Young Conifer Forests Research Articles

UAV or satellites? How to find the balance between efficiency and accuracy in above ground biomass estimation of artificial young coniferous forest?

The accurate estimation of Above Ground Biomass (AGB) is the basis for plantation forest carbon trading. This study focused on Picea crassifolia artificial plantations, extracting individual tree crown diameters and heights using Unmanned Aerial Vehicles (UAV) data and calculating the individual tree biomass using allometric growth equations. These results were then used to train a satellite image AGB prediction model. In additional, satellite images were resampled to different resolutions to assess the impact of satellite image resolution on model the accuracy. Finally, the model with the highest accuracy among the deep learning algorithms was selected to predicts the AGB within the P. crassifolia plantation forest. The results indicated that the accuracy of single tree crown diameters extracted from P. crassifolia point clouds significantly surpassed those extracted from general point clouds and Crown Height Model (CHM), while the accuracy of the heights extracted from all three sources was similar; RepLKNet outperformed GoogLeNet and ResNet in identifying plantation forest; random forest slightly outperformed XGBoost in the capability of AGB prediction, while the accuracy of the AGB prediction models initially increasd and then decreasd with satellite image resolution, reaching the highest accuracy at a resolution of 50 m. This indicates that the optimal satellite image resolution for estimating the AGB in the study area was affected by scale effects of 50 m. Compared with the combination of satellite data and manual field measurements, the concurrent use of UAVs and satellites offers significant advantages in terms of efficiency and accuracy. UAVs can replace manual sampling for carbon sequestration transactions for plantations.

Resilience changes of carbon stocks to quantify the long‐term effects of ecological engineering projects in subtropical forests of China based on satellite‐derived net ecosystem production time series and inventory data

AbstractUnderstanding how resilient forests are to ecological engineering projects (EEPs) is essential to forest management and ecosystem health. Despite growing evidence that EEPs achieve increasing carbon stocks, whether such benefits can be sustainable and what are the consequences of EEPs on forest health remain unclear. This study aimed to investigate the long‐term effects of EEPs using forest resilience from aspects of resistance and recovery, by applying a change detection algorithm (breaks for additive seasonal and trend; BFAST) spatially on net ecosystem production (NEP) (proxy for carbon stocks) time series (1981–2019) in red soil hilly region (RSHR) of subtropical China. The spatial parameters (e.g., the number, magnitude, and time of changes) used to construct resilience metrics were generated based on BFAST‐derived breakpoints. These metrics were then utilized to analyze the dynamics of forest resilience in relation to EEPs factors in terms of plantation area, forest type, and stand age. Our results observed 92.77% of breakpoints in NEP after 2000, which corresponds well with the periods that multiple EEPs were conducted. NEP resilience showed great variability during 2001–2019, with a positive increasing trend in resistance (R2 = 0.72) and a continuous decline (R2 = 0.37) in recovery, indicating an unhealthy ecosystem in RSHR. Our findings revealed that forest resistance was strongly associated with plantation area (R = 0.71), and the presence of monoculture and young coniferous forest may be the potential factors for the decline in recovery. This suggested that forest resilience in RSHR is mainly modulated by large‐scale EEPs.

Long-term effects on water chemistry and macroinvertebrates of selective thinning along small boreal forest streams

The maintenance of narrow strips of trees (forest buffers) along the shorelines of surface water bodies during logging is a common measure to protect freshwater habitats. The functionality of forest buffers may be improved by actively managing the streamside forest early in the rotation for their eventual function as buffers, including by increasing the proportion of broadleaf trees in spruce-dominated stands. In this study, long-term effects of different selective thinning regimes along two small forest streams were investigated in south-central Sweden. In a young coniferous forest, a c. 10 m-wide band along the streams was selectively thinned in 1998 to create a band with purely broadleaf trees along one of the streams and purely conifers along the other. Forest stand characteristics, water chemistry and benthic macroinvertebrates data were collected during 1996–2003 (before and after selective thinning). The streams were re-investigated 20–22 years after thinning, together with three streams representing operational forest management. The forest adjacent to all five streams was inventoried and litterfall, stream water chemistry, and benthic macroinvertebrates composition were monitored between spring and late autumn during 2018–2020. Twenty years after thinning, the thinned bands beside the streams were still dominated by either broadleaf trees or conifers, depending on the stream. Over the longer term, the differences in water chemistry between the streams with selective thinning were mainly related to lower pH, ANC, Tot-P and Tot-N concentrations in the stream bordered by mainly broadleaf trees. Analysis of benthic macroinvertebrates was based on environmental quality indices (ASPT and EPT), diversity and abundance metrics, and relative abundances of functional feeding groups. Streams with higher broadleaf litter inputs tended to score better on the ASPT and EPT indices than those with lower broadleaf inputs, as well as supporting higher relative abundances of one or more groups of invertebrate detritivores (leaf shredders, collector-gatherers and/or passive filter feeders). This suggests that management of the density of broadleaf trees beside these streams might support higher ecological status and will support a greater proportion of detritivores in benthic food webs.

