Tree stand falls: A persistent cause of neurological injury in hunting

AIM: To characterize and compare our current series of patients to prior reports in order to identify any changes in the incidence of neurological injury related to hunting accidents in Rochester, New York.METHODS: All tree stand-related injuries referred to our regional trauma center from September 2003 through November 2011 were reviewed. Information was obtained from the hospital's trauma registry and medical records were retrospectively reviewed for data pertaining to the injuries.RESULTS: Fifty-four patients were identified. Ninetysix percent of patients were male with a mean age of 47.9 years(range 15-69). The mean Injury Severity Score was 12.53 ± 1.17(range 2-34). The average height of fall was 18.2 feet(range 4-40 feet). All patients fell to the ground with the exception of one who landed on rocks, and many hit the tree or branches on the way down. A reason for the fall was documented in only 13 patients, and included tree stand construction(3), loss of balance(3), falling asleep(3), structural failure(2), safety harness breakage(3) or lightheadedness(1). The most common injuries were spinal fractures(54%), most commonly in the cervical spine(69%), followed by the thoracic(38%) and lumbar(21%) spine. Eight patients required operative repair. Head injuries occurred in 22%. Other systemic injuries include rib/clavicular fractures(47%), pelvic fractures(11%), solid organ injury(23%), and pneumothorax or hemothorax(19%). No patient deaths were reported. The average hospital length of stay was 6.56 ± 1.07 d. Most patients were discharged home without(72%) or with(11%) services and 17% required rehabilitation. CONCLUSION: Falls from hunting tree stands are still common, with a high rate of neurological injury. Compared to a decade ago we have made no progress in preventing these neurological injuries, despite an increase in safety advances. Neurosurgeons must continue to advocate for increased safety awareness and participate in leadership roles to improve outcomes for hunters.

Effects of thinning on stand structure and tree stability in an afforested oriental beech(Fagus orientalis Lipsky) stand in northeast Turkey

We studied relationships between stand structure and stand stability according to thinning intensity in an afforested oriental beech stand. Various thinning intensities were applied in sample stands. We sampled eight plots in stands that were lightly thinned, eight plots in heavily thinned stands and eight plots in unthinned stands as a control. Height and diameter distributions of the stands were measured to assess stand structure. We quantified individual tree stability and collective stability. Heavy thinning during the first thinning operation damaged the storied structure of the stand in thicket stage and affected collective structuring ability. While most control plots had multi-storied stands, after light and heavy thinning two-storied structure became more common.Large gaps occurred in the canopy after heavy thinning. On average, nine tree collectives were formed per sampling plot in the untreated stand, seven collectives after thinning in 2008 and four collectives after thinning in 2009. Stable trees accounted for 17 % of trees in control plots, 24 % in lightly thinned plots, and 15 % in heavily thinned plots. Collective stability values were 83 % in control plots, 82 % in lightly thinned plots and 36 % in heavily thinned plots. We conclude that it is necessary to retain collective structuring capacity during thinning operations for sustaining stand stability.

Competition-density effect of tree organs in Acacia auriculiformis stands

The competition-density (C-D) effects for mean mass for tree, stem, branch and leaf were analyzed in Acacia auriculiformis stands. Mean tree mass-density and mean organ mass-density were well explained by the C-D equation of tree and the C-D equation of tree organ, respectively. An equation describing the relationship between mean leaf area u and density was formulated that fit the u-data well. The relationship between mean tree mass w and the ratio of each organ to mean tree mass (wo/ w) was examined. With increasing w, the stem mass ratio wS/w increased, whereas the branch mass ratio wB/w and the leaf mass ratio wL/w decreased. The yield difference between the lowest-density stand and the high-density stand became greater with stand growth. However, the yield of the mid-density stand was slightly lower than the yield of the high-density stand during the experimental period. To produce the most desirable combination of demanding individual-tree size and relative high stem yield, the mid-density is recommended as proper planting density for future management of A. auriculiformis stands.

