六盘山北侧华北落叶松树干直径生长变化及其对环境因子的响应

2005年5-11月在宁夏六盘山北侧的叠叠沟林场,应用带状树木径向变化记录仪研究9株华北落叶松树干的直径生长变化过程及其对环境因子的响应.结果表明:树干直径的日最大值出现在6:00-9:00,最小值则在16:00-20:00;直径生长的季节变化表现为前期快后期慢,8月下旬以后基本停止生长;林分内优势度大的林木生长较快;树干直径生长过程随时间的变化符合幂函数曲线,方程的确定系数为0.78～0.92.对影响直径生长变化的环境因子进行主成分分析,结果表明温度和水分是主要影响因子;结合偏相关分析,筛选出日最高温、空气相对湿度、日平均太阳辐射通量和土壤含水量作为影响树干直径生长变化的主要因子.建立线性回归模型.     

塞罕坝地区华北落叶松人工林土壤水肥变化规律的研究

通过对塞罕坝地区华北落叶松人工林不同年份、不同立地条件、不同土层土壤水肥含量的研究,分析了土壤的水肥变化规律,其结果表明,在生长季内,各层土壤含水量均经历了升高一降低一再升高的变化历程;林地存在土壤酸化、地力衰退现象。研究结果还发现,随林木成熟期的接近,林地速效氮含量整体下降明显。     

燕山北部白桦华北落叶松次生林种群结构与动态研究

为了阐明白桦华北落叶松次生林的动态变化规律,对燕山北部白桦华北落叶松次生林种群进行了系统研究,分析了白桦和华北落叶松种群的径级结构、静态生命表、存活曲线。结果表明,燕山北部白桦和华北落叶松种群,中径级个体多,大小径级个体少,呈现衰退型趋势。从期望寿命来看,白桦种群和华北落叶松种群在Ⅱ径级时,期望寿命达到最大,表明此阶段种群生理活动达到旺盛期。随着径级的增加,白桦和华北落叶松死亡率和消失率基本呈现相同的趋势,即先降低后增加的趋势,在小径级和大径级时,其死亡率高,表明这两个种群有衰退的趋势。适当间伐白桦和华北落叶松对其次生林天然更新和恢复具有重要意义。     

Stand structure and composition of a 60-year-old larch (Larix kaempferi) plantation with retained hardwoods

Tree retention is understood as a key practice in creating complexity, leading to heterogeneity in resources and habitats in managed stands. In this article, we clarify the long-term effects of tree retention on stand structure and tree-species composition in a 60-year-old Larix kaempferi plantation in central Japan. In our study plot (1.5 ha) there were 18 stems/ha of retained trees (determined by tree-ring analysis), mostly Quercus crispula. We conducted spatial analyses and tested the hypothesis that tree abundance, size structure, and species composition and diversity change with distance from the retained trees. Near the retained trees, L. kaempferi showed a reduction of 40%–60% in basal area, due presumably to the shading effect. In contrast, the nearby area showed greater species diversity in the canopy layer. The retained trees created patches of different species composition in the understory. The spatial gradient of shade and colonization opportunity provided by retained trees greatly affect the distribution of the colonized species, according to their shade tolerance and seed-dispersal ability, which resulted in the stand structure with a heterogeneous shrub-layer vegetation. Retention proved particularly important for the enhancement and long-term maintenance of structural and compositional complexity in L. kaempferi plantations.     

冀北山地华北落叶松人工林与天然次生油松林不同坡位生长状况研究

在冀北木兰围场自然保护区内,通过对比华北落叶松[Larixgmellini（Rupr．）Rupr]人工林与天然次生油松（P／nustabulaeformiscarr）林不同坡位的连年生长量与平均生长量,建立生长过程曲线方程并拟合树高与胸径之间的关系,分析两种林型内乔木树种的生长过程。结果表明：（1）落叶松人工林不同坡位样地内,标准木的拟合生长模型基本相似;材积连年及平均生长速率排序为：坡底落叶松〉坡中落叶松〉坡顶落叶松。（2）天然次生油松林不同坡位样地内材积平均生长量均随着年龄的增长而增加,油松标准木的生长过程基本相同,且标准木的拟合生长模型基本相似。但坡中油松立木材积平均生长量高于坡地和坡顶。（3）相同坡位样地内人工林与天然林间的连年生长曲线存在明显差异性。油松林生理年龄高于落叶松林,标准木达到材积数量成熟的年龄比落叶松大,单株立木材积量较大。（4）人工落叶松林和天然油松次生林内乔木树种的胸径与树高问存在密切的相关性,其相关系数均达到0．9以上。     

