乌江峡谷瘠薄地造林整地试验研究

通过在乌江峡谷瘠薄地立地条件相似的两个试验点上进行的造林整地试验，对供试树种造林成活率及生长情况的调查分析表明：乌江峡谷瘠薄地造林整地以鱼鳞坑整地方式为首选。刺桐、柏木、黄花槐在乌江峡谷瘠薄地造林效果较好。     

影响I—69杨造林成活因素的调查分析

杨树是徐滩平原地区重要的速生用材树种，特别是I－69杨，它生长迅速，适应性广，抗逆性强，是目前徐滩地区造林的主栽树种，深受广大农民喜爱。但由于该地区冬、春季较早，加之I－69标本身成活较难，故自推广以来，造林成活率低一直是困扰该地区林业发展的一个突出问题。为探讨影响I－69杨造林成活率的主要因素．对徐州市所属7个县（市、区）近年栽植的I－69杨成活情况连续两年进行了调查，现将调查结果总结分析如下：1调查时间、内容和方法调查时间为1992年5月下旬和1993年5月上旬。调查采用临时样地的方法，记载各样地的栽植成活率．栽…     

元宝枫旱区造林研究

简要介绍了元宝枫的造林措施和方法，调查了干旱区４个立地条件下的元宝枫造林情况，结果表明，元宝枫的造要成活率高于一般树种，且生长良好。     

元宝枫旱区造林研究

简要介绍了元宝枫的造林措施和方法，调查了干旱区４个立地条件下的元宝枫造林情况，结果表明，元宝枫的造要成活率高于一般树种，且生长良好。     

3个树种在海岛困难立地造林试验

通过完全随机试验,调查并分析了9种处理方法对普陀樟(Cinnamomum japonicum var.chenii)、木荷(Schima superba)、湿地松(Pinus elliottii)3个树种造林成活率、高生长及地径生长等指标的影响,结果表明:不同处理对3个树种造林成活率的影响差异较为显著,而对同一树种成活率的影响差异不显著;不同处理对不同树种高生长量和地径生长量之间差异极显著;选择高生长、地径生长、成活率及造林成本4个指标,利用隶属函数法对普陀樟、木荷、湿地松3个树种在9种处理条件下的造林效益进行综合评价,结果表明对于3个树种施肥100 g、保水剂15 g处理条件下造林综合效益最高。     

困难立地条件下梭梭苗木造林效果研究

通过实地样方调查,对民勤不同困难立地条件人工栽植梭梭成活率进行了调查,以研究困难立地梭梭苗木的适应性。结果表明:不同立地条件下苗木生长状况差异显著,8月不同立地梭梭成活率依次为砾石戈壁(样地类型Ⅲ)沙漠(样地类型Ⅳ)低山丘陵(样地类型Ⅱ)盐碱沙滩地(样地类型Ⅰ)。各立地类型区,6月和8月苗木成活率差异显著,沙漠区(样地类型Ⅳ)6月成活率85%,8月成活率50%,两者相差35个百分点;砾石戈壁(样地类型Ⅲ)6月成活率80%,8月成活率60%,两者相差20个百分点;盐碱沙滩地区(样地类型Ⅰ)6月成活率50%,8月成活率10%,两者相差40个百分点。     

不同立地条件对木麻黄成活率及生长量的影响

以木麻黄在不同立地条件下造林为研究对象,利用样地调查法对同一造林技术措施在沙岸地、泥岸地、岩岸地木麻黄造林成活率和生长情况进行比较分析,结果表明:沙岸地营造木麻黄成活率85%~90%;泥岸地营造木麻黄成活率80%~83%;岩岸地营造木麻黄成活率60%~70%。沙岸地木麻黄比泥岸地木麻黄生长快,长势好;泥岸地木麻黄比岩岸地木麻黄生长快,长势好。     

元宝枫旱地造林调查

简要介绍了元宝枫的造林措施和方法。调查了干旱区４个立地条件下的元宝枫生长情况，结果表明在阴向梯地生长最好，在阳向梁坡灌丛地生长最差。不同苗龄造林成活率试验结果以１年生最高。     

