大兴安岭北坡火烧迹地森林郁闭度恢复及其影响因子分析

1987年发生在大兴安岭北坡的特大火灾造成了森林资源的巨大损失,其森林景观恢复一直是人们关注的热点.本研究选取与森林生产力具有密切联系的郁闭度因子作为研究对象,以 ArcView、ArcGIS等地理信息系统软件为研究平台,采用1987年和2000年两期森林资源二类调查数据,对郁闭度、火烧强度、抚育类型、地形因子等进行分级,通过数据叠加,探讨了森林郁闭度格局的恢复状况以及火烧强度、更新类型、地形因子对郁闭度恢复的影响.结果显示:2000年郁闭度等级构成与1987年火前相比发生了明显变化,无林地以及高郁闭度等级比重明显下降,较低郁闭度等级比重显著上升;火烧强度是影响火后恢复的初始因子,火烧强度与郁闭度等级呈负相关;更新措施短期内对郁闭度恢复影响不显著,但可以缩短森林演替的周期,对未来针叶林群落生产力恢复具有重要促进作用;地形因子中坡度对郁闭度恢复影响最为明显,其次为坡位,坡向影响最弱.     

Factorial analysis on forest canopy density restoration in the burned area of northern Great Xing＇an Mountains, China

The restoration of forest landscape has drawn much attention since the catastrophic fire took place on the northern slope of Great Xing‘an Mountains in 1987. Forest canopy density, which has close relation to forest productivity, was selected as a key factor to find how much the forest quality was changed 13 years after fire, and how fire severity, regeneration way and terrain factors influenced the restoration of forest canopy density, based on forest inventory data in China, and using Kendall Bivariate Correlation Analysis, and Distances Correlation Analysis. The results showed that fire severity which was inversely correlated with forest canopy density grade was an initial factor among all that selected. Regeneration way which did not remarkably affect forest canopy density restoration in short period, may shorten the cycle of forest succession and promote the forest productivity of conophorium in the future, Among the three terrain factors, the effect of slope was the strongest, the position on slope was the second and the aspect was the last.     

洞庭湖区防浪林林分林冠结构的研究

对洞庭湖区河洲、滩地上的不同林龄的旱柳、杨树防浪林、芦苇林进行了标准地调查,选取标准株(地),对其茎杆、枝条、叶片的空间分布进行了测定,通过对其差异进行比较分析,旨在间接测定不同防浪林的防浪效益的差异。     

长白山林区次生阔叶林冠下红松人工更新与培育技术

通过对长白山林区林隙环境、林隙对红松生长的影响及肛伐强度对阔叶树生长、红松更新的研究,为科学地确定上红松更佳的最佳上层郁闭度,提高林分生长量,确定红松采伐年龄,促进天然林保护工程的发展提供科学的依据和技术。     

基于TM影像数据的林分冠层郁闭度反演技术研究

本文以崂山林场为研究区域,利用森林资源二类调查数据和TM影像数据,分析了林分郁闭度与遥感因子之间的定量关系,在此基础上利用多元回归分析法结合实测数据构建郁闭度估测模型,并对模型精度进行检验,结果表明,预估精度达到81.6%,估测效果较好。利用该模型,反演了研究区的林分冠层郁闭度,将崂山林场的林分冠层郁闭度分为四个等级,即非林地区,低郁闭度区,中郁闭度区和高郁闭度区,研究区的森林郁闭度分布呈现西北部和东南部较低,而中部和南部相对较高。     

GPS森林病虫害监测数据处理模块设计与开发

文章首先总结了GPS在我国森林病虫害调查与监测中的应用现状和问题,并简要介绍了GPS技术、Garmin GPS12接收机、ArcView系统及其Avenue语言。主要阐述了基于ArcView 3.x的GPS数据处理模块的设计、功能和开发实践方法,并从GPS和GIS集成的角度论述了该模块的现实意义。     