Appropriate density of water and soil conservation of Pinus tabulaeformis and Robinia pseudoacacia forests in loess area, North China

In this paper, based on a long-term monitoring of water cycle in the water and soil conservation forest stands of Pinus tabulaeformis and Robinia pseudoacacia, the soil moisture deficit is calculated. Following the principles of runoff-collecting forestry and applying the forest structure investigation results, the authors developed a formula to calculate appropriate density for forests on the basis of different diameters at breast height (DBH). Using this method to manage forests, the natural water requirement of forests can be met and soil drought can be avoided. In addition, with long-term monitoring of soil moisture in stands, the authors also give an appropriate managing density specifically for the water and soil conservation forests of P. tabulaeformis and R. pseudoacacia in the loess area which is according to soil moisture content, or with the lowest soil moisture content and invalid moisture frequency as the indexes. __________ Translated from Science of Water and Soil Conservation, 2007, 5(2): 55–59 [译自: 中国水土保持科学]     

辽东山区长白落叶松天然更新调查

调查辽东山区长白落叶松人工林的长白落叶松天然更新数量、幼苗的存活和生长状况以及其幼树出现的生境.结果表明:在结实的长白落叶松人工林内均有1年生落叶松幼苗,其数量与人工林种子库落叶松种子数量有关,其存活和生长(高生长和叶片数量)状况明显受林分开阔度、地面植被盖度和枯落物的影响.1年生长白落叶松幼苗在林内生长缓慢,一般高生长不超过6 cm,地径生长不超过0.1 cm,叶片数量不超过25针.长白落叶松天然更新幼苗4月末开始出现,6月份幼苗数量最多,9月份林内大部分幼苗死亡.这表明长白落叶松幼苗在林下不能正常存活和生长,而影响其存活和生长的主要因素是光照、草本灌木和地面枯落物.另外,长白落叶松林下很难见到幼树,只有在有种源、光照充足、草本灌木和枯落物少,以及土壤较湿润的生境中能见到其幼树.     

Function and value of water conservation in different age classes of Acacia mangium plantations

For this paper, we studied the water-holding capacity of canopy, vegetation layer under canopy and litter layer, the water-holding capacity and permeability of soil as well as their changes with growth of stands in Acacia mangium plantations of three different age classes (four-, seven-and 11-year-old). Results show that total water-holding above ground in the order of 11-year stand age (52.86 t/hm²)>seven-year stand age (41.90 t/hm²)>seven-year stand age (25.78 t/hm²), the increment tendency increased with stand age. Similar sequence also obtained on the water-holding capacity and permeation capacity of soil (0–40 cm). The total water-storage capacity both above ground and soil in four-year-old, seven-year-old and 11-year-old of A. mangium plantations were 2,023.0, 2,158.4 and 2,260.4 t/hm², respectively, and the all value of water conservation were 1,372.70, 1,474.42 and 1,549.91 yuan (RMB)/hm², respectively. Therefore, A. mangium plantation had a good ability to modify soil structure and good water conservation function. __________ Translated from Journal of Soil and Water Conservation, 2006, 20(5): 5–8, 27 [译自: 水土保持学报]     

Height growth of young larch (Larix kaempferi) in relation to the frequency of deer browsing damage in Hokkaido, Japan

The effect of browsing frequency by Sika deer (Cervus nippon yezoensis) on the height growth of Japanese larch (Larix kaempferi) in Hokkaido, Japan, was analyzed. Tree heights at the time of the census and at the start of the current growing season were determined for 100 trees selected randomly at each site. The tallest shoot on each tree was identified and the number of browsing occurrences on the current-year shoot was determined. Young larches browsed by deer repeatedly develop new shoots during a growing season. Larch is a browsing-tolerant species, and the average height growth of the most heavily browsed trees was >15 cm. Although resprouting partly compensated for decreased height growth caused by browsing, the annual increase in height decreased with increased browsing frequency. Thus, browsing frequency during a growing season best reflects the intensity of browsing damage to larch trees.     

