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1.
林间摘茧挂袋养困法防治落叶松毛虫,虫口密度由34.1 头/株降至4 头/株,虫株率由100% 降至65% 。室内养茧发现有寄生蜂和寄生蝇两类天敌,平均寄生率20% 。试验结果表明,虫茧养困法防治落叶松毛虫是重要的生物防治手段之一。  相似文献   

2.
对河南省兰考县1985 ~1995 年泡桐大袋蛾治理情况、虫口密度以及寄生率的数据进行分析,结果表明:按受害面积可以将泡桐大袋蛾的发生划分为蔓延期(1985 ~1990) ,这时的年平均扩散速率为115 % ;高峰期(1991 ~1992) ,年平均扩散速率约为0 % ;消亡期(1993 ~1995) ,这期间大袋蛾种群急剧消亡.防治措施能有效保护泡桐叶片.但由于对有虫树木不能彻底地防治,因而不能有效防止害虫的扩散;同时,这种防治措施也不是导致大袋蛾种群消亡的原因.数据分析还表明大袋蛾的发生周期更象是与寄生天敌相互作用的结果,天敌的作用是大袋蛾种群消亡的促进因子之一,但不是决定性的因子.本文提出了泡桐大袋蛾种群破产阈值的观点,并计算得到破产阈值指标 Tcr = 355 头/ 百叶,即当幼龄(1 ,2 龄) 虫口密度超过355 头/ 百叶、扩散速率为0 % 时,大袋蛾种群将自然、迅速地消亡.因为极高的虫口密度导致了剧烈的种内竞争,并且环境负荷量已无法满足种群的需要.  相似文献   

3.
飞机喷洒绿色威雷、吡虫啉防治松褐天牛林间试验   总被引:3,自引:0,他引:3  
采用“运五”农用飞机喷洒绿色威雷防治松褐天牛Monochamus alternatus Hope,施药后12小时,挂于飞防区松林中饲养笼内的松褐天牛死亡率为47.5%;24小时后,死亡率为100%。喷药32天后,室内饲喂的松褐天牛死亡率为70%;喷药15、22天后,飞防区诱捕器平均诱捕量分别为0.5头和1.2头,对照区分剐为2.3头和3.3头。飞防后,通过样地(株)调查,非发病区松褐天牛虫口密度为1.6头/株,虫口减退率为74.6%;在松材线虫病发病区飞机喷洒吡虫啉缓释胶囊后,当年秋季调查,松材线虫病痛死株率为4.8%,与防治前的上一年度相比,发病率下降了72.4%。  相似文献   

4.
松墨天牛对南岳华山松的危害与分布规律研究   总被引:1,自引:0,他引:1  
南岳风景区的华山松受到松墨天牛的严重危害,有虫株率达39.9%,致死株率达26.7%,平均虫口密度为21.2头/株,最高达60头/株,该虫在感虫木上主要分布在树干中上部及枝条内,枝条内虫中点总口数的15.7%-68.2%;在枯立木上的分布规律不明显,但枝条内虫口仍占总虫数的3.6-32.4%,该天牛化蛹初期蛹的自然死亡率为43.7%,木质部内幼虫的自然死亡率为5.7%,及时清除活立木及感虫木上的枯枝弱枝是防治该虫的方法之一。  相似文献   

5.
应用管氏肿腿蜂防治双条杉天牛技术研究   总被引:7,自引:0,他引:7  
2001—2005年北京市密云县进行了管氏肿腿蜂防治双条杉天牛技术的研究与推广,5 a放蜂1200万头,累计防治面积3000 hm^2。管氏肿腿蜂5 a平均寄生率达69.68%,寄生率随着放蜂密度的增加而增加。林内放蜂后侧柏的被害率由放蜂前22.78%下降到0.49%;被害木虫口密度由25.4头/株下降到3头/株,下降率88.2%;被害木管氏肿腿蜂密度由放蜂前的0.2头/株上升到2005年的2.5头/株,基本达到有虫不成灾。  相似文献   

