基于生态景观格局的松材线虫病分析及风险预测——以宜昌市为例

三峡库区周边县市松材线虫病疫情严重,给生态环境造成极大压力,传统的疫情处治方式需耗费大量的物力人力且效果小。利用景观生态学基本理论,以松材线虫病年均发生面积为统计基础,研究其与景观斑块和景观格局之间的关系,并据此进行疫情风险分析。通过宜昌全市和夷陵区、宜都市、市辖区两个尺度下斑块面积、斑块密度、形状指数、景观丰富度指数和Shannon多样性指数等斑块和景观格局指数评价景观现状,建立其与疫情之间的Pearson相关性,再据此对宜昌市辖区、宜都市和夷陵区进行插值风险分析。结果表明,夷陵区和宜都市疫情较为严重。研究区寄主斑块的面积和形状复杂程度和疫情有显著正相关性,相关系数为0.826和0.818;人为活动斑块和疫情间没有显著相关性;基于寄主斑块的插值风险分析表明,各区域需要对点状的大面积寄主斑块和形状复杂程度高的斑块进行重点清理,减小物力和财力的支出。     

夷陵地区异质景观对松材线虫病的抵抗力及生态风险分析

以宜昌市夷陵地区为研究区域, 探讨在疫区通过异质性的景观控制松材线虫病扩散流行的方法及当前疫区的生态风险。结合景观生态学和森林保护学理论, 基于松材线虫病生物学特征和现有土地利用类型, 经过重分类, 构建了夷陵区景观格局, 并以景观格局指数为评价指标, 通过空间分析和克里金插值法对夷陵区生态风险进行评价。结果表明, 研究区异质性景观对松材线虫病的相对抵抗力从大到小依次为水域及水利设施景观、人为活动景观、其他林园地景观和耕地景观, 马尾松等针叶林景观最弱。风险评价结果表明夷陵区中部, 沿长江流域带生态风险值较高。预防策略上应通过景观格局的合理配置, 优化土地利用现状、合理规划利用, 采取重点生态保护措施和综合治理对策控制松材线虫病的扩散。     

三峡库区松材线虫病扩张速度对人为活动的响应

松材线虫病是我国森林重要的检疫性病害,除自然媒介天牛传播,人为因素介导的传播在松材线虫病扩散和蔓延中起着至关重要的作用。选择在我国松材线虫病的重点发生区域三峡库区,研究马尾松林景观格局和以人为活动强度为主要因子的松材线虫病扩散规律,尝试揭示松材线虫病扩散机制。结果显示三峡库区的疫点数在近年有上升趋势,各地区发病率得到一定控制;在疫区和非疫区,马尾松林斑块聚合度最大的是非疫区的大渡口,为98.6406;斑块分离度最大的是非疫区的秭归,为0.9318;方差分析结果显示马尾松林景观格局和松材线虫病之间没有相关性。进一步研究了松材线虫病和人为活动强度的联系,结果显示松材线虫病发病率和地区路网密度、人口总量具有较强的相关性,和地区GDP、货运周转量相关性小。宜昌的松材线虫病发病率和路网密度的相关系数为0.985,和人口总数的相关系数为0.866;重庆的松材线虫病发病率和路网密度相关系数为0.924,和人口总数相关系数为0.999;其次基于路网密度和人口总数,对三峡库区松材线虫病疫情在未来十年进行了预测,结果显示随着路网密度和人口总数的扩增,宜昌松材线虫病也将呈现逐步增大的趋势,R~2值为0.919和0.637;重庆发生趋势一致,R~2值为0.976和0.992。     

遥感影像空间分辨率及粒度变化对城市景观格局分析的影响

尺度是景观生态学和遥感领域的重要问题,已有研究主要考虑景观的粒度效应,很少涉及遥感影像空间分辨率对景观格局,尤其是对城市景观格局的影响.基于2000年和2002年分别由ETM 和IRS-PAN影像解译得到的土地利用图,从景观和类型两个层次分析了不同粒度下上海市一城市化样带的景观格局.结果表明,城市景观有明显的尺度效应,空间分辨率和粒度变化都会影响城市景观格局,而道路等线性廊道对尺度变化的敏感则是造成这一影响的主要原因.斑块密度、边界密度、平均斑块分维度、景观聚集度和最大斑块指数的粒度效应比较明显,而景观比例、Shannon多样性指数对粒度变化并不敏感.高分辨率影像适用于城市景观格局,尤其是破碎度的分析,其用于分析的合适粒度是5～10m.     