Effects of moisture in wood materials on the SNR of GPS signals

This study was performed to investigate the factors responsible for the reduction in the signal-to-noise ratio (SNR) of a global positioning system (GPS) when used in a forest. We investigated the relationship between the SNR values of GPS signals and the moisture in wood materials and clarified this relationship through experimentation and simulation. Although the wood material itself had a minimal effect on SNR reduction, moisture in the wood had an obvious effect. It is noteworthy that wood material with a moisture resistance quantity (Mw) of 2 g/cm² caused a reduction of more than ~10 dB in the SNR. This Mw value corresponds to Japanese cedar with a green stem thickness of ~7 cm. Under unobstructed sky conditions, SNR is less than ~20 dB, so a reduction of 10 dB has a marked effect on GPS reception. The reduced SNR under canopies resulted from moisture in stems and the canopy. Furthermore, a simulation performed in a Japanese cedar forest revealed that 77.8% of the SNR reduction was caused by stems, 8.1% by branches, and 14.1% by needles.     

山东省临沂市林下经济现状与可持续生态发展研究

概述了林下经济的概念和特点,分析研究了临沂市林下经济类型及模式、存在困难与问题、发展优势,提出了可持续生态发展临沂市林下经济的技术途径和工作措施。     

3种不同林型下蕨类多样性和林冠开阔度的关系

光照和水分对林下植物的分布具有重要作用,浅根系的地生蕨类植物对光照和水分比较敏感,可以作为林下生境变化的指针。研究选取热带雨林、喀斯特森林以及人工橡胶林3种不同的林型,研究林冠开阔度对地生蕨类生物多样性的影响。采用2.5 m×1 m的样方,每个样方10 m的间距比较地生蕨类生物多样性。结果显示,热带雨林和喀斯特森林具有类似的地生蕨类多样性(2.52±1.68,2.47±0.68),两者的多样性指数明显高于人工橡胶林(1.47±0.72,P<0.000 1)。但是热带雨林具有更多的个体总数(2 769)和更高的物种丰富度(3.29±0.04),而同样指标喀斯特森林(319,2.94±0.05)和人工橡胶林(175,2.39±0.09)则相对较低。另外,随着林冠开阔度增加,地生蕨类多样性和丰富度急剧降低。地生蕨类的分布状态取决于上层的林冠开阔度,光照对地生蕨类的生物多样性具有决定性的影响,相对较弱的地表根系缺乏足够的吸水能力,不足以应付强光照带来的蒸腾损失。因此绝大多数的地生蕨类植物在林下空地间采取了避退策略。由于相对较低的林冠开阔度,使得喀斯特森林保存了相对较高的林下生物多样性,它具有重要的生态价值而必须加以保护。     

Dynamics of leaf area index and canopy openness of three forest types in a warm temperate zone

Deciduous broad-leaved forests (DBF), Larix principis-rupprechtii (LF) and Pinus tabulaeformis plantations (PF) are three typical forest communities in the warm temperate zone of the Dongling Mountains. In this study, we used an indirect method, hemispheric photography, to measure and analyze the dynamics of leaf area index (LAI) and canopy openness of the three forest communities. The results show that the LAI values of DBF and LF increased gradually with plant growth and development. The highest LAI value appeared in August, while canopy openness changed inversely with LAI. The lowest value appeared in November. DBF maintained a higher LAI in August and had a more open canopy in November compared with LF. For PF, we observed little changes in the LAI and canopy openness which was attributed to the leaf retention of this evergreen species. However, a similar relation between LAI and canopy openness was found for the three forest communities: canopy openness varied inversely with LAI. The relation is exponential and significant. Therefore, canopy openness is a good indicator of LAI in forests. This result can be used to test the validity of the LAI based on remote sensing and to provide a reference for the study of the canopy heterogeneity and its effect. This also benefits modeling for fluxes of carbon, water and energy from the level of the stand to landscape. __________ Translated from Journal of Plant Ecology, 2007, 31(3): 431–436 [译自: 植物生态学报]     