燕山山地造林树种筛选试验初报

针对冀北山地造林树种短缺的问题,选择黄檗(Phellodendron amurense)、华山松(Pinus armandii)、毛棶(Cornus walteri)、花楸(Sorbus pohuashanensis)、胡桃楸(Juglans mandshurica)、黄栌(Cotinus coggygria)6个树种进行造林试验,结果表明黄檗、胡桃楸、毛梾、华山松和花楸5个树种均适宜在阴坡宜林荒山造林,黄栌适宜在阳坡宜林荒山造林,可作为本区宜林荒山人工造林树种。黄檗在半阳坡宜林地造林虽然成活率与保存率较高,但生长量与健壮程度显著低于阴坡造林地,因此水肥条件差的半阳坡宜林地不宜营造黄檗林。胡桃楸在石质沟谷地造林虽然生长量与保存率低于阴坡造林地,但保存率在85%以上且生长较好,为该立地条件较佳的造林树种和造林模式。     

黄土高原沟壑区南小河沟立地条件类型划分和适地适树的研究

黄土高原沟壑区沟壑纵横,不同部位的自然条件千差万别,致使同一种树种在沟壑造林后有着优劣成败极大悬殊。造好林必须弄清不同部位随着坡向、地形、土壤、植被的变化,知道它的干、湿、肥、瘠程度来划分造林立地条件类型。并通过试验调查掌握不同立地条件下造林树种的适应性能,科学的把两者结合起来,才能达到适地适树的目的。一、试验调查的地点与内容本项试验的地点设于庆阳县南小河沟的支沟杨家沟,董庄沟和范家山,魏家洼四处,构成一个阳坡、阴坡和东坡、西坡两个大断面。在这两个大断面上进行地貌,土壤、植被调查,结合地形、坡向、土壤、优势植物分布等因素归纳出几个不同土地类型。在这些不同土地类型上以地形为主,逐一详尽作植物分布,土壤种类,土壤剖面发育变化调查,选土壤水分点定期测定土壤水分等,根据调查的数据分析,提出一套划分立地条件类型的方法,划出不同立地条件类型。并进一步调查人工林、天然林在这些立地条件类型上的生长情况,摸清树种的生物学特性和造林学特性,在实践中与立地条件结合起来,选择出适宜造林的树种。     

林分密度和立地对油松人工林生长的影响

以北京山区25块油松人工林样地为研究对象,调查了40年生油松人工林在不同林分密度和立地条件下的生长状况,建立了林分密度与平均胸径、平均树高、平均冠幅和单木材积之间的回归方程,相关指数都在0.9以上;以样地平均优势木的解析材料确定40年生优势木树高,按单项立地因子实际分布区间分组,进行方差分析、差异显著性检验、多重比较。结果表明:随着林分密度的增大,平均胸径、平均树高、平均冠幅、单木材积逐渐减小;北京山区40年生油松人工林密度应控制在1 500株/hm2以下;明确了北京山区油松人工林生长与立地因子的关系,初步确定了油松人工林适宜的立地条件为:低山、阴坡、有效土层厚度(A+B层)45cm以上。     

Mineral nutrition, soil factors and growth rates of Gmelina arborea plantations in the humid lowlands of northern Costa Rica

