Integrated approach for understanding spatio-temporal changes in forest resource distribution in the central Himalaya

Intense anthropogenic exploitation has altered distribution of forest resources. This change was analyzed using visual interpretation of satellite data of 1979, 1999 and 2009. Field and interactive social surveys were conducted to identify spatial trends in forest degradation and data were mapped on forest cover and land use maps. Perceptions of villagers were compiled in a pictorial representation to understand changes in forest resource distribution in central Himalaya from 1970 to 2010. For- ested areas were subject to degradation and isolation due to loss of con- necting forest stands. Species like Lantana camara and Eupatorium adenophorum invaded forest landscapes. Intensity of human pressure differed by forest type and elevation. An integrated approach is needed to monitor forest resource distribution and disturbance.

RESEARCH FOR THE STRAIN ENERGY RELEASE RATE OF COMPLEX CRACKS BY USING POINT-BY-POINT CLOSED EXTRAPOLATION APPROACH

A new extrapolation approach was proposed to calculate the strain energy release rates of complex cracks. The point_by_point closed method was used to calculate the closed energy, thus the disadvantage of self_inconsistency in some published papers can be avoided. The disadvantage is that the closed energy is repeatedly calculated: when closed nodal number along radial direction is more than two, the displacement of nodes behind the crack tip that is multiplied by nodal forces, the closed energy has been calculated and the crack surfaces have been closed, and that closed energy of middle point is calculated repeatedly. A DCB (double cantilever beam) specimen was calculated and compared with other theoretical results, it is shown that a better coincidence is obtained. In addition the same results are also obtained for compact tension specimen, three point bend specimen and single edge cracked specimen. In comparison with theoretical results,the error can be limited within 1 per cent. This method can be extended to analyze the fracture of composite laminates with various delamination cracks.

Effectiveness of Firewise Approach(FWA)in Controlling Forest Fire:A Case of Uluguru Nature Forest Reserve(UNFR),Morogoro,Tanzania

Forest fire has received considerable attention in literature because it is considered one of the most common factors causing disturbances in ecosystems and at the same time considered vital in maintaining ecosystems.Firewise Approach(FWA)has been proposed and used for controlling forest fire and achieving sustainable forest management.The approach requires involvement of communities in managing forest fire incidences in reserved forests.Despite considerable period since FWA has been practiced,there is insufficient scholarly knowledge on effectiveness of the approach in managing forest fire.This paper examines the effectiveness of FWA in managing forest fires in Uluguru Nature Forest Reserve(UNFR).The study employed cross-section research design that involved quantitative and qualitative data collection.The data were analysed using Statistical Package for Social Science(SPSS)software and content analysis.The study found alternating periods:the period of overall decrease of wildfire incidences within initial five years of practising the approach.The study concludes that the FWA is useful in reducing forest fire incidences during early period of practising the approach and another period of huge fire occurrence beyond five years.However,the FWA has challenges of sustaining successes in controlling forest fires including limited fire management training to common community.The study recommends sustaining communities’trainings on forest fire management.

CDCC Approaches and Roles of Closed Channels in d-Nucleus Reactions

The effect of deuteron breakup in d-nucleus reaction is treated with the continuum discretized coupledchannels (CDCC) approach,and the effects on the total reaction cross sections and elastic scattering angular distributionsare studied by comparing the calculations of CDCC and spherical optical model with our global deuteron optical potential[Phys.Rev.C 73 (2006) 054605] below 200 Me V,for target nuclei ranging from ^(12)C to ~(208Pb.The contributions fromthe dosed channels to the total reaction and breakup cross sections,and angular distributions of elastic scattering arealso seriously discussed.

An approach to spatially explicit reconstruction of historical forest in Northeast China

The spatially explicit reconstruction of historical land-cover datasets plays an important role in studying the climatic and ecological effects of land-use and land-cover change（LUCC）. Using potential natural vegetation（PNV） and satellite-based land use data, we determined the possible maximum distribution extent of forest cover in the absence of human disturbance. Subsequently, topography and climate factors were selected to assess the suitability of land for cultivation. Finally, a historical forest area allocation model was devised on the basis of the suitability of land for cultivation. As a case study, we used the historical forest area allocation model to reconstruct forest cover for 1780 and 1940 in Northeast China with a 10-km resolution. To validate the model, we compared satellite-based forest cover data with our reconstruction for 2000. A one-sample t-test of absolute bias showed that the two-tailed significance was 0.12, larger than the significant level 0.05, suggesting that the model has strong ability to capture the spatial distribution of forests. In addition, we calculated the relative difference of our reconstruction at the county scale for 1780 in Northeast China. The number of counties whose relative difference ranged from-30% to 30% is 99, accounting for 74.44% of all counties. These findings demonstrated that the provincial forest area could be transformed into forest cover maps well using the model.

