栗瘿蜂虫瘿在板栗林内空间分布格局研究

应用聚集度指标法、Iwao回归分析法、Taylor幂指数法对怀柔区试验地板栗林内栗瘿蜂虫瘿空间分布格局进行了分析.结果表明:栗瘿蜂虫瘿在板栗林内呈现出聚集分布的特点,而且种群在一切密度下都是聚集的,聚集强度随种群密度的升高而增加.栗瘿蜂虫瘿数量在树冠东、西、南、北4个方向上的分布差异显著,以南方向最多,北方向最少.树冠上、中、下层虫瘿分布存在显著差异,以下层分布最多,上层最少.采用Iwao的方法分析了不同方位、不同层次分布特点和空间分布形式.结果表明:各个方向、不同层次上虫瘿分布普遍呈现聚集分布的特点.根据Iwao提出的新序贯抽样理论,列出了试验地区的序贯抽样表,为林间抽样调查和防治提供了依据.     

基于图像处理技术梨果实尺寸测定系统的研发与应用

根据标准参照物确定梨果实尺寸的计算机2D图像处理模型,开发了基于AForge.net图像类库和MatLab图像处理工具的梨果实尺寸测定软件工具包。结果表明,利用该工具包可对一幅果实2D数字图像内多个果实的多个表型（果实纵径、果实横径、果形指数、果实截面积、果心纵径、果心横径与果梗长度）进行精确度量,具备准确、快速、易于操作等优点,有一定推广应用价值。此外,配套的图像采集装置与图像编辑工具可帮助研究人员建立规范的表型图像数据集。     

灵芝膜喙扁蝽的空间分布型及抽样技术研究

根据1995～1997年在灵芝田对灵芝膜喙扁蝽[Mezira membranacea(Frab)]的调查结果,计算了6种分布型指数,经lwao聚集度指标、Taylor幂法和lwao回归法测定,结果表明,该虫在灵芝田呈聚集分布,其分布强度随种群密度的升高而增强。聚集原因既有环境因子,又有该虫本身的特性。同时建立了该虫的理论抽样公式。     

Simple Neural Network Reveals Unexpected Patterns of Bird Species Richness in Forest Fragments

The study of links between bird species richness and forest fragmentation contributes to a better understanding of landscape biodiversity. Difficulties arise from the necessity to deal with multiple non-linear relationships between the involved variables. Neural network models provide an interesting solution thanks to their internal set of non-linear neuron-like components. Their ability is well established for prediction, but their complex structure limits the understanding of underlying processes. To open the ‘black box’ and get a more transparent ‘glass box’ model, we selected a simple neural network (2 inputs, 1 hidden layer with 3 neurons and 1 output neuron), that improves the prediction of birds species richness (lower root mean square error) compared to linear, log-linear and logistic models, and simple enough to analyze its internal components and identify patterns in the data. The first hidden neuron provided a sigmoid relationship related to the forest area, the second was like a Boolean operator separating two groups according to the distance to the nearest source forest larger than 100 ha, and the third acted on the smallest isolated woodlots. We revealed a group of isolated woodlots with a higher species richness than less isolated woodlots for a given forest area. This result, unexpected according to the literature, was not obvious in the raw data, and could be explained by a regional differentiation in fragmentation history. Our neural network showed its ability to improve prediction accuracy in respect to other models, to remain ecologically understandable and to give new insights into data exploration.     

Recent forest cover type transitions and landscape structural changes in northeast Minnesota,USA

Landsat TM satellite data covering an approximate 5-year interval (1990–1995) were used to quantify spatial pattern and transition rates between forest ecological states for a 2.76 million ha region in northeast Minnesota. Changes in forest cover were stratified by Ecological Subsection, management status, and by ownership categories using a 1995 digital ownership layer. Approximately 4.2% of the 1990 mature forested area was converted to early successional types by 1995. Of this 4.2%, private lands accounted for 33%, federal lands 31%, county lands 20% and state lands 16%. Notable conversion percentages by cover type category were spruce-fir (−5.3%), aspen-birch(−4.7%), jack pine (−4.6%) and black spruce(−3.0%). Transition rates were also adjusted to fit ten-year time intervals. Shannon-Weaver Eveness and edge density of cover types increased over the study period as relative contagion and interior forest area decreased. These trends suggest both smaller patches and a more even distribution of cover types. Area of upland conifers, lowland conifers and lowland hardwoods decreased while the area of mature upland hardwoods increased in most patch size classes except the > 500 ha class which showed a substantial decrease in area. The area of early successional types increased in most patch size classes. Non-industrial private forestland had the lowest proportion of interior forest of all ownership categories -decreasing by 13.5% in five years. Smaller average cut-unit size sand uncoordinated forest management is the likely cause since cutting rates between private and public forestland were similar. This revised version was published online in July 2006 with corrections to the Cover Date.     

