A preliminary study on forest edge effect and application

Researches and analyses were carried on the mechanism of forest edge effect by theclassification of its types in forest ecosystem.Two kinds of practical models were put forward to ex-tricate forestry from"Two Crisises"and increase the utilization efficiency of solar energy and the netprimary productivity on unit area by combination forest edge effect theory with forestry production.1.Cultivating fast growth and rich yield plantation directionally in optimal community structure byuse of forest edge effect theory.2.Establishing artificial—natural compound forest community byopenning up effect belts in natural secondary forest.     

经营强度对高节竹生物量的影响

对集约和粗放经营的高节竹不同器官生物量及凋落物量进行研究.结果表明:相对于粗放经营,集约经营高节竹林的1-3年生竹占比从71％增长至81％,单株叶、枝、秆生物量比粗放经营分别高66.7％、60.8％、79.4％,整株生物量比粗放经营高74.63％.集约经营高节竹林单位面积叶、枝、秆、根鞭、凋落物和总生物量分别为10.1...     

不同抚育强度对冠下红松生长影响的调查与分析

对上层林木采取大强度、中强度、小强度抚育,林分郁闭度分别保持在0.60、0.65、0.70左右时的林分生长量进行调查分析,结果表明:大强度抚育林分冠下红松的树高、胸径、蓄积生长量分别是小强度抚育林分的2.26倍、3.24倍和6.50倍;从整个林分蓄积生长量看,采取大强度抚育林分的生长量最高,是小强度抚育林分的1.30倍...     

Impact of wildfire intensity and logging on fungal and nitrogen-cycling bacterial communities in British Columbia forest soils

Wildfire and logging are common disturbances in the forests of northwestern North America, causing changes in soil chemistry and microbiology, including fungal and nitrogen-cycling bacterial communities. These organisms play key roles in nutrient cycling, and affect the regeneration of tree seedlings after disturbance. We studied the effects of wildfire and logging on fungal and nitrogen-cycling communities in the rhizosphere of 16 month-old Douglas-fir seedlings as they regenerated in burned and logged soils. Seeds were planted against root windows that were set up vertically in the soil, with a removable front panel used to access the seedling rhizosphere soil surface. Windows were established in control, lightly burned, and severely burned plots, as well as two types of logged plots (clearcut and screefed clearcut). Soil scrapings from the root window–soil interface were taken and the structure of fungal and nitrogen-cycling communities was resolved using length-heterogeneity PCR (LH-PCR) of fungal nuclear ribosomal RNA genes, and terminal restriction fragment length polymorphism (T-RFLP) analysis of nifH and nosZ genes. We found striking differences in the community structure of fungal, denitrifying, and N-fixing communities in response to burning and logging. With the exception of clearcut and screefed clearcut, which were generally similar, each treatment had a unique impact on community structure for these genes. Burning and logging also impacted the relative richness and evenness of these communities. Fungal relative richness and evenness increased in response to logging and severe burning, while denitrifier relative richness and evenness increased in all disturbance treatments, and N-fixing bacterial relative richness and evenness decreased in response to burning. The greatest differences in microbial community structure, relative richness, and evenness were found in the comparisons of lightly burned and logged treatments. The results suggest that the presence of an intact forest floor influences soil microbial communities less than the presence of living trees.     

华北落叶松人工林林缘光照度研究

林内光照环境是林分更新的基础。本试验以华北落叶松人工林为研究对象,采用30m的样带法,比较了林分内部及林缘光照度的变化规律。结果表明:华北落叶松人工林林缘相对光照度随距林缘距离的增加而减小,之后趋于稳定;密度为630株/hm2时,随林缘距离的变化不太明显;林缘相对光照度与林分边缘不同距离呈明显的二次多项式关系;相对光照度能较好地反映林缘效应;随林分密度的增加林内光照度逐渐降低,相对光照度与密度呈显著幂函数关系。     

Edge type effect on germination of oak tree species in the Highlands of Chiapas,Mexico

The purpose of this study was to examine the effect of habitat edges on the probability of acorn germination of three oak species (Quercus crassifolia Humb. and Bonpl., Quercus rugosa Née and Quercus laurina Humb. and Bonpl.). The effects of edge type (hard and soft), habitat type (grassland, edges and forest) and leaf litter cover (covered or uncovered acorns) on acorn germination was evaluated by the experimental establishment of acorns along transects crossing habitat edges. More acorns developed into seedlings in grasslands (38%) than in the forest edge (18%) or the forest interior (15%). In sites with soft edges, a higher number of seedlings emerged from acorns covered by litter compared with acorns sowed in the adjacent forest edge and forest interior (P < 0.05). In sites with hard edges, fewer seedlings emerged in the edge (14%) compared with the adjacent grassland (38%), and the adjacent forest (20%) presented intermediate values. However, in sites with soft edges significant differences in seedling emergence were recorded between the grassland (38%) and the forest (10%), whereas the edge presented intermediate values (23%). The effect of leaf litter cover on acorn germination was only significant in grasslands in sites with soft edges (P < 0.05). Acorns in grasslands received relatively little insect damage (10%) compared with the edge (19%) and the forest (30%, P < 0.05), emphasising the importance of acorn dispersal for successful oak establishment. The implications for regeneration of these oak species and the dynamics of montane oak forests in Mexico are discussed.     