The Consequential Role of Aesthetics in Forest Fuels Reduction Propensities: Diverse Landowners’ Attitudes and Responses to Project Types, Risks, Costs, and Habitat Benefits

Private landowners in the southern Willamette Valley of Oregon, USA were surveyed. The survey queried probabilities of implementing specific fuels reduction projects in extensive areas of specific forest types on their property. The projects were described in relation to the beginning and target forest types, the actions required, costs, and long-term maintenance. Forest types were first rated for scenic beauty and informed levels of wildfire risk reduction, scarce habitat production, and associated property rights risks. Propensities to perform each fuels reduction project were then obtained. These were adversely affected by disbelief in heightened wildfire risks or climate change, higher project costs, feelings of hopeless vulnerability to wildfire, and low aesthetic affections for target forests. Propensities were enhanced by aesthetic affection for target forests, belief in the efficaciousness of fuels reduction, previous experience with wildfire evacuation, and higher incomes. All landowners favored thinning of young conifer forests, but some were averse to thinning of mature conifer forests. Anthropocentric landowners, mainly farmers, foresters, and some small holders, tended to favor conventional thinnings toward commercially valuable conifer forests and avoided long-term habitat maintenance. Nature-centric landowners, mainly some rural residents and wealthy estate owners, leaned more toward long term habitat goals and oak forests.

Landscape and temporal influences on the winter diet of a threatened diurnal raptor, the Hen Harrier Circus cyaneus

ABSTRACT Capsule Habitat composition plays a key role in determining the winter diet of the Hen Harrier Circus cyaneus, which varies across the winter season and between years. Aims To determine the winter diet of the Hen Harrier and examine temporal and spatial variations in diet composition. Methods A total of 1117 Hen Harrier pellets were collected from 11 winter roosts between 2017 and 2021 in Ireland. Results Hen Harrier winter diet was dominated by avian prey (95.9% of pellets), with mammalian prey found in 12.0% of pellets. The occurrence of small birds and small mammals in the diet was positively associated with the proportion of arable, wild bird cover, and low-intensity agriculture around the roost sites. The frequency of medium-sized birds (primarily Redwing Turdus iliacus and Common Snipe Gallinago gallinago) in the diet was positively associated with the proportion of bog and young conifer forests surrounding roost sites. Diet varied across regions, with pellets from roosts in lowland coastal areas having a greater prevalence of small birds and small mammals, and pellets from roosts in upland areas having a greater prevalence of medium-sized birds. The proportion of medium-sized birds in the diet changed across months, with that of small birds and small mammals remaining stable. There was also variation between winters in the proportion of small- and medium-sized birds in the diet. Conclusions Habitat, along with region and time, are important drivers of variation in Hen Harrier diet. Our findings highlight the opportunity for the enhancement of Hen Harrier habitat through land management, and can be used to inform effective conservation strategies for wintering Hen Harriers at a landscape scale.

The recent expansion of Fox Sparrow (Passerella iliaca iliaca) breeding range into the northeastern United States.

The breeding range of the Eastern Fox Sparrow (Passerella iliaca iliaca) is generally recognized as comprising the boreal forest of Canada. However, recent observations suggest that the species is present during the summer months throughout much of the northeastern US, unexpected for a species characterized as a passage migrant in the region. To clarify, I conducted a literature review to document the historical status of the species in the northeastern US and then analyzed observations submitted to eBird to describe its recent and current status in the region. Historical accounts consistently identify Fox Sparrow as a passage migrant through the region during early spring and late fall. Beginning in the early 1980s, observers began noting regular extralimital records of Fox Sparrow in northern Maine. A single nest was discovered in the state in 1983, and another in northern New Hampshire in 1997. Despite the paucity of breeding records, observations submitted to eBird suggest that the southern limit of the breeding range of Fox Sparrow has expanded rapidly to the south and west in recent years. The proportion of complete checklists submitted to eBird that contained at least one observation of Fox Sparrow grew at an annual rate of 18% from 2003–2016 and was independent of observer effort. Fox Sparrow now occurs regularly on mountaintops and in young stands of spruce (Picea spp.) and balsam fir (Abies balsamea) during the breeding season throughout northern and western Maine and northern New Hampshire, with occasional records from the Green Mountains of Vermont and the Adirondack Mountains of New York. The cause of this rapid expansion of its breeding range is unknown, but may be related to an increase in the amount of young conifer forest in the northeastern US created by commercial timber harvest.