Approach Analyses to Promote Sustainable Forest Management with Forest Certification in China

The paper was based on the current development status of forest certification to analyze the basic characteristics of forest certification from the development point of view in terms of origin, development, main drivers and impacts, and then conducted the approach analysis to promote sustainable forest management with forest certification in China. The result showed that China shall establish her own forest certification scheme, with the focus on the improvement of forest sustainable management concept through forest certification, the promotion of forest certification through the leadership of large companies and the strengthening of capacity building. It is unrealistically expected to employ forest certification to facilitate China’s forest management immediately on the track of sustainability.

Based on point merge for paired approach sequencing on closely spaced parallel runways

The paired approach is a kind of efficiency approach to closely spaced parallel runways(CSPRs),and the point merge system has the powerful interval management function,which is effective to realize the converge of traffic flows from different approach directions.In order to improve the operation efficiency of the airport terminal area,a model of paired approach sequencing based on point merge is proposed to investigate the problem of increasing the operation capacity of the closely spaced parallel runways.Taking the minimum average flight delay time as the objective,the flight distance on sequencing legs,wake turbulence separation and paired approach safety separation as constraints,the genetic algorithm is used to optimize the paired approach sequencing of arrival flights.Taking the closely parallel runways of Shanghai Hongqiao International Airport run south as an example,the point merge program is designed and the effect of model was analyzed.The results show that after optimization,the average delay time and average landing time are reduced by 40.6%and 51.8%respectively,the capacity of the closely spaced parallel runways are 1.1 times higher than the actual,the flight uptime rate can reach 100%.It is concluded that the proposed model is feasible,which can effectively reduce delay times and alleviate congestion in terminal areas.

Remote Sensing for Analyzing Forested Landscape Structure and Land-Use Histories in Guyana’s Bauxite Mining Landscapes

Monitoring secondary forest regrowth is a priority in forest restoration strategies. A site history helps in understanding the present status of natural regeneration in the three landscapes impacted by bauxite mining. Nonetheless, high rainfall in bauxite residue storage areas can facilitate natural regeneration of forest. This research analyzed the natural regeneration of forest after thirty years of different land use histories at three bauxite mining areas of the Upper Demerara—Berbice region of Guyana. There are no man made forest plantations in the three landscapes being reviewed. The methodology included: 1) the selection of three sampling landscapes with different land use histories 2) the generation Land Use/Land Cover maps using KMeans unsupervised classification of satellite images in each landscape and 3) the assessment of landscape structure of the land cover classes for year 2020 at class and landscape level using landscape metrics. The assessment of landscape structure of the land cover classes was carried-out with landscape metrics for the comparisons at class and landscape level. Principal component analysis enables the identification of main patterns among landscape-level metrics and land cover classes. Discriminant classification of the landscape classes was analyzed with the different metrics. The results suggest that Normalized Difference Vegetation Index and KMeans unsupervised classification can be used to evaluate the difference in natural forest regeneration among landscapes with differing land use histories. The landscape metrics revealed secondary stages of forest succession. The Landscape Shape Index and Edge Density were the most significant for landscape differentiation. The result of the various land uses reveals a mosaic of early, intermediate, and late successional sequences.

A combined modulated feedback and temperature compensation approach to improve bias drift of a closed-loop MEMS capacitive accelerometer