Patterns of forest vegetation responses to edge effect as revealed by a continuous approach

Context

Understanding the variability of vegetation distribution and its determinants is a central issue for addressing the effects of edges on ecological processes. Recent studies have revealed inconsistencies in the patterns of responses to edge effects that raise important questions about their determinants. We investigated the edge effect response patterns by adapting a recently proposed continuous approach to the case of small forest fragments in southwestern France.

Methods

We surveyed forest understory vegetation (composition, species richness, and percent cover) and abiotic variables (soil temperature, moisture, pH, and canopy openness) along 28 transects across hard forest edges. We tested five statistical models to describe the response pattern of each variable (1) over all transects and (2) per transect. We then compared the response patterns as a function of the attributes of the edge (orientation, topography, and adjacent land cover) and forest patch size.

Results

Over all transects, a general decreasing trend was observed for all variables as the distance from the edge increased. In the individual transects, we evidenced a large variability in the response patterns that was not related to edge attributes or to patch size.

Conclusion

It is difficult to assess the depth of edge influence in highly fragmented forests and to identify the determinants of edge effects. We recommend that care should be taken with studies using pool of transects, and that further studies should be carried out including situations with neutral patterns, in order to gain a broader understanding of edge effects on vegetation.     

城市森林群落配置模式浅议——以景宁县为例

城市森林群落是城市生态系统重要的组成部分,城市森林群落的配置是否科学合理将直接关系到城市生态系统功能的发挥、森林城市建设的总体水平和森林城市目标的实现.在综述城市森林群落配置特点和基本原则的基础上,重点阐述了城市公园、道路系统、单位绿地、居住区绿地、生产绿地等森林群落配置模式.     

对完达山林区森林分布及类型的探讨

分析了完达山区域水平地带性和垂直地带性的森林特征,并对该林区不同区域分布的不同森林类型进行了评价。     

廊道景观边缘效应研究

运用景观生态学原理,依据绿色廊道的生态功能,对长沙市廊道景观边缘和内部的主要植物种类及其重要值进行了调查和分析。结果表明:在同一条件下,廊道景观边缘植物种类多于内部植物种类。这可为长沙市廊道景观的生态建设提供参考依据。     

Responses of stream macroinvertebrate communities to progressive forest harvesting: Influences of harvest intensity,stream size and riparian buffers

Harvesting of forests causes a range of disturbances, including changes to hydrology, nutrient inputs, water quality, food sources, habitat structure and channel morphology, which can impact streams over several years and are reflected in changes in community structure. We aimed to determine the relative magnitudes of impact and rates of recovery of benthic macroinvertebrate communities, and associated changes in biotic indices (Quantitative Macroinvertebrate Community Index and an Index of Biotic Integrity), in reaches of different sized streams within progressively logged catchments. We conducted annual summer surveys over seventeen years in fifteen New Zealand streams that differed in size (upstream catchment area between 40 and 2360 ha, mean channel widths between 2.5 and 16 m) and harvest intensity in the surrounding catchment. The largest post-harvest changes in biotic indices and community structures occurred in streams draining relatively small to medium catchments (<500 ha) where >40% of the upstream catchment had been harvested, and particularly after harvesting of overstorey riparian vegetation adjacent to study reaches. The impacts of harvest on invertebrate communities were less evident in wider streams draining catchments over 500 ha, but the largest changes from pre-harvest biotic indices and community structure still generally occurred after harvesting of riparian vegetation along these streams. The changes in community structure after harvesting of riparian vegetation typically included increases in the densities of Diptera, Mollusca and Oligochaetes, and decreases in the densities of Ephemeroptera. These results demonstrate that impacts on benthic macroinvertebrate communities increased as the proportion of upstream catchment harvested increased and/or after riparian vegetation was harvested. Some of the communities in headwater streams had largely recovered towards pre-harvest structures, whereas post-harvest recovery was less evident in relatively large streams, over the duration of the study.     

Structural diversity of forest communities on Baihuashan Mountain, Beijing

The structural diversity of forests on Baihuashan Mountain, Beijing, was surveyed by a plotless method combined with branch and leaf coverage estimation in the different layers. New structural indices were constructed, calculated and compared among different communities. On the basis of previous work, structural diversity of forest communities at the stand level was described by a vertical complexity index and a horizontal heterogeneity index. From a correlational analysis among the new indices and other commonly used biodiversity indices, we concluded that the new indices are closely related to a tree height inequality index and the Shannon-Wiener index of the tree and shrub layer, which indicated that the new indices were good at indicating structural diversity in the different forests on Baihuashan Mountain. The results show that, in natural forests, structural diversity of pioneer communities is much lower than in late successive communities. In plantations, structural diversity is determined by the stage of development and tree species. Tending would increase horizontal heterogeneity and decrease vertical complexity. __________ Translated from Journal of Beijing Forestry University, 2007, 29(1): 7–13 [译自: 北京林业大学学报]     

