Stand Structure, Diversity and Regeneration Status of Woody Species in Open and Exclosed Dry Woodland Sites around <i>Molapo</i>Farming Areas of the Okavango Delta, Northeastern Botswana

Stand structure, diversity and regeneration status of woody species were investigated in open and exclosed dry woodland sites in Island Safari, Shorobe and Xobe, northeastern Botswana. A total of 105, 111 and 130 quadrats, measuring 20 × 20 m each, were laid down along parallel line transects in the three sites, respectively, to collect data. A total of 47 species, representing 16 families and 24 genera, were recorded in the study sites. Of these, 33 species representing 13 families and 20 genera, 41 species representing 15 families and 23 genera and 27 species representing 10 families and 14 genera were encountered in Island Safari, Shorobe and Xobe, respectively. The most diverse family was Fabaceae followed by Combretaceae and Tiliaceae at all the three sites. The most diverse genus was Acacia, followed by Combretum and Grewia. The diversity of woody species in the study sites were 2.18, 2.15 and 1.5 in Shorobe, Island Safari and Xobe, respectively, while their corresponding evenness values were 0.6, 0.6 and 0.5, respectively. The mean densities of the woody species encountered in Island Safari, Shorobe and Xobe were 2629, 4271 and 2745 individuals ha&#451, respectively. The five densest species were Colophospermum mopane, Dichrostachys cinerea, Acacia tortilis, Philenoptera violacea and Terminalia prunioides in Island Safari, C. mopane, A. tortilis, A. erioloba, P. violacea and D. cinerea in Shorobe and Acacia mellifera, A. tortilis, P. nelsii, A. luederitzii and A. erubescens in Xobe. The highest important value index values were exhibited by C. mopane, D. cinerea, A. tortilis, P. violacea and T. prunioides in Island Safari, C. mopane, A. erioloba, A. tortilis, P. violacea and C. imberbe in Shorobe, and A. mellifera, A. tortilis, P. nelsii and A. luederitzii in Xobe. The alarming result was the fact that 71%, 80% and 85% of the woody species recorded in Island Safari, Shorobe and Xobe, respectively, exhibited hampered regeneration and, thus, unhealthy population structures. Therefore, there is an urgent need to address the observed unhealthy population structures of the woody species through investigation of the major causes of their hampered regeneration, and also designing measures that will facilitate natural and artificial regeneration of these species at the three study sites.

Socio-economic vulnerability level in the Jeneberang watershed in Gowa Regency,South Sulawesi Province,Indonesia

Jeneberang watershed is vital,particularly for people living in Gowa Regency(South Sulawesi Province,Indonesia),who benefit from its many advantages.Landslides and floods occur every year in the Jeneberang watershed,so it is imperative to understand the socio-economic vulnerability of this region.This research aims to identify the vulnerability level of the Jeneberang watershed so that the government can prioritize areas with high vulnerability level and formulate effective strategies to reduce these the vulnerability.Specifically,this study was conducted in 12 districts located in the Jeneberang watershed.The primary data were collected from questionnaires completed by community members,community leaders,and various stakeholders,and the secondary data were from the Landsat satellite imagery in 2020,the Badan Push Statistic of Gowa Regency,and some governmental agencies.The socio-economic vulnerability variables were determined using the Multiple Criteria Decision Analysis(MCDA)method,and each variable was weighted and analyzed using the Geographical Information System(GIS).The study reveals that the levels of socio-economic vulnerability are affected by variables such as population density,vulnerable groups(disabled people,elderly people,and young people),road network and settlement,percentage of poor people,and productive land area in the Jeneberang watershed.Moreover,all of the 12 districts in the Jeneberang watershed are included in the medium vulnerability level,with the mean percentage of socio-economic vulnerability around 50.92%.The socio-economic vulnerability of Bajeng,Pallangga,and Somba Opu districts is categorized at high level,the socio-economic vulnerability of Bungaya,Parangloe,and Tombolo Pao districts is classified as medium level,and the remaining 6 districts(Barombong,Bontolempangan,Bontomarannu,Manuju,Parigi,and Tinggimoncong)are ranked as low socio-economic vulnerability.This study can help policy-makers to formulate strategy that contributes to the protection of biodiversity and sustainable development of the Jeneberang watershed,while improving disaster resilience and preparedness of the watershed.

