广西桉树人工林生态效益分析与评价

[目的]评价广西桉树人工林生态效益,筛选出能够促进桉树发展的主要技术指标。[方法]通过调查分析广西8个代表性地区的桉树人工林经营发展现状,采用文献查找借阅、实证研究、定量化研究与定性化研究相结合的方法,对广西桉树人工林发展进行生态效益评价。[结果]桉树人工林单项生态服务价值量从小到大依次为净化空气价值、水源涵养价值、固碳释氧价。生态健康价值=固碳释氧价值+水源涵养价值+净化空气价值。广西各地区桉树人工林生态健康价值平均为16.51万元/(hm2·a)。[结论]该研究可为更好地发展广西地区桉树人工林生态效益提供理论依据。     

不同坡位桉树人工林生长和土壤理化性质比较

[目的]了解不同立地条件下桉树人工林木生长和林地土壤肥力的差异。[方法]以2年生桉树人工林为研究对象,对不同坡位桉树林木生长和土壤物理性质、化学性质进行了分析比较。[结果]桉树人工林林下土壤普遍呈酸性,表层土壤酸性强于深层土壤;随着坡位的降低,林木生长状况和土壤理化性质逐渐好转,呈正相关趋势,同一坡位表层土壤肥力状况优于深层土壤。整体来看,造林地土壤肥力处于偏低水平,氮、磷缺乏严重。[结论]今后在营建桉树人工林时,优先选择山坡中、下部立地条件较好的造林地造林,对于山坡上部土壤养分较缺乏的地块,造林后应加大施肥量,适当补充微量元素,以保证林木的正常生长发育。     

基于森林资源调查的北京西山油松人工林生物量动态变化研究

基于森林资源调查数据分析西山林场油松人工林生物量多年动态变化情况,结果表明:2004-2014年,油松人工林以近熟林和成熟林为主,成熟林面积和生物量大幅增长,幼龄林、中龄林、近熟林面积和生物量明显减少,单位面积生物量及生产力最高的立地类型为低阴中松,单位面积生物量按大小排序:阔叶混交林>针阔混交林>针叶混交林>针叶纯林。     

滨海沙地3种人工林表层土壤微生物量及其影响因素

为探究福建东南沿海不同人工林砂质土壤微生物生物量碳(MBC)和生物量氮(MBN)及其影响因子,以肯氏相思(Acaica cunninghamia)、纹荚相思(Acacia aulacocarpa)和木麻黄(Casuarina equisetifolia)人工林为对象,采用通径分析模型,分析土壤微生物量对土壤理化性质、凋落物和细根生物量的响应。结果显示:3种人工林土壤MBC和MBN质量分数分别为42.60~51.56和5.38~6.88 mg·kg~(-1),且木麻黄的MBC和MBN质量分数均显著高于纹荚相思和肯氏相思(P0.05)。土壤w(MBC)∶w(MBN)为7.49~7.98;微生物碳熵(w(MBC)∶w(SOC))和氮熵(w(MBN)∶w(TN))的变化范围分别为1.09%~1.17%和1.34%~1.50%。Pearson相关分析表明,MBC、MBN质量分数与DOC、SOC、TN、凋落物生物量和细根生物量呈极显著正相关(P0.01)。通径分析表明,影响土壤MBC最重要的因子是细根生物量,其次是SOC;影响土壤MBN最重要的因素是细根生物量,其次是凋落物生物量。3种人工林的MBC和MBN质量分数、微生物碳氮熵与国内多数森林土壤相比均处于较低水平。     

黄河三角洲盐碱地人工林土壤肥力质量的综合评价

以黄河三角洲滨海盐碱地柽柳、杜梨、盐柳、白蜡人工林为研究对象,未造林荒地为对照,对不同人工林的土壤养分、土壤酶活性进行测定,利用隶属函数分析法对不同人工林的土壤肥力进行综合评价。结果表明:与对照荒地相比,各人工林平均土壤有机质、铵态氮、硝态氮、有效磷、速效钾质量分数,分别提高了177.89%、76.47%、757.74%、32.76%、30.13%;土壤中磷酸酶、过氧化氢酶、脲酶、蔗糖酶活性,比对照荒地分别提高了47.09%,11.52%,41.07%,76.00%;土壤肥力综合评价分值,从大到小依次为白蜡(0.777)、杜梨(0.694)、柽柳(0.572)、盐柳(0.436)、荒地(0.030)。     