STUDY ON THE TREE GROWTH, ARCHITECTURE AND STAND STRUCTURE OF KOREAN PINE PLANTATION

The artificial pure and mixed Korean pine (Pinus koraiensis) forests were investigated at Dailing Forestry Bureau in Xiaoxing'an mountains from 1990 to 1992. Depending on the distance between the samplings of Korean pine and their neighbor trees, the neighbor tree height, the size of neighbor tree canopy, and dimension of neighbor tree. The forest structure was classified into three types: (1) prowth of a tree in the light (open), (2) Growth of a tree in the canopy gap (Gap), (3)Growth of a tree under broad-leaved tree canopy. The frequeney, height, and age of stem divergence of Korean pine tree were investigated by sampling trees. The temporal and spatial model of the tree growth was applied on basis of the height of stem divergence, ratio of height and DBH, and character of tree stem.The morphology and growth character of Korean pine trees during different development stage were forecasted.

Tree species diversity and stand structure along major community types in lowland primary and secondary moist deciduous forests in Tripura,Northeast India

Tree species diversity and population structure at different community types were described and analyzed for primary and secondary lowland moist deciduous forests in Tripura. Overall 10,957 individual trees belonging to 46 family, 103 genera and 144 species were counted at ≥30 cm DBH （diameter at breast height） using 28 permanent belt transects with a size of 1 ha （10 m × 1000 m）. Four different tree communities were identified. The primary forests was dominated by Shorea robusta （mean density 464.77 trees.ha^-1, 105 species） and Schima wallichii （336.25 trees.ha^-1, 82 species）, while the secondary forests was dominated by Tectona grandis （333.88 trees.ha^-1, 105 species） and Hevea brasiliensis （299.67 trees.ha^-1, 82 species）. Overall mean basal area in this study was 18.01m2.ha^-1; the maximum value was recorded in primary Shorea forest （26.21 m2.ha^-1）. Mean density and diversity indices were differed significantly within four different communities. No significant differences were observed in number of species, genera, family and tree basal cover area. Significant relationships were found between the species richness and different tree population groups across the communities. Results revealed that species diversity and density were increased in those forests due to past disturbances which resulted in slow accumu- lation of native oligarchic small tree species. Seventeen species were recorded with 〈2 individuals of which Saraca asoka （Roxb.） de Wilde and Entada phaseoloides （L.） Men＇. etc. extensively used in local ethnomedicinal formulations. The present S. robusta Gaertn dominated forest was recorded richer （105 species） than other reported studies. Moraceae was found more speciose family instead of Papilionaceae and Euphorbiaceae than other Indian moist deciduous forests. Seasonal phenological gap in such moist deciduous forests influenced the population of Trachypithecus pileatus and capped langur. The analysis of FIV suggested a slow trend of shifting the population of Lamiaceae group by Moraceae species in secondary T. grandis L. dominated community.

Effects of the second-generation larch plantations onsoil fertility and tree growth

In order to realize the effect of second generation of larch plantations on soil fertility and tree growth and to provide the theoretical base and the reasonable management measures, the growth of larch plantations for different generations at different soil conditions were inventoried and compared. The relationship between soil nutrition and tree growth of the second-generation larch plantations was analyzed. Comparing with the first generation, the second generation of larch did not present acidation phenomenon on the dark brown soil. With respect to the organic matter, rapidly available K and N, the values of the second-generation larch is close to that of first generation at later time. Platform-preparation is good measures for improving soil conditions

Exploratory analysis of structural diversity indicators at stand level in three Italian beech sites and implications for sustainable forest management

The present study introduces an exploratory data analysis based on structural indicators with the aim to assess the effect of silvicultural practices on tree stand structure. The study was carried out in three Italian beech forests of different ages with stand structures that originated from dissimilar regeneration and cultivation techniques(Cansiglio, northern Italy, Chiarano, central Italy,and Mongiana, southern Italy). Ten structural indicators were considered when investigating the latent multivariate relationship between stand structure attributes before and after thinning operations by using a multiway factor analysis(MFA). The MFA results identified the older stand at Cansiglio as more homogeneous for cultivation regimes,and more stable to practices when compared with the younger sites(Chiarano and Mongiana). Heterogeneous stands were sensitive to silvicultural practice thus suggesting their possible impact on forest attributes. The proposed approach proved to be an operational tool to evaluate comprehensively the response of forest structure to planned interventions.