山西忻州地区1900-2012年典型森林的健康历史

PDF HTML阅读 XML下载 导出引用 引用提醒 山西忻州地区1900-2012年典型森林的健康历史 DOI: 10.5846/stxb201612222650 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31330015） History of forest health from 1900 to 2012 in Xinzhou Prefecture, Shanxi Province, China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:健康的森林对维持其区域生态系统服务起着至关重要的作用，了解树木的生长历史对评估气候变化背景下森林的健康状况具有促进作用。选择山西高原中北部忻州地区保存较好的4个森林为研究对象，利用树木年轮学方法分析其生长变化特征，获得了该地区森林健康的时间和空间特征。结果表明：该地区森林在过去1个世纪中，存在3次不健康事件（1910-1940、1970-1987和1990-2012年）且在空间上表现出明显的同步性，不同时期的不健康事件持续时间和强度不尽相同，1930s的不健康事件持续时间最长也最为显着。树木径向生长与气象观测资料的相关分析显示，该地区森林生长主要与当年5-6月份温度呈负相关，与7月份降水和5-9月PDSI指数显着正相关。生长季持续的高温或降水减少造成的极端干旱事件是不健康事件空间一致性的主要驱动力，各采样点树种以及林分组成差异是影响时间特征不一致的可能原因。研究结果提供的森林健康历史数据对评估极端气候条件对森林健康生长的影响及制定合理的森林保护措施具有积极的现实意义。 Abstract:Forest health is a serious problem worldwide. Knowledge of the intensity and causes of rapidly declining forests is important for managing various forest types under the scenario of climate change. In the present study, we report on the health conditions of four young conifer forests by applying dendrochronological techniques to measure unexpected growth decline in Xinzhou District, northern Shanxi Plateau. A total of 86 samples in the form of increment cores were obtained from the study sites. The widths of tree-rings from all the samples were measured and cross-dated, then each individual tree series was standardized to identify health conditions using spatial characteristics of temporal growth. We defined unhealthy tree growth intervals as being a decrease in the growth of the individual (tree-ring index < 0.9) for at least five years when the mean tree-ring index was less than 0.7 and at least one year of tree-ring index values reached a minimum of 0.5. We calculated the percentage of trees that were unhealthy in each year, and defined an unhealthy event for the site if greater than 30% of the trees were in decline. We found three major unexpected decline growth events in the majority of individual trees in the four forests, these being 1910-1940, 1970-1987, and 1990-2012. However, the growth declines in each forest showed deviations in intensity and duration such as declines were more vigorous in the KeLan forest during the 1930s than in the other forests. To better understand the causes of the unhealthy events, a correlation analysis was performed for the three tree ring width chronologies and the meteorological records. The correlation coefficients showed that forest growth was negatively associated with May-June temperatures. However, precipitation revealed positive correlation in July and the Palmer Drought Severity Index showed positive correlation over the growing season of May-September. To validate these results, we compared our study with historical records and local paleoclimate studies. The drought events recorded in the historical documents and other paleoclimate reconstructions reasonably matched our results. These results suggest that extreme drought events caused by persistent high temperature or reduction of precipitation in the growing season are the main driving factors for radial growth decreases in trees, which was the main reason for the spatial coherence of unhealthy events. The differentiation of local stand characteristics or tree species might play a role in the inconsistency of the time characteristics. Therefore, the present study provides useful information for forest health, which has positive and realistic significance for assessing the impact of extreme climatic conditions on the healthy growth of forests and for developing reasonable forest protection measures. 参考文献 相似文献 引证文献

Evaluating harvest costs and profit of commercial thinnings in softwood stands in west-central Maine: A case study