大棚草莓斜纹夜蛾的空间分布型

斜纹夜蛾Spodoptera litura(Fabricius)是大棚草莓生长初期的重要害虫。为明确斜纹夜蛾在草莓上的时空动态,连片调查了草莓上低龄幼虫数、中高龄幼虫数、受害叶片数以及叶片受害率,利用聚集度指标法、Taylor幂法则和IwaoM-m的回归法进行分析。结果表明低龄幼虫呈明显的聚集分布,中高龄幼虫则呈随机分布或均匀分布,受害叶片和受害率呈明显的聚集分布;通过聚集均数(λ)判断低龄幼虫高密度时λ>2,聚集由于成虫产卵块、初孵幼虫成聚集危害引起;低龄幼虫低密度时λ<2,聚集由植株间距等影响初孵幼虫的扩散因子引起;中高龄幼虫呈随机分布的田块的λ<2。*     

加工番茄早熟性状的相关性分析及QTL定位

利用加工番茄TD-13和TD-41杂交的185个F2群体,分析与早熟性相关的各生育期性状,并对相关性状进行QTL分析。结果表明:成熟期与始花期、始花节位、结果期、开花至成熟天数呈极显著正相关,与早期结果数,平均单果重相关性不显著。利用复合区间作图法检测到与加工番茄早熟性状相关的12个QTLs。控制始花期和始花节位的QTLs分别检测到3个,控制成熟期和平均单果重的QTLs分别检测到2个,控制开花至成熟天数和早期结果数的QTL分别检测到1个。     

Simulating Spatial Nitrogen Dynamics in a Forested Reference Watershed, Hubbard Brook Watershed 6, New Hampshire, USA

We demonstrate that available information on spatial heterogeneity in biotic, topographic, and climatic variables within a forested watershed, Hubbard Brook Experimental Forest (HBEF) Watershed 6, New Hampshire, USA, was sufficient to reproduce the observed elevational pattern in stream NO₃ concentration during the 1982–1992 period. Five gridded maps (N mineralization factor, N uptake factor, precipitation, elevation, and soil depth factor) were created from spatial datasets and successively added to the spatially explicit model SINIC-S as spatially varying input parameters. Adding more spatial information generally improved model predictions, with the exception of the soil depth factor. Ninety percent of the variation in the observed stream NO₃ concentration was explained by the combination of the spatial variation of the N mineralization and N uptake factors. Simulated streamflow NO₃ flux at the outlet point was improved slightly by introducing spatial variability in the model parameters. The model exhibited substantial cell-to-cell variation in soil N dynamics and NO₃ loss within the watershed during the simulation period. The simulation results suggest that the spatial distributions of forest floor organic matter and standing biomass are most responsible for creating the elevational pattern in stream NO₃ concentration within this watershed.     

Assessing Spatial Uncertainty Associated with Forest Fire Boundary Delineation

Uncertainty in managing forested landscapes arises from many sources, including complexities inherent in forest ecosystems and their disturbance processes. However, gaining knowledge about forested ecosystems at the landscape level is often impeded by limitations in collecting comprehensive, representative, as well as accurate data sets. Historical reference data sets about past disturbances are also mostly lacking. In the case of ground fires, however, records of past fires can be obtained by analyzing fire scars using dendrochronology. While the temporal series of disturbance can be determined, there is still uncertainty about the spatial limits of individual forest surface fires. Here, we investigate how a patch-based method (fuzzy set membership) and a boundary-based uncertainty method (boundary membership) can help determine the spatial uncertainty related to forest fire events and their boundary locations. We compare these methods using fire scar data from ponderosa pine (Pinus ponderosa) and Douglas-fir (Pseudotsuga menziesii) sampled at 33 1-ha plots in a 1500-ha study area within the Stein River watershed (British Columbia). Patch-based fire maps, using multiple constraints, were derived for years 1785–1937. We compared the resulting total fire event maps with the boundary-based method, finding that depending on values chosen for the patch-based method, negative correlation was present (though very modest: r = − 0.1, p ≤ 0.05) between some maps. However, significant positive correlation between maps (though again modest: r = 0.22, p ≤ 0.05) was found under the least constrained patch-based methods, suggesting that fire patches are counted more than once in riparian zones. Our results suggest that these two methods provide complementary information about historical fire size and spatial limits. Quantifying spatial uncertainty about fire size and fire boundary location using a boundary membership method can contribute to not only understanding past fire regimes but also to providing better estimates of area burned.     