Stand structure and height-diameter relationship of a degraded Populus euphratica forest in the lower reaches of the Tarim River, Northwest China

Understanding stand structure and height-diameter relationship of trees provides very useful information to establish appropriate countermeasures for sustainable management of endangered forests. Populus euphratica, a dominant tree species along the Tarim River watershed, plays an irreplaceable role in the sustainable development of regional ecology, economy and society. However, as the result of climate changes and human activities, the natural riparian ecosystems within the whole river basin were degraded enormously, particularly in the lower reaches of the river where about 320 km of the riparian forests were either highly degraded or dead. In this study, we presented one of the main criteria for the assessment of vitality of P. euphrafica forests by estimating the defoliation level, and analyzed forest structure and determined the height-diameter （height means the height of a tree and diameter means the diameter at breast height （DBH） of a tree） relationship of trees in different vitality classes （i.e. healthy, good, medium, senesced, dying, dead and fallen）. Trees classified as healthy and good ac- counted for approximately 40% of all sample trees, while slightly and highly degraded trees took up nearly 60% of total sample trees. The values of TH （tree height） and DBH ranged from 0-19 m and 0-125 cm, respectively. Trees more than 15 m in TH and 60 cm in DBH appeared sporadically. Trees in different vitality classes had different distribution patterns. Healthy trees were mainly composed more of relatively younger trees than of degraded tress. The height-diameter relationships differed greatly among tress in different vitality classes, with the coefficients ranging from 0.1653 to 0.6942. Correlation coefficients of TH and DBH in healthy and good trees were higher than those in trees of other vitality classes. The correlation between TH and DBH decreased with the decline of tree vitality. Our results suggested that it might be able to differentiate degraded P. euphratica trees from healthy trees by determining the height-diameter correlation coefficient, and the coefficient would be a new parameter for detecting degradation and assessing sustainable management of floodplain forests in arid regions. In addition, tree vitality should be taken into account to make an accurate height-diameter model for tree height prediction.

Late-entry commercial thinning effects on Pinus banksiana:growth, yield, and stand dynamics in Québec, Canada

We studied late-entry commercial thinning effects on growth, yield, and regeneration in a 48-year-old jack pine(Pinus banksiana Lamb.) stand. Applied thinning intensities were 27, 32, and 47% of merchantable basal area(BA) excluding skidding trails. After 15 years, mean diameter at breast height of surviving trees in the 47% BA removal increased by 4.9 cm(25%) compared to the unthinned control. The 47% BA removal also increased gross merchantable volume(GMV) tree-1by 46% compared to the control. The 27% BA removal had twice as much GMV ha-1compared to the 47% BA removal after15 years. Moreover, cumulative GMV ha-1was much higher in the 27% BA removal than in the unthinned control. The highest thinning intensity produced larger trees on average, while the lowest thinning intensity maximized volume production per hectare. Maintenance of acceptable growing stock throughout the 15-year period in the 27% BA removal could provide other ecosystem functions such as biodiversity enhancement or wildlife habitat by delaying senescence. Regeneration data showed that a shift in species composition occurred in the understory. After 15 years, the understory was dominated by black spruce(Picea mariana(Mill.) B.S.P.), white birch(Betula papyrifera Marsh.), and trembling aspen(Populus tremuloides Michx.). If regenerating jack pine is an objective after final overstory removal, additional efforts will be needed to re-establish this species.

An imputation/copula-based stochastic individual tree growth model for mixed species Acadian forests： a case study using the Nova Scotia permanent sample plot network

Background： A novel approach to modelling individual tree growth dynamics is proposed. The approach combines multiple imputation and copula sampling to produce a stochastic individual tree growth and yield projection system. Methods： The Nova Scotia, Canada permanent sample plot network is used as a case study to develop and test the modelling approach. Predictions from this model are compared to predictions from the Acadian variant of the Forest Vegetation Simulator, a widely used statistical individual tree growth and yield model. Results： Diameter and height growth rates were predicted with error rates consistent with those produced using statistical models. Mortality and ingrowth error rates were higher than those observed for diameter and height, but also were within the bounds produced by traditional approaches for predicting these rates. Ingrowth species composition was very poorly predicted. The model was capable of reproducing a wide range of stand dynamic trajectories and in some cases reproduced trajectories that the statistical model was incapable of reproducing. Conclusions： The model has potential to be used as a benchmarking tool for evaluating statistical and process models and may provide a mechanism to separate signal from noise and improve our ability to analyze and learn from large regional datasets that often have underlying flaws in sample design.