The effects of selective logging on stand structure and the regeneration of subboreal forests in Hokkaido, northern Japan

We investigated the effects of selective logging on stand structure and regeneration in selectively logged subboreal forests in Taisetsuzan National Park in Hokkaido in northern Japan. The basal area decreased and the size structure of trees altered in the stands studied due to repeated, intense selective logging, in which larger trees were cut down as a priority. Sapling density in the stands was much lower than that in primary forests. In the simple and multiple regression analyses that were used to estimate the effects of selective logging on sapling density, sapling density had a significant positive correlation with tree density and had little correlation with the density of logged stumps or the height ofSasa (dwarf bamboo) growing on the forest floor. These results suggest that the establishment sites around canopy trees influenced the establishment of saplings, rather than the gaps caused by selective logging. However, both the coefficient of determination and the standardized partial regression coefficient of multiple regression analysis were higher for the stand with a dense cover ofSasa than for the stand with a sparse cover ofSasa. Thus, the success of regenerating forests with selective logging depends on both the site of advanced regeneration and the light conditions that regulate growth.     

Environmental and plant-based controls of water use in a Mediterranean oak stand

In this work, new information is reported on water relations of the Mediterranean oak species Quercus pyrenaica based on environmental and physiological measurements carried out during the growing seasons of 2006 and 2007. The interest in this species has increased due to its use in reforestation programs and its impacts on the water resources due to the extensive spontaneous afforestation after the abandonment of forest (firewood, charcoal, livestock, etc.) and agricultural activities, in general in some areas in the Mediterranean region and in particular, in the studied area (Sistema Central range, Spain). The objectives were to evaluate the long-term water use of this stand and its limit and to analyse the specific traits to cope with summer drought, especially the use of stem water storage and deep soil water reserves. Tree water stress associated with depletion of soil water reserves was not observed since the oak trees appeared to avoid a marked water stress using water reserves from deeper soil layers as summer drought progresses. The contribution of mean daily stem water storage to transpiration was low (4%), although it could be greater under dryer conditions. Only at the end of summer of 2006, the transpiration and canopy conductance were reduced due to soil drought. Despite the absence of marked water stress an upper limit was found in transpiration (slightly higher than 3 mm day⁻¹). The heavy use of soil water resources by this species (75% of available soil water in this study) should be considered when evaluating the impact of spontaneous afforestation and reforestation programs on water resources.     

Effect of soil chemical properties on growth,foliation and nutrition of Norway spruce stand affected by yellowing in the Bohemian Forest Mts., Czech Republic

In 1998, a fertilizer experiment aiming to investigate the effects of slow-release N, P, K and Mg fertilizer (SILVAMIX Mg NPK^®) on a 60-year-old spruce stand with symptoms of yellowing was established. In this paper, trees were selected to investigate the relation between annual diameter increment, yellowing, foliation, needle and soil chemical properties: ten from the fertilized treatment (F), ten green trees from the control (CG) and ten yellow trees from the control (CY). CG and CY trees were growing in close proximity at a distance of only several meters apart under the same soil conditions. In treatment F, increased annual diameter increment, improved foliation, needle Mg concentration, plant-available Mg and P concentrations in the soil and absence of yellow trees were recorded 7 years after a single application of the fertilizer. During the last 15 years, annual growth increment and foliation of CY trees have continuously decreased while relatively stable values were recorded for CG trees and increased for F trees. In 2006, CG and CY trees differed significantly in Mg concentration in needles, foliation, yellowing and annual diameter increment. Although differences in soil chemical properties between CG and CY treatments were not significant, lower concentrations of plant-available Mg²⁺ and higher concentrations of H⁺ and Al³⁺ were found in soils under CY trees. There was a negative correlation between soil concentration of Mg and yellowing, but this correlation was relatively weak, indicating that there is no simple relation between soil and needle concentrations of Mg. In the investigated locality, the “new type” of yellow tree decline has been a long-term gradual process.     

Effects of competitive and cooperative interaction among neighboring trees on tree growth in a naturally regenerated even-agedLarix sibirica stand in considering height stratification

This study attempted to explain the variation in growth of individual trees in a naturally regenerated, even-agedLarix sibirica stand using indices that represented the competitive and cooperative interactions among neighboring trees. These interaction indices and DBH were used in stepwise multiple regression procedures to model the growth of individual trees. However, when the data from all trees were used, DBH was the only factor accepted in the growth model. Since DBH can be influenced by the cumulative effect of past interaction and other environmental factors, we stratified the stand into three height strata and repeated the stepwise procedure for each stratum to remove the cumulative effect represented by DBH. Several competition and/or cooperation indices were accepted in growth models of the lower, middle and upper strata. In each stratum, the residual mean square of the growth model was smaller than that of all strata. These facts suggested that height stratification was generally successful in reducing the cumulative effect of past interaction and other factors. The cooperation indices that suggested protection from wind stress by neighboring trees was a significant variable in the growth models of all three strata. This demonstrated that cooperative interaction should be considered in the explanation of variation in tree growth in dry and windy climates such as the present study region. This study was supported with grants from The Nissan Science Foundation, and from the Heiwa Nakajima Foundation.     