Simulation on Distribution of Photosynthetically Active Radiation in Canopy and Optimum Leaf Rolling Index in Rice with Rolling Leaves

By replacing leaf area index （LAI） with effective leaf area index （ELAI） through introduction of leaf rolling index （LRI）, the distributions of photosynthetically active radiation （PAR） in the canopies of three hybrid rice combinations, Liangyou E32 with high LRI, Liangyoupeijiu with moderate LRI and Shanyou 63 with non-rolling leaves （normal）, were simulated. The model based on ELAI could predict more accurately than that based on LAI. The PAR interception, conversion and utilization efficiency in the three combinations were studied to evaluate their optimal LRI and LAI. The PAR utilization efficiency of Liangyou E32 was lower due to excessive rolling leaves and less ELAI, and that of Shanyou 63 was also lower because of the faulty PAR interception and lower photosynthetic rate and saturation point at lower layer in canopy. Compared with the above two combinations, Liangyoupeijiu showed more appropriate distribution of PAR interception and conversion efficiency in canopy, and higher PAR utilization efficiency. The optimal LRI and LAI for Liangyoupeijiu were 0.11 and 7.6, respectively, which were close to the observed value, 0.11 and 7.9, respectively. However, the optimum LAI was 9.8 for Liangyou E32 and 6.2 for Shanyou 63, larger or smaller than those under the current plant density, which led to lower efficiency of PAR utilization. Besides, the optimum LRI for Liangyou E32 and Shanyou 63 were 0.12 and 0.08, respectively, which were close to the actual LRI for Liangyoupeijiu （0.11）.

Evolution of Jobs-housing Spatial Relationship in Beijing Metropolitan Area:A Job Accessibility Perspective

With the urban expansion and economic restructuring, the jobs-housing relationship has become an important issue in studies on urban spatial structure. This paper employed a job accessibility model, which is an evaluation instrument to measure the jobs-housing relationship in Beijing Metropolitan Area from a job accessibility perspective. The results indicate that the population in the central city is declining, whereas the population in the suburbs is consistently growing and forming new population centers. However, the distribution pattern of employment is still highly centralized. Job accessibility varies in different locations, but the inner-city areas(within the Third Ring road) have seen improved job accessibility over time while job accessibility in the suburbs(especially outside the Fourth Ring road) has decreased, and this has led it to become a primary area of residential and employment mismatch. At the same time, the new towns in the outer suburbs have not yet demonstrated great potential to attract more jobs. In addition we find that, to some extent, urban planning changes the jobs-housing relationship, but a polycentric urban spatial structure is not yet evident. The floating population and related housing policy also affect the jobs-housing relationship. We propose some measures to resolve the spatial mismatch as well as some future research directions.

陕西省延安市成年人群血清n-HDL-C水平参考区间的建立及影响因素分析

目的建立陕西省延安市成年人血清非高密度脂蛋白-胆固醇(non-high-density lipoprotein cholesterol,n-HDL-C)的参考区间并分析影响因素。方法采用随机整体抽样的方法,抽取2023年1~9月陕西省延安市10个乡镇16921例成人为研究对象。调查年龄、性别、吸烟、饮酒、锻炼、高血压、糖尿病、血脂异常、慢性病、居住、饮食习惯、婚姻状况、文化程度、月收入等。测量身高、体重、腰围和血压。检测血清三酰甘油(TG)、总胆固醇(TCHO)、高密度脂蛋白-胆固醇(HDL-C)、低密度脂蛋白-胆固醇(LDL-C)、载脂蛋白A1(ApoA1)、载脂蛋白B(ApoB)及脂蛋白a[Lp(a)]水平,计算n-HDL-C水平,n-HDL-C(mmol/L)=TCHO(mmol/L)-HDL-C(mmol/L)。按照WS/T402-2012《中华人民共和国卫生行业标准》建议的百分位数法计算95%参考区间(P_(2.5)~P_(97.5))。采用多因素Logistic回归分析影响血清n-HDL-C水平的影响因素。结果男性和女性血清n-HDL-C水平均呈非正态分布(S=2.119,2.091,均P<0.001)。男性>60岁血清n-HDL-C水平[2.98(2.50,3.37)mmol/L]与18~30岁[2.84(2.49,3.26)mmol/L],31~40岁[2.98(2.62,3.42)mmol/L],41~50岁[3.10(2.62,3.47)mmol/L]和51~60岁[3.05(2.64,3.46)mmol/L]比较,差异具有统计学意义(H=3.618~5.680,均P<0.05);女性51~60岁血清n-HDL-C水平[3.08(2.71,3.44)mmol/L]与18~30岁[2.64(2.29,3.07)mmol/L],31~40岁[2.67(2.31,3.08)mmol/L],41~50岁[2.94(2.58,3.29)mmol/L]比较(H=8.161~13.445,均P<0.001),>60岁血清n-HDL-C水平[2.98(2.57,3.34)mmol/L]与18~30岁、31~40岁、41~50岁比较,差异具有统计学意义(H=7.985~14.018,均P<0.001)。将无统计学意义的年龄组合并,得到成年人群血清n-HDL-C水平参考区间:男性18~60岁(1.97~3.97mmol/L),>60岁(1.86~3.91mmol/L);女性18~50岁(1.82~3.74mmol/L),>50岁(1.94~3.88mmol/L)。将纳入的16921例成人分为n-HDL-C水平正常组和异常组,两组血清TG(1.02±0.31 mmol/L vs 1.24±0.37mmol/L),TCHO(3.97±1.02 mmol/L vs 4.66±1.25 mmol/L),LDL-C(2.37±0.58mmol/L vs 2.59±0.67 mmol/L)水平及年龄(43.55±11.52岁vs 46.27±8.13岁)比较,差异具有统计学意义(t=2.041~3.151,均P<0.05),血清n-HDL-C水平异常率42.50%。经多因素Logistic回归分析,男性、锻炼缺乏、超重和肥胖、血脂异常、城市居民、高中及以上学历是该地区成年人血清n-HDL-C水平的影响因素(均P<0.05)。结论初步建立了该地区成年人血清n-HDL-C水平参考区间,男性、锻炼缺乏、超重和肥胖、血脂异常、城市居民、高中及以上学历是该地区成年人血清n-HDL-C水平异常的影响因素。