广西南宁巨尾桉(DH32-28)植苗林调查因子关系模型研究

[目的]调查广西南宁巨尾桉(DH32-28)植苗林各调查因子间的关系。[方法]对在广西南宁树木园新塘和横县林区内生长正常的巨尾桉(DH32-28)植苗林进行调查,分别测定每株树的胸径、树高、年龄等树木调查因子,并对其相关性进行分析,建立胸径与造林时间、树高与造林时间、胸径与树高等因子之间的一系列数学模型,并进行模型的实用性和精度检验。[结果]胸径、树高与造林时间的对数函数关系比较密切,树高与胸径的二次函数模型关系比较密切。胸径与造林时间的关系可以用对数函数模型y=-3.310+4.132lnx来反映,树高与造林时间的关系可以用对数函数模型y=-15.881+8.816lnx来反映,胸径与树高的关系可以用二次函数模型y=0.635+0.822x+0.042x~2来反映。[结论]模型揭示了广西南宁巨尾桉(DH32-28)植苗林各调查因子之间的生长规律性,同时还可以用于桉树人工林林分生长预估中单株树木潜在的生长分析,对桉树人工林的可持续经营利用和森林生态系统恢复具有一定的指导意义。     

不同生境对蚂蚁功能群的影响* ——以云南省绿春县为例

为探究土地利用变化主导的生境变化对蚂蚁功能群的影响,采用陷阱法和Winkler袋法调查了云南省绿春县天然次生林(N)、桉树林(E)、紫胶林(L)、橡胶林(R)、紫胶-玉米混农林(M)、旱地(D)和农田(F)7种生境类型的蚂蚁群落。共采集蚂蚁37 891头,隶属于8亚科52属137种;依据竞争关系、生境要求、行为优势以及对环境压力和干扰的响应等4个生态学特性,将52属划分为7个功能群:优势臭蚁亚科(DD)、从属弓背蚁族(SC)、广义切叶蚁亚科(GM)、机会主义者(O)、隐蔽物种(C)、气候特化种(CS)和专业捕食者(SP)。不同功能群的物种丰富度排序为机会主义者(10属32种)气候特化种(15属29种)广义切叶蚁亚科(3属24种)隐蔽物种(14属21种)从属弓背蚁族(2属16种)专业捕食者(6属14种)优势臭蚁亚科(2属2种)。从属弓背蚁族、气候特化种、隐蔽物种3个功能群的蚂蚁多度在天然次生林、桉树林和紫胶林中所占比例较高,而优势臭蚁亚科功能群则在干扰多的农田中比例较高;除优势臭蚁亚科仅2属2种外,在天然次生林、桉树林、紫胶林和紫胶-玉米混农林中大多数功能群的蚂蚁物种丰富度明显高于农田,而专业捕食者功能群蚂蚁物种丰富度在不同生境中差异不大。桉树林和紫胶林蚂蚁功能群的群落结构与天然次生林较为接近,橡胶林、紫胶-玉米混农林和旱地蚂蚁功能群的群落结构相似。气候特化种、广义切叶蚁亚科、机会主义者和从属弓背蚁族在不同类型样地中的物种组成变化程度大于同一类型生境重复样地间的变化程度。广义切叶蚁亚科、机会主义者和从属弓背蚁族3个功能群的蚂蚁群落在不同生境中变化明显,整体上表现为桉树林、紫胶林和天然次生林的蚂蚁群落与旱地和农田不相似;隐蔽物种和气候特化种仅在桉树林和紫胶林蚂蚁群落较为相似;专业捕食者功能群蚂蚁群落在不同生境中的变化不明显。蚂蚁功能群能够指示生境变化,广义切叶蚁亚科、从属弓背蚁族和机会主义者的指示效果较好,实质上是不同功能群中不同物种的多度及功能群内的群落组成变化对生境变化导致的干扰及资源可利用程度的响应有差异。     

