significant correlation，and the spatial distribution pattern of individual biomass was stronger；for Q.engleriana，B.albo-sinensis and F.rufa，ex-cept the significant correlations among trunk，branch and leaf，the interaction effect among other organ biomasses was not obvious.

Conclusions and Discus-sions

（1）Taking tree height（H），diame-ter at breast height（D）and the combi-nation（D2H）as independent variables，byestablishing and screening the model，45 biomass models of every organ and individual tree each for Q.engleriana，B.albo-sinensis，A.faxoniana and F.rufa were preliminarily established；by analyzing and compar-ing the precision and the complexity of the fitted equation，the biomass mod-els of each organ and individual tree of the four tree species were determined，and the model precision was totally higher.

（2）In the space allocation of indi-vidualbiomass ofthe four tree species，the trunk biomass was obvi-ously higher than other vegetative or-gans，which was the same as the re-search results of Fan Houbao et al.［7］and Lv Xiaotao et al.［8］.In the four tree species，the proportion of leaf biomass was the lowest，but the proportions of branch and root biomasses had cer-tain volatility；the order of the biomass proportions of different vegetative or-gans was different due to different tree species.From analyzing the propor-tion of each organ biomass，it can be seen that the proportion of each organ biomass of different tree species had certain differences；in the experiment，the selected tree species were in dif-ferent growth stages，this may have an impact on the order of the biomass proportions of different vegetative or-gans.For the same vegetative organ， the biomass proportions of different tree species also had greater differ-ences.

（3）In the comparison of correla-tivity between the proportions of biomasses of all nutrition organs and biomass of single plant，the relations were generally significant，the tree trunks were positively related while the roots were negatively related，the tree branches and leaves were positively or negatively related.Therefore，with the increase of the biomass of single plant，the proportion of tree trunk of four tree species would also increase while the proportion of tree root would decrease，the proportions ofbranches and leaves would be different with different tree species.The organ biomasses of B.albo-sinensis and F.rufa had signifi-cant relationship with the biomass of single plant，showing better growth rhythm.

（4）In the experiment，the propor-tion of trunk biomass of each tree species had significantly negative cor-relation with branch and leaf biomass-es，while there was significantly posi-tive correlation between branch biomass and leaf biomass，that was，when the proportion of trunk biomass increased，the proportions of branch and leaf biomasses would decrease obviously；when the proportion of branch biomass increased，the pro-portion of leaf biomass would in-crease.Other organs also had certain correlation，but the rule was not obvi-ous.From tree species，the proportion of each organ biomass of A.faxoniana had significant correlation，and the spatial distribution pattern of individual biomass was stronger；for Q.engleriana，B.albo-sinensis and F.rufa，ex-cept the significant correlations among trunk，branch and leaf，the interaction effect among other organ biomasses was not obvious.

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Responsible editor：Nanling WANG

Responsible proofreader：Xiaoyan WU

北川自然保护区植被恢复模式区4种主要树种生物量研究

冯永林1*，沈金亮1*，张建设1，邓东周2，邵文1，王刚1，孙志鹏1，苏春英1，王刚1**（1.四川农业大学，四川成都 611130；2.四川省林业科学研究院，四川成都610081）

以北川自然保护区植被恢复模式区巴东栎、红桦、岷江冷杉、青川箭竹为研究对象，对四种树种生物量模型、单株生物量分配规律以及各器官生长规律等进行研究。结果表明：在各树种生物量组成中，干生物量比例最大，叶最小，枝和根生物量比例因树种不同而有所差异；在各营养器官生物量比例与其单株生物量相关关系的比较中，整体上关系明显，树干为正相关，树根为负相关；树种干生物量比例与枝和叶生物量比例存在显著的负相关关系，而枝和叶生物量之间存在显著的正相关关系。

北川自然保护区；生物量；回归模型；分配比例

北川羌族自治县汶川地震灾后大熊猫等保护及栖息地恢复重建项目。

冯永林（1969-），男，四川邻水人，讲师，主要从事数学生态学研究；沈金亮（1974-），男，四川巴中人，硕士，主要从事数学生态学研究。*为同等贡献作者。**通讯作者，教授，博士生导师，主要从事数学生态学研究，E-mail：13908000519@qq.com。

2015-05-22

Supported by the Restoring&Reconstruction Project of Giant Panda Habitat after the Wenchuan Earthquake in Beichuan Qiang Minority Autonomous County.

*Co-first author.

**Corresponding author.E-mail：13908000519@qq.com

Received：May 22，2015 Accepted：September 24，2015

修回日期 2015-09-24