数字经济、农村劳动力迁移与农民农村共同富裕

文章使用2012—2022年我国30个省份的数据,实证考察数字经济、农村劳动力迁移与农民农村共同富裕三者之间的关系,并实证检验人口密度的调节作用。研究发现,数字经济发展水平和农民农村共同富裕水平均呈现稳步上升趋势;数字经济能够促进农民农村共同富裕,农村劳动力迁移在其中起到部分中介作用。进一步研究发现,人口密度在数字经济对农民农村共同富裕的影响过程中具有正向调节作用。面板门槛模型的回归结果显示,在经济发展环境越好的地区,数字经济对农民农村共同富裕的推动作用越强。

Growing stock variation in different teak (Tectona grandis) forest stands of Mizoram,India

The growing stock assessment of three different teak forest stands （Tuirial： 500 m asl, Sairang： 200 m asl and Phunchawng： 550 m asl） was done in 2006 in Mizoram, India. Five diameter classes were arbitrarily established for knowing the volume attribute data and population structure, viz. a （10-20 cm）, b （20-30 cm）, c （30-40 cm）, d （40-50 cm）, and e （50-60 cm）. Results revealed that the density of the individuals among the studied stands varied from 280 stems/ha to 620 stems/ha. The average diameter of all the individuals ranged between 27.48 cm and 35.43 cm. Similarly, the average height was oscillated between 17.87 m and 22.24 m. The total basal area was recorded between 24.28 m2.ha-1 and 45.80 m2.ha＂l. The maximum and minimum values of total growing stock under all the diameter classes were 669.01 m3.ha-1 and 284.7 m3.ha-1, respectively. The representation of population structure of different stands explained that the perpetuation of this species was ensured for a quite long time.

Morphometry of Axons in Optic Nerves of Siamese's Twins

Purpose: To observe the development of optic nerve, we examined four optic nerves from Siameses Twins by absolute counts of axons.Methods: Mean axon diameter, mean axon density, totally axonal population and optic nerve area were noted for each optic nerve. The mean axon diameter and the mean axon density were compared between paraxial (inner sectors)and cortical (outer sectors)areas of the nerves.Results: More myelinated axons were seen in the inner sectors as compared to the outer sectors(average 11 axons/1 000 μm2 in inner sectors and 34 axons/l 000 μm2 in outer sectors( P＝0. 036) . The myelinated fibers were also smaller(63 microns) in the outer sectors as compared to the inner sectors(72 microns) ( P ＝ 0. 001 ). The average cross sectors area for the four 40 week stage optical nerves of Siamese Twins was 3.32 × 103 as compared to 1 million axons for 32-week-old normals.Conclusion: Our finding of fewer axonal number and small myelinated fibers in the Siamese Twins suggests hypoplasia. Myelination was more abnormal in the paraxial optic nerve than that in the peripheral sectors, suggesting anomalous development of optic nerve peripherally and delayed developnent centrally. Axonal density is higher in inner sectors than that in outer sectors, suggesting delayed development of the outer nerve sector.