Spatial dependence and the relationship of soil organic carbon and soil moisture in the Luquillo Experimental Forest,Puerto Rico

We used geo-spatial statistical techniques to examine the spatial variation and relationship of soil organic carbon (SOC) and soil moisture (SM) in the Luquillo Experimental Forest (LEF), Puerto Rico, in order to test the hypothesis that mountainous terrain introduces spatial autocorrelation and crosscorrelation in ecosystem and soil properties. Soil samples (n = 100) were collected from the LEF in the summer of 1998 and analyzed for SOC, SM, and bulk density (BD). A global positioning system was used to georeference the location of each sampling site. At each site, elevation, slope and aspect were recorded. We calculated the isotropic and anisotropic semivariograms of soil and topographic properties, as well as the cross-variograms between SOC and SM, and between SOC and elevation. Then we used four models (random, linear, spherical and wave/hole) to test the semi-variances of SOC, SM, BD, elevation, slope and aspect for spatial dependence. Our results indicate that all the studied properties except slope angle exhibit spatial dependence within the scale of sampling (200 – 1000 m sampling interval). The spatially structured variance (the variance due to the location of sampling sites) accounted for a large proportion of the sample variance for elevation (99%), BD (90%), SOC (68%), aspect (56%) and SM (44%). The ranges of spatial dependence (the distances within which parameters are spatially dependent) for aspect, SOC, elevation, SM, and BD were 9810 m, 3070 m, 1120 m, 930 m and 430 m, respectively. Cross correlograms indicate that SOC varies closely with elevation and SM depending on the distances between samples. The correlation can shift from positive to negative as the separation distance increases. Larger ranges of spatial dependence of SOC, aspect and elevation indicate that the distribution of SOC in the LEF is determined by a combination of biotic (e.g., litterfall) and abiotic factors (e.g., microclimate and topographic features) related to elevation and aspect. This demonstrates the importance of both elevation and topographic gradients in controlling climate, vegetation distribution and soil properties as well as the associated biogeochemical processes in the LEF.This revised version was published online in May 2005 with corrections to the Cover Date.     

Statistical models of landscape pattern metrics,with applications to regional scale dynamic forest simulations

Forest managers in Canada need to model landscape pattern or spatial configurationoverlarge (100,000 km²) regions. This presents a scalingproblem, as landscape configuration is measured at a high spatial resolution,but a low spatial resolution is indicated for regional simulation. We present astatistical solution to this scaling problem by showing how a wide range oflandscape pattern metrics can be modelled from low resolution data. Our studyarea comprises about 75,000 km² of boreal mixedwoodforest in northeast Alberta, Canada. Within this area we gridded a sample of 84digital forest cover maps, each about 9500 ha in size, to aresolution of 1 ha and used FRAGSTATS to compute a suite oflandscape pattern metrics for each map. We then used multivariate dimensionreduction techniques and canonical correlation analysis to model therelationship between landscape pattern metrics and simpler stand table metricsthat are easily obtained from non-spatial forest inventories. These analyseswere performed on four habitat types common in boreal mixedwood forests: youngdeciduous, old deciduous, white spruce, and mixedwood types. Using only threelandscape variables obtained directly from stand attribute tables (totalhabitatarea, and the mean and standard deviation of habitat patch size), ourstatistical models explained more than 73% of the joint variation in fivelandscape pattern metrics (representing patch shape, forest interior habitat,and patch isolation). By PCA, these five indices captured much of the totalvariability in the rich set of landscape pattern metrics that FRAGSTATS cangenerate. The predictor variables and strengths of association were highlyconsistent across habitat classes. We illustrate the potential use of suchstatistical relationships by simulating the regional, cumulative effects ofwildfire and forest management on the spatial arrangement of forest patches,using non-spatial stand attribute tables.This revised version was published online in May 2005 with corrections to the Cover Date.     