Effects of radial growth rate on selected indices for juvenile and mature wood of the Japanese larch

To examine the differences between juvenile and mature wood, 12 aged sample trees from two areas of Nagano Prefecture were harvested; and the radial development of tracheid length, the ring density, and the relation of the radial growth rate (observed by ring width) with some selected indices of ring structure were investigated. The results proved that the radial variation of tracheid length with ring number can be described by a logarithmic formula, and both plantations reached the demarcation of juvenile and mature wood at age 18. With the segmented regression method, we also analyzed radial variation of mean density and found that the demarcation of juvenile and mature wood was at age 15 for sample trees from Saku and at age 21 for those from Yabuhara. By using the results of estimates from juvenile and mature wood based on ring density, we found that high growth rates resulted when producing lower-density wood during the juvenile period, but these rates did not occur during the mature period. The basic reason for this phenomenon is the variation in patterns of earlywood and latewood in juvenile and mature wood, respectively. This result advised us that when managing plantations of Japanese larch it is necessary to take different measurements at different growth periods.     

Spatial distribution pattern and dynamics of the primary population in a natural Populus euphratica forest in Tarim Basin, Xinjiang, China

One 50 m × 50 m standard plot was sampled in a natural forest of Populus euphratica in Awati County, situated at the edge of the Tarim Basin, Xinjiang Uygur Autonomous Region, China. The field investigation was conducted with a contiguous grid quadrate method. By means of a test of variance/mean value ratio, aggregation intensity index and theoretical distribution models, the spatial distribution pattern and the dynamics of primary populations in P. euphratica forest were studied. The results showed that the spatial distribution pattern of two dominant arbor populations conformed to clumped distribution. The aggregation intensity of the P. euphratica population was higher than that of P. pruinosa population. The spatial distribution pattern of two companion plant populations in the shrub layer also conformed to clump type, though the aggregation intensity of Tamarix chinensis was higher. In the herb layer, the distribution patterns of Glycyrrhiza uralensis and Asparagus persicus conformed respectively to a clumped pattern and a random pattern. The results of a Taylor power method test and Iwao’s regression model also verified that both P. euphratica and P. pruinosa populations belong to a clumped pattern. Although the distribution pattern of P. pruinosa population at different development stages all belonged to a clumped distribution pattern, the aggregation intensity dropped gradually along with age development. The distribution patterns of the P. euphratica population at different development stages changed from random type to clumped type, and further to random type. The differences in spatial distribution patterns of different populations at different development stages were related not only to ecological and biological characteristics of each species in the communities in the light of competitive exclusion principle among the populations, but were also closely related to the habitats in which the species lived in. __________ Translated from Journal of Southwest Forestry College, 2007, 27(2): 1–5 [译自: 西南林学院学报]     

Capacity of stem water conductivity for two eucalyptus ( Eucalyptus urophylla ) plantations in South China

The sap flux density (SFD) was used as a measure of water capacity through stems of eucalyptus in this paper. It was found that daily SFD increased with daily vapor pressure deficit (VPD) in nonlinear regression Y=AX ³+BX ²+CX+D (R ²=0.702 1, n=135, p=0.01) at both sites (Hetou and Jijia) in the Leizhou Peninsula, Guangdong Province, China, where Y was daily SFD, X was mean daily VPD, A, B, C, D were constants. But extremely high VPD might limit stem water conductivity. The environmental factors, such as air vapor pressure deficit (VPD), solar radiation (RAD), etc., were the main determinants of SFD for E. urophylla plantations. The upper threshold of diurnal SFD was 51.55–55.65 mL·cm⁻²·h⁻¹ under the selected extremely high environmental conditions.     

Modelling daily root interactions for water in a tropical shrub and grass alley cropping system

A two-dimensional physically-based model for the daily simulation of root competition for water in an alley cropping system associating Gliricidia sepium with Digitaria decumbens is developed. This paper deals with the impact of root distribution on soil water partitioning. By adapting existing principles of root water uptake modelling for pure crops, the model accounts simultaneously for the sink terms of each species in a defined soil domain. Soil-root water transport functions are solved at the level of discrete volumes of soil; each of them are characterized by the inherent soil physical properties, root length density, soil-root distances, and the calculated sink terms of each species. The above ground boundary conditions, such as transpiration and soil evaporation, were managed by simple equations found from the literature or provided by experimental measurements. Running the model with two contrasting observed root maps, an evaluation was carried out over a 10-day period following a rainfall event. With both root maps, the simulated soil water potential profiles at the row, at 0.75 m and 1.50 m from the row did not differ significantly, and were in good agreement with the measurements. However, although water was not limiting during this period, the simulated cumulative water absorption profiles of G. sepium and D. decumbens contrasted markedly, and matched their observed root distribution. This model, although still under further development, forms the basis for development of an above and below ground coupled model to simulate plant interactions for water in intercrops or agroforestry.This revised version was published online in November 2005 with corrections to the Cover Date.     

