样木解析法及其在材积表编制中的应用研究

提出了一种材积表编制样本资料收集的新方法———样木解析法。即在标准地中采用随机或机械抽样方法选取样木,进行树干解析,获得样木生长过程;通过建立树皮系数与树皮率回归模型,将样木解析后的各龄阶去皮直径和去皮材积转化为带皮直径和带皮材积,一株样木可获得龄阶数个编表样本。经四川农业大学实习林场楠木一元材积表、二元材积表编制实践,有减少编表样本收集工作量、消耗林木少的优点,且能达到精度要求,同时,也为珍稀树种材积表编制样本资料收集提供了新的方法。     

Predicting equations of main factors affecting regional climate in the "Three-North" Protective Forest Area

lntroductionInordertosolvetheseriousecologicaIproblemwefacedandimprovethephenomenonoflanddesertifi-cationinthenorthareaofChina.ChinahasbeguntoconstructtheThree-NorthProtectiveForestSystemsince1978.Withthehardworkoftwentyyears,itistold"Thegreatestecologicalprojectoftheworld"and"ThegreengreatwaIl".AIthoughthecountryinvestedIotsofcapitaItobuiIdtheThree-Northshelter-forestsystemthroughmanywayssuchasThree-Northspecialinvestment,financeappropriatefunds,finan-cialloansandtakeoutfundsforbringup…     

蛭石与人造沸石氨氮等温吸附理论式与判别式

为比较在高起始氨氮浓度C0点和介质用量W0点上,吸附理论通式Qe=W0qmC0/[qmKw W0(qm-qe) C0]与其简化方程Qe=W0qmC0/[qm(Kw W0) C0]的适用性,测定了给定pH值和温度条件下反应平衡时NH4Cl溶液中蛭石和人造沸石的氨氮吸附量(Qe).在该试验条件下确定的蛭石单位介质吸附容量qm和介质系数Kw值分别为22 mg/g和15.5 g/L,人造沸石的qm和Kw的值分别为45 mg/g和8 g/L.在整个试验氨氮浓度C0和介质用量W0范围内,用该通式描述两介质刘氨氮的等温吸附过程具有很高的精确度.而简化方程仅在有限范围内即C0相对小或W0相对大时才适用.若给定预测相对误差(RD),则C0/qm(Kw W0)≤RD可作为简化方程应用的判别式.     

杉木人工林最佳削度方程的研究

以福建省顺昌县 10 0株杉木样木资料为基础 ,对现有国内外发表的几个较高精度的削度方程进行拟合与评价 ,分析结果表明 ,曾伟生 (1997)提出的削度方程是迄今为止效果最好的杉木削度方程。     

Allometric model of the height–diameter curve for even-aged pure stands of Japanese cedar (<Emphasis Type="Italic">Cryptomeria japonica</Emphasis>)

We derived an allometric model of the height–diameter curve for even-aged pure stands, which was a modification of the earlier model proposed by Inoue (2000a). An individual-dependent allometric equation was used as the height–diameter curve. Using the discriminant analysis method, all trees composed of a stand were stratified into upper and lower trees. It was assumed that both relationships between mean tree height H _m and upper tree height H _u and between mean DBH D _m and mean DBH of upper trees D _u could be described by the time-dependent allometric power equations. The height–diameter curve showed an average relationship between tree height and DBH of a given stand at a given time, and hence it could be assumed that the height–diameter curve contained two points (D _m , H _m ) and (D _u , H _u ). With these assumptions, we derived an allometirc model of height–diameter curve, which allowed the coefficients of the curve to be estimated from mean tree height and mean DBH. The proposed model was fitted to Japanese cedar (Cryptomeria japonica D. Don) data. The error ratio of the allometric model ranged from 2.254% to 13.412% (mean = 6.785%), which was significantly smaller than that of the earlier model. When the error of mean tree height was ±1.0 m or less, the effect of the error of mean tree height on the error ratio was comparatively small. This suggested that the error of ±1.0 m in mean tree height could be accepted in the estimation of height–diameter curve using the allometric model. These features enable us to combine the allometric model with Hirata’s vertical angle-count sampling or growth models. In conclusion, the allometric model would be one of the most practical and convenient approaches for estimating the height–diameter relationship of even-aged pure stands.     