6.
大袋蛾是刺槐、悬铃木、泡桐等树木的主要害虫,食性杂,危害重。利用四斑尼尔寄蝇防治大袋蛾试验,结果表明,在7月中下旬,每公里林带释放四斑尼尔寄蝇6000只,寄生率达到92.7%,叶片保存率82%以上。以虫治虫,一次释放,多年受益,达到了有虫不成灾,保护环境,降低防治成本的效果。  相似文献   

7.
应用文山松毛虫质型多角体病毒(CPV),于1991年、1992年、1994年,在献词主林区防治文山松毛虫,达1729.27hm^2,松毛虫开遍率分别为90.78%、85.7%、89.6%,示范林内固定样地的松毛虫校正死亡率达93.29%,有虫株率由98.6%下降到27.66%,虫口密度由14.24头/株下降到0.618头/株。病毒能流行传染持续控制松毛虫的危害最佳防治虫龄是3~5龄,林间空气湿润的  相似文献   

8.
弧纹虎天牛生物学特性及防治技术   总被引:1,自引:0,他引:1  
弧纹虎天牛Chlorophorus miwai Gressitt危害柏树、栎类等树木。1992年河南首次在南阳市博物馆院内古柏林中发现。在南阳市1年发生1代,以2 ̄3龄幼虫在木质南部表面虫道内越冬。采用涂药环、虫孔注药、涂白、营木措施进行综合防治,虫株率由3.1%下降到0.3%,虫口密度由11 ̄16头/株下降到0.04 ̄0.7头/株。  相似文献   

9.
1991年调查,济南市市区柳树蛀干害虫危害株率为78.2%至85.2%,平均80.35%,部分重灾区高达90%至100%,虫口密度为28.5头/株至33头/株,平均30.8头/株,使树势极度衰弱,并伴随发生枯枝病危害,每年树冠枯枝率达20%,要花费大...  相似文献   

10.
根据美国白蛾的生活史及生物学特性,通过对河北省文安县飞机喷洒灭幼脲Ⅲ悬浮剂对美国白蛾的防治效果调查发现,飞机防治食叶害虫具有安全、经济、高效等特点。配合灭幼脲Ⅲ,可以把害虫的危害控制在经济阈值以下。飞防7d后美国白蛾的虫株率、虫口密度分别为2.8%和23.8头/株;飞防15d后的虫株率和虫口密度分别为0.2%和1.0头/株。  相似文献   

11.
昆虫带电特性及影响因子   总被引:1,自引:0,他引:1  
本文对大供蛾等昆虫的带电特性进行了定量测量,同时,由昆虫自身带电和与环境相互作用带电分析,给出了昆虫自身带电的分形特征,测定了不同介质上静止爬行和振翅对大供蛾雄峨带电量,讨论了昆虫带电的原因和规律。  相似文献   

12.
大袋蛾ClaniavariegataSnelen在我省一年1代,少数年份有二代分化。雌性比每年有差异。4龄前种群年龄组成较为复杂,种群数量增长为离散性,Nt+1=RoNt。影响种群数量变动的因子主要是气候和天敌:与1月份和全年的平均温度相关极显著;与5、6月份的温湿系数相关极显著;与全年的降雨量相关显著;种群数量变动与林型、树种无关。天敌因素对种群数量的影响是无天敌状况下的2.96倍  相似文献   

13.
Stand density management tools help forest managers and landowners to more effectively allocate growing space so that specific silvicultural objectives can be met. Due to the economic importance of Oriental beech (Fagus orientalis Lipsky) forests in Turkey, a stand density management tool was developed for this species to optimize regeneration success rate and tree growth. For the development of this tool, named stand density management diagram (SDMD), we utilized forest inventory data from the Kastamonu Regional Forest Directorate in Turkey. Previously published forest management approaches and models were employed during the development of the tool. The SDMD illustrates the relation among four forest indexes: the basal area per hectare, number of trees per hectare, forest stand volume per hectare, and quadratic mean diameter of the beech stands. The stand stocking percent (SSP) can be determined based upon any two of these four measurements. The results suggest that SSP is a better predictor of tree growth than BA in Oriental beech forests. The newly developed SDMD allows for a more effective use of the growing space to achieve specific silvicultural objectives including tree regeneration, timber production, thinning planning, and wildlife protection in Oriental beech forests.  相似文献   