间伐强度对华北落叶松人工林植被物种多样性的影响

在北京市延庆县营盘村附近低山，对造林密度为5151株/hm2的23a生华北落叶松人工林，设置4个间伐强度处理。5a后，通过比较林下植被组成、外貌及多样性的变化，研究不同间伐强度对华北落叶松人工林群落稳定的影响。结果表明，间伐改变了群落的生活型谱，随间伐强度增大，地面芽植物和地下芽植物所占比重上升，而高位芽植物却呈相反的趋势。间伐强度不同，华北落叶松林下植被的建群种各异。间伐可提高林下植被的丰富度和多样性，这种效应以弱度间伐最为明显。间伐对草本层物种丰富度、多样性影响较灌木层大，而对林下植被分布均匀性影响甚微。因此，及时对郁闭林分进行合适强度的间伐，促进林下植被发育，是实现华北落叶松人工林可持续发展的有效途径。23a初植密度5151株/hm2的华北落叶松选择58.75%左右的间伐强度林下植被发育最优     

Relative contribution of initial root and shoot morphology in predicting field performance of hardwood seedlings

Single and multiple linear regression techniques were used to explain the capacity of initial seedling root volume (Rv) and first-order lateral roots (FOLR) relative to shoot height, diameter, and fresh mass to serve as important indicators of stock quality and predictors of first- and second-year height and diameter on an afforestation site in southern Indiana, USA. This was accomplished for northern red oak (Quercus rubra L.), white oak (Quercus alba L.), and black cherry (Prunus serotina Ehrh) seedlings graded into four Rv categories at establishment. Field survival was high (85–97%) for all species. Initial diameter, height, fresh mass, and Rv provided similar predictive ability of second-year field response for absolute height (R² = 0.59–0.77) and diameter (R² = 0.50–0.73) for both oak species. Initial seedling Rv was a better predictor of field response than FOLR for both oak species, though not for cherry. Multiple-variable models accounted for a greater proportion of the total variation in seedling field height and diameter than did single-variable equations. The high R² (up to 0.95) of regression models suggests field performance of these species can be reliably predicted and confirms the importance of initial seedling morphology in dictating early plantation performance.     

Multiscale spatial variation of the bark beetle Ips sexdentatus damage in a pine plantation forest (Landes de Gascogne,Southwestern France)

Bark beetles are notorious pests of natural and planted forests causing extensive damage. These insects depend on dead or weakened trees but can switch to healthy trees during an outbreak as mass-attacks allow the beetle to overwhelm tree defences. Climatic events like windstorms are known to favour bark beetle outbreaks because they create a large number of breeding sites, i.e., weakened trees and for this reason, windthrown timber is generally preventively harvested and removed. In December 1999, the southwest of France was struck by a devastating windstorm that felled more that 27 million m³of timber. This event offered the opportunity to study large-scale spatial pattern of trees attacked by the bark beetle Ips sexdentatus and its relationship with the spatial location of pine logs that were temporally stored in piles along stand edges during the post-storm process of fallen tree removal. The study was undertaken in a pure maritime pine forest of 1300 ha in 2001 and 2002. We developed a landscape approach based on a GIS and a complete inventory of attacked trees. During this study more than 70% of the investigated stands had at least one tree attacked by I. sexdentatus  . Spatial aggregation prevailed in stands with n≥15$n\ge 15$ attacked trees. Patches of attacked trees were identified using a kernel estimation procedure coupled with randomization tests. Attacked trees formed patches of 500–700 m² on average which displayed a clumped spatial distribution. Log piles stemming from the sanitation removals were mainly distributed along the large access roads and showed an aggregated spatial pattern as well. The spatial relationship between patches of attacked trees and log pile storage areas was analyzed by means of the Ripley’s statistic that revealed a strong association at the scale of the studied forest. Our results indicated that bark beetle attacks were facilitated in the vicinity of areas where pine logs were stored. The spatial extent of this relationship was >1000 m. Similar results were obtained in 2001 and 2002 despite differences in the number and spatial distribution of attacked trees. The presence of a strong “facilitation effect” suggests that log piles should be removed quickly in order to prevent outbreaks of bark beetles.