Precommercial thinning (PCT) is a common silvicultural treatment in the management of young conifer forests. The positive effects of PCT on tree growth are well documented, however, there have been few operational studies of thinning productivity associated with later harvests in such stands and associated cost comparison with high-density, small-diameter stands. In the winters of 2012/2013 and 2013/2014 a long-term herbicide and PCT study in west-central Maine was commercially thinned using cut-to-length (CTL) and whole-tree (WT) harvesting systems in PCT and non-PCT stands, respectively. Thinning prescriptions consisted of three nominal removal intensities (33%, 50%, and 66% of the standing softwood volume) in a randomized block design with three to four replications. Stand density, basal area, hardwood content, and removal intensity were not significant in explaining variation in harvester and feller-buncher productivity. An analysis of unit cost of production indicated that wood chip production using a WT system in non-PCT stands is less costly than the production of roundwood using a CTL system in PCT stands. Profit, however, is similar for products harvested by either system. Our conclusion is that the WT system used in the study is economically feasible to treat highdensity, small-diameter stands in a commercial thinning.

Resting site selection by large herbivores – The case of European bison (Bison bonasus) in Białowieża Primeval Forest

Resting site selection by European bison (Bison bonasus, L., 1758), the largest terrestrial mammal of Europe, was studied in the free-ranging population in Białowieża Primeval Forest (Poland) in 2009–2010. In total, 104 sites of 21 bison (both collared and uncollared) were analysed to determine the most important microhabitat characteristics selected by resting bison during summer and winter and to study the influence of supplementary feeding on resting behaviour of this herbivore. Resting sites were identified on the basis of GPS locations and activity records collected by GPS collars, as well as direct observations of bison, and were compared with control sites. Microhabitat selection by bison did not differ significantly between the sexes. During summer and winter, bison resting sites displayed a high tree density, low visibility and high complexity (structures providing cover). Summer resting sites were also characterised by a significantly lower abundance of blood-sucking insects and denser canopy than control sites. Winter resting sites showed a lower complexity and higher visibility than summer sites, and were less often located in mixed forest habitats. During winter, bison rested more frequently in forest below 50 years of age than in older forest. Resting sites of non-fed bison were more often located in young coniferous forests, were lower in visibility and situated closer to open areas than sites of bison using supplementary winter feeding, suggesting a trade-off between food and cover. The results indicate that European bison select their resting sites in areas of mosaic habitat structure providing cover from disturbances with access to profitable natural forage grounds.

Functional connectivity of lynx at their southern range periphery in Ontario, Canada

Peripheral populations are often small and isolated compared to those in the range core, in part due to the patchy distribution of suitable habitats at range margins. It follows that peripheral populations typically occur at lower densities and are more susceptible to extinction, but their persistence may be facilitated through connectivity with core areas. Relationships between connectivity and the distribution of animal populations have not yet been fully evaluated, especially for large carnivores having extensive spatial needs and specialized habitat requirements. Using observations of snow tracks, we modeled occurrence of Canada lynx (Lynx canadensis) in relation to landscape characteristics along their southern range periphery in Ontario, Canada; we sought to assess functional connectivity of lynx habitat along the southern margins of the range. As observed in other studies, young coniferous forests had the highest probability of lynx occurrence, likely due to their association with snowshoe hares (Lepus americanus). We used the occurrence model to parameterize a resistance surface and then circuit theory to predict functional connectivity along the southern periphery of lynx distribution. Lynx typically travelled through landscapes with higher connectivity than random paths, implying that lynx habitat requirements in their southern range likely extend beyond habitat composition, and that conservation efforts should seek to preserve metapopulation dynamics through functional connectivity of suitable habitat across larger spatial scales.

Long-term responses of mammalian herbivores to stand thinning and fertilization in young lodgepole pine (Pinus contortavar.latifolia) forest

Snowshoe hares (Lepus americanus Exrleben, 1777), mule deer (Odocoileus hemionus (Rafinesque, 1817)), and moose (Alces alces (L., 1758)) commonly occur in young coniferous forests. This study was designed to test the hypothesis that large-scale pre-commercial thinning (PCT) and repeated fertilization 15–20 years after the onset of treatments in young lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Wats.) stands would enhance relative habitat use by hares, deer, and moose compared with unmanaged stands. Study areas were located in south-central British Columbia, Canada. Habitat use was measured by fecal pellet and pellet-group counts. Understory vegetation and coniferous stand structure were measured in all stands. Habitat use by deer and moose was highest in heavily thinned stands, probably due to the higher levels of forage and cover provided by understory shrubs and conifers in thinned stands. Habitat use by snowshoe hares was highest in high-density stands, but also in lower-density (≤1000 stems·ha–1) stands where an increase in understory conifers provided essential cover for hares. Managers should consider the long-term nature of understory development in young stands managed for timber production. Heavy thinning (≤1000 stems·ha–1) will generate suitable understory habitat for these herbivores sooner than conventional PCT at higher stand densities.

