Effect of different pre-sowing treatments on seed germination percentage and growth performance of Acacia auriculiformis

Seed morphology,germination and seedlings growth of Acacia auriculiformis were studied.The experiment was conducted in the nursery of Forestry and Wood Technology Discipline,Khulna University,Bangladesh.Matured seeds of the species were collected from healthy trees of road side plantation from different areas of Khulna District,Bangladesh and treated with five pre-sowing treatments（control,immersion in cold water,immersion in hot water,scarification with sand paper and immersion in concentrated H2SO4）.The average length,breadth and thickness were found to be（0.58±0.017） cm,（0.44±0.007） cm and（0.20±0.089） cm,respectively.Germination was conducted in polybags with a mixture of top soil,coconut husk,coarse sand,and fine sand in a ratio of 3：4：1：1.Results reveal that pre-sowing treatments influences the germination rates of seeds that significantly increase the percentage germination compared with those in control（43%） and cold water treatment（52%）.The highest germination success rate was found 83% in hot water treatment followed by 78% in scarification with sand paper,and 75% with immersion in H2SO4.Germination started from 7 to 12 days and completed between 28 and 35 days period in all treatments.ANOVA showed the significant difference（p0.05） among the treatments in seed germination,but no significant difference among treatment with regard to starting day,closing day and total germination period.In case of height and diameter growth,seedlings originated from the seeds with hot water treatment shows significantly higher in wet season（from May to July）.Hot water treatment can be recommended on seed germination of the species in rural Bangladesh.

Competition-density effect of tree organs in Acacia auriculiformis stands

The competition-density (C-D) effects for mean mass for tree, stem, branch and leaf were analyzed in Acacia auriculiformis stands. Mean tree mass-density and mean organ mass-density were well explained by the C-D equation of tree and the C-D equation of tree organ, respectively. An equation describing the relationship between mean leaf area u and density was formulated that fit the u-data well. The relationship between mean tree mass w and the ratio of each organ to mean tree mass (wo/ w) was examined. With increasing w, the stem mass ratio wS/w increased, whereas the branch mass ratio wB/w and the leaf mass ratio wL/w decreased. The yield difference between the lowest-density stand and the high-density stand became greater with stand growth. However, the yield of the mid-density stand was slightly lower than the yield of the high-density stand during the experimental period. To produce the most desirable combination of demanding individual-tree size and relative high stem yield, the mid-density is recommended as proper planting density for future management of A. auriculiformis stands.

A comprehensive review on phytopharmacological investigations of Acacia auriculiformis A.Cunn. ex Benth

Acacia auriculiformis A.Cunn. ex Benth. is a perennial shrub having a wide range of medicinal potentials and is widely distributed throughout the world. It is being used traditionally to overcome various medical complications like sore eyes, aches, rheumatism, allergy, itching, and rashes. Besides, Acacia auriculiformis has been proven for many pharmacological activities like central nervous system depressant activity, antioxidant, antimicrobial, antimalarial, anti-filarial, cestocidal, antimutagenic, chemopreventive, spermicidal, wound healing, hepatoprotective and antidiabetic activity due to its low toxicity(LD50 = 3 741.7 mg/kg) and high efficacy. In addition, various phytochemical investigations reveal the presence of chief constituents as flavonoids(Auriculoside) and triterpenoid saponin glycosides(acaciasides-acaciaside A & B) in different parts of this plant. Since many years researchers have been carrying out various studies on this medicinal important shrub to elicit the various biological activities. This review attempts to highlight the pharmacognostical, phytochemical and pharmacological observations from 1965 to 2018 retrieved from SciF inder, Scientific journals, books, Google Scholar, and botanical electronic database websites. The various plant extracts evaluated for different pharmacological activities showed significant efficacy. Bioactive phytoconstituents isolated from various parts of the plant are highlighted. Pharmacognostical standardization of the plant done with various standard parameters is also reported. The low toxicity of this plant and the presence of major bioactive phytoconstituents like flavonoids and triterpenoid saponin glycosides are responsible for a therapeutic remedy for various diseases and pharmacological activities respectively. This review provides exhaustive information about the pharmacognostical, phytochemical, and pharmacological investigations of Acacia auriculiformis till date.