A basal area increment model for individual trees in mixed continuous cover forests in Iranian Caspian forests

The aim of this study was to develop and test a new basal area growth model in mixed species continuous cover forests in northern Iran.Weanalyzed 421 core samples from 6 main species in the forest area to develop our growth model.In each plot,we measured variables such as total tree height(m),diameter at breast height(DBH)(cm)and basal area of larger trees as cumulative basal areas of trees(GCUM)ofDBH[5 cm.The empirical data were analyzed using regression analysis.There was a statistically significant nonlinear function between the annual basal area increment,as the dependent variable,and the basal area of the individual trees and competition as explanatory variables.Reference area from the largest trees,was circular plot with area of 0.1 ha.GCUM was estimated for trees of DBH>5 cm.Furthermore,we investigated the dependencies of diameter growth of different species on stand density at different levels of competition,and diameter development of individual trees through time.The results indicate that competition caused by larger neighborhood trees has a negative effect on growth.In addition,the maximum diameter increment is affected by competition level.Therefore,the maximum diameter increment of species occurs when the trees are about 35–40 cm in dense-forest(40 to 0 m^2 per ha)and when the trees are about 60 to 70 cm in very dense forest(60 to 0 m^2 per ha)which is more likely to Caspian natural forests with high level density due to uneven-aged composition of stands.

Relationship between stand characteristics and soil properties of two typical forest plantations in the mountainous area of Western Sichuan, China

There is uncertainty and limited knowledge regarding stand characteristics and soil properties of middle-aged pure forest plantations in the mountainous area of Western Sichuan. Plantation forests are almost exclusively planted as monocultures in the Pengzhou forest farm in the western mountainous area of Sichuan Province. This study aimed to assess the spatial and ecological characteristics of middle-aged Cunninghamia lanceolata(Lamb.) Hook. and Cryptomeria fortunei Hooibr. in the Pengzhou forest farm. The relationships and differences between stand growth characteristics and forest soil composition were assessed on the two forests planted simultaneously within the same area and exposed to the same environmental conditions. Cr. fortunei grew sparse, and slower than Cun. lanceolata. Principal component analysis indicated that the soil properties in the Cr. fortunei plantation were better than those in the Cun. lanceolata plantation. Redundancy analysis revealed that the differences in stand structure were affected significantly by the total nitrogen content and pH value. Thus, we propose that Cr. fortunei is planted for priority consideration in the subtropical high mountain area. Further, tending operations and application of fertilizers need to be conducted in Cun. lanceolata forests. Based on theoretical and experimental data, the present study explains why local farmers are more willing to plant Cr. fortunei, and thus provides a useful theoretical reference for the development of sustainable plantations in the future.

阔叶红松林林木与林分生长对采伐干扰的响应

提升森林质量、修复生态功能是东北阔叶红松林生态修复的核心,而阐明林木与林分生长对采伐干扰的响应机理是其中的关键。森林对采伐干扰的响应会受到空间尺度、时间尺度以及干扰程度等因素的综合影响。以往的研究侧重于比较不同采伐处理下林木生长的相对大小,而忽视了不同恢复时间下,林木和林分生长随干扰程度的变化。以吉林蛟河阔叶红松林采伐样地为对象,基于连续四次样地调查数据(2011、2013、2015、2018年),分别探讨了林木和林分生长在不同恢复阶段对不同程度采伐干扰的响应,并通过构建分段模型确定采伐干扰阈值。结果显示:林木和林分生长对采伐干扰的响应并不一致,采伐促进了林木生长,并且林木生长量随采伐强度的升高而升高;采伐降低了林分生产力,林分生产力随采伐强度的升高而降低。林木和林分生长对采伐干扰的响应存在时滞效应:林木和林分生长在采伐后两年内并无显著变化,而在采伐三年后才发生明显变化。此外,分段模型的结果显示:当保留木断面积为21.6 m^(2)/hm^(2)时,林分生产力最高,表明通过密度调整使阔叶红松林胸高断面积维持在21.6 m^(2)/hm^(2)附近,可使林分处于较高的生产力水平、促进森林恢复。研究结果能够为制定科学的阔叶红松林生态修复策略提供技术支撑。

