漳河源自然保护区铁坚油杉种群分布格局研究

为保护和恢复漳河源自然保护区铁坚油杉天然种群,采用相邻格子样方调查方法,运用扩散系数(C)、负二项参数,Cassie指标,Lloyd平均拥挤度,聚块性指数,DavidMoore的丛生指标,Morisita扩散型指数对个铁坚油杉种群的分布格局进行了研究。结果表明:在16m~2,25m~2和50m~2面积上,S1样地呈均匀分布,S2和S3样地呈Poisson分布;3个样地种群聚集强度随取样面积增大而上升。S1的分布格局可能与人为环境干扰有关;4m×4m尺度上Poisson分布最为明显。种群的保护与恢复,应注重聚集强度最大的取样尺度。     

森林结构调查中最适样方面积和数量的研究

以30块100 m×100 m的模拟样地为研究材料,从林木空间分布格局吻合率关系对模拟的小样方进行研究,并以1块100 m×100 m的实地调查样地为例,验证新确定样方的合理性和可行性;根据实际调查样地的调查时间来分析比较样方间的调查时间和成本,进而确定较优的样方面积和样方数.结果表明:(1)空间结构参数中的角尺度与抽取的样方面积大小和样方数量有关.随着样地面积的增大和样方数量的增加,所估计的林木空间结构均趋于稳定;(2)从林木空间格局来看,样方面积为10 m×10 m、15 m×15 m、20 m×20 m、25 m×25 m、30 m×30 m抽样数分别为42、23、12、9、4时,均能准确的表达林分的空间分布格局;(3)在考虑调查时间和成本时,样方面积为30 m×30 m、抽样数为4是林分空间结构调查时较适合样方调查面积和调查数.     

黄荆山红椿种群动态分析

为探究珍稀植物红椿天然种群濒危机制,在黄荆山红椿采用相邻格子法设置2个20 m×20 m样方进行调查,划分了红椿龄级结构,分析了种群龄级数量动态指数,编制了种群的特定时间生命表,分析了存活曲线。结果表明:12个种群均为增长型种群;2T1种群第5龄级dx达到峰值,消失率Kx最大;T2种群dx峰值在第6龄级,消失率Kx最大;2个种群Ex最大值均在第1龄级,随龄级递增逐渐下降;3存活曲线为DeeveyⅡ型,表明各龄级具有相同的死亡率。红椿种群的龄级结构特征与其强阳性特征和竞争密切相关人为"正向干扰"可以促进红椿天然群落的更新与保护。     

粽粑竹无性系种群结构及空间分布格局

从年龄结构、径级结构、高度级结构3方面分析了粽粑竹无性系种群的结构特征,采用Greig-Smith的相邻格子样方调查法和方差/均值比率法、聚集度指标法分析了粽粑竹无性系种群的空间分布特征。结果表明,Ⅱ龄级的分株所占比例最高(42.3%),其次是Ⅰ龄级的分株(28.9%),表明粽粑竹无性系种群年龄结构呈增长型;地径主要分布在0.81~1.40cm,占总分株数的88.54%;高度主要集中在169.1~229.0 cm,占总分株数的51.8%。粽粑竹无性系种群空间分布格局与龄级有关,除Ⅰ龄级呈随机分布外,其余均为聚集分布。     

不同林分杨树云斑天牛种群空间格局地统计学分析

【目的】研究不同林分杨树林地云斑天牛种群不同虫态的地统计学空间格局,为不同林分杨树林地云斑天牛的防治提供理论指导。【方法】通过调查公路林、片林、渠道林和村庄林4种林分类型的杨树林地,以刻槽、排粪孔和羽化孔为调查指标,确定云斑天牛卵、幼虫、成虫(蛹)的种群数量,利用地统计学方法,研究不同林分不同虫态种群的空间格局。【结果】云斑天牛的刻槽、排粪孔和羽化孔在不同林分杨树林地的拟合模型分别为:公路林均为球形模型,片林均为指数模型,渠道林分别为指数模型、球形模型和高斯模型,村庄林分别为球形模型、指数模型和指数模型。不同林分类型云斑天牛各虫态的拟合半变异函数模型存在差异,但其指的定空间分布格局均为聚集分布。林分类型影响虫口的数量和分布,不同林分类型下各虫态的半变异函数模型和模型参数存在较大差异。云斑天牛危害片林时卵、幼虫和成虫(蛹)的变程a、块金值C_0、基台值C_0+C较其他3种林分类型的统计值明显偏小。【结论】危害杨树云斑天牛种群的卵、幼虫、成虫(蛹)在公路林、片林、渠道林和村庄林中均为聚集分布,即云斑天牛在不同林分杨树林地危害时各虫态的空间分布格局均表现为聚集分布。林分类型与云斑天牛聚集分布的习性关系不大,但影响相应虫态的半变异函数模型和模型参数。     