Role of phenolics as antioxidants,biomolecule protectors and as anti-diabetic factors-Evaluation on bark and empty pods of Acacia auriculiformis

Objective:To search for an efficient and inexpensive source of phytoconstituents with antioxidant potential and health promoting traits from bark and empty pods of Acacia auriculiformis （A.auriculiformis）.Methods:Samples of bark and empty pod extracts were analyzed for bioactives（phenolics,flavonoids and proanthocyanidins） and subjected to free radical scavenging activity on DPPH*,ABTS?,OH?,O2*,and NO along with the determination of reducing power, iron chelating activity and peroxidation inhibition.Defensive action of extracts on biomolecules and cell membranes were evaluated by DNA nicking assay and haemolysis inhibition assay respectively,α-amylase andα-glucosidase inhibitory potentials were also determined. Results:All the bioactives analyzed were higher in bark（B） than empty pods（EP）[TPC:B （574.51±16.11）;EP（96.80±3.45） mg GAE/g.TFC:B（94.71±7.65）;EP（24（?）87±20.45） mg RE/g. Proanthocyanidins:B（2.81±0.31）;EP（1.25±0.01） mg LE/100 g DM]except flavonoids.Both the extracts showed higher quenching capacity on DPPH and ABTS（DPPH:B（0.21±0.01）;EP（1.51±0.17） g extract/g DPPH.ABTS:B（111 519.14±79 340.91）;EP（80 232.55±32 894.12） mmol TE/g） with the FRAP of B（84 515.63±3 350.69） and EP（47 940.79±1 257.60） mmol Fe（（?））/g.Iron chelation was not observed.In addition,they showed lower quenching activity on OH?（B（48.95±1.72）;EP（34.94±1.62）%） and equivalent quenching on O2?（B（53.47±3.92）;EP（24.41±2.61）%）,NO（B（49.04±5.04）; EP（51.00±5.13）%）,peroxidation inhibition（B（67.50±5.50）;EP（55.l±2.3）%） and antihaemolytic potential（B（87.60±6.84）%） towards authentic antioxidant standards.Interestingly,Empty pod extracts are devoid of antihaemolytic activity.Both the extracts showed dose dependent DNA protection.Besides this,bark and empty pod extracts exhibited dual inhibiting potential againstα-amylase andα-glucosidase enzymes.Conclusions:On summarization,it insinuated that both bark and empty pods can be used for the preparation of antioxidant/nutraceutical supplements and in anti-diabetic formulations.

Survival of Seedlings of Native Woody Species in the Rehabilitation of Gold Mined-Site within a Three Years Old Acacia mangium Willd Plantation of St. Elizabeth-Mahdia, Guyana

Active restoration is a critical component of biodiversity conservation for degraded tropical forest ecosystems caused by artisanal gold mining, and the success of restoration is dependent on native species selection. However, significant knowledge gaps exist regarding when and where to plant trees. This article reports on a revegetation trial undertaken in St Elizabeth, Mahdia, Guyana, to assess the survival and RGR (Relative Growth Rate) of three native woody trees and shrubs planted within three years old Acacia mangium Willd trees pruned and unpruned blocks. ANOVA (Analysis of Variance) for a completely randomized block design with four blocks, two pruned and two unpruned, within A. mangium plots. Biochar treatment was added to the plants during transplanting. Thirty-six (36) wildlings of Humiria balsamifera (Aublet.) (Tauroniro), Goupia glabra Aublet (Kabukalli), and Vismia guianensis (Aublet.) Choisy (Bloodwood) were collected and raised in a tree nursery for two weeks. The native plants were transplanted 3 m apart, survival observations and each seedling’s initial height and diameter were measured and recorded. After the experiment, 13% of seedlings from a population of 720 had died, with the highest mortality being experienced at the 92 days of the experiment (t ≤ 122 days). While the overall survival rates were high, emphasizing the importance of field trials on native and exotic species in different environments is essential to fill the knowledge gaps on suitable species for restoration in degraded areas with other land use histories.