闽楠-木荷混交林空间结构及其养分利用

【目的】为探讨混交林中闽楠和木荷的种间关系,确定木荷能否作为闽楠的伴生树种营建健康高效的闽楠-木荷混交林。【方法】以金洞林场16年生的闽楠-木荷混交林以及闽楠纯林、木荷纯林为研究对象,通过分析闽楠-木荷混交林的根系分布特性与林分空间结构特性来探讨闽楠-木荷混交林地上与地下部分的种间关系;通过分析不同物候期下3种林分的闽楠与木荷叶片养分的动态规律来阐明闽楠与木荷之间的养分利用关系。【结果】1)在16年生闽楠-木荷混交林中,在闽楠周围1.5 m内闽楠和木荷的根系分布虽有部分重叠,但闽楠仍占据优势地位,闽楠和木荷在地下生长空间和养分吸收利用方面存在竞争但竞争不激烈;2)整体林分空间结构上,闽楠、木荷纯林略优于闽楠-木荷混交林,说明混交林的树种不同,树种之间的生长特性和生态特性不一样,林分的均一性会差一些,对其调整结构的难度要大于纯林。混交林中,木荷已对闽楠形成了一定的竞争优势;3)闽楠-木荷混交林中,对养分吸收利用在物候期上部分不同步,存在相对有利的互补关系;从所有的物候期来看,闽楠叶片的N、P、K含量在大部分时期都高于木荷,表明闽楠-木荷混交更有利于闽楠对养分的吸收利用,木荷对养分的需求更低;4)16年生混交林中闽楠、木荷的生长速度要优于相应的纯林,表明前期竞争促进了林分的生长。【结论】闽楠与木荷混交有利于闽楠获得更多的养分,适度竞争促进了林木的生长,木荷是闽楠较好的伴生树种。

高阿丁枫人工中龄林生长对坡向和密度的响应

为了解高阿丁枫人工林的生长过程,2021年对林龄21 a的高阿丁枫人工林进行每木检尺,以胸径作为标准木选择的依据,西南坡不同密度中各选择1株,南坡不同密度中各选择3株高阿丁枫标准木作为解析木,分析不同坡向和造林密度组合的林木生长差异。结果表明:林龄21 a时,不同坡向和造林密度组合的高阿丁枫林木的平均胸径、树高和材积分别为17.60~20.78 cm、25.73~28.51 m和0.3186~0.4293 m3,林木尚处于旺盛的生长阶段;处理组合间以上生长量均呈现极显著的差异。林龄1~9、1~10、8~16 a期间分别是胸径、树高和材积的速生期,其连年生长量最高分别达2.19 cm/a、2.74 m/a和4.3966×10^(-2)m^(3)/a。坡向、密度及其交互作用显著或极显著地影响高阿丁枫林木的生长。高阿丁枫隶属热区长寿命大径材树种,速生期延续较长,其生长对立地和密度较为敏感。优质高效的高阿丁枫人工林培育应选择最适宜的立地和造林密度,并且适时开展密度的动态调控。综上所述,造林密度通过影响树高生长从而影响材积生长,南坡采用3 m×2 m×5 m非均匀密度造林的单株总材积最大。研究结果可应用于生产实践中高阿丁枫优质高效人工林培育的立地选择和密度控制。