14.
Simulation models such as forest patch models can be used to forecast the development of forest structural attributes over time. However, predictions of such models with respect to the impact of forest dynamics on the long-term protective effect of mountain forests may be of limited accuracy where tree regeneration is simulated with little detail. For this reason, we improved the establishment submodel of the ForClim forest patch model by implementing a more detailed representation of tree regeneration. Our refined submodel included canopy shading and ungulate browsing, two important constraints to sapling growth in mountain forests. To compare the old and the new establishment submodel of ForClim, we simulated the successional dynamics of the Stotzigwald protection forest in the Swiss Alps over a 60-year period. This forest provides protection for an important traffic route, but currently contains an alarmingly low density of tree regeneration. The comparison yielded a significantly longer regeneration period for the new model version, bringing the simulations into closer agreement with the known slow stand dynamics of mountain forests. In addition, the new model version was applied to forecast the future ability of the Stotzigwald forest to buffer the valley below from rockfall disturbance. Two scenarios were simulated: (1) canopy shading but no browsing impact, and (2) canopy shading and high browsing impact. The simulated stand structures were then compared to stand structure targets for rockfall protection, in order to assess their long-term protective effects. Under both scenarios, the initial sparse level of tree regeneration affected the long-term protective effect of the forest, which considerably declined during the first 40 years. In the complete absence of browsing, the density of small trees increased slightly after 60 years, raising hope for an eventual recovery of the protective effect. In the scenario that included browsing, however, the density of small trees remained at very low levels. With our improved establishment submodel, we provide an enhanced tool for studying the impacts of structural dynamics on the long-term protective effect of mountain forests. For certain purposes, it is important that predictive models of forest dynamics adequately represent critical processes for tree regeneration, such as sapling responses to low light levels and high browsing pressure.  相似文献   

15.
【目的】解析和定量评价林分因子对赤松赤枯病发生(发病率和病情指数)的影响,为昆嵛山赤松纯林的营林措施和赤枯病的预防提供理论指导。【方法】在昆嵛山区域选取林龄相对一致(约34年)的赤松纯林为研究对象,调查林分密度、郁闭度、树高、枝下高、胸径和冠幅6个林分因子及赤枯病的发病率和病情指数,采用方差分析、相关性分析和多重比较分析各项林分因子与赤松赤枯病之间的关系,并通过冗余分析得影响赤枯病发生的关键因子。【结果】赤枯病在赤松林中普遍发生,发病样地占调查样地的96.3%。整体上,高密度林( 2 956 ~4 089株·hm -2 )的发病率和病情指数显著高于低密度林(688~1 822株·hm -2 )和中密度林(1 823~2 955株·hm -2 )的发病率和病情指数;疏林(郁闭度<30%)的发病率和病情指数显著低于中疏林(郁闭度30%~70%)和密林(郁闭度> 70%)的发病率和病情指数;在不同的树高、枝下高、冠幅和胸径分组中,发病率和病情指数均随着分组值的增大而减小。相关性分析表明:林分密度对赤枯病发病率和病情指数的影响均达到极显著正相关水平( r =0.761, P < 0.01;r =0.748, P < 0.01);赤枯病的发病率和病情指数也均受到郁闭度的极显著影响( r =0.509, P < 0.01;r =0.442, P < 0.01);二者与树高均呈极显著正相关( r =-0.443, P < 0.01;r =-0.362, P < 0.01);赤枯病的发病率和病情指数均随枝下高的增大而极显著减小( r =-0.460, P < 0.01;r =-0.419, P < 0.01);二者与胸径均呈负相关关系,且相关性极显著( r =-0.425, P < 0.01;r =-0.373, P < 0.01);随着冠幅的增大,林木发病率和病情指数均极显著降低( r =-0.345, P < 0.01;r =-0.381, P < 0.01)。冗余分析证明林分密度和枝下高对赤枯病发生的贡献最大。【结论】松赤枯病在昆嵛山区域发生较普遍但不严重,其发病率和病情指数在不同林分因子分组中均有差异,且均受各林分因子极显著影响。RDA分析证明,林分密度和枝下高对松赤枯病影响最显著,建议对昆嵛山区域赤松纯林赤枯病的防治工作要以重要因子为主要调控对象,进行合理修剪和间伐。  相似文献   