Analysis of Elevation Changes Detected from Multi-Temporal LiDAR Surveys in Forested Landslide Terrain in Western Oregon

Research Article| November 01, 2010 Analysis of Elevation Changes Detected from Multi-Temporal LiDAR Surveys in Forested Landslide Terrain in Western Oregon WILLIAM J BURNS; WILLIAM J BURNS 1Oregon Department of Geology and Mineral Industries, 800 NE Oregon Street, Portland, OR 97232 Search for other works by this author on: GSW Google Scholar JEFFREY A COE; JEFFREY A COE 2U.S. Geological Survey, Denver Federal Center, Mail Stop 966, Denver, CO 80225 Search for other works by this author on: GSW Google Scholar BASAK SENER KAYA; BASAK SENER KAYA 3Colorado School of Mines, Division of Engineering, Golden, CO 80401 Search for other works by this author on: GSW Google Scholar LINA MA LINA MA 4Oregon Department of Geology and Mineral Industries, 800 NE Oregon Street, Portland, OR 97232 Search for other works by this author on: GSW Google Scholar Author and Article Information WILLIAM J BURNS 1Oregon Department of Geology and Mineral Industries, 800 NE Oregon Street, Portland, OR 97232 JEFFREY A COE 2U.S. Geological Survey, Denver Federal Center, Mail Stop 966, Denver, CO 80225 BASAK SENER KAYA 3Colorado School of Mines, Division of Engineering, Golden, CO 80401 LINA MA 4Oregon Department of Geology and Mineral Industries, 800 NE Oregon Street, Portland, OR 97232 Publisher: Association of Environmental & Engineering Geologists First Online: 02 Mar 2017 Online ISSN: 1558-9161 Print ISSN: 1078-7275 Copyright © 2010 EEGS Environmental & Engineering Geoscience (2010) 16 (4): 315–341. https://doi.org/10.2113/gseegeosci.16.4.315 Article history First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation WILLIAM J BURNS, JEFFREY A COE, BASAK SENER KAYA, LINA MA; Analysis of Elevation Changes Detected from Multi-Temporal LiDAR Surveys in Forested Landslide Terrain in Western Oregon. Environmental & Engineering Geoscience 2010;; 16 (4): 315–341. doi: https://doi.org/10.2113/gseegeosci.16.4.315 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyEnvironmental & Engineering Geoscience Search Advanced Search Abstract We examined elevation changes detected from two successive sets of Light Detection and Ranging (LiDAR) data in the northern Coast Range of Oregon. The first set of LiDAR data was acquired during leaf-on conditions and the second set during leaf-off conditions. We were able to successfully identify and map active landslides using a differential digital elevation model (DEM) created from the two LiDAR data sets, but this required the use of thresholds (0.50 and 0.75 m) to remove noise from the differential elevation data, visual pattern recognition of landslide-induced elevation changes, and supplemental QuickBird satellite imagery. After mapping, we field-verified 88 percent of the landslides that we had mapped with high confidence, but we could not detect active landslides with elevation changes of less than 0.50 m. Volumetric calculations showed that a total of about 18,100 m3 of material was missing from landslide areas, probably as a result of systematic negative elevation errors in the differential DEM and as a result of removal of material by erosion and transport. We also examined the accuracies of 285 leaf-off LiDAR elevations at four landslide sites using Global Positioning System and total station surveys. A comparison of LiDAR and survey data indicated an overall root mean square error of 0.50 m, a maximum error of 2.21 m, and a systematic error of 0.09 m. LiDAR ground-point densities were lowest in areas with young conifer forests and deciduous vegetation, which resulted in extensive interpolations of elevations in the leaf-on, bare-earth DEM. For optimal use of multi-temporal LiDAR data in forested areas, we recommend that all data sets be flown during leaf-off seasons. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Herb establishment in a young Pseudotsuga menziesii forest: a seven-year seed addition experiment1