黄山松人工林球果生物量的测定

采取平均木法实测不同立地条件的 10年生黄山松球果生物量 ,阐明黄山松球果生物量与立地条件以及测树因子之间的相互关系。 10年生黄山松山脊球果生物量最高平均每株 0 5 8kg ,而山坡最低为 0 4kg。应用树高和胸径分别推导出预测黄山松球果生物量的回归方程。     

印楝实生苗年生长规律研究

研究了1年生印楝实生苗生长动态、苗木生物量积累与分配模式以及苗木生长与气象因子的关系,结果表明:印楝苗的年生长规律符合Logistic曲线特征,据此方程可以建立苗高、地径与生长时间的拟合模型,结合二次多项式对苗木连日生长量的动态模拟,可将苗木生长划分为4个阶段:出苗期、生长初期、速生期和生长后期,其中处于速生阶段苗木的高和地径生长量均超过全年总量的70%,地径处于生长初期阶段的时间短于苗高,但生长量占全年总量之比是苗高的2倍;苗木生物量积累与苗高和地径的相关性极为密切,其中地上部分生物量占全株的69.1%,全株含水量是干质量的1.58倍;在制约苗木生长节律的气象因子中,偏相关分析表明:温度是苗木生长的主导因子.     

美洲黑杨新无性系苗期年生长规律研究

以5个黑杨派(P.deltoides)杨树无性系为材料,利用Logistic方程对各个无性系的1a生扦插苗木的苗高、地径的年生长节律进行拟合。根据因素数列的几何形状发展态势的接近程度,将苗木的生长量与影响苗木生长的气象因子空气温度、空气相对湿度、降水量和日照时数组成1个灰色系统,进行面积关联度分析。结果表明:利用Logistic方程拟合效果显著,相关系数皆在0.95以上。关联度分析表明降水量对苗木的高生长影响最大,日照时数影响最小;而日照时数对苗木的粗生长影响较大,降水量影响最小。     

Growth and nutrient accumulation of Brazil nut trees (Bertholletia excelsa) in agroforestry at different fertilizer levels

The Brazil nut tree(Bertholletia excelsa) is a frequent component of agroforestry systems in the Amazon because of its adaptation to nutrient-poor upland soils and multiple uses.We investigated the aboveground biomass production(kg dry weight),nutrient uptake and requirements(N,P,Ca,Mg,K) of Brazil nut trees of different sizes grown under agroforestry conditions and fertilized at different levels.Eight of 70 experimental trees with different size were harvested and stem,branches and leaves were separated.Nutrient contents were determined for three trees of varying size.Average tree growth was fast,but variability was high,suggesting considerable potential for the improvement of this economically important species.The trees responded to increased levels of fertilizer and lime with significantly increased foliar nutrient contents and growth,probably because of the improved availability of Mg and Ca for which the species seems to have a relatively high demand.In contrast to Brazil nut trees grown in forest or dense plantations,the agroforestry trees invested a substantial part of their biomass and nutrients in large branches and developed spreading crowns.To improve stem form,reduce competition with associated crops for light and recycle nutrients,regular pruning of lower branches or planting arrangements that favor self-pruning are recommended.These measures would also increase the recycling of Ca and Mg,large quantities of which are contained in the branches.     

周年轮作休耕模式对土壤球囊霉素和团聚体稳定性的影响

为探究周年轮作休耕模式对土壤球囊霉素和团聚体稳定性的影响规律与机制,通过田间试验设置苕子-玉米轮作、豌豆-玉米轮作、休闲-玉米和全年休闲4个处理,分析不同种植模式下团聚体、球囊霉素相关土壤蛋白(GRSP)及有机碳(SOC)的变化规律。结果表明:与休闲-玉米、苕子-玉米轮作、豌豆-玉米轮作相比,全年休闲能显著增加大团聚体(>0.25 mm)含量,提高团聚体稳定性;在不同团聚体粒级下,与休闲-玉米相比,苕子-玉米轮作、豌豆-玉米轮作和全年休闲均能有效增加GRSP和SOC的含量,且全年休闲效果更佳;结构方程模型的结果显示,GRSP对SOC和可溶性有机碳(DOC)有直接的正面影响,对团聚体稳定性有间接影响,各因子对平均质量直径的总效应由大到小依次为WSA_>0.25(>0.25 mm水稳性团聚体)>DOC>总GRSP>SOC>易提取GRSP;相关性分析表明,不同团聚体粒级下GRSP与SOC均呈线性正相关关系,但在不同粒级下的相关系数的大小有所差异。研究表明,合理的轮作休耕模式有助于恢复地力,改善耕地质量,减少水土流失。