16.
We estimated forest biomass carbon storage and carbon density from 1949 to 2008 based on nine consecutive forest inventories in Henan Province,China.According to the definitions of the forest inventory,Henan forests were categorized into five groups: forest stands,economic forests,bamboo forests,open forests,and shrub forests.We estimated biomass carbon in forest stands for each inventory period by using the continuous biomass expansion factor method.We used the mean biomass density method to estimate carbon stocks in economic,bamboo,open and shrub forests.Over the 60-year period,total forest vegetation carbon storage increased from34.6 Tg(1 Tg = 1×10~(12)g) in 1949 to 80.4 Tg in 2008,a net vegetation carbon increase of 45.8 Tg.By stand type,increases were 39.8 Tg in forest stands,5.5 Tg in economic forests,0.6 Tg in bamboo forests,and-0.1 Tg in open forests combine shrub forests.Carbon storageincreased at an average annual rate of 0.8 Tg carbon over the study period.Carbon was mainly stored in young and middle-aged forests,which together accounted for 70–88%of the total forest carbon storage in different inventory periods.Broad-leaved forest was the main contributor to forest carbon sequestration.From 1998 to 2008,during implementation of national afforestation and reforestation programs,the carbon storage of planted forest increased sharply from 3.9 to 37.9 Tg.Our results show that with the growth of young planted forest,Henan Province forests realized large gains in carbon sequestration over a 60-year period that was characterized in part by a nation-wide tree planting program.  相似文献   

17.
A canopy height model (CHM) is a standard LiDAR-derived product for deriving relevant forest inventory information, including individual tree positions, crown boundaries and plant density. Several image-processing techniques for individual tree detection from LiDAR data have been extensively described in literature. Such methods show significant performance variability depending on the vegetation characteristics of the monitored forest. Moreover, over regions of high vegetation density, existing algorithms for individual tree detection do not perform well for overlapping crowns and multi-layered forests. This study presents a new time and cost-efficient procedure to automatically detect the best combination of the morphological analysis for reproducing the monitored forest by estimating tree positions, crown boundaries and plant density from LiDAR data. The method needs an initial calibration phase based on multi attribute decision making-simple additive weighting (MADM-SAW). The model is tested over three different vegetation patterns: two riparian ecosystems and a small watershed with sparse vegetation. The proposed approach allows exploring the dependences between CHM filtering and segmentation procedures and vegetation patterns. The MADM architecture is able to self calibrate, automatically finding the most accurate de-noising and segmentation processes over any forest type. The results show that the model performances are strongly related to the vegetation characteristics. Good results are achieved over areas with a ratio between the average plant spacing and the average crown diameter (TCI) greater than 0.59, and plant spacing larger than the remote sensing data spatial resolution. The proposed algorithm is thus shown a cost effective tool for forest monitoring using LiDAR data that is able to detect canopy parameters in complex broadleaves forests with high vegetation density and overlapping crowns and with consequent significant reduction of the field surveys, limiting them over only the calibration site.  相似文献   