The abundance of old-growth associated herbs in young Pseudotsuga menziesii forests is limited in part by the low availability of propagules of these species, but it remains unclear whether the slow post-logging development of old-growth species in younger forests also reflects a lack of microhabitats suitable for seed germination. This study attempts to fill an almost total lack of knowledge about germination of understory species in second-growth Douglas-fir forests, and in young coniferous forests in general, while providing a preliminary exploration of the relative importance of these two limiting factors. The ability of six common forest herbs to germinate in a 40-year-old Pseudotsuga menziesii stand was tested, and survival and growth were monitored for seven years. Five of the six species germinated well (8–50% germination), while one open-site species failed to germinate. After seven years, survival of four old-growth associated species was ∼10% (of the original seed number), while only 1% of seeds of a disturbance-adapted species were still present as seedlings. For all species, seedlings grew slowly and did not reach reproductive size, forming a seedling bank analogous to that of shade-tolerant tree seedlings. All old-growth associated species showed higher overall seedling numbers or greater survival in gaps than in non-gap microsites, and two species showed higher survival in the more mesic lower part of the watershed. Naturally occurring seedlings were rare and included only easily dispersed species that are forest generalists or characteristic of mature, but not of old-growth forests. I conclude that germination of late-seral herb species in young Pseudotsuga menziesii forests is not strictly microsite limited, but that these species are instead limited by a combination of low propagule availability and low resource levels with concomitant slow growth rates.

Physiological effects of forest recreation in a young conifer forest in Hinokage Town, Japan

It is widely believed that coming into contact with forest environments is somehow beneficial to human well-being and comfort. In Japan, “Shinrin-yoku” (taking in the atmosphere of a forest) has been proposed to be a relaxation activity associated with forest recreation. The purpose of this study was to examine the physiological effects of forest recreation on the autonomic nervous activity. The subjects were twelve male university students (21.8 ± 0.8 years old). On the first day of the experiment, six subjects were sent to a forest area, and the other six to a city area. On the second day, each subject was sent to the area he did not visit on the first day as a cross check. The subjects walked (15 minutes) around their assigned areas before noon, and sat on chairs viewing (15 minutes) the landscapes of their assigned areas in the afternoon. Heart rate variability (HRV), blood pressure, and pulse rate were measured as physiological indices. Measurements were taken at the place of accommodation in the morning, before and after walking, and before and after viewing at their assigned field areas. Pulse rate, diastolic blood pressure and LF/(LF+HF) (LF – low frequency, HF – high frequency) components of HRV were significantly lower in the forest area than in the city area. HF components of HRV tended to be higher in the forest than in the city. In conclusion, the results of the physiological measurements show that forest recreation enabled effective relaxation in people, both of the mind and body.

Education and advice contribute to increased density of broadleaved conservation trees, but not saplings, in young forest in Sweden

The effectiveness of different conservation policies is debated, but the policies are rarely evaluated quantitatively. A voluntary or ‘soft’ policy based mainly on education provides information about ecosystems and effects of land use, to encourage conservation action. Swedish forestry relies mainly on soft policy, with substantial resources for education and advice to more than 200,000 forest owners, while legal regulation is weak. Increased retention of broadleaved trees at clear-cutting, with environmental benefits in the conifer-dominated forestry, is important in the policy. We used the Swedish National Forest Inventory to analyse this policy for young forests in southern Sweden. Between 1983–1987 and 1998–2002 the policy had no positive effect on saplings (1.3 m tall to 4.9 cm dbh) of birch, oak, beech and other species that mostly decreased in density, due to planting of conifers and browsing by ungulates. However, broadleaved conservation trees (≥15 cm dbh) increased in density, e.g. to about one oak and six birches per ha in young coniferous forest in 1998–2002. The relative increase in density was higher for large (≥20 cm dbh) than for small trees (15–20 cm dbh). The density of conservation trees was higher on forestland of high than of low productivity. Thus, the soft conservation policy did not influence regeneration of saplings in this type of forestry system, but large broadleaved trees were increasingly saved at ‘clear-cuttings’. Advice and educational programmes probably contributed to this result. A continued increase in conservation trees at harvest may require economical support to forest owners.

Do coniferous forests evaporate more water than broad-leaved forests in Japan?