Effects of slope and canopy trees on light conditions and biomass of dwarf bamboo under a coppice canopy

Dwarf bamboo, Pleioblastus chino, grows extensively in abandoned coppice woodlands on the Kanto Plain in central Japan and suppresses other understory plants. In order to clarify the factors determining the growth of P. chino, we considered the effect of light conditions under a coppice canopy and examined its relationship with slope aspect, slope angle, and basal area of the trees. The relative photon flux density under the canopy was highly correlated with canopy coverage (R ² = 0.97). The light conditions under the canopy were almost the same at all sites in the summer leafy season regardless of the stand type, while they were remarkably different among the sites and depended on the basal area of evergreen trees in the winter leafless season. The biomass of P. chino on the forest floor was described by the equation: y = 3.18 x ₁ – 0.05 x ₂ + 3.11 (R ² = 0.77, P < 0.01), where y is the log-transformed value of P. chino biomass (gdrymassm^–2), x ₁ is cos at solar noon at the winter solstice, and x ₂ is the canopy coverage during the winter leafless season. is the angle between the suns rays and the normal to the surface and changes with slope aspect and angle. We concluded that light conditions under the canopy in the leafless season had a great effect on P. chino biomass, and that the basal area of evergreen trees and slope characteristics can provide useful guidelines in the control and management of P. chino.     

Effects of undisturbed canopy structure on population structure and species coexistence in an old-growth subalpine forest in central Japan

We investigated structural and compositional characteristics of an old-growth subalpine forest in central Japan, to ascertain forest dynamics and species coexistence. The forest appeared to have been fairly-undisturbed, at least during several recent decades, judging from the maximum occupancy of space by living canopy trees and an unchanged canopy structure between pre- and post-mortality phase. This stable forest showed minimum-scale dynamics that occurred primarily at a single-tree scale. Within this forest, the dominant species were Abies mariesii, A. veitchii and Picea jezoensis var. hondoensis. The two Abies species were abundant and showed advance regeneration, resulting from their high shade-tolerance. On the other hand, Picea showed the greatest basal area, in spite of its lower density. Picea showed steeper initial height-diameter allometric slopes, suggesting that its understorey saplings could increase height more rapidly under sunny conditions. Picea regenerates, given the opportunity of larger disturbances, as approximately even-aged cohorts, and then escapes competition from other shade-tolerant species by attaining the uppermost part of the canopy, resulting from rapid height growth of sapling, longer longevity and emergent attainable height. However, beneath the undisturbed canopy of this forest, in spite of its many seedlings, Picea entirely lacked regenerating individuals, suggesting that its regeneration is in a fairly-limited stage. This suggests that within the undisturbed forest, a demographic trait of Picea, in which the lower mortality of its canopy trees can compensate for its lower recruitment, is not enough to explain its stable coexistence with shade-tolerant Abies spp. Thus, not only the demographic trait, but also the spatial/temporal disturbance magnitude is important for an explanation of the coexistence of Picea with Abies. Consequently, it seems that not only equilibrium process, such as species differences in life-history traits, but also non-equilibrium process, such as disturbances, is crucial for their coexistence in this subalpine forest in central Japan.     

Small area estimations of proportion of forest and timber volume combining Lidar data and stereo aerial images with terrestrial data

Abstract

Methods for small area estimations were compared for estimating the proportion of forest and growing stock volume of temperate mixed forests within a district of a member state (canton) in Switzerland. The estimators combine terrestrial data with remotely sensed auxiliary data. By using different model types, different sources of auxiliary data and different methods of processing the auxiliary data, the increase in estimation precision was tested. Using the canopy height derived from remote sensing data, the growing stock volume and the proportion of forest were estimated. The regression models used for the small area estimation provided a coefficient of determination of up to 68% for the timber volume. The proportion of plots correctly classified into forest and non-forest plots ranged between 0.9 and 0.98. Models calibrated over forest area only resulted in a maximal coefficient of determination of 37%. Even though these coefficients indicate a moderate model quality, the use of remote sensing data clearly improved the estimation precision of both the proportion of forest and the growing stock volume. Generally, Lidar data led to slightly higher estimates compared to data from aerial photography. It was possible to reduce the variance of the estimated proportion of forest to nearly one tenth compared with the variance based on the terrestrial measurements alone. Similarly, the variance of the growing stock volume could be reduced to one fourth as compared with the variance based solely on the terrestrial measurements.     