庙岛群岛北五岛景观格局特征及其生态效应

海岛由于自然特征的空间差异、人类活动的日益增强以及生态系统的脆弱性,其景观格局空间分异性明显且生态效应趋于复杂。以庙岛群岛北五岛为研究区,基于现场调查和3S技术,从景观尺度、海岛尺度和区块尺度分析海岛景观格局空间特征,进而探讨景观格局与净初级生产力(NPP)、植物多样性和土壤性质的关系。结果显示:(1)不同尺度景观格局均表现出了空间差异。景观尺度上,针叶林、阔叶林和草地3类植被景观面积最大,斑块密度、边缘密度和平均形状指数总体较高,建筑用地也具有较大规模,其斑块密度较高,平均形状指数处于最低值,裸地也具有一定规模,其各项景观指标处于中间位置;海岛尺度上,随着海岛面积、人口和GDP的增加,斑块密度和人为干扰指数均明显增大;区块尺度上,斑块密度、边缘密度和平均形状指数与海拔呈显著正相关,人为干扰指数与海拔和坡度均呈显著负相关。海岛面积、地形和人类活动分别是北五岛景观格局的基本因子、重要限制因子和直接驱动因子。(2)海岛景观格局的生态效应与尺度密切相关。景观尺度上,各项生态效应指标在不同景观类型上均具有显著差异,海岛尺度上的生态效应指标对景观格局的响应不甚灵敏;区块尺度上,生态效应指标与景观格局指数表现出了显著的简单相关性和偏相关性,但二者结果具有差异。NPP和土壤水分主要受到景观类型和植被生长状况的影响,多样性和土壤养分同时受到景观类型和景观格局破碎度、边缘效应的影响,人为活动强度的增大地带来了各项生态效应指标的降低。控制建设规模、优化景观布局与改进开发利用方式是维系海岛生态系统稳定性的重要措施。     

江西省赣州市南康区松材线虫病发生特征

松材线虫病是我国南方森林面临的主要灾害之一。本文基于野外调查和高分一号(GF-1)卫星WFV影像数据,采用随机森林模型构建松材线虫病空间识别模型,探究地形、人类活动和林分因子等对病害发生的影响,监测病害空间分布,并采用空间自相关性分析评估江西省赣州市南康区松材线虫病发生特征。结果表明：构建模型对松材线虫病的识别效果良好(AUC值=0.99,总体精度=0.96),可以实现对区域松材线虫病空间分布情况的有效监测;归一化差异绿度指数(NDGI)、距高速公路的距离、归一化植被指数(NDVI)是重要的建模因子;空间自相关性分析表明,松材线虫病的发生存在明显的空间正相关性即空间聚集性特征;南康区松材线虫病高发生区集中于赤土乡、朱坊镇和十八塘乡,低发生区集中于蓉江街道附近;分析变量的边际效应发现,离高速公路远、离县道近的低海拔地段是松材线虫病易发区域。研究结果可服务于区域松材线虫病分布的快速监测,对该病害防治和管理具有一定的指导意义。     

主题分辨率对NDVI空间格局的影响

景观格局与尺度的相互关系一直是景观生态学的研究重点。景观生态学中的尺度内涵包括时间、空间和分析（观察）等。近年来景观格局与空间、时间尺度关系受到广泛关注,而分析尺度对格局的影响探讨较少。地理空间信息的主题分辨率反映了地理空间信息的制图细节,即专题图的分类数。以NDVI（Normalized Difference Vegetation Index）为专题图内容,选择福州行政区、福州城区和永泰县为研究区域,通过改变NDVI分类数,研究主题分辨率对空间格局的影响。NDVI格局指数包括：斑块数量（NP）、最大斑块占景观面积比例（LPI）、斑块平均大小（AREA-MN）、面积加权平均形状指数（SHAPE-AM）、面积加权平均分维数（FRAC-AM）、蔓延度指数（CONTAG）、散步与并列指数（IJI）、香农多样性指数（SHDI）。结果表明格局指数对主题分辨率（分类数）的连续响应特征如下：初始条件敏感区（分类数2—4类）、敏感响应区（分类数为4—8类）、适合分析尺度区（分类数8—12类）、不敏感区（分类数≥12类）;格局指数与主题分辨率的关系有对数增长、线性增长和幂函数下降等。分析尺度对NDVI空间格局影响的本质原因是相对应的生态系统等级结构的存在     