Summary It is a commonly held belief in Japan, based on a US case study, that coniferous forests evaporate more water than broad-leaved forests. If this is true, converting coniferous forests into broad-leaved forests would result in an increased water yield. However, it is not known whether the US case study is applicable to Japanese forests. A simple model was developed to calculate annual forest evapotranspiration E based on the review of 67 dry-canopy and 16 wet-canopy evaporation studies. We calculated the E values for broad-leaved and coniferous forests under meteorological conditions found in Japan. E of broad-leaved forests was approximately the same as E of young coniferous forests and higher than E of old coniferous forests. The results predicted by the model were supported by water balance data from three Japanese experimental catchments. The conclusion from the data is that coniferous forests do not evaporate more water than broadleaved forests in Japan. a 2007 Elsevier B.V. All rights reserved.

A new feller-buncher for harvesting energy wood: Results from a European test programme

In recent years, some manufacturers have developed new downsized feller-bunchers that are particularly suited to small-tree harvesting. One of these machines was tested in some of the most promising small tree resources of Europe, namely: Finnish young conifer forests, French hornbeam coppice and Italian sycamore plantations. The tests were conducted within the scope of a 3-year long European project, whose goal was to assess the suitability of this new technology to the production of wood biomass from silvicultural operations. Depending on site characteristics, the machine reached an average productivity between 4 and 8 green tonnes per net working hour, comparing favourably with other European shear-type felling heads and qualifying for deployment on a European scale.

The Spatial-temporal Dynamics Analysis of Landscape Pattern and Process in Watershed Scale:a Case Study of 1977-2000 in Siletz Basin, Oregon

在集水区尺度利用景观生态学的原理进行分析和管理是现代生态学与地理科学的一个重要课题.在人口增长和经济发展的压力下,集水区的格局和过程己受到人类活动越来越强烈地干扰.赛勒支盆地是一个典型的美国太平洋西北部沿海地区的集水区,本文以此为例,研宄了美国俄勒冈州中部集水区尺度的景观格局和过程在人类活动干扰下的时空动态.通过卫星遥感影像的应用,我们对1977年到2000年间赛勒支盆地土地覆盖的变化进行了检测.我们用陆地资源卫星1977年的多光谱影像(MSS), 1988年的专题影像(TM)' 2000年的增强专题影像(ETM+)高精度地定量分析了森林演替系列(如,演替后期的老针叶林和成熟针叶林,演替前期的年轻针叶林,以及更新的幼林）和其它土地覆盖类型的变化.景观的空间格局通过多种格局指数,例如,缀块指数、缀块形状复杂性指数、以及连接指数等进行了分析.同时,基于美国太平洋西北部主要森林类型和其它土地覆盖类型碳通量和碳贮量的空间数据库和文献资料,我们对 1977-2000年赛勒支盆地中的碳库及其在人类活动干扰下的变化作了测定.研宄结果揭示出,因为森林皆伐,老针叶林和成熟针叶林在1977-2000年间显著地减少,分别由占整个盆地土地覆盖面积的23%和12%, 减少为12%和7%;与此相反,年轻针叶林和无林地则分别从24%和5%增加为43%和14%.同时,因为采伐等干扰,留存的老针叶林和成熟针叶林空间分布格局的破碎度也迅速增加.集水区的碳收支在 1977-2000期间发生了巨大的变化.在收获干扰的压力下,在1977-2000年间,整个集水区的生态系统碳贮量从 17640797t 减少到 13405720t;净生态系统生产力(Net Ecosystem Production, NEP)由每年 100462tC 减少为每年76800tC.;The landscape ecology applied in the analysis and management of watershed is an important issue in modem ecology and geography. Because the population growth and economic development, the pattern and process of watershed influenced strongly by human activity. In this paper, we discussed the spatial-temporal dynamics of landscape pattern and process in watershed scale in central Oregon. Siletz basin is a typical watershed in US Pacific Northwest. The land cover change of Siletz basin between 1977 to 2000 was determined through the satellite remote sensed data application. We used the Landsat MSS of 1977, Landsat TM of 1988 and Landsat ETM+ of 2000 imagery to quantified the forest succession serial (e.g. late serial old and mature conifer forests, early serial young conifer and regeneration forests) and other land covers with high accuracy. The spatial pattern of landscape was analyzed through the multiple pattern metrics, for example, patchiness indices, patch shape complexity indices, and connectivity indices. Based on the spatial databases and literature data, we parameterized the carbon fluxes and stocks information for the forest types and other lands in the US Pacific Northwest, and estimated the carbon fluxes and stock pools and the dynamics from 1977 to 2000 as the anthropogenic disturbance. We revealed the changes of land cover are significant from 1977 to 2000. The old conifer and mature conifer forests decreased quickly as the clearcut logging. In 1977-2000 periods, the percentage of old conifer and mature conifer area in entire Siletz basin from 23% and 12% decreased to 12% and 7%, respectively. In contrast, the young conifer forest and non-forest land from 24% and 5% increased to 43% and 14%, respectively. The fragmentation of old and mature conifer forest spatial pattern increased quickly as the harvest disturbance between 1977 and 2000. Carbon budget also was found changed significantly between 1977 and 2000. The ecosystem carbon pool decreased from 17640797t to 13405720 t, Net Ecosystem Production (NEP), an indicator of carbon sink and source, we found the pool of NEP had been changed from 100462 t/a to 76800 t/a between 1977 and 2000 as the land cover alternated by harvest disturbance.