18.
The United Nations Framework Convention on Climate Change (UNFCCC) requires reporting net carbon stock changes and anthropogenic greenhouse gas emissions, including those related to forests. This paper describes the design and implementation of a nation-wide forest inventory of New Zealand’s planted post-1989 forests that arose from Land Use, Land-Use Change and Forestry activities (LULUCF) under Article 3.3 of the Kyoto Protocol. The majority of these forests are planted with Pinus radiata, with the remainder made up of other species exotic to New Zealand. At the start of the project there was no on-going national forest inventory that could be used as a basis for calculating carbon stocks and meet Good Practice Guidelines.A network of ground-based permanent sample plots was installed with airborne LiDAR (Light Detection and Ranging) for double sampling using regression estimators to predict carbon in each of the four carbon pools of above- and below-ground live biomass, dead wood and litter. Measurement, data acquisition and quality assurance/control protocols were developed specifically for the inventory, carried out in 2007 and 2008. Plots were located at the intersection of a forest with a 4 km square grid, coincident with an equivalent 8 km square grid established over the indigenous forest and “grassland with woody biomass” (Other Wooded Land). Planted tree carbon within a ground plot was calculated by an integrated system of growth, wood density and compartment allocation models utilising the data from measurements of trees and shrubs on the plots. This system, called the Forest Carbon Predictor, predicts past and future carbon in a stand and is conditioned so that the calculated basal area and mean top height equals that obtained by conventional mensuration methods at the time of the plot measurement. Mean per hectare carbon stocks were then multiplied by an estimate of the total area of post 1989 forests obtained from wall to wall mapping using a combination of satellite imagery and ortho-photography.The network of permanent samples plots and LiDAR double sampling methodology was designed to be simple and robust to change over time. In the future, using LiDAR should achieve sampling efficiencies over using ground plots alone and reduces any problems regarding restricted access on the ground. The network is to be remeasured at the end of commitment period 1, 2012, and the carbon stocks re-estimated in order to calculate change.  相似文献   

19.
As a result of extensive deforestation, the survival of many tropical forest species may depend on disturbed forests. However, recent studies demonstrate that tree regeneration following logging can be slow, decreasing the conservation value of disturbed forests. Here we test whether the dominating herb, Acanthus pubescens, in the understory of logged forest, suppresses tree regeneration in Kibale National Park, Uganda. We compare the establishment, growth, and survival of tree seedlings over 2.5 years between sites cleared of A. pubescens and controls. We also consider the role of elephants (Loxodonta africana) in inhibiting tree regeneration. Seedling abundance and species richness was greater in cleared than control plots at the start of the study. Seedling abundance decreased over the study, but remained greater in cleared than control plots. Species richness did not vary over the study. However, species composition of the cleared plots was marginally different from control plots at the start, but converged on the composition of control plots by the end of the study. This suggests a common regeneration assemblage derived from reorganisation of species, rather than recruitment of new species. There was no difference in recruitment rates between cleared and control plots. These findings suggest no strong direct effects of the herb on tree regeneration in this disturbed forest. However, when we modelled (i.e., removed) the effect of elephants on regeneration, the abundance of seedlings increased in both plot types and remained reasonably constant over time. The decline in density of regenerating stems over the study was most likely caused by elephants visiting the plots. We conclude that elephants have a far greater effect in suppressing tree regeneration at Kibale than the herb stratum and are ultimately responsible for arresting succession in disturbed forest. However, as intensive logging creates conditions favourable for A. pubescens, which is eaten by elephants, the best management intervention is to constrain logging intensities to below levels above which widespread establishment of A. pubescens is promoted, thus limiting elephant activity in regenerating areas.  相似文献   

20.
Large-scale inventories of forest biomass and structure are necessary for both understanding carbon dynamics and conserving biodiversity. High-resolution satellite imagery is starting to enable structural analysis of tropical forests over large areas, but we lack an understanding of how tropical forest biomass links to remote sensing. We quantified the spatial distribution of biomass and tree species diversity over 4 ha in a Bolivian lowland moist tropical forest, and then linked our field measurements to high-resolution Quickbird satellite imagery. Our field measurements showed that emergent and canopy dominant trees, being those directly visible from nadir remote sensors, comprised the highest diversity of tree species, represented 86% of all tree species found in our study plots, and contained the majority of forest biomass. Emergent trees obscured 1–15 trees with trunk diameters (at 1.3 m, diameter at breast height (DBH)) ≥20 cm, thus hiding 30–50% of forest biomass from nadir viewing. Allometric equations were developed to link remotely visible crown features to stand parameters, showing that the maximum tree crown length explains 50–70% of the individual tree biomass. We then developed correction equations to derive aboveground forest biomass, basal area, and tree density from tree crowns visible to nadir satellites. We applied an automated tree crown delineation procedure to a high-resolution panchromatic Quickbird image of our study area, which showed promise for identification of forest biomass at community scales, but which also highlighted the difficulties of remotely sensing forest structure at the individual tree level.  相似文献   

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