目的:根据Allan方差定义,分析引起闭环MEMS电容式加速度计中长期漂移的因素,研究相应的消除和补偿方法,实现降低漂移、提高闭环MEMS加速度计稳定性的目的。创新点:首先设计利用载波调制反馈电压信号的方法,避开并滤除反馈通道上的低频噪声,降低Allan方差的偏置不稳定性;然后在反馈通道上加入参考信号,利用该参考信号经过模拟部分后被解调的相位来表征温度,进行温度补偿,进一步降低Allan方差的长期漂移。方法:首先,根据Allan方差的偏置不稳定性定义,其影响因素来自于闭环系统的低频噪声。根据文献资料和作者之前的实验测试情况,大部分低频噪声来自于反馈通道,因反馈信号是低频电压信号。为降低反馈通道低频噪声,设计载波调制反馈信号及通过高通滤波器滤除低频噪声的方案MFA(图4)。经测试,采用MFA的输出噪声和1小时的稳定性明显优于反馈信号直接反馈的方案DFA(图10-12)。在MFA基础上,继续增加一个参考信号,该信号通过整个系统的模拟部分后被数字系统解调,其相位信息携带了外界温度变化信息,从而可利用该相位信息进行实时温度补偿(图5、6)。对温度补偿方案进行静态温度范围测试(图16),补偿后的度系数是补偿前的1/46;在快速动态温度变化下(图17),实时补偿结果是未补偿的1/8,显示了较好的补偿特性。温度补偿后的Allan方差长期漂移获得明显降低,而偏置不稳定性略微升高(图18、19)。总体上看,利用MFA和温度补偿,闭环MEMS电容式加速度计的整体漂移特性得到较好抑制。结论:针对闭环MEMS电容式加速度计漂移问题,提出载波调制反馈和新型温度补偿方案。两种方案能够在同一闭环系统中同时使用,分别降低了偏置不稳定性和长期温度漂移,1 h的Allan方差显示,偏置不稳定性约为13μg,100 s积分时间的漂移为17μg,温度系数降到0.1 mg/°C,显示了较好的稳定性。

基于CASA模型的常州市森林植被净初级生产力及碳汇估算

森林植被在碳循环过程中发挥着关键作用,其碳汇分析对于城市生态系统管理有重要意义。基于多种卫星遥感数据、林地分布以及气象资料,结合CASA(Carnegie-Ames-Stanford Approach)模型,对2022年常州市森林碳汇进行模拟估算,综合分析其时空变化特征及驱动机制。结果表明:2022年常州市森林年度碳汇量总体达29.94万t,4—8月碳汇量较高;不同类型林地碳汇能力不同,乔木林碳汇能力较强,7月碳汇量最高可达80 gC/m2;气象因素对于森林碳汇具有相关影响,其中温度的影响要高于降水量。

大食物观理念下森林食物供给现状与对策研究

对我国森林食物2013—2021年间的产量变化及森林食物的供给潜力进行了分析,在此基础上,针对现阶段我国森林食物供给面临的政策、市场、科技等制约因素,提出了完善林地资源管理政策、提高良种培育力度、强化科技创新支撑力度、畅通流通渠道、加大扶持力度等对策建议。

Competition effects in an afrotemperate forest

Background： Information about competition responses is mainly available for monospecific stands or mixed stands with a small number of species. Studies on complex multi-species and highly structured forest ecosystems are scarce. Accordingly, the objective of this study was to quantify competition effects and analyse competition responses in a species-diverse afrotemperate forest in South Africa, based on an observational study with mapped tree positions and long-term diameter increment records. Methods： The sensitivity to competition was analysed for individual species and involved the calculation of the slope of the linear relation between the value of a competition index （CI） and diameter growth as a measure of sensitivity. In a next step different competition indices were combined and tree diameters were grouped in three classes as surrogates for canopy status and ontogenetic stage. Results： Five competition indices were found to be effective in showing sensitivity to competition for a number of canopy and sub-canopy species. Significant linear regressions were fitted for 18 of a total of 25 species. Species reactions varied significantly in their sensitivity to the different CIs. The indices were classified as belonging to two groups, those that responded more to local crowding and those that are more sensitive to overtopping, which revealed species-specific sensitivities to both factors. The analysis based on diameter classes revealed that species clearly changed their sensitivity to crowding or overtopping depending on diameter. Canopy and sub-canopy species showed distinct differences in their reactions. Conclusions： The application of multiple CIs brought novel insights relating to the dynamics of afrotemperate forests. The response patterns to different competition indices that focus on crowding and overtopping are varied and tree diameter dependent, indicating that oversimplified assumptions are not warranted in the interpretation of Cl- growth relations.

杉木人工林套种不同树种对林分生长和植物多样性的影响

研究杉木林间伐后,于林下套种香梓楠、华盖木、红豆杉、缅茄4种树种,对比未套种杉木纯林,分析套种后林分的生长状况和植物多样性,为杉木人工林近自然改造与可持续经营提供参考依据。结果表明:香梓楠、华盖木、红豆杉与杉木形成异龄复层混交林,香梓楠胸径、树高生长量及保存率最高,分别达到10.5 cm、9.8 m、82.22%,显著高于其他树种;缅茄胸径、树高生长量及保存率最低,分别为2.4 cm、1.7 m、15.66%。套种缅茄、香梓楠、华盖木对杉木胸径有促进作用,套种缅茄后杉木树高显著提高。5种杉木林分林下植被中共出现33科52属60种植物,草本层出现植物15科25属27种,以禾本科和菊科植物为主;灌木层出现植物18科27属33种,以大戟科、茜草科和桑科植物为主;4种杉木混交林林下出现植物比杉木纯林增加24种。杉木×香梓楠、杉木×华盖木林下植物多样性比杉木×缅茄和杉木纯林显著提高。综合杉木间伐后套种不同树种表现,套种香梓楠对林分生长和植物多样性更具优势,可作为今后杉木近自然改造的参考模式。