松阔混交对侵蚀退化地土壤有机碳和微生物群落结构的影响

树种是调控森林土壤有机碳(SOC)积累的重要因子。为明确树种变化对红壤侵蚀退化地表层SOC积累的影响,采用配对实验设计,选择不同恢复年限的马尾松纯林和马尾松+木荷混交林(19和39 a)为研究对象,对比分析表层(0~10 cm)SOC质量分数的差异,并利用相关性分析与结构方程模型探讨其与凋落物特征、土壤氮素水平和微生物群落组成的关系。结果表明:1)恢复19 a的纯林和混交林SOC质量分数无显著差异,而恢复39 a混交林SOC质量分数较恢复19 a纯林、恢复19 a混交林以及恢复39 a纯林分别高39.8%、48.0%和93.6%(P<0.05);2)SOC质量分数与土壤微生物生物量碳、土壤微生物生物量氮、磷脂脂肪酸总量、矿质氮和细菌呈显著或极显著正相关,与凋落物C/N和真菌细菌之比(F/B)呈显著或极显著负相关;3)结构方程模型分析表明,凋落物C/N是松阔混交后表层SOC质量分数变化的触发因子,矿质氮是微生物群落结构变化的关键因子。凋落物C/N可直接驱动SOC质量分数的变化(-0.35*),或通过矿质氮(-0.70***)诱导F/B、丛枝菌根真菌和细菌的变化起间接调控作用,以上因子共解释SOC质量分数变异的86.8%。综上,松阔混交促进侵蚀退化地SOC的积累,且其有效性随恢复年限增强。这个过程主要通过提升凋落物质量、增加微生物养分来源和土壤氮有效性、改变微生物群落结构完成。在我国实施“双碳”战略的背景下,多树种混交对红壤区退化马尾松林SOC提升具有重要意义。

宁夏六盘山北部华北落叶松林树高与胸径生长的多因子响应耦合模型构建

【目的】分析宁夏六盘山半干旱区叠叠沟小流域华北落叶松人工林林龄、密度和主要立地因子对树高和胸径生长的影响,建立树木生长的多因子响应耦合模型,为该地区华北落叶松人工林生长预测和可持续经营提供理论依据。【方法】2018和2019年,在六盘山半干旱区叠叠沟小流域分别选择42和57块华北落叶松人工林样地,调查树高、胸径、林龄、密度等林分结构特征以及坡向、土壤厚度等立地因子,并收集2003—2017年在叠叠沟小流域调查的93块样地历史数据。基于192块样地数据,分析树高和胸径对林龄、密度、坡向、土壤厚度等因子的响应规律,利用2/3和1/3的数据建立和验证树高与胸径生长的多因子响应耦合模型。【结果】树高和胸径对林龄、密度、坡向、土壤厚度的响应规律各异;树高和胸径随林龄增加先快速增加,后在林龄超过20年时缓慢增加;树高和胸径随密度增加先表现为稳定,后在密度分别超过2000、1500株·hm^(-2)时缓慢下降,在密度超过3000、2300株·hm^(-2)时加快下降;树高和胸径随坡向偏离正北方向的角度增加先表现为稳定,后在坡向超过80°时迅速降低;树高和胸径随土壤厚度增加先表现为增加,后在土壤厚度分别超过90、80 cm渐趋稳定。基于连乘耦合、立地指数和立地因子3种林木生长模型表达式,建立树高和胸径响应林龄、密度、坡向、土壤厚度和立地指数的耦合模型并拟合模型参数;树高模型的确定系数分别为0.804、0.902、0.806,NS系数分别为0.793、0.903、0.762;胸径模型的确定系数分别为0.846、0.803、0.834,NS系数分别为0.837、0.840、0.818;3种模型拟合效果均较好。【结论】宁夏六盘山半干旱区华北落叶松人工林树高和胸径生长随林龄、密度、坡向、土壤厚度增加分别表现为先快后慢增加、先稳定后下降、先稳定后降低、先升高后稳定,建立的连乘耦合、立地指数和立地因子多因子耦合模型精度均较高,但鉴于研究区尚未确定立地指数分布规律并综合考虑各模型精度、应用难度、结构复杂程度差异,建议采用多因子连乘耦合模型预测华北落叶松人工林树高和胸径生长。