黄土丘陵区景观格局对水土流失过程的影响——景观水平与多尺度比较

以黄土丘陵沟壑区河口-龙门区间内42个水文站控制流域土地利用和径流泥沙数据为基础,借助GIS和RUSLE,运用景观格局指数分析法,从景观水平和多尺度上探讨景观格局对流域水土流失过程的影响。结果表明:河龙区间流域景观格局和水土流失过程特征存在明显空间分异和相对差异。在斑块类型水平上草地的连结度(COHESION3)和分维数变异度(FRAC_CV3)、耕地和居民建设用地的丛生度(CLUMPY1、CLUMPY5)、居民建设用地边缘密度(ED5)是影响流域水土流失过程的重要指标,其中草地连结度对流域水土流失过程变异的解释度最高。在景观水平上景观连结度(COHESION)、平均斑块面积(AREA_MN)、景观聚集度(AI)、景观丰富度(PR)是影响水土流失过程的主要因子,其中景观聚集度(AI)对流域水土流失过程变异的解释程度最高。斑块类型水平景观格局对水土流失过程空间变异的解释能力要高于景观水平。景观格局具有明显的嵌套特性并强烈影响着流域水土流失过程,在嵌套水平上草地连结度(COHESION3)和耕地丛生度(CLUMPY1)是控制流域侵蚀产沙的主要格局因子,草地分维数变异程度(FRAC_CV3)可以抑制流域泥沙输移过程。景观格局对水土流失过程的影响机制和景观指数与反应变量间的统计学关系随尺度不同而异。     

三峡库区低山丘陵区多尺度景观指数响应及适宜粒度

景观格局具有典型的空间异质性和尺度依赖性。在对景观格局进行分析研究时需跨越多个尺度,空间粒度大小在尺度聚合分析中至关重要。三峡库区低山丘陵区斑块破碎、景观格复杂性显著、景观格局特征及尺度变异规律仍待明确,本文以三峡库区秭归县为研究区,设定1—400m内23个粒度梯度水平,定量评估县域、乡镇以及小流域不同幅度上的景观格局指数以及拟合函数,探讨多空间幅度景观格局指数随粒度大小的变化特征。基于景观指数的粒度效应特征和拟合函数的曲线特征(最大曲率点、极值点),明确适宜不同幅度的山地景观格局指数研究的粒度阈值,以揭示库区低山丘陵区景观结构的复杂性和变异性。结果表明：不同景观指数对空间粒度变化和空间幅度变化的响应存在差异,不同景观指数的空间粒度响应主要呈现增加、降低、波动和无明显规律变化的趋势,其中斑块密度、最大斑块面积等指数对斑块形状和大小的变化敏感,而多样性指数的粒度变化敏感度较低;部分指数如斑块密度、边缘密度、周长面积分维数等对空间幅度的变化并不敏感,而最大斑块面积、景观形状指数、散布与并列指数、分离度等指数对空间幅度的变化敏感,适合进行不同幅度适宜粒度阈值的推定;边缘密度、平均斑块大小、景...     