Native oak retention as a key factor for the conservation of winter bird diversity in managed deciduous forests in northern Italy

Birds can serve as useful model organisms to investigate community level consequences of forestry practices. In this study we investigated the relationships between wintering bird communities and habitat and landscape characteristics of lowland managed forests in Northern Italy. This area is characterized by the spread of the black locust, an alien species that has been favored by forestry practices at the expense of natural oak forests. Birds were censused in winter by point counts in randomly selected plots of 50 m radius. We first addressed bird community–habitat relationships by means of habitat structure measurements, then we investigated bird community–landscape relationships by using GIS techniques. We used generalized linear models (GLM) to test for the effects of habitat and landscape variables on bird community parameters (namely bird species richness, diversity and abundance). Bird community parameters were influenced by oak biomass and tree age, and by oak area and core area, while the other forest habitat types showed less influence. In forest management terms, the main conclusion is that the retention of native oaks is the keyfactor for the conservation of winter bird diversity in local deciduous woods. At the habitat level black locust harvesting may be tolerated, provided that old, large, native oaks are retained in all local woodlots to preserve landscape connectivity and foraging resources. At the landscape meso-scale, large native oak patches, should be preserved or, where necessary, restored. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Watershed analysis of forest fragmentation by clearcuts and roads in a Wyoming forest

Remotely sensed data and a Geographic Information System were used to compare the effects of clearcutting and road-building on the landscape pattern of the Bighorn National Forest, in north-central Wyoming. Landscape patterns were quantified for each of 12 watersheds on a series of four maps that differed only in the degree of clearcutting and road density. We analyzed several landscape pattern metrics for the landscape as a whole and for the lodgepole pine and spruce/fir cover classes across these maps, and determined the relative effects of clearcutting and road building on the pattern of each watershed. At both the landscape- and cover class-scales, clearcutting and road building resulted in increased fragmentation as represented by a distinct suite of landscape structural changes. Patch core area and mean patch size decreased, and edge density and patch density increased as a result of clearcuts and roads. Clearcuts and roads simplified patch shapes at the landscape scale, but increased the complexity of lodgepole pine patches. Roads appeared to be a more significant agent of change than clearcuts, and roads which were more evenly distributed across a watershed had a greater effect on landscape pattern than did those which were densely clustered. Examining individual watersheds allows for the comparison of fragmentation among watersheds, as well as across the landscape as a whole. Similar studies of landscape structure in other National Forests and on other public lands may help to identify and prevent further fragmentation of these areas.     

白菜黑斑病空间分布型研究及杀菌剂筛选

通过对白菜黑斑病的空间分布型进行研究,结果表明:在发病初期,白菜黑斑病空间分布型为随机分布;在病害发生1代以后白菜黑斑病多为聚集分布;在病害发生后期,单株病斑数大于1 000的地块,白菜黑斑病可能成为均匀分布.通过室内杀菌剂的筛选,结果表明:退菌特对白菜黑斑病菌的毒力最强,福美双、代森锰锌(新万生)对白菜黑斑病菌的毒力也很强,杀毒矾、速克灵、百菌清对白菜黑斑病菌也有较好的毒力.     

Spatial Patterns in European Rabbit Abundance After a Population Collapse

Assessing the associations between spatial patterns in population abundance and environmental heterogeneity is critical for understanding various population processes and for managing species and communities. This study evaluates responses in the abundance of the European rabbit (Oryctolagus cuniculus), an important prey for predators of conservation concern in Mediterranean ecosystems, to environmental heterogeneity at different spatial scales. Multi-scale habitat models of rabbit abundance in three areas of Doñana, south-western Spain, were developed using a spatially extensive dataset of faecal pellet counts as an abundance index. The best models included habitat variables at the three spatial scales examined: distance from lagoons (broad scale), mean landscape shrub coverage and interspersion of pastures (home-range scale), and shrub and pasture cover (microhabitat scale). These variables may well have been related to the availability of food and refuge for the species at the different scales. However, the models’ fit to data and their predictive accuracy for an independent sample varied among the study regions. Accurate predictions in some areas showed that the combination of variables at various spatial scales can provide a reliable method for assessing the abundance of ecologically complex species such as the European rabbit over large areas. On the other hand, the models failed to identify abundance patterns in a population that suffered the strongest demographic collapse after viral epidemics, underlining the difficulty of generalizing this approach. In the latter case, factors difficult to implement in static models such as disease history and prevalence, predator regulation and others may underlie the lack of association. Habitat models can provide useful guidelines for the management of landscape attributes relevant to rabbits and help improve the conservation of Mediterranean communities. However, other influential factors not obviously related to environmental heterogeneity should also be analyzed in more detail.     