四川省滑坡灾害危险性评价模型比较研究

为探讨四川省滑坡灾害分布状况及对滑坡灾害危险性评价建模效果进行比较,以四川省为研究区,分析地质灾害尤其是滑坡灾害的时空分布,运用信息量法、基于信息量的逻辑回归法、随机森林法3种方法,取坡度、植被覆盖率、地震烈度、断层密度及年累计降雨量5个因子建立危险性评价模型,结合ROC曲线和AUC值对模型性能进行精度比较。研究结果表明:(1)坡度因子对滑坡灾害的贡献最大,3种评价模型中坡度、地震烈度及降雨3个因子均有较大贡献。(2)滑坡灾害主要分布于地震带附近,在成都平原处灾害发生几率最小。(3)3种评价方法均适用于滑坡危险性区划工作,具有良好的建模效果。相对于其他两种模型,逻辑回归模型在实际情况下更加适合四川省滑坡灾害的危险性评价工作。

辽西油松人工纯林不同间伐抚育方式对比研究

以位于辽西地区的北票市47 a油松人工纯林为研究对象,对近自然经营及传统经营(株数间伐强度10%左右)间伐5 a后的林分的胸径、树高、冠幅增长量及分级株数比例分布情况进行了对比研究,结果表明:同等株数间伐强度下,近自然经营中以目标树为导向的采伐Ⅱ、Ⅲ级木的间伐方式对保留木胸径、树高生长的整体促进效果要明显优于国内传统的采伐Ⅳ、Ⅴ级木的间伐方式,且可以在一定程度上保持林分胸径结构分布的相对稳定性,间伐后保留木按胸径分级株数比例分布曲线整体偏向右移。传统经营及近自然经营间伐抚育方式对间伐后保留木的树高生长均有不同程度的促进作用,后者的整体促进效果要稍优于前者。然而,以上两种间伐方式对间伐后保留木的冠幅生长并未表现出明显的促进效果。近自然经营间伐抚育要想收到明显的抚育效果,建议株数间伐强度应至少在20%以上。

STUDIES ON FOREST WATER CYCLING

Principal ideas, research approaches and installations in both Liangshui and Maoershan Ecological Stations were diseussed. Significance of comparability and synchronous detennination in research methods were stressed. Comparison analysis was done on the results gained from diferent methods. Adaptive mechanisms of Mongolian oak (Quercus mongolica) to drought and unproductive sites wer expounded through hydrological cycling studies. Surface runoff and flood peak were decreased and the developing processes of flood peak were postponed or delayed because of the presence of huge forest canopy and forest floor. However, the conclusions of forest influences on total runoff,especially in spring and in the dry season t are significant to agricultul practices in notheast China and turned out contrary for satershed sizes or different approaches, which should be studied further.

An analysis of close approaches and probability of collisions between LEO resident space objects and mega constellations

With the undergoing and planned implementations of mega constellations of thousands of Low Earth Orbiting(LEO)satellites,space will become even more congested for satellite operations.The enduring effects on the long-term space environment have been investigated by various researchers using debris environment models.This paper is focused on the imminent short-term effects of LEO mega constellations on the space operation environment concerned by satellite owners and operators.The effects are measured in terms of the Close Approaches(CAs)and overall collision probability.Instead of using debris environment models,the CAs are determined from integrated orbit positions,and the collision probability is computed for each CA considering the sizes and position covariance of the involving objects.The obtained results thus present a clearer picture of the space operation safety environment when LEO mega constellations are deployed.Many mega constellations are simulated,including a Starlink-like constellation of 1584 satellites,four possible generic constellations at altitudes between 1110 km and 1325 km,and three constellations of 1584 satellites each at the altitudes of 650 km,800 km,and 950 km,respectively,where the Resident Space Object(RSO)spatial density is the highest.The increases in the number of CAs and overall collision probability caused by them are really alarming.The results suggest that highly frequent orbital maneuvers are required to avoid collisions between existing RSOs and constellation satellites,and between satellites from two constellations at a close altitude,as such the constellation operation burden would be very heavy.The study is not only useful for satellite operators but a powerful signal for various stakeholders to pay serious attention to the development of LEO mega constellations.