甘肃引黄灌区典型天然群落分布特征

通过对甘肃引黄灌区典型天然植被群落调查,研究了主要种群的分布特征。结果表明:(1)甘肃引黄灌区主要天然群落内典型的种群有猫头刺、白刺和油蒿;(2)3个不同种群立地条件和土壤特征差异显著,油蒿种群为固定沙丘,猫头刺种群为固定、半固定沙丘,白刺种群为半固定沙丘,其pH值和全盐量从高至低依次为:白刺、猫头刺、油蒿;(3)研究区共有植物种29种,隶属10个科26个属,其中灌木或小灌木5种,占植物种数的17.24%;(4)研究区植被整体表现出了结构简单,灌木层物种相对单一且数量较少,草本层物种相对丰富且数量较大的特征。     

基于机器学习的辽东山区落叶松林蓄积量估算研究

作为森林资源信息的采集工具,遥感技术能及时有效的获取准确信息,是了解森林资源现状和获取森林结构参数的理想手段。以三类设计的作业小班为基础,小班中心为质点做25 m×25 m样方,取其公顷蓄积量作为因变量,提取影像各波段像元亮度值(digital number, DN)、植被指数、地形因子作为自变量指标,利用多元线性回归算法和人工神经网络建立了模型估算森林蓄积量。并利用实地调查的蓄积数据反演精度,对其算法的优劣进行了评价。经检验得知：多元线性回归平均绝对误差为35.68,相对均方根误差为39.32%;神经网络平均绝对误差为30.45,相对均方根误差为34.87%。典型地区精度可以达到80%。由评价表明：该模型使用良好,且误差在可接受范围内,利用人工神经网络方法获得的模型更优。     

民勤荒漠绿洲过渡带不同发育阶段白刺灌丛沙堆点格局特征

【目的】研究不同发育阶段白刺灌丛沙堆植被特征、沙堆形态特征及沙堆空间点格局分布,分析发育过程中白刺灌丛沙堆随尺度增加的空间点格局分布特征和变化规律,以期阐明各发育阶段不同级别白刺灌丛沙堆的空间关联性,揭示白刺灌丛发育过程中的种群形成特征及其生态格局维持机制。【方法】基于野外调查观测,在民勤绿洲荒漠过渡带选择4个不同发育阶段(雏形阶段、发育阶段、稳定阶段和活化阶段)的白刺灌丛沙堆典型样地,根据空间二维坐标,采用数量统计方法,按照沙堆体积大小将灌丛沙堆分为1级小沙堆、2级中沙堆和3级大沙堆3个等级,利用单变量O-ring函数对灌丛沙堆进行空间格局分析,并用双变量O-ring函数进行不同尺度各级沙堆关联性分析。【结果】随沙堆发育过程的进行,白刺灌丛的整体生长状况由好显著变差,植被覆盖度先增后减(雏形阶段最低为51.4%,逐渐升高到稳定阶段最高68.8%,活化阶段降低为60%),而植被枯枝率基本呈增加状态(由雏形阶段的15%增加到活化阶段的27%);各级沙堆在不同尺度中表现出不同的分布格局:雏形阶段,白刺灌丛沙堆在0～5 m的尺度上趋于均匀分布,在5～25 m尺度上为随机分布,而在25的尺度上趋于聚集分布;发育阶段,白刺灌丛在0～5 m的尺度上倾向于均匀分布,在5～30 m尺度上为随机分布;稳定阶段与活化阶段,各级白刺灌丛在小尺度上(5 m)都表现出均匀分布的倾向,但在5 m尺度上为随机分布。各发育阶段大小级别不同的白刺灌丛沙堆随尺度变化表现出不同的关联特性,除发育阶段小沙堆间(1、2级)无关联外,其他阶段小沙堆间(1级和2级)主要表现为随空间尺度增加正关联性逐渐增强,2级和3级沙堆在10 m尺度上表现为负关联,而在10 m的尺度上表现为负向联系加强或无关联。【结论】各发育阶段不同级别白刺灌丛沙堆所占比重不同但均未表现出明显的聚集现象,随沙堆发育过程的逐渐推进,大沙堆趋于随机分布;各级沙堆之间的关联性在小尺度上表现出小沙堆间的正关联性逐渐增强,而在中大尺度上中大沙堆表现出负关联加强或无关联,表明白刺灌丛沙堆植物群落组成和沙堆结构随发育过程的进行越来越不稳定。     