杨树人工林边缘效应的初步研究

对3930杨树人工林边缘效应的一系列研究表明杨树人工林边缘效应显著。杨树人工林的边缘效应率达1.26,边缘效应深度达林内30 m,边缘部分杨树的光合速率明显高于林内,多出108.6%。对杨树人工林土壤养分含量的测定显示,土壤养分含量随着边缘的深度不断深入,表现为先降低后增高,并随着边缘深度的增加,升高的趋势逐渐变缓。     

不同干扰程度对常绿阔叶林迹地群落结构的影响

对常绿阔叶林迹地，选择了微干扰下形成的常绿阔叶林和持续干扰下形成的杉木林进行了比较研究。结果表明，微干扰下形成的常绿阔叶林在高生长，径级生长以及物种多样性方面均优于持续干扰下形成的杉木林，而且在林木生长方面也优于后者。说明在植被恢复过程中，应立足于生态学的思想，从整体出发观察森林，力求利用森林生态系统所发生的自然过程。把生态与经济最合理的结合起来，实现一种近自然的森林经营模式。     

掌上电脑PDA在森林资源二类调查中的应用

根据PDA的综合性能,对其在森林资源二类调查中的具体运用进行了探讨。     

退耕还林不同人工林类型对土壤养分的影响

对内蒙古敖汉旗2006年退耕还林的樟子松纯林、山杏纯林、山杏沙棘混交林和荒草地（对照）不同深度的土壤养分状况进行研究,结果表明：3种人工林的土壤有机质和碱解氮含量明显增加,山杏沙棘混交林中沙棘林带表层的速效磷含量明显增加,山杏纯林浅层的速效钾含量明显增加;3种人工林和荒草地的土壤养分随着土壤深度的增加而降低,表层土壤养分条件较好,说明土壤养分具有很强的表聚性;3种人工林与荒草地相比都不同程度地提高了土壤养分水平,樟子松纯林和山杏沙棘混交林中沙棘林带的土壤养分条件较好.     

安徽岭南森林群落物种多样性的研究

在安徽岭南自然保护区内4种群落类型中进行样地调查的基础上,采用物种丰富度指数、多样性指数、均匀度指数对保护区森林群落物种多样性进行了研究,发现自然恢复的群落中植物种类多,分布均匀,优势种不明显;人工更新的林分中植物多样性低,优势种明显;群落结构上,4种类型多样性的大小顺序是灌木>乔木>草本。     

泡桐幼龄林配方施肥的初步研究

在测定土壤平衡解析磷和土壤钾位缓冲容量的基础上,根据林木施肥立地养分效应模型法,结合泡桐林的目标产量,提出了中等立地条件下白花泡桐幼龄林的施肥量,并进行了田间肥效校验试验研究。肥效校验试验共设计6个处理,即Ⅰ(N1P1K1)、Ⅱ(N2P2K2)、Ⅲ(N3P3K3)、Ⅳ(N4P4K4)、Ⅴ(N5P5K5)、Ⅵ(CK),3次重复。研究结果表明:不同施肥处理对泡桐幼龄林的胸径和树高增长均有显著性影响,区组间无显著差异。LSD多重比较检验后得出,施肥第一年后,处理Ⅲ对白花泡桐幼龄林的胸径增长效果最显著,但对树高增长的影响没有达到显著水平。施肥第二年后,处理Ⅳ对胸径增长效果最显著。而从树高的增长来看,处理Ⅱ的增长效果最佳。综合考虑,泡桐幼林生长最佳的N、P、K施肥量及最佳配比为Ⅲ(N3P3K3)。     

On the influence of windward edge structure and stand density on the flow characteristics at forest edges

Experimental investigations in an atmospheric boundary layer wind tunnel were carried out in order to study both the influence of the windward edge structure and the stand density on the flow characteristics near the canopy top of forest edges. For the edge structure investigation, two different types of forest edges were used. The taper angle was varied three times for both edge types, and all tapered edges were combined with both dense and sparse forest stands. In addition, a configuration was investigated where the airflow in the trunk space of the dense forest was blocked completely by an impermeable wall. In order to study the influence of stand density, forest stands were varied three times by removing whole rows of the originally dense model forest. The measurements show that a forest edge induces strong disturbances in the flow field at the near-edge region leading to an increased momentum transfer and to an increased wind loading on trees. The region of significant disturbances extends to a distance of about eight tree heights. Both edge density and taper angle determine the amount of volume influx through the edge, which seems to be primarily responsible for the flow field properties near the canopy top. It was found that for sparse forest stands, sloping tapered edges reduce the wind velocities nearest to the canopy. It could also be shown that the positive skewness of the near-canopy longitudinal velocity distribution is diminished with decreasing taper angle indicating that higher wind velocity fluctuations are reduced.