Stand structure and establishment process of an old-growth stand in the mixed deciduous broadleaf/conifer forest of Mt. Moiwa Forest Reserve, central Hokkaido, Northern Japan

Stand structure of an old-growth forest was studied by tree (≥4.0 cm in DBH) census in a main plot of 1.3 ha and 8 additional plots (0.525 ha in total) located in the Mt. Moiwa Forest Reserve, central Hokkaido, northern Japan. Major tree species with ≥1.0% of the relative basal area and of relative number of trees (Acer mono, A. mono var.mayrii, Kalopanax pictus, Magnolia kobus var.borealis, M. obovata, Prunus ssiori, Tilia japonica, andUlmus laciniata) have positive values of skewness in DBH, which shows the abundance of smaller-sized stems. All stems over 1.3 m high in the main plot were mapped to clarify the relationship between stem densities and canopy states. Although advances from sapling (>1.3 m tall and <4.0 cm DBH) to small tree (10.0 cm ≤ DBH <25 cm) for all major component species, exceptP. ssiori andU. laciniata, were independent of canopy states, those ofP. ssiori andU. laciniata depended on canopy gaps.Betula spp. was the most abundant gap makers, butT. japonica andA. mono (including var.mayrii) were dominant species in the main plot. This suggests the shift of dominant species in the forest of the study site. Historical records of disturbance demonstrated that selective cuttings of conifers during the late 19th century were responsible for the dominance ofBetula spp. and the subsequent shift of dominant species. This fact suggests that artificial disturbance plays an important role in the establishment ofTilia japonica-Acer mono forest considered to be a climax of the mixed deciduous broadleaf/conifer forests.     

Trees and farming in the dry zone of southern Honduras II: the potential for tree diversity conservation

The potential of the dry zone agro-ecosystem of southern Honduras to contribute to the conservation of Mesoamerican dry forest tree diversity is evaluated. Four rural communities containing eight land uses were surveyed using rapid botanical sampling resulting in the identification of 241 tree and shrub species. As a result of ordination analysis, it is concluded that the land uses are relatively similar in their species composition, particularly maize fields (milpas), fallows, pastures and woodlots, because of the predominance of natural regeneration. Therefore all land uses might contribute to local tree diversity conservation. Those land uses in which planting also contributes to diversity, home gardens (solares) and orchards, are more distinct; however the tree species found there are widespread and often exotics and thus not the usual focus of conservation measures. Across the landscape the total complement of species considered a global priority for biodiversity conservation is very low and therefore this agro-ecosystem does not represent a good place in which to implement dry forest tree diversity conservation programmes. Instead its value is likely to be in the contribution that tree diversity makes to rural livelihoods. Particular consideration is given to Swietenia humilis Zucc. (small leaved mahogany) and its status as a threatened species is questioned because of its abundance within this landscape and its wide distribution. This revised version was published online in June 2006 with corrections to the Cover Date.     

A simple step-wise procedure for predicting stand development of Acacia mangium plantations based on the maximum size–density line in South Sumatra, Indonesia

A simple step-wise procedure for predicting the course of stand development on log–log coordinates of stand density and quadratic mean diameter was presented based on a distance of measurement from the maximum size–density line of Acacia mangium. This procedure first predicts annual increment of diameter with a multiple linear regression having the distance, site index, and current diameter as independent variables, and then the associated mortality is calculated with the rate of reduction in stand density to the diameter growth derived from a fitted trend with the distance. The cumulative predictions, starting at 3 years after planting until 9 years of age, agreed well with the observations of group-age means of measurements calculated for the three levels of initial density. Contrasting trend of basal area growth between the three levels of initial density and those for their site index: the differences were decreasing in the former while they remained constant in the latter, was clearly illustrated with the procedure indicating a good potential for use in yield prediction. The simulations for stand growth under different spacing and thinning options were demonstrated in a stand density control diagram suggesting reasonable flexibility for practical application.