尖峰岭热带山地雨林土壤物理性质小尺度空间异质性研究

采用地统计学的方法,对海南岛尖峰岭热带山地雨林原始林土壤物理性质小尺度空间异质性进行了研究,结果表明:(1)土壤各物理性质空间异质性明显,其半方差函数可以用指数模型、高斯模型和球状模型拟合,变程变化范围为10.810 48.650 m,块金值与基台值比值范围为10.2%87.8%,表明各物理性质有不同程度的空间自相关性;土壤孔隙度和持水特性有较大的块金值,说明存在小尺度(<10 m)的空间异质性;(2)普通克里格插值及绘制物理性质空间分布轮廓图表明,土壤各物理性质在空间分布上具有斑块性,各物理性质在不同土壤深度的空间分布有一定的一致性,地形是影响土壤物理性质空间分布格局的一个主要原因。     

西南桦人工林群落取样面积探讨

西南桦是热带、南亚热带山地的速生珍贵树种。通过相邻格子样方法研究西南桦人工林种－ 面积曲线及其取样样方数， 认为西南桦人工林群落最小取样面积为２５０ｍ２ （１５８ ｍ ×１５８ｍ） ， 以相邻格子样方法调查时基本样方取５ ｍ ×５ｍ ， 样方数目９ 个以上。     

三峡库区杉木马尾松混交林和马尾松纯林的土壤含水量空间变异性

土壤水分含量是对地表生态过程有着重要影响的生态因子,在三峡库区生态环境保护中具有重要作用。选取三峡库区典型植被类型杉木、马尾松混交林(A)和马尾松纯林(B),通过网格(3.00 m×3.00 m)取样,地统计学方法研究群落(30.00 m×30.00 m)0.00 - 20.00 cm土壤水分的空间特征。结果表明:(1)两种典型植物群落土壤含水量空间变异性不同,样地A和样地B土壤含水量的变异系数分别表现出弱和中等强度的变异性;(2)两种典型植物群落土壤水分具有良好的半方差结构,半方差函数曲线可以用球状模型进行拟合。土壤水分的空间相关范围存在明显的差异,有效变程分别为51.00 m和12.37 m;土壤水分分布格局呈明显的斑块状分布;(3)在本研究区域内,植被、地形和地貌等是影响土壤含水量空间异质性的主要因素。     

沙漠地区中基于航空相片的白刺高度测量

基于内蒙古瞪口县地区的调查数据,用航空像片进行林业制图和植物测量。以沙漠典型的白刺为例,进行了沙漠地区植物高度测量研究。结果表明：利用得到的正射影像图以及阴影法进行的沙漠地区植物测量,其相对误差达到20%,基本能够满足沙漠地区植物调查的精度要求。     

Comparison of satellite images with different spatial resolutions to estimate stand structural diversity in urban forests

The structural diversity in urban forests is highly important to protect biodiversity. In particular, fruit trees and bush species, cavity-bearing trees and coarse, woody debris provide habitats for animals to feed, nest and hide.Improper silvicultural practices, intensive recreational use and illegal harvesting lead to a decline in the structural diversity in forests within larger metropolitan cities. It is important to monitor the structural diversity at definite time intervals using effective technologies with a view to instituting the necessary conservation measures. The use of satellite images seems to be appropriate to this end. Here we aimed to identify the associations between the textural features derived from the satellite images with different spatial resolutions and the structural diversity indices in urban forest stands(Shannon–Wiener index, complexity index, dominance index and density of wildlife trees).Rapid Eye images with a spatial resolution of 5 m 9 5 m,ASTER images with a spatial resolution of 15 m 9 15 m and Landsat-8 ETM satellite images with a spatial resolution of 30 m 9 30 m were used in this study. The firstorder(standard deviation of gray levels) and second order(GLCM entropy, GLCM contrast and GLCM correlation)textural features were calculated from the satellite images.When associations between textural features in the images and the structural diversity indices were assessed using the Pearson correlation coefficient, very high associations were found between the image textural features and the diversity indices. The highest association was found between the standard deviation of gray levels(SDGLRAP) derived from RVIRAPof Rapid Eye image and the Shannon–Wiener index(Hh) calculated on the basis of tree height(R2= 0.64). The findings revealed that Rapid Eye satellite images with a spatial resolution of 5 m 9 5 m are most suitable for estimating the structural diversity in urban forests.     