The purpose of this study was to determine the factors which are responsible for clearly visible growth irregularities in Gmelina arborea stands by relating growth rates to soil and site properties. All Gmelina plantations under study, established on degraded pasture soils in the Atlantic lowlands of Costa Rica, showed the same growth pattern: very poor growth and chlorotic foliage of trees in mid-slope positions, and fast growth and healthy leaves of trees on hilltops and hillbases. The variation in site and soil properties and tree growth rates was analysed, investigating 24 plots in eight different plantations. Leaf samples were taken from 120 trees (five trees per site). Foliar analysis revealed that the tree growth is highly dependent on the supply of N, P, K and S, indicating that poorly growing trees suffer from a multiple nutrient disorder. To identify the most restricting soil factor, simple correlations between growth rates and soil chemical and physical properties were applied to the entire data set. The best correlation was obtained with exchangeable soil K (r=0.78, P<0.001). Subdivision of the data set into plots on brown soils (eight) and plots on red soils (16) and subsequent correlation analysis resulted in much stronger relationships. Growth depressions in mid-slope positions had other causes on brown soils than on red soils. On the acid brown soils the combination of the variables Al saturation and bulk density could explain 82% of the variation of tree growth. Al saturation of up to 80% in brown soils inhibits nutrient uptake, particularly of N and P. The red soils dominate on Ca---Mg-enriched, alluvial terraces and were among the first soils to be cultivated in the region. During the agricultural use and at the establishment of the tree plantations, they received dolomitic lime to reduce Al toxicity. Here, very low K/Mg ratios (less than 0.03) may induce K deficiency. Therefore, the best multiple regression model for tree growth rates on red soils is obtained with K/Mg ratio and thickness of the humic A-layer (r²=0.75, P<0.001). Inclusion of the variable bulk density resulted in a clear improvement of the model, explaining 91% of the growth variability.     

Calibrating and testing a gap model for simulating forest management in the Oregon Coast Range

The complex mix of economic and ecological objectives facing today's forest managers necessitates the development of growth models with a capacity for simulating a wide range of forest conditions while producing outputs useful for economic analyses. We calibrated the gap model ZELIG to simulate stand-level forest development in the Oregon Coast Range as part of a landscape-scale assessment of different forest management strategies. Our goal was to incorporate the predictive ability of an empirical model with the flexibility of a forest succession model. We emphasized the development of commercial-aged stands of Douglas-fir, the dominant tree species in the study area and primary source of timber. In addition, we judged that the ecological approach of ZELIG would be robust to the variety of other forest conditions and practices encountered in the Coast Range, including mixed-species stands, small-scale gap formation, innovative silvicultural methods, and reserve areas where forests grow unmanaged for long periods of time. We parameterized the model to distinguish forest development among two ecoregions, three forest types and two site productivity classes using three data sources: chronosequences of forest inventory data, long-term research data, and simulations from an empirical growth-and-yield model. The calibrated model was tested with independent, long-term measurements from 11 Douglas-fir plots (6 unthinned, 5 thinned), 3 spruce-hemlock plots, and 1 red alder plot. ZELIG closely approximated developmental trajectories of basal area and large trees in the Douglas-fir plots. Differences between simulated and observed conifer basal area for these plots ranged from −2.6 to 2.4 m²/ha; differences in the number of trees/ha ≥50 cm dbh ranged from −8.8 to 7.3 tph. Achieving these results required the use of a diameter-growth multiplier, suggesting some underlying constraints on tree growth such as the temperature response function. ZELIG also tended to overestimate regeneration of shade-tolerant trees and underestimate total tree density (i.e., higher rates of tree mortality). However, comparisons with the chronosequences of forest inventory data indicated that the simulated data are within the range of variability observed in the Coast Range. Further exploration and improvement of ZELIG is warranted in three key areas: (1) modeling rapid rates of conifer tree growth without the need for a diameter-growth multiplier; (2) understanding and remedying rates of tree mortality that were higher than those observed in the independent data; and (3) improving the tree regeneration module to account for competition with understory vegetation.     