城市化景观格局对本土植物多样性的多尺度影响——以北京市顺义区为例

景观格局对植物多样性的影响已经在很多研究中得到了验证,但有关城市景观的影响仍然知之甚少。为了探究城市化景观格局对植物多样性的影响及其尺度效应,本研究在北京市顺义区调查了105个样地,计算每个样地的α和β多样性指数;并以100 m为步长,分析了100～1000 m范围内的10个尺度43个城市的景观格局指数。结果表明: 在所有尺度上,城市景观面积指数、核心类指数和边缘指数与本土植物多样性均呈负相关;形状复杂性指数在小尺度内有利于植物多样性,而面积加权复杂性指数则在较大尺度上影响明显。其他指数如城市斑块的连接性、邻近性、内聚性、破碎性和散布并列指数与本土植物多样性之间的关系轻微且不稳定。城市化强度与尺度呈负相关,与各个尺度的植物多样性呈负相关。合理将城市区域分为许多边缘简单的小斑块,能够更好地保护本土植物多样性。该研究提出了保护城市植物多样性的景观格局建议,为生态城市建设提供参考。     

Influence of watering and trenching ponderosa pine on a pine sawfly

Summary Neodiprion autumnalis (Smith) larvae were caged for two successive years on root-trenched, watered, and untreated ponderosa pine (Pinus ponderosa Doug. ex Laws.) to determine effects of host moisture stress on larval feeding. Levels of moisture stress (as measured by the Scholander pressure chamber) differed significantly among treatment levels during 1984 and 1985 larval feeding periods. Differences in larval feeding success were not detected in 1984. In 1985, however, larvae on trenched (stressed) trees clipped and rejected more foliage, consumed more needles, had lower pupal weights, lower survival, and a longer feeding period than larvae on watered or untreated trees. Frass production did not differ among treatment levels. The length of the feeding period was shorter for larvae on watered trees than for larvae on untreated trees, but other measures of feeding success did not significantly differ between watered and untreated trees.     

Influence of induced water stress in ponderosa pine on pine sawflies

Summary Three levels of water stress were induced on pole-size ponderosa pine (Pinus ponderosa) to determine the influence of plant moisture stress on oviposition, survival, and growth of two species of pine sawfly (Neodiprion fulviceps and N. autumnalis). It was found that water stress affected oviposition and subsequent egg survival but not larval development or survival. Stress had a negative effect on early season oviposition (N. fulviceps) and a positive effect on late season oviposition (N. autumnalis). Egg hatch was different between species and years and among treatment levels. Larval development, feeding, and survival were not affected by water stress. Overall, the effect of stress was not sufficient to explain population outbreaks of sawflies. Several hypotheses are presented as possible explanations for the observed experimental results.     

A dispersal-aggregation model for mountain pine beetle in lodgepole pine stands

In this paper a dispersal-attack theory for bark beetle attacking trees is developed from a set of simple assumptions, and the resulting theoretical model is fit to data from four epidemic studies. Implications of the theory are discussed in relation to the dynamics of lodgepole pine-mountain pine beetle interactions.     

Development of secondary pine forests after pine wilt disease in western Japan

Abstract. The development of secondary Pinus densiflora (Japanese red pine) forests after pine wilt disease was studied through phytosociological analysis, estimation of forest structure before disease and size-structure, tree ring and stem analyses. Following the end of the disease, the growth of previously suppressed small oak trees was accelerated. This is quite different from the development of forests following fire, which starts with the establishment of pine seedlings. Pine wilt disease shifted the dominance of secondary forests from Pinus densiflora to Quercus serrata oak forest. In pine forests, disturbance by fire is important for forest maintenance. In contrast, disturbance by pine wilt disease leads to an acceleration of succession from pine forest to oak forest.     

Effects of spring-killed pine trees on the epidemics of pine wilt disease

Pine wilt disease (PWD) is caused by the pinewood nematode (PWN), Bursaphelenchus xylophilus (Steiner et Buhrer) Nickle, and is transmitted by cerambycid beetles. In some pine trees infected with the PWNs in Japan, foliage changes from green to brown in summer to autumn of a nematode infection year (summer- autumn-killed trees) and the others in the following spring of a nematode infection year (spring-killed trees). The vector beetles require 1 or 2?years for development in cool summer areas and 1?year in warm summer areas. To evaluate the effects of the spring-killed trees and vectors with a long developmental time on the PWD epidemics, we presented simple mechanistic mathematical models. The models showed that it was possible for spring-killed trees to cause PWD epidemics when the transmission rate was high, and the efficacy of spring-killed trees as infection source was similar to that of summer?C autumn-killed trees. Spring-killed trees and vector beetles with a developmental time of 2?years harbored in summer- autumn-killed trees delayed epidemic timing by 3?C10?years or actually suppressed epidemics.     