近自然经营对马尾松林优势树种生态位及种间关系的影响

探究近自然经营对马尾松林的生态位和种间关系的影响,可以为经营管理提供实践基础和科学依据。以实施近自然经营10余年的马尾松林为研究对象,分别从幼苗(胸径<1 cm)、幼树(1 cm≤胸径<5 cm)和成树(胸径≥5 cm)3个阶段,探讨近自然经营对马尾松林12个优势树种的生态位及种间关系的影响。结果显示:(1)马尾松在成树和幼树阶段的生态位宽度变小,幼苗和大部分优势树种的生态位宽度增加;(2)各优势树种种对间生态位重叠度变小,生态位分化程度增加;(3)群落总体关联性大多呈现正关联,但极显著正联结种对较少;Spearman秩相关检验结果显示不同生长阶段经营和对照林分种对间存在差异但并不显著。综上,研究区马尾松林仍处于演替初期,群落结构不稳定,近自然经营对马尾松林种间关系的改善具有一定效果但并不理想,建议针对研究区纯林化程度过高且密度过大的马尾松林分,在密度调控的基础上结合林下补植枫香和麻栎、白栎等栎类树种,加速群落演替,尽快实现改善种间关系和提升群落稳定性的目的。

Gender Roles in the Utilization and Challenges in the Management of Mangrove Forests in Casiguran, Aurora, Philippines

Mangrove utilization and management were observed done by men and women depending on their needs and priorities in Casiguran, Aurora. This study, therefore, tried to investigate the gender roles in the utilization and management of mangrove forests, the existing mangrove management practices and their challenges, and the relationship between gender and mangrove resources management. A mixed-method approach was used and data were obtained through triangulation. Respondents were obtained through snowball sampling and interviewed using a structured questionnaire with a few open-ended questions. Results revealed that the majority of the respondents were women (60.7%) and residents of Brgy. Esteves (52.5%) live within or near the mangrove forest. Mostly married (59%) who were providing food and income for the family. They utilized mangrove woods (58.20%) with an average quantity of less than 10 board feet (34.4%) for cooking (40.2%). Roots were utilized in minimal amounts (2.50%) for mythical, medicine, and cork purposes. Mollusks (93.44%), commonly bivalves (93.4%), were primarily gleaned by women for food consumption (93.4%) and as a source of income (93. 61%). On the other hand, catching of crabs (57.4%) for consumption (56.6%) and as a source of income (14.8%) and catching of fish (31.1%) for consumption (27.9%) were done by men. Both genders were involved in mangrove management practices, although only 65% of them had actual involvement in mangrove planting, 19% in mangrove nursery development and maintenance, and 16% in mangrove plantation maintenance. Challenges in management include low survival rate of planted mangroves (33%), lack of maintenance activity (20%), and lack of funds for mobilization (20%). A chi-square test of independence revealed that both men and women have no significant difference in their involvement in nursery establishment and maintenance, mangrove planting, and plantation management.

闭合复位股骨大粗隆入路交锁髓内钉内固定治疗股骨干骨折的临床效果

目的:研究闭合复位股骨大粗隆入路交锁髓内钉内固定治疗股骨干骨折的临床效果。方法:选择聊城市第三人民医院骨科2020年9月—2022年9月收治的股骨干骨折患者118例为研究对象。采用单盲法将患者分为对照组和试验组。对照组59例患者施以切开复位股骨大粗隆入路交锁髓内钉内固定治疗,试验组59例患者施以闭合复位股骨大粗隆入路交锁髓内钉内固定治疗。对比两组患者关节活动功能、临床效果、住院时长及骨折愈合时间、不良事件发生率、血清炎症因子水平。结果:术后6个月,试验组关节活动评分高于对照组(P<0.05)。试验组临床总有效率(98.31%)高于对照组(86.44%)(P<0.05)。试验组住院时长及骨折愈合时间均短于对照组(P<0.05)。试验组不良事件发生率(1.69%)低于对照组(15.25%)(P<0.05)。手术后1周,试验组血清炎症因子水平均低于对照组(P<0.05)。结论:采用闭合复位方法,通过股骨大粗隆入路结合交锁髓内钉内固定治疗股骨干骨折,具有良好的临床效果。闭合复位能够缩短患者的住院时间、骨折愈合时间,改善关节活动度,降低不良事件的发生率,改善炎症因子水平,临床意义重大。