基于地理加权随机森林的青藏地区放牧强度时空格局模拟

精确刻画放牧强度时空格局是深刻理解青藏地区高寒草地服务功能动态及其驱动机制的重要基础,对辅助制定区域生态安全和可持续发展战略具有意义。基于牲畜年末存栏量、牧区人口密度、生长季NDVI、年降水量、年平均气温和居民点分布等数据,采用地理加权随机森林模型,模拟了2000年、2010年和2020年3期青藏地区放牧强度的空间格局,并定量评价了环境因子对放牧强度空间分布解释性的区域差异。结果表明:(1)地理加权随机森林模拟结果可精细地刻画青藏地区放牧强度的空间特征,与经典随机森林模型相比,判定系数更高,平均绝对值误差和均方根误差更低。(2)青藏地区放牧强度呈现东南高、西北低的基本特征,其中,西北部地区放牧强度低于25羊单位/km~2的区域约占青藏地区面积的1/2。(3)与2000年和2010年相比,2020年青藏地区放牧强度呈现总体下降、局部抬升的态势;其中,较2010年,2020年放牧强度下降超过1羊单位/km~2的区域占牧区面积的61.69%。(4)牧区人口密度是解释放牧强度空间异质性最主要的因素,其相对重要性呈现西高东低的特征,而降水量和生长季NDVI的相对重要性则呈现西北高、东南低的特征。研究结论可为青藏地区草地可持续管理和生态安全屏障建设提供科学参考。

中南半岛农田/森林活跃火与人口密度的相关性动态特征

人类活动是活跃火发生发展的重要诱因,明确人-火关系对火情规律揭示、碳排放估算与公共健康管理等具有重要意义。利用2003—2019年MODIS Collection 6(MODIS C6)活跃火和LandScan人口密度数据产品,基于GIS公里渔网、双变量空间相关性等分析方法,定量揭示了中南半岛农田/森林活跃火发生强度与人口分布的时空关联特征及其动态发展特征。结果表明:1)中南半岛约八成“有火区”的活跃火发生强度与人口密度存在空间正相关,且中等正相关及以上(r>0.4)格网近占3/4,主要分布在泰国中/东部、缅甸东/西部、老挝北部和柬埔寨东北部等。2)中南半岛年内“农火区”人口多于“林火区”,且前者超九成格网、后者近3/4格网与人口分布存在空间正相关性。3)“农火区”强正相关格网主要分布在缅甸南部、泰国中/东部等人口密度为25~100人/km^(2)的区域,而“林火区”相应格网多分布于缅甸东/西部、老挝北部、柬埔寨东北部等人口密度<25人/km^(2)的区域。4)受人口增长影响,2003—2010年农火和林火发生强度与人口分布相关性虽均明显高于2011—2019年,但后期“农火区”与“林火区”年均人口均有明显增幅。

剔除县域人口密度极端值对地形因子与人口密度关系的影响

人口密度随地形梯度升高而减小的规律性仅适用于一定的人口密度范围,若在相关研究中注意该特性,将有利于更科学地开展解释和建模。通过对比地形因子(海拔、起伏度及坡度)与人口密度的关系在剔除人口极端分布县域前后的差别,并在人口适度密集县域范围内分析了各类地形因子对人口密度的影响特征,提出区分人口极端分布县域与人口适度密集县域的方法。结果表明:(1)剔除人口极端分布县域后,人口密度与三类地形因子的关系均更趋简单,其中坡度和起伏度对人口密度的拟合能力明显增强,尤其坡度的解释力从相对最弱转变为相对最强;(2)在人口适度密集县域,沿地形因子梯度上升方向看,人口密度在低海拔区段和小起伏区段有规律地剧烈减小,在较大起伏区段和几乎全部坡度区段有规律地缓慢减小,在中等海拔区段波动较大,且这些特征在2000-2020年间保持稳定。

建筑区夜间灯光的人口空间化模拟

基于夜间灯光的人口空间网格化通常使用行政区全境的夜间灯光,忽略了土地覆盖信息,而人口的空间分布与建筑区的夜间灯光具有紧密关系。分别利用建筑区与行政区全境的NPP/VIIRS夜间灯光数据结合DEM和NDVI数据,选取了线性回归、支持向量机与随机森林3种代表性模型,对南昌市2020年人口进行了100 m的空间网格化模拟。结果表明,基于建筑区的网格化结果,不论在不同模型的拟合精度,还是不同区县的人口模拟精度上都要优于基于行政区全境网格化结果;在单个市级区域,选择的3种代表性模型中线性模型能取得最好的效果。基于建筑区的人口空间网格化结果去除了无人区地物的影响,能直观地展现城市内建筑区的人口密度分布,对城市管理有重要的意义。