马占相思 (Acacia mangium)与湿地松 (Pinus elliotii)人工林枯落物层的水文生态功能

分析了马占相思与湿地松人工林枯落物的蓄积量、年凋落量及凋落动态、枯落物层对大气降水的截留、以及枯落物抑制土壤水分蒸发和阻滞径流的效应。结果表明 :1 1 5龄的马占相思林枯落物蓄积量 32 .3t/hm2 ,年凋落量 1 1 .1 4 t/hm2 ,最大持水率 2 53.7% ,最大持水量 2 8.2 6t/hm2 ;1 5龄的湿地松林枯落物蓄积量 1 8.7t/hm2 ,年凋落量 7.30 t/hm2 ,最大持水率 2 1 6.7% ,最大持水量 1 5.82 hm2 ;2 2种林分对大气降水的截留率分别为 1 5.9%和 1 1 .7% ,截留率随 1次降水降水量 ( >1 0 mm)的增加而减少 ;3 2～ 4 cm枯落物覆盖下不同含水量的土壤水分蒸发比无覆盖的土壤减少 1 8.2 %～ 78.3% ,枯落物层减少土壤水分蒸发的效应随枯落物层厚度和土壤含水量的增大而增加 ;4 2种枯落物对径流流出时间的阻滞效应随径流深 ( <3mm)和坡度的增加而减小 ,随枯落物层厚度的增加呈直线增加。通过与部分其它森林类型枯落物层水文生态功能比较 。

不同年龄阶段马占相思(Acacia mangium)人工林营养元素的生物循环

对马占相思人工林6种营养元素(N、P、K、Ca、Mg、S)的含量、积累、分布和生物循环特点以及随林分年龄的变化趋势进行了研究。结果表明:(1)林木不同组分营养元素含量的大小次序为树叶>干皮>活枝>枯枝或树根>干材;各组分和凋落物中营养元素含量以N最高,其次是Ca或K,然后是S和Mg,P最低;林地土壤中,以K的含量最高,其次是Ca、Mg、N和P,S最低;随林龄的增加,0～40cm土壤N、P和S含量呈增加趋势;(2)4年、7年生和11年生林分营养元素总积累量分别为1022.08、1997.08和2633.45kg.hm-2,其中乔木层营养元素贮存量依次占73.64%、82.39%和83.65%,林下植被层依次占13.74%、8.74%和6.20%,地表现存凋落物层依次占12.62%、8.87%和10.16%;乔木层以N积累量最大,占总贮存量的53.90%～60.07%,P最小,仅占0.90%～1.23%;(3)马占相思林中不同组分营养元素积累量的分配随林龄的增长发生变化,由4年生以树叶和树枝占主导,逐渐转移到7年生和11年生以干材和树皮为主导;(4)林分营养元素年积累量依次为7年生(235.06kg.hm-.2a-1)>11年生(200.26kg.hm-.2a-1)>4年生(188.16kg.hm-.2a-1);林木各组分营养元素年积累量总的变化趋势为:树干>树叶>树枝>根系>树皮,同一组分各营养元素年积累量与各组分营养元素积累量变化顺序一致,即为N>Ca>K>S>M>P;(5)林分营养元素年吸收量分别为382.35、432.04kg.hm-.2a-1和403.15kg.hm-2.a-1,年归还量分别为194.19、196.98kg.hm-.2a-1和202.89kg.hm-.2a-1,营养元素的循环系数分别为0.51、0.46和0.50,利用系数为0.51、0.26和0.18,周转期为3.88、8.35和10.86。可见,马占相思人工林早期营养元素利用率低,归还速率较快,林分生长到近熟期(11a)时营养元素的周转期较长,但其归还速率仍然较快,有利于林地地力的恢复、维持和提高。