R程序包ForestStatTool在林学单木和林分因子统计中的应用

【目的】为了实现林学中单木和林分指标的快速、准确计算,开发了通用的R包ForestStatTool,并通过具体示例介绍其在单木和林分因子统计计算中的应用。【方法】在R语言环境中,编写了12个实用函数,涵盖重复标签处理、重复坐标处理、样地分割、空间结构指标计算、竞争指标计算、生物多样性指标计算和林分因子统计这7大类。以北京十三陵林场的侧柏纯林0.06 hm2圆形样地和吉林省汪清林业局金沟岭林场的云冷杉针阔混交林1 hm2方形大样地的数据为例,介绍了ForestStatTool包的主要功能及使用方法。【结果】ForestStatTool包通过分析各类样地数据,成功计算了林木的空间结构、竞争指数和生物多样性等指标。结果表明:ForestStatTool包可有效识别林木的空间分布特征,量化林木的竞争压力,并揭示了林分结构和多样性分布的特征;还能够满足大样地和复杂林分的快速统计分析需求,适用于多种林业应用场景。【结论】ForestStatTool包可方便、快速、准确地完成样地数据检查与预处理,并完成林学单木和林分因子的相关统计计算。ForestStatTool包可应用于森林经理、森林培育、森林生态等领域。

基于YOLOv8的陕西黄土高原刺槐林枯立木识别

黄土高原在生态恢复的过程中由于不适宜造林加之极端干旱频发,导致人工刺槐林出现退化甚至死亡,从而产生枯立木。为准确识别陕西黄土高原刺槐林枯立木,进而分析其空间分布格局,本研究以典型人工林刺槐为对象,沿陕西黄土高原降水梯度设置6个样地,利用无人机获取刺槐林高分辨率RGB影像,结合多个深度学习目标检测模型识别刺槐林枯立木,通过对比与分析证明了YOLOv8模型在检测效率以及检测精度方面的优越性。通过对刺槐林数据集训练与测试以及刺槐林RGB影像的拼接,从而分析刺槐林枯立木的分布格局,用枯立木指数(SDTI)反映刺槐林退化程度,同时分析了坡向对其影响。YOLOv8模型训练后平均帧率FPS达到了68.7帧/s,且其验证集平均精度均值(mAP)达到了94.6%,F1得分为0.92,均好于其他模型。综合不同目标检测模型的各项主要评价指标及泛化能力,选择YOLOv8模型分析刺槐林枯立木分布格局,表明陕西黄土高原刺槐林SDTI随降水梯度递减呈递增趋势;不同坡向SDTI呈阳坡>半阳坡>半阴坡>阴坡的变化规律。本研究可为黄土高原刺槐林退化程度评估及其合理的经营管理提供科学依据。

临猗县不同林龄苹果林地枯落物及土壤水源涵养功能研究

探讨不同林龄苹果林地枯落物和土壤水源涵养能力的变异特征,明确苹果林地的水分特征,对建立合理的果园管理制度等具有重要意义。以运城市临猗县不同林龄(4、6、15、30 a)苹果林地为研究对象,通过野外调查和室内试验,对苹果林地枯落物和土壤水源涵养能力进行定量描述和差异性研究。结果表明,4种林龄苹果林地枯落物层总蓄积量为0.82~2.09 t/hm^(2),最大持水量介于4.91~13.09 t/hm^(2),有效拦蓄量在3.36~9.38 t/hm^(2),随着林龄的增长,以上参数量均表现为先增大再减小的趋势,以15 a为最大。枯落物层持水量、吸水速率与浸水时间分别存在良好的对数和幂函数关系。在0~60 cm范围内,随着林龄的增长,苹果林地土壤容重逐渐减小,总孔隙度和最大持水量逐渐增加,以30 a为最大。随着土层加深,不同林龄苹果林地土壤容重呈现先增大再减小的趋势;除林龄4 a外,其余林龄土壤总孔隙度逐渐减小,但各土层之间差异性不显著。30 a苹果林地土壤最大持水量随土层加深逐渐降低,其余林龄呈现先减小再增加的趋势,均以0~10 cm土层持水量最大,20~40 cm土层最低。坐标综合评定法得出林龄在15 a时枯落物层和土壤层(0~60 cm)总水源涵养功能最强,30 a林龄次之,4 a林龄最弱。