Stand delineation and composition estimation using semi-automated individual tree crown analysis

Stand delineation and species composition estimation are cornerstones of forest inventory mapping and key elements to forest management decision making. Improved mapping techniques are constantly being sought in terms of speed, consistency, accuracy, level of detail, and overall effectiveness. Semi-automated analysis of high-resolution imagery at the individual tree crown level may offer such benefits. Methods, however, need to be developed and tested under a variety of forest conditions. High-resolution (60 cm) multispectral airborne imagery was acquired over a predominantly young conifer forest and plantation test area on the west coast of Canada. Automated tree isolation algorithms were applied to the data in order to delineate tree crowns or clusters of crowns. An object-oriented single tree classification was conducted using a maximum likelihood classifier. Stands of similar species composition, closure, and stem density were defined through a sequence that first generated images of these parameters from the automated delineation and classification, used these as input to an unsupervised classification, and then filtered and smoothed the resulting classification clusters. Because of the dense nature of the stands and small crowns on the site, the isolation process often delineated clusters of several trees. Species classification accuracy was determined by comparing the average stand composition from the automated technique to that derived from ground transects or plots. Species classification was good, with average composition error (difference between field measured and automated composition) over all 16 test stands being 7.25%. Most errors for individual species in stands were below 20%, but a few were up to 30%. The automatically generated stand boundaries mimicked well those of known plantation and interpreted inventory boundaries. The automated technique created a few larger stands and some additional small stands in areas of complex forest structure. Overall, for the young fairly uniform stands of the site, both stand delineation and species composition estimation were of a quality suitable for operational use in inventory and forest management. Further development and testing is needed to extend results to situations covering large areas, multiple flight lines, varied topography, and different forest conditions.

The growth potential of downy birch (Betula pubescens (Ehrh.)) in Ireland

Birch in Ireland has long been regarded a timber species of minor importance, and it is noted more often for its invasiveness in young coniferous forests and clearfelled areas than for its potential as a commercial forestry species. While research on other native hardwood species such as oak or ash has been ongoing for a number of years, very little is known about the Irish birch resource. The lack of quantitative data relating to height growth, diameter growth and volume increment of birch in this country is of particular concern. The objective of this study was to examine the growth potential of birch in Ireland. Following a field survey, eight well‐stocked, unthinned birch stands were selected for inclusion in the study. All of the selected stands were determined to be downy birch. Following analysis of sample tree disc sections, two stands were excluded (because of indistinct annual rings) and the study was restricted to the six remaining stands. A total of 100 sample trees were felled at the six sites. Tree ring data were collected from a total of 1333 sample tree disc sections. Using these ring data, the historic patterns of radial growth at breast height, height growth and volume growth of the six stands were reconstructed, examined and analysed in detail. The results showed that for well‐stocked, unthinned, even‐aged stands the period of maximum radial growth, and therefore diameter growth, occurred between the ages of 5 and 20 years. The fastest growing tree achieved a diameter of 25 cm in 32 years. It is suggested that for the stands included in this study, the lack of management, in particular the lack of adequate thinning, will have resulted in excessive crown competition and consequently reduced diameter growth. Maximum height increment occurred before the age of 20 years and fast growing trees achieved a height growth of > 1 m per year during this period. The results showed that a well‐stocked, unthinned downy birch stand can achieve a standing volume (under‐bark) of 200 m 3 ha −1 in 42 years. While some of the stands included in the study had not reached the age of maximum mean annual increment, comparison with the Forestry Commission yield models showed that stands of downy birch in Ireland can achieve a yield class of 8 and, given the correct thinning regime, total recovered volume production could possibly be raised to that equivalent with yield class 10.