基于树干液流测定值的马占相思(Acacia mangium)冠层气孔导度计算及数值模拟

为深入揭示华南地区马占相思冠层气孔导度对环境因子的响应规律,在2005年7月至11月,利用Granier热消散式探针法对马占相思(Acacia mangium)的树干液流(sapflow)进行了连续测定,计算出整树的蒸腾,并由Penman-Monteith方程得出马占相思的冠层气孔导度值。通过分析,发现:马占相思冠层气孔导度是控制马占相思树整树蒸腾的主要因素;冠层气孔导度随着水汽压亏缺增加呈负指数函数下降的趋势。使用包括了太阳总辐射、水汽压亏缺和气温的Jarvis模型可以较好地模拟马占相思冠层气孔导度对环境因子的响应特征;模拟结果表明:环境变量对模型精确度的影响程度依次为:水汽压亏缺>太阳总辐射>气温。

马占相思(Acacia mangium)树干液流密度和整树蒸腾的个体差异

利用Granier热消散探针观测了华南丘陵地区马占相思人工林（18a树龄）的树干液流（Sap Flow）。日变化的观测结果显示，不同大小胸径的14株样树液流密度（山）个体间的差别较大（CV：36．42％-80．80％），日间最大液流密度从最高的80．05（gH2Om^-2s^-1）到最低的11．25（gH2Om^-2s^-1），差异显著。液流密度的个体差异与树形的大小并不显著相关（P〉0．24），即液流密度的大小不是与树木形态相关联的固有特征。然而，树木胸径的大小却是影响液流随时间变化的重要因子。树形较大的树木日总液流量（E1，kgH2Otree^-1d^-1）较高，但中等大小的树木却具有较高的单位基面积日液流量（E2，kgH2Odm^-2d^-1），发现，单位基面积的日流量最大值并不出现在胸径最大的树木，而出现在胸径稍小的树木，意味着后者对自身结构的水分利用效率较高。由液流密度计算的整树蒸腾，个体间差异也比较大（3．35—72．42kgH2Otree^-1d^-1），且与胸径以幂函数的形式呈现正相关（P〈0．001）。尽管整树蒸腾在个体之间的差别较大，但随时间的变化规律却是一致的，整树蒸腾的变化格型基本上受环境因子的控制。以液流反映马占相思的蒸腾与冠层的实际蒸腾存在明显的时滞，14株样树的液流变化比光合有效辐射滞后40,in至110,in，相关分析显示，时滞的长短与树木的胸径、高度、边材面积和冠幅均不呈现明显的相关性（P〉0.36）。

马占相思(Acacia mangium)的生长、固氮及叶状柄的营养成分

马占相思（Ａｃａｃｉａ ｍａｎｇｉｕｍ）在厦门地区生长良好，生长速度和地上部生物量均大于肯氏相思 （Ａ．ｃｕｎｎｉｎｇｈａｍｉａ）和大叶相思（Ａ．ａｕｒｉｃｕｌａｅｆｏｒｍｉｓ）。４年生的马占相思和大叶相思人工林年凋落物的 干重分别为 １１ ５０ ｇ ｍ~－２和 ６６８ ｇ ｍ~－２。马占相思和肯氏相思根瘤的固氮酶活性均有明显的季节变 化，８月份＞１０月份＞５月份＞２月份。马占相思叶状柄营养丰富，含有较高的蛋白质和氨基酸，特 别是必需氨基酸苏氨酸、缬氨酸、苯丙氨酸、酪氨酸、异亮氨酸等，而且还含有尿囊素。马占相思 不仅可作为纸浆材、胶合板材、建筑和家具用材，以及水土保持林，而且是饲料、食用菌培养基和提 取尿囊素的资源，有广阔的开发利用前景。