Influence of herbicides and felling,fertilization, and prescribed fire on longleaf pine establishment and growth through six growing seasons

Recovery of longleaf pine (Pinus palustris P. Mill.) is necessary to arrest the decline of many associated plants and animals, and the establishment of longleaf pine on much of its original range requires artificial regeneration and diligence. In central Louisiana, USA, two fertilization levels (No [NF] or Yes [F-36 kg/ha N and 40 kg/ha P]) in combination with three vegetation treatments (check, two prescribed fires [PF], or multi-year vegetation control by herbicidal and mechanical means [IVM]) were applied to container-grown longleaf pine plantings in two studies. In Study 1 (grass dominated), 6-year-old longleaf pine survival was 52% on the F–checks, 78% on the F–PF plots, and averaged 93% on the other four treatment combinations. Longleaf pine trees on the IVM plots (3.4 m) were significantly taller than on the other two vegetation treatments, and trees on the PF plots (1.8 m) were taller than trees on the check plots (1.2 m). In Study 2 (brush dominated), survival averaged 65% across the six-treatment combinations after 6 years. The longleaf pine trees were 4.7 m tall on the IVM plots and averaged 3.9 m tall on the check and PF plots. Fertilization increased P concentrations in the soil and longleaf pine foliage, while fertilization did not significantly affect longleaf pine height growth. Native fertility was not apparently limiting longleaf pine development contrary to prior research recommendations for these soils. In both studies, the IVM treatment reduced early herbaceous competition and the number and height of arborescent plants. The PF treatment reduced arborescent plant height on the grassy site where fires were more intense than on the brushy site.     

半干旱区石质坡面坑道式造林整地小气候效应观测初报

为改善半干旱区石质坡面立地条件,试验尝试了坑道式造林整地模式,并于2011年5—9月对其所产生的小气候效应进行了初步观测。结果表明:植苗点的坑道内较自然坡面(对照点)地面温度与地中温度在生长季有朝着利于林木成活与生长的方面转化趋势——在5月与9月温度高于对照,在6、7、8月低于对照;水面蒸发减少194.1mm,在半干旱地区这一变化趋势有利于林木成活与生长。     

Explaining growth of individual trees: Light interception and efficiency of light use by Eucalyptus at four sites in Brazil

The growth of wood in trees and forests depends on the acquisition of resources (light, water, and nutrients), the efficiency of using resources for photosynthesis, and subsequent partitioning to woody tissues. Patterns of efficiency over time for individual trees, or between trees at one time, result from changes in rates photosynthesis and shifts in the relative partitioning to wood. We measured the production ecology (stem growth, light interception, and light use efficiency) to explain patterns of growth among trees within plots through stand development, and tested three hypotheses: (1) dominant trees have higher light use efficiency than subordinate trees; (2) lower variation in the size distribution of trees within plots allows higher light use efficiency; and (3) uniform stand structure and high light use efficiency reduce the age-related decline in tree growth. The experiment used clonal plantations of Eucalyptus at four locations in eastern Brazil. Irrigation and fertilization treatments ensured the major resource limitation for tree growth would be light supply. The influence of variation in the sizes of trees within plots was tested by comparing plots with all trees planted in a single day (uniform treatment) with plots where planting was spread over 80 days (heterogeneous treatment). Light interception per tree was simulated with the MAESTRA model. Across sites, treatments and whole-rotation stand development, dominant trees showed higher rates of stem growth, light interception, and light use efficiency than subordinate trees (supporting the first hypothesis). For example, dominant trees (80th percentile rank) at the end of the rotation grew four-times faster than suppressed trees (20th percentile rank), as a result of 2.1-fold greater light interception, and 1.8-fold greater stem growth per unit of light interception. In some cases, greater variation among tree sizes within plots led to lower efficiency of light use by average-size trees, providing mixed evidence for the second hypothesis. Greater uniformity of sizes of trees within plots did not substantially mitigate the decline in stem growth from mid-rotation to the end of the rotation, refuting the third hypothesis. The high efficiency of dominant trees underscores the marginal contribution of subordinate trees to total stand growth, and should spur further work on thinning to increase growth and lengthen rotations for dominant trees.     