Modeling configuration dynamics of harvested forest landscapes in the Canadian boreal plains

Habitat configuration has important implications for the persistence of faunal and floral populations at a variety of spatial scales. Forest harvesting alters habitat configurations. However, measuring and predicting such alterations remains challenging, in part because previously developed metrics of habitat configuration are often not statistically independent of habitat amount. Thus, their ability to measure independent effects of habitat configurations and habitat amount on ecosystem components such as wildlife populations has been limited. Here, we evaluate habitat configuration based on newly developed metrics that are independent of habitat amount but do not depend on regression residuals of abundance and configuration relationships on any population of landscapes. We use these new metrics to measure and predict changes in habitat configuration following forest harvesting in the boreal forest of Alberta, Canada. Our findings clearly demonstrate changes in habitat configuration resulting from forest harvesting can be predicted precisely with information about initial habitat patch structure and harvesting patterns. Because forest harvesting has significant implications for habitat configuration, accurately predicting these changes is critical for determining if forest harvesting strategies are sustainable for ecosystem components and processes. This study provides a set of novel, robust metrics for tracking landscape-scale changes in habitat configuration in harvested boreal forests.     

A note on contagion indices for landscape analysis

The landscape contagion index measures the degree of clumping of attributes on raster maps. The index is computed from the frequencies by which different pairs of attributes occur as adjacent pixels on a map. Because there are subtle differences in the way the attribute adjacencies may be tabulated, the standard index formula may not always apply, and published index values may not be comparable. This paper derives formulas for the contagion index that apply for different ways of tabulating attribute adjacencies — with and without preserving the order of pixels in pairs, and by using two different ways of determining pixel adjacency. When the order of pixels in pairs is preserved, the standard formula is obtained. When the order is not preserved, a new formula is obtained because the number of possible attribute adjacency states is smaller. Estimated contagion is also smaller when each pixel pair is counted twice (instead of once) because double-counting pixel adjacencies makes the attribute adjacency matrix symmetric across the main diagonal.     

越冬柑桔锈螨的空间格局与抽样技术

应用6个聚集度指标分析了越冬柑桔锈螨成虫的空间格局,并对抽样技术进行了探讨。结果表明,越冬柑桔锈螨成虫的空间格局为聚集型;田间的最适抽样部位是植株上、中部叶片的叶腋处。提出了越冬成虫密度估计的序贯抽样方案。     

Regeneration Strategies,Disturbance and Plant Interactions as Organizers of Vegetation Spatial Patterns in a Pine Forest

To determine how vegetation pattern in early successional forests may be related to plant traits and types of disturbance, we measured percent cover of individual taxa annually in a South Carolina Pinus elliottii forest, starting one year before, and ending four years after harvest and tree girdling disturbances were applied. The 17 most important taxa surveyed were grouped into four regeneration strategies chosen a priori, and the spatial patterns of these groups and of the soil were investigated using global variability, semivariograms and kriged maps. We also examined spatial correlations across years, across taxa, and between species and soil disturbance. Seed bank taxa represented by Dichanthelium spp. increased rapidly and formed large patches, and then quickly declined. Taxa that regenerate by newly dispersed seeds, represented by Rhus copallina and Rubus spp. occurred at first in a few patches, and became widespread later. Stump sprouters, represented by Quercus spp. and Myrica cerifera, had rapid increases in cover, but their spatial patterns were largely determined by their pre-disturbance patterns. Prunus serotina, which relies on both sprouting and dispersed seed, had moderate cover and a random distribution. Within-species temporal correlation of spatial pattern was lower in girdled than in harvested plots, and was not clearly related to regeneration strategy. Forest floor disturbance was patchy and affected the pattern of Dichanthelium spp. in the harvested plots. Negative correlations between herbs and woody plants in harvested plots reflected the role of biotic (i.e., successional) filters on vegetation pattern. Surprisingly, no spatial correlations were detected between the nitrogen fixer, Myrica cerifera and other taxa in this N-limited system. In comparing the spatial and temporal patterns, we found kriged maps more informative than analysis of semivariograms alone. The maps and correlation statistics demonstrated that regeneration traits, spatial patterns of soil disturbances, and interactions among taxa influence dynamics of the spatial patterns of the plants. We also demonstrated that disturbance types affected the importance and interactions among these three factors, and caused different spatial patterns of the plant taxa.     

基于图像处理技术的柑桔园估产系统研制

通过利用柑桔园代表性植株成熟期普通数码照片,运用计算机图像处理、图形识别、智能推衍等技术识别植株挂果数,建立柑桔园产量估算模型,进而对拟测产目标果园取样单株进行图像分析处理,估算出单株产量和单位面积产量,最终实现果园产量的准确估算.