不同径级马占相思(Acacia mangium)整树蒸腾的湿、干季变化

利用Granier树干液流测定系统对广东鹤山丘陵地马占相思（Acacia mangium）林进行长期监测,并同步监测环境因子（空气温度、相对湿度、光合有效辐射、土壤体积含水量）,选择胸径具有代表性的样树,结合马占相思的形态学参数,计算马占相思的整树蒸腾。通过对光合有效辐射（PAR）分级,建立不同辐射强度等级的湿季（土壤水分θ≥33%）整树蒸腾与水汽压亏缺（VPD）的相关方程,以干季（θ≤24%）的VPD代入对应PAR等级的湿季的拟合方程,求出干季的潜在蒸腾,以潜在蒸腾和干季实际蒸腾之差分析不同径级整树蒸腾在不同季节的实际变化。在所有的PAR分级内,干季整树蒸腾显著低于湿季,仅占湿季蒸腾的10%-20%,就蒸腾减少的绝对量而言,优势木〉中间木〉劣势木。土壤水分下降缩小了不同径级树木之间液流密度的差异,土壤水分亏缺限制了树木的蒸腾,对马占相思的生长造成一定程度的水分胁迫。

桉树林和马占相思林的林下植物多样性及其与环境因子的关系

2021年因海南热带雨林国家公园的建立,园内部分人工林停止经营并进入次生自然演替状态,使其林下植物较往年更为丰富,亟待研究.通过研究该区域林下植物组成、性状构成以及植物群落特征与环境因子的关系,在马占相思林设置了60个10 m×10 m的样方,桉树林设置了53个10 m×10 m的样方,详细记录了林下植物的信息,同时采用典范分析分析了桉树林与马占相思林林下植物群落的分布格局及其与环境因子的关系.主要结果如下:(1)马占相思林下维管束植物共计109科312属530种,桉树林林下维管束植物共计96科302属445种;(2)通过对研究区域的植物群落与环境因子进行典范分析(CCA),解释率达58%,能够较好地反映林下植物群落与环境因子的关系,其中年降水量、年平均气温、海拔、平均气温日较差、郁闭度对林下植物群落的影响显著(P<0.05);(3)林下植物多样性受多种环境因素相互作用的影响,海拔和郁闭度是影响热带雨林人工林林下植物群落特征最显著的生境因子,雨林的高湿高温环境对林下植物多样性有负面影响.这一研究结果深化了对马占相思和桉树林林下植物群落的了解,同时为该区域生态系统功能和生物多样性保护提供了科学基础.

不同改造模式下马占相思林凋落物和土壤水文效应分析

为研究不同间伐强度和乡土阔叶树种套种对华南地区马占相思Acacia mangium人工林(林龄25年)地表凋落物和土壤水源涵养的影响,以东莞市大岭山森林公园内东莞市林业科学园的马占相思人工林为研究对象,设置3种间伐强度:0、30%、60%,编号为A、B、D,间伐后以相同措施均匀套种49种乡土阔叶树种,以不间伐、不套种的马占相思纯林为对照(编号C)。改造15年后,采用典型样地调查法,在各样地设立12个凋落物收集器,采集凋落物;采用环刀法采集表层土壤(0~20 cm)。用浸水法和烘干法研究凋落物、土壤的持水能力。不同改造模式下马占相思人工林凋落物生物量、最大持水量、最大拦蓄量、有效拦蓄量变化范围分别为0.72~1.18 t·hm^(-2)、17.70~28.64 t·hm^(-2)、136.46~234.37 t·hm^(-2)、113.32~195.37 t·hm^(-2),均呈现A>B>D>C,且不同改造模式差异显著(P<0.01)。通过回归拟合发现,累积持水量与浸水时间呈显著的三次关系,吸水速率与浸水时间呈显著的倒数关系;累积失水量与失水时间呈显著的三次关系,失水速率与失水时间呈显著的倒数关系。不同改造模式下的土壤毛管孔隙度变化范围为19.63%~26.85%;非毛管孔隙度变化范围为13.94%~19.6%;总空隙度的变化范围为38.27%~43.84%;土壤容重变化范围为1~1.09。研究还发现,土壤总孔隙度和毛管孔隙度越高,土壤保水能力越好。该研究结果表明:不同间伐强度和乡土阔叶树种套种对凋落物和土壤的水文效应的影响较为显著。从林分质量和森林经营可持续发展的角度考虑,间伐与套种相结合的模式在增加生物多样性、促进森林更新与演替、提高枯落物和土壤水源涵养功能等方面更具优势。