Acid-Fastness of pine pollen

This is a study of the acid-fast staining characteristics of pine pollen and an investigation of factors causing loss of acid-fastness after pine pollen has been in contact with tisues or mucous membranes. Intact loblolly pine pollen was readily stained with cold carbol-fuchsin, and retained its acid-fastness after decolorization with 3% HC1 in 95% ethyl alcohol for 2 min, followed by methylene blue counterstain. Pine pollen resembles spermatozoa in ease of staining and resistance to decolorization. Acid-fastness was destroyed by crushing or by germination of the pollen grain, and by contact for several hours with serum or saline solutions, but was unchanged by exposure to 0.1% solution of streptomycin in water. Nonviable pine pollen did not lose acid-fastness after suspension for several days in serum or water. When counterstain was omitted, crushed or germinated pollen appeared red to pink after staining with carbol-fuchsin and decolorization with acid alcohol, thus indicating that lipids of an acid-fast nature were still present. The large size and biologic properties of pine pollen provide a unique means of studying the chemical and physical aspects of the acid-fast phenomenon.     

Monitoring the European pine sawfly with pheromone traps in maturing Scots pine stands

Abstract

• 1 During 1989–93, field studies were conducted in Finland to develop a method based on pheromone traps to monitor and forecast population levels of the European pine sawfly (Neodiprion sertifer Geoffr.) and tree defoliation.
• 2 Three traps per site were baited with 100 µg of the N. sertifer sex pheromone, the acetate ester of (2S,3S,7S)‐3,7‐dimethyl‐2‐pentadecanol (diprionol), in maturing pine stands in southern and central Finland. In addition, three different dosages (1, 10 and 100 µg) of the pheromone were tested in 1991–92.
• 3 The highest number of males was observed in traps baited with the highest dose. On average, there was a 10‐fold increase in trap catch between lure doses.
• 4 Density of overwintering eggs was used to evaluate the effectiveness of pheromone traps in predicting sawfly populations. The proportion of healthy overwintering eggs was determined each year. A model based on the number of current shoots on sample trees, diameter at breast height and tree height was formulated to estimate eggs per hectare.
• 5 Linear regression analysis produced high coefficients of determination between number of males in traps and density of total eggs in the subsequent generation, when populations were at peak densities. The relationships were not significant for low population densities. The results indicate a risk of moderate defoliation when the seasonal trap catch is 800–1000 males per trap or higher.

     

Loblolly pine grown under elevated CO2 affects early instar pine sawfly performance

Seedlings of loblolly pine Pinus taeda (L.), were grown in open-topped field chambers under three CO₂ regimes: ambient, 150 l l^–1 CO₂ above ambient, and 300 l l^–1 CO₂ above ambient. A fourth, non-chambered ambient treatment was included to assess chamber effects. Needles were used in 96 h feeding trials to determine the performance of young, second instar larvae of loblolly pine's principal leaf herbivore, red-headed pine sawfly, Neodiprion lecontei (Fitch). The relative consumption rate of larvae significantly increased on plants grown under elevated CO₂, and needles grown in the highest CO₂ regime were consumed 21% more rapidly than needles grown in ambient CO₂. Both the significant decline in leaf nitrogen content and the substantial increase in leaf starch content contributed to a significant increase in the starch:nitrogen ratio in plants grown in elevated CO₂. Insect consumption rate was negatively related to leaf nitrogen content and positively related to the starch:nitrogen ratio. Of the four volatile leaf monoterpenes measured, only -pinene exhibited a significant CO₂ effect and declined in plants grown in elevated CO₂. Although consumption changed, the relative growth rates of larvae were not different among CO₂ treatments. Despite lower nitrogen consumption rates by larvae feeding on the plants grown in elevated CO₂, nitrogen accumulation rates were the same for all treatments due to a significant increase in nitrogen utilization efficiency. The ability of this insect to respond at an early, potentially susceptible larval stage to poorer food quality and declining levels of a leaf monoterpene suggest that changes in needle quality within pines in future elevated-CO₂ atmospheres may not especially affect young insects and that tree-feeding sawflies may respond in a manner similar to herb-feeding lepidopterans.