Validation of GIS layers in the EU:getting adapted to available reference data

An optimal validation of a thematic map would ideally require in-situ observations of a large sample of units specifically conceived for the map under validation.This is often not possible due to budget limitations.The alternative can be using photo-interpretation of high or very high resolution images instead of in-situ observations or using available data sets that do not fully comply with the ideal characteristics:unit size,reference date or sampling plan.This paper illustrates some examples of use of available data in the European Union.For land cover maps,the best existing data set is probably Land Use/Cover Areaframe Survey(LUCAS)that has been conducted by Eurostat on four occasions since 2001.Because LUCAS is based on systematic sampling,advantages and limitations of systematic sampling are discussed.A fine-scale population density map is presented as an example of a situation in which reference data on a statistical sample cannot be collected.

基于村落尺度的丘陵山区人口分布特征与规律——以甘肃天水为例

在以农业生产为主的丘陵山地，人口分布具有明显的分散性和差异性。基于村落尺度分析人口分布更接近实际。位于秦岭山地向黄土丘陵区过渡的天水地区，从市域、县域、乡镇到村落，随着分辨尺度的缩小，人口空间分布上的疏密不均现象越突出，变异系数迅速扩大。在7915个由城镇、村落和居民点构成的斑块上，面积在1．0～10hm^2范围的较小斑块占84．7％，表明分散的、小规模的村落仍是人口分布的主要形式。用非线性函数分析人口密度与村落用地比例、单位西积上的斑块数量、斑块大小的关系，可以较好地揭示人口分布上的一些特征和规律。天水人口分布在地域上明显地表现为河谷高密度区、丘陵中密度区、山地低密度区三种类型，反映人口分布特征的劳作半径和村落间距离在三种类型中都有显著差异。

基于贝叶斯判别分析的地震应急响应等级初判方法

破坏性地震发生后,相关部门须启动适当的应急响应等级并按照应急预案开展救灾。对响应等级的判断可视为对一个地震灾害事件严重程度分类判别的问题。贝叶斯判别分析法是一种应用广泛的判别分析统计方法,本文论述了贝叶斯判别分析法在判断地震应急响应等级中的应用;通过对1949—2008年中国大陆成灾震例的整理分析,以震级、震区人口密度等地震有关信息为依据,建立起地震应急响应等级的分类判别规则,从而提供了一种简便、快速的地震应急响应等级初判方法;经检验该方法是有效的。

典型草原退化群落不同恢复演替阶段羊草种群空间格局的比较

羊草(Leymus chinensis)为典型草原群落的主要建群种之一,在群落中扮演着重要角色。应用摄影定位法测定处于不同恢复演替阶段的羊草种群空间格局,通过点格局、种群空斑、种群领地及种群领地密度等方法分析发现,羊草种群在恢复演替过程中经历了种群增长和种群衰退的过程。在此过程中,羊草种群数量出现最高点,此点之前,种群拓殖大于自疏,种群整体增长;此点之后,种间竞争及种内竞争致使种群衰退,而种间竞争占主导地位,种内竞争相对较弱。羊草种群的增衰导致种群空斑发生变化,从而引起种群格局类型发生相应的变化,表现为在恢复21a的群落中,羊草种群在10m×10m的取样范围内表现出两种格局分布类型:在0～4.85m之间呈现聚集分布,当尺度大于4.85m时,则表现为随机分布;在恢复8a的群落中,羊草种群在10m×10m的取样范围内出现3种格局分布类型:在0～3.01m之间呈聚集分布,在3.01～3.37m之间为随机分布,当尺度大于3.37m时则表现为均匀分布;在严重退化群落中,羊草种群在整个10m×10m测定尺度上呈现聚集分布。由此可见,羊草种群格局在恢复演替过程中是变化的,这种变化主要由群落剩余资源驱动下的种群拓殖及种内种间竞争所致。