马占相思优势木择伐对林下灌木多样性的影响

【目的】择伐是促进林下灌木生长与更新的有效手段,分析马占相思优势木择伐对林下灌木多样性影响效果与范围,构建影响范围预估模型,对制定科学合理的马占相思林择伐技术具有重要指导意义。【方法】以海南省南崖林场76株马占相思优势木为研究对象,开展优势木择伐试验(监测年限为2014—2021年)。通过设置不同样圆大小(0.6倍冠幅、0.8倍冠幅、1.0倍冠幅、1.2倍冠幅、1.4倍冠幅)的优势木影响半径,比较与确定马占相思优势木的最大影响范围,分析不同恢复年限对林下灌木多样性的影响,构建马占相思优势木的影响范围预估模型。【结果】马占相思优势木影响灌木Shannon指数和Pielou指数的最大影响范围分别为1.0倍实测冠幅和1.2倍实测冠幅;马占相思优势木择伐能显著提高林下灌木多样性(P<0.05),通常灌木Shannon指数和Pielou指数在择伐后的5年内显著增加(P<0.05),5年以后的增幅不明显(P>0.05);影响灌木Shannon指数和Pielou指数的范围预估模型均以理查德式为最优,其决定系数均为0.702,相对均方根误差均为14.341%。【结论】从单木影响范围的角度分析马占相思优势木择伐对林下灌木多样性的影响,优势木择伐在一定范围和一定年限内可以显著改善林下灌木多样性,且最大影响范围与马占相思优势木的胸径大小密切相关。研究结论可以为后续马占相思林的密度控制以及林分改造提供有效指导。

琼西北3种林分类型枯落物与土壤的持水能力

为探讨琼西北典型水土流失区蚂蝗岭流域不同林分类型枯落物和土壤水文效应,采用浸泡法、环刀法对桉树人工林、橡胶树人工林、马占相思人工林3种不同林分类型枯落物和土壤水文功能进行定量分析,采用熵权法(EWM)综合评价水源涵养能力。结果表明:3种林分类型枯落物储量为3.01~14.66 t·hm^(-2),表现出马占相思人工林>橡胶树人工林>桉树人工林,均以半分解层为主,占比为75.09%~81.86%;最大持水量为8.60~33.95 t·hm^(-2),有效拦蓄量为6.92~26.73 t·hm^(-2),均为马占相思人工林>桉树人工林>橡胶树人工林。枯落物持水量与浸泡时间呈对数函数关系(R^(2)>0.940);枯落物吸水速率与浸泡时间呈幂函数关系(R^(2)>0.880)。3种林分类型土壤容重为1.45~1.52 g·cm^(-3),总孔隙度为32.82%~37.56%,有效持水量为61.80~77.16 t·hm^(-2),土壤持水能力排序为马占相思人工林>桉树人工林>橡胶树人工林。土壤初渗速率为24.74~29.67 mm·min^(-1),其中,马占相思人工林最高;土壤稳渗速率为1.01~1.38 mm·min^(-1),土壤入渗速率与入渗时间呈幂函数关系(R^(2)>0.920)。3种林分类型水源涵养能力综合排序为马占相思人工林(81.0987)>桉树人工林(69.7416)>橡胶树人工林(67.1514),土壤入渗性能和枯落物储量是影响该区域水源涵养能力的主导因素。综合3种林分类型枯落物及土壤持水能力,马占相思人工林的水源涵养能力较强,建议在对桉树人工林及橡胶树人工林更新时可种植马占相思,以提高其保持水土、涵养水源的功能。