云南省松材线虫适生区的精细化评估

以90 m×90 m为最小面积单元,评估了云南省松材线虫的适生性.按高度适生、适生、中度适生、不适生4个水平,给出了全云南省每一个栅格单元水平上的适生性分布地图.结果表明高度适生区土地面积在70%以上的县有13个,在50%～70%之间的县有17个,在25%～50%之间的县有27个,在5%～25%之间的县有26个,5%以下县有26个.在像素点水平上建立空间模型进行适生区分析或风险区分析是一种新的技术方法,能为基层单位的病虫害防治提供精细化的空间数据.     

Eucalypt growth in monoculture and silvopastoral systems with varied tree initial densities and spatial arrangements

Brazil has large stretches of degraded land, mainly occupied by pasture. Recently, the Brazilian government created a program providing financial support to recover these lands throughout the country by establishing agroforestry systems, among others. To select the most appropriate initial spatial arrangements and tree planting density for such systems, the plant growth and leaf area index (LAI) of a Eucalyptus camaldulensis clone were evaluated in five spatial arrangements: 3.6 × 2.5 m, and 3.3 × 3.3 m (monoculture), and (2 × 2) + 10 m, (3 × 3) + 9 m, and 9 × 3 m (silvopastoral systems), with 1,111, 918, 833, 556 and 370 plants per hectare, respectively. The arrangement did not affect plant height growth (p > 0.05) up to 50 months. The average diameter was affected by plant proximity in the planting line, being smaller (p < 0.05) in the arrangements (2 × 2) + 10 m, and 3.6 × 2.5 m, and by the number of lines in the rows, as the plants in the single line arrangement (9 × 3 m) attained the highest diameter. Individual volumes of high initial density stand were lower than in the silvopastoral systems. The arrangements (2 × 2) + 10 m, 3.6 × 2.5 m, and 3.3 × 3.3 m did not differ (p > 0.05) in volume per hectare, which was higher (p < 0.05) than for the other arrangements studied. LAI decreased with age and it was higher (p < 0.01) in the monoculture as compared to the silvopastoral systems. The silvopastoral system can be established in the (2 × 2) + 10 m arrangement for high biomass production besides having the additional benefit of financial returns from the pasture, as compared with the monoculture. The 9 × 3 m arrangement is preferable for large diameter log production.     

Tree row spacing affected agronomic and economic performance of Eucalyptus-based agroforestry in Andhra Pradesh, Southern India

The 3 × 2 m spacing currently used for eucalyptus plantations in the state of Andhra Pradesh, southern India does not permit intercropping from the second year. This discourages small landholders who need regular income from taking up eucalyptus plantations and benefiting from the expanding market for pulpwood. Therefore, on-farm experiments were conducted near Bhadrachalam, Khammam district (Andhra Pradesh) for over 4 years from August 2001 to November 2005 to examine whether wide-row planting and grouping of certain tree rows will facilitate extended intercropping without sacrificing wood yield. Eucalyptus planted in five-spatial arrangements in agroforestry [3 × 2 m (farmers’ practice), 6 × 1 m, 7 × 1.5 m paired rows (7 × 1.5 PR), 11 × 1 m paired rows (11 × 1 PR) and 10 × 1.5 m triple rows (10 × 1.5 TR)] was compared with sole tree stands at a constant density of 1,666 trees ha^?1. Cowpea (Vigna unguiculata) was intercropped during the post-rainy seasons from 2001 to 2004, and fodder grasses (Panicum maximum and Brachiaria ruziziensis) were intercropped during both the seasons of 2005. At 51 months after planting, different spatial arrangements did not significantly affect height and diameter at breast height (dbh). Total dry biomass of eucalyptus in different spatial arrangements ranged between 59.5 and 52.9 Mg ha^?1, the highest being with 6 × 1 m and the lowest with 10 × 1.5 TR, but treatment differences were not significant. The widely spaced paired row (11 × 1 PR) and triple row (10 × 1.5 TR) arrangements produced 62–73% of sole cowpea