The impact of climate,drainage and fertilization on the survival and growth of pinus sylvestris L. in afforestation of open,low‐production peatlands

The objective of this study was to analyse the conditions for forest production on open, low‐production peatlands in Sweden with respect to climate, and water and nutrient regimes. The study focused on survival and growth of Scots pine (Pinus sylvestris L.) seedlings, planted 18 yrs ago in five experimental areas evenly distributed between south and north Sweden. Different ditch spacing and NPK fertilizer treatments were combined systematically in all experiments. Survival was positively correlated with temperature sum, fertilization and drainage intensity. Tree growth was not influenced by variations in temperature sum after merely draining, but in combination with fertilization, growth was strongly correlated with climate. In the southern experiments, fertilization increased stand growth eight to nine times, whereas stands on the northern sites did not respond to fertilization. The most important fertilizer element was P. The application of N had no effect on growth. More intensive drainage increased stand growth by 60%. In the southern areas, height development in the most intensive drainage and fertilizer treatments indicates a mean annual increment of 6–7 m³ ha^?1, and no sign of decline in growth was seen. Turf‐planting had positive effects on both survival and growth, especially in less intensively drained plots. A large proportion of damaged trees was observed in the experiment. The frequency of damaged trees was positively correlated with treatment intensity but negatively correlated with temperature sum. The results show clearly that merely draining is not sufficient for successful afforestation of low‐production peatland sites. Fertilization by P and K is a necessary prerequisite, but the effect of fertilization varies with climatic conditions, probably owing to the amount of plant‐available N.     

Crown development in young Picea abies stands

A dynamic model of branch length and weight growth was developed for two contrasting sites, both with young stands of spruce. At one site sample trees were obtained from both unfertilised plots and from plots with increased growth rate maintained by annual fertilisation. At the second site unfertilised trees and trees subject to single applications of fertiliser were modelled. A model of the same structure was developed for each site and tested by application at the alternate site. In view of the close agreement between sites, model parameters were calculated based on all data combined. The model is driven by height increment and branch age. The sample trees were mostly open grown so that only a tentative estimate of the effects of between tree competition is given. The limitations of the model are stressed.     

Evaluation of native tree species for the rehabilitation of deforested areas in a Mexican cloud forest

Four native tree species (Liquidambar styraciflua, Juglans pyriformis, Podocarpus matudae, and Carpinus caroliniana) were evaluated for their suitability in rehabilitating degraded areas of Mexican cloud forest. Plant survival and growth in height and diameter were determined in three mixed-experimental plantations with different land use histories; their performance was compared with two on-farm plantations started by landowners for forest restoration. Nearby forest fragments were controls for soil compaction. An experimental plantation with remnant trees had the highest plant survival (82%), height, basal diameter and relative growth rate. The plantation with the steepest slope had high plant survival (63%) and growth. The plantation characterized by dominance of grasses and compacted soils had the lowest survival (22%) and growth. On-farm plantations had good establishment of planted trees (5–10 species planted), and facilitated the recruitment of 9–11 woody species. Carpinus and Liquidambar appear to be suitable species for reforestation in all these areas. Podocarpus grew relatively slowly, although it performed well in two experimental sites. Juglans had high survival (76%) under the stressful conditions of the most adverse site, and therefore may be useful for rehabilitation of degraded sites. Differences among species and sites strongly suggest that species success depends on plantation site quality.     

长白落叶松工业纤维林立地控制技术的研究

通过室外样地调查和室内木材材性分析及硫酸盐制浆实验,研究了不同立地条件下长白落叶松工业纤维林的生长过程、木材纤维特性、化学组成、物理性质和制浆特点,指出了立地条件对林分生长、木材纤维含量、纤维长度、纤维长宽比、得浆率、纸浆物理强度的影响。结果表明,长白落叶松工业纤维林生长最佳的立地条件是山地下部Ⅰ、Ⅱ地位级。立地条件对木材材性和纸浆特性有直接影响。在研究的林分密度和立地条件范围内,立地条件越差,木材纤维含量越少,纤维长度越短,纤维长宽比越小,1%NaOH提取物越多。而且这种现象有随林龄增长而加重的趋势。但立地条件对得浆率和纸浆的物理强度影响不明显。综合林分生长和木材材性,长白落叶松工业纤维林的培育最好在山地下部Ⅰ地位级和Ⅱ地位级的立地条件下进行。表4参17。