尾叶桉人工林和固氮树种马占相思人工林碳储量差异特征

以广东省阳江市国有花滩林场的尾叶桉(Eucalyptus urophylla)和固氮树种马占相思(Acacia mangium)人工林为研究对象,探究2种人工林的乔木层和土壤层的碳储量差异,为提升粤西地区人工林碳汇能力提供数据参考。结果表明:(1)尾叶桉和马占相思不同器官碳含量大小为树干>树根>树枝>树叶,且尾叶桉树干的碳含量及其占植株总碳含量的比例均显著高于马占相思(P<0.05),而马占相思的树根、树枝和树叶的碳含量均显著高于尾叶桉(P<0.05);(2)2种林分土壤的碳含量和碳储量均随着土层的加深而显著降低,0~40 cm土层碳储量占1 m深土层碳储量的比例分别达56.59%、53.35%,表明2种人工林土壤碳主要分布在上层;(3)尾叶桉人工林乔木层的碳储量及其占人工林碳储量的比例均显著高于马占相思(P<0.05);相反,马占相思人工林土壤碳储量比尾叶桉高13.92%,且马占相思林的土壤碳储量占人工林碳储量的比例显著高于尾叶桉(P<0.05),说明马占相思人工林将较高比例的碳分配在土壤中。本研究结果表明,利用固氮树种进行人工造林对提升土壤碳汇能力具有较大的潜力。

3种热带相思树种木材物理力学及纤维特征研究

相思树种在我国热带及南亚热带地区生长迅速,适应性强,人工林种植发展甚为迅速。了解相思树种的木材物理力学及纤维性能,可为相思树种的定向培育及其木材高质量加工利用提供理论指导。本研究分别以5年和8年生马占相思Acacia mangium、大叶相思A.auriculiformis、厚荚相思A.crassicarpa木材为对象,按照国家标准对其物理力学指标(密度、干缩特性、硬度、顺纹抗压强度和抗弯强度)和纤维性状(木纤维长度、宽度、腔径和双壁厚)进行系统测试和分析。结果表明:3种相思的木材基本密度达0.37~0.56 g/cm^(3),体积干缩率仅7.83%~8.91%,木材硬度、顺纹压力、抗弯强度分别为3.90~6.85 KN、41.82~52.56 MPa、83.53~l07.30 MPa,其木材变形性远小于尾叶桉Eucalyptus urophyllus、巨桉E.grandis等树种;纤维长度在1066.71~1326.90μm,是优良的阔叶材造纸原料。厚荚相思和大叶相思的木材基本密度和木材物理力学性明显高于马占相思。纤维形态上厚荚相思较细长,马占相思较宽大,大叶相思相对较短。综合不同年份的隶属函数分析,厚荚相思综合性能最佳。

Stand Structure,Allometric Equations,Biomass and Carbon Sequestration Capacity of Acacia mangium Wild.(Mimosaceae)in Cote d’Ivoire