Influence of typhoon disturbances on the understory light regime and stand dynamics of a subtropical rain forest in northeastern Taiwan

In 1996 and 1997 we examined the effects of typhoon disturbance on the understory light environment and sapling dynamics of the Fu-shan Experimental Forest, a subtropical rain forest in northeastern Taiwan. Mean understory light levels were approximately 30% of those in the open immediately following the two 1996 typhoons which affected the forest, yet in 1997, following two more typhoons, mean understory light levels were 10%–20% of those in the open. The decline of understory light levels to those present prior to the typhoons was more rapid in 1996 than in 1997, even though the two typhoons in 1996 were more intense than those in 1997. This difference might be the result of the timing of the typhoons. In 1996 the typhoons occurred earlier in the growing season, before August 1 rather than the middle and end of August in 1997. The regular defoliation caused by the frequent typhoons that impact Fu-shan (average of 1.4 per year) and the low stature of the forest (mean canopy height of 10.6m), results in much higher light levels beneath the canopy (9%–30% of levels in the open) than those found in most tropical and temperate forests. As a result, understory light levels are not limiting the distribution of canopy tree saplings within the forest and there is no evidence that canopy gaps play an important role in canopy tree regeneration within the Fu-shan Experiment Forest. This is in contrast with the pattern reported for some tropical forests. With frequent typhoons impacting northeastern Taiwan, the forests of this region are perpetually recovering from wind disturbances.     

不同施肥方法对毛竹林冠下多花黄精生长的影响

试验于2013～2015年期间在毛竹林冠下种植多花黄精,连续2年选用氯化钾复合肥采用穴施、环状沟施、放射状沟施3种不同施肥方法和不施肥（对照）进行毛竹林冠下多花黄精生长效果对比试验,结果表明：放射状沟施的多花黄精的各项生长量指标最高,平均保存率、平均地径、平均高度、平均根茎重量分别达94.9%、0.62 cm、65.1 cm、1389.62 kg/hm2;各项指标分别比环状沟施高出4.5%、12.7%、9.2%、16.3%,比穴施高出9.5%、26.5%、26.9%、22.5%,比不施肥（对照）高出24.5%、67.6%、58.8%、82.9%。     

Effects of field plot configurations on the uncertainties of ALS-assisted forest resource estimates

The effects of field plot configurations on the uncertainties of plot-level forest resource estimates were analyzed using airborne laser scanner data, aerial photographs and field measurements. The aim was to select a field sample plot configuration that can be used for both large area and management inventories. Error estimates were evaluated at the plot level using six different training plot configurations. Additionally, separate plots with two different sizes were used for evaluation. Stem volume and five other forest resource characteristics were considered. The field measurement costs of the different plot configurations were also studied. RMSEs and mean deviations for airborne laser scanning ALS-assisted estimates were practically the same for the fixed radius plot, the two concentric plots and the angle count plot with a basal area factor of q = 1 for all three evaluation plot sizes. Angle count plots with basal area factors of q = 1.5 and 2 increased the RMSEs. For the former plot configurations, the RMSEs for the ALS-assisted estimates could be attributed to inaccuracy in the predicted relationships between the field data and ALS data, not to the training plot configuration. Tree measurements and costs can, therefore, be reduced from those of the Finnish management inventories without increasing RMSEs.     