卷叶水稻的光分布模拟及适宜叶面卷曲度分析

以叶面高度卷曲的水稻组合两优E32、中等卷曲组合两优培九和不卷曲组合汕优63为材料,引入叶面卷曲度因子,用有效叶面积指数代替传统的叶面积指数(LAI),模拟水稻冠层内的辐射传输,比较了不同叶面卷曲度因子材料的光合有效辐射截获率、转化率和利用率,探讨了不同材料的最适叶面卷曲度及最佳群体密度。结果表明,有效叶面积指数比传统的叶面积指数能更准确地预测冠层内光合有效辐射的分布。两优E32叶片过度卷曲,有效叶面积指数偏小,光合有效辐射利用率不高;而汕优63叶片平展且披散,下层叶片长期受光条件不良,光合能力弱,光合有效辐射利用率也不高。相比之下,两优培九的光合有效辐射截获率、转换率分布较为合理,光合有效辐射的利用率也较高,最适LAI为7.6,与常规栽培条件下的群体密度(LAI=7.9)接近。两优E32和汕优63的最适LAI分别为9.8和6.2,而常规栽培条件下的群体密度过小或过大,导致光合有效辐射利用率不高。利用孕穗期至齐穗期有效辐射利用率的实测值,通过输入不同的叶面卷曲度因子,得到两优E32、两优培九和汕优63的最佳叶面卷曲度因子分别为0.12、0.11和0.08,均非常接近两优培九的实际叶面卷曲度因子(0.11)。

基于地形起伏度的山区人口密度修正——以岷江上游为例

山区人口承载能力评价是山区国土空间管理的基础之一,而准确的人口密度数据是正确评价人口承载能力的基础。传统的人口密度算法并未考虑地形起伏度对人口分布带来的影响,不能客观反映山区人口聚集程度。引入地形起伏度、海拔高度因子,选择岷江上游作为研究区,首先运用GIS技术提取地形起伏度,再运用SPSS软件对人口密度与地形起伏度相关性进行分析,确定县域不同地形起伏度与海拔人居适宜标准,剔除阈值以外不适宜人口聚居的面积,对人口密度进行修正。研究结果表明:1岷江上游人口分布受地形起伏度的影响显著,二者的对数曲线拟合度为0.89,汶川县、茂县、理县、黑水县与松潘县地形起伏度与人口分布的相关性分别为:0.841、0.773、0.643、0.696和0.730;2应用地形起伏度对岷江上游人口密度修正,为真实反映山区人口密度提供了新的考量依据,剔除了人口密度空间噪音,5县地形起伏度与海拔适宜标准分别为:汶川3.2°和3 693 m,茂县4°和4 033 m,理县4.3°和3 790 m,黑水4.4°和3 853 m、松潘4.2°和3 966 m;地形起伏度高值区面积越大,修正前后的人口密度偏差越大,地形起伏度较大的理县和黑水县修正后的人口密度分别提高了7.8倍和5.6倍;地形起伏度较低的汶川县与茂县修正后人口密度仅分别提高2.3倍与2.4倍;3岷江上游人口潜在压力大,不同区域应因地制宜,汶川和茂县采取重点集约发展战略,理县和黑水县采取适度开发战略,松潘县应采取恢复与保护生态策略。

黄山风景区松材线虫病危险性评估 Ⅰ.松蛀虫种类、种群分布及动态监测

报道了黄山风景区松蛀虫种类、主要松蛀虫成虫活动期、种间种群数量比率和种内种群数量垂直分布比率 ,2 0 0 1年 5种松蛀虫成虫种群数量变动规律、不同监测期松墨天牛雌成虫孕卵量及比率。研究结果表明 ,黄山风景区繁衍着 14种松蛀虫 ,主要松蛀虫有 5种 :马尾松角胫象、松墨天牛、短角幽天牛、褐幽天牛、松树皮象。其种群数量比率分别为 6 1.6 %、2 7.0 %、5 .5 %、3.8%和 2 .2 %。松墨天牛成虫最高分布区为海拔 16 5 8m的天海景点 ,海拔 318m的白亭景点种群数量分布比率最高 ,达80 .9% ,诱获的松墨天牛雌成虫平均孕卵量为 2 5 .

基于Google earth的城市人口密度研究——以广东清远为例

引入Google Earth软件,讨论了一种快速、免费、便捷的研究城市人口密度的方法,该思路与方法在缺乏基础资料(如城市地形图、研究区域人口等数据)时能够作为一种有效的分析手段。文中通过获取各类地物信息,将土地利用、道路、建筑物等因素与人口密度建立起对应关系,绘制出研究区域的人口密度分布图,并对人口密度进行分析。此外,根据城市人口分布现状,提出人口引导控制区概念,为城市规划建设、环境保护等提供参考。