In addition to bioenergy production, Acacia magium, a fast growing species, plays a major role in climate change mitigation through carbon sequestration from the atmosphere. The objective of this study was to improve estimates of aboveground biomass of 3, 7 and 11 years old stands of Acacia mangium set up through natural regeneration at Anguédédou in C?te d’Ivoire. Tree measurements were done in circular plots of 615 m2 located at the center of each stand. 24 trees of circumference at breast height (cbh) between 31 and 116 cm were felled, weighed and measured. Multiple linear regressions were used to develop allometric equations linking aboveground biomass of trees to cbh and/or height. The carbon stock and sequestration capacity of each stand was assessed using these predictive models. The average cbh was 39.4 cm, 73.5 cm and 91.4 cm respectively for 3, 7 and 11 years old stands with a density ranging between 845 trees·ha-1 and 553 trees·ha-1. The allometric equations for biomass estimation were Btotal aboveground = exp(-3.455 + 2.081 × ln(C)), Btrunk = exp (-5.153 + 1.681 × ln(C) + 1.056 × ln(H)), Bbranches = exp(-2.005 + 0.498 × ln(C2 × H)), Bleaves = exp(-2.415 + 1.339 × ln(C)). Total height had no influence on total and leaf biomass but increased precision of trunk and branch biomass. The carbon sequestration capacity of aboveground biomass was highest in Acacia mangium stand of 7 years old with 45.14 teqCO2·ha-1·year-1 and lowest in the 3-year stand with 33.90 teqCO2·ha-1·year-1.

杂交相思、巨尾桉及其混交林水源涵养能力比较

[目的]比较了杂交相思、巨尾桉及其混交林枯落物层和土壤层的水源涵养能力,为调整树种结构提供依据。[方法]对杂交相思纯林、巨尾桉纯林及其混交林(1杂交相思×1巨尾桉、2杂交相思×2巨尾桉)进行枯落物层与土壤层水文功能定量分析,并采用坐标综合评定法对水文效应相关因子进行综合评价。[结果](1)杂交相思纯林枯落物蓄积量最大,显著大于巨尾桉纯林;除巨尾桉纯林外,其他3种林分半分解层枯落物蓄积量大于未分解层。杂交相思纯林枯落物持蓄水能力最好,显著大于巨尾桉纯林。(2)0~20 cm土层,杂交相思纯林土壤容重显著低于其他3种林分;20~80 cm土层,1杂交相思×1巨尾桉土壤容重显著高于其他林分;土壤容重随着土层加深而加大。杂交相思纯林、巨尾桉纯林总孔隙度、毛管孔隙度分别在0~20 cm、20~40 cm土层最大,均显著大于1杂交相思×1巨尾桉;40~80 cm土层,2杂交相思×2巨尾桉的总孔隙度、毛管孔隙度、非毛管孔隙度最大,总孔隙度、毛管孔隙度显著大于1杂交相思×1巨尾桉和杂交相思纯林;土壤孔隙度随着土层加深呈不同的曲线变化。0~20 cm土层,杂交相思纯林持蓄水能力显著大于其他林分;20~40 cm土层,杂交相思纯林自然含水率最大且显著大于1杂交相思×1巨尾桉、巨尾桉纯林,2杂交相思×2巨尾桉的最大持水量、毛管持水量、有效持水量最大且显著大于1杂交相思×1巨尾桉;40~80 cm土层,2杂交相思×2巨尾桉的持蓄水能力最大,1杂交相思×1巨尾桉最小。随着土层加深,1杂交相思×1巨尾桉和杂交相思纯林的自然含水率为先降低后增加,2杂交相思×2巨尾桉和巨尾桉纯林的自然含水率为先增加后降低,1杂交相思×1巨尾桉、杂交相思纯林、巨尾桉纯林的最大持水量、毛管持水量、有效持水量逐渐减小,2杂交相思×2巨尾桉的最大持水量、毛管持水量、有效持水量呈曲线变化。(3)坐标综合评定法结果表明,4种林分的水源涵养能力高低依次为:杂交相思纯林>2杂交相思×2巨尾桉>1杂交相思×1巨尾桉>巨尾桉纯林。[结论]杂交相思纯林水源涵养能力整体优于其他3种林分,杂交相思与巨尾桉混交林优于巨尾桉纯林。杂交相思可以作为桉树轮作或混交造林的树种。