Effects of site productivity on forest harvest scheduling subject to green-up and maximum area restrictions

Green-up requirements are of great interest for forests near cities since these forests are commonly used for recreational activities by the local population as well as for commercial forestry activities. We present three formulations to establish green-up requirements, based on a dynamic green-up approach and constructed by means of: (i) a predefined fixed length for the green-up time, (ii) a predefined variable length for the green-up time and (iii) height information produced by the growth simulator. Additionally, restrictions on harvested volume and maximum open areas were applied. All the green-up formulations were applied to five datasets comprising different initial forest conditions regarding age and site index distribution. Results show that higher net present values are obtained by the formulation that allow a predefined variable length for the green-up time and by using the height information from the growth simulator compared to the formulations using a predefined fixed length for the green-up time. The increase in NPV was most pronounced for the old forest datasets and varied between 4.23% and 8.15%. The optimal solution was always found when modeling the green-up requirement using the height information. This formulation also tended to find optimal solutions faster than other formulations.     

Effects of diversity of tree species and size on forest basal area growth,recruitment, and mortality

The objective of this study was to determine the relationship, or lack thereof, between growth and diversity of tree species and size in conifer stands of western North America. Growth was measured by net basal area growth and its components: survivor growth, recruitment, and mortality. The analysis used inventory data from permanent plots in the Douglas-fir/western hemlock forest type in Oregon and Washington, and in the mixed-conifer forest type in California. The methods consisted of generalized least square regression with spatial autocorrelation, controlling for the effect of other stand characteristics. Other things being equal, in the two forest types under study there was a strong positive relationship between net basal area growth and tree-species diversity. This effect was associated with higher recruitment in stands of higher tree-species diversity. Neither mortality nor growth of survivors was related to tree-species diversity. The relationship between growth and tree-size diversity was less clear. For Douglas-fir/western hemlock, net basal area growth was negatively correlated with tree-size diversity, essentially because recruitment was lower on plots of high tree-size diversity. For mixed conifers, net basal area growth tended also to be lower in plots of high tree-size diversity, but this was mostly because mortality was higher in plots of higher tree-size diversity.     

Effects of forest landscape change and management on the range expansion of forest bird species in the Mediterranean region

In the western Mediterranean region of Catalonia (NE Spain), during the last 20 years of the 20th century, the range of many forest bird species has expanded. Our objective was to characterize the roles of (a) spatial population processes (related to dispersal), (b) changes in forest structure (due to forest maturation and management), and (c) landscape composition (resulting from afforestation and fires) in the range expansion of these bird species at the landscape scale (10 × 10 km). After correcting for the differences in sampling effort, colonizations appeared to be more likely near areas in which the species had been present in the 1980s. Patterns of the range expansion were also strongly associated with forest maturation, which seems to affect the spatial arrangement of birds at multiple scales. Changes in forest landscape composition due to afforestation and fires were minor determinants of range changes, and forest management did not seem to prevent range expansion at the spatial scale studied. Colonization events appeared to be driven primarily by landscape changes occurring in nearby localities rather than within the colonized locations themselves, presumably because of source–sink dynamics and connectivity patterns. Our results showed that in Catalonia, at a landscape scale, the impact of forest management on forest bird communities is much smaller than the impact of the widespread maturation of forests following a large-scale decline in traditional uses.     

不同林型对林下光照和辐射消减的影响

在中山市长江库区水源林市级保护区内选择4种不同的林分类型,进行每木检尺和冠层影像拍摄,处理得到林下光照因子和辐射消减因子,分析不同林型对林下光照和辐射消减的影响。结果表明:不同林型对林冠结构和林下光照影响显著,针叶林与针阔混交林的林下光照接近,林冠较差,沟谷季雨林与常绿阔叶林接近,林冠较好;辐射消减在不同林型间差异显著,针叶林和针阔混交林辐射消减较差,常绿阔叶林和沟谷季雨林辐射消减较好;林下光照与辐射消减相关性强,特别是两个林冠结构因子与辐射消减关系密切。在进行林分改造时,建议选择叶片较大较厚,冠幅大而优美的常绿阔叶树种进行更新,天然起源的林分与常绿阔叶林的林冠结构较好,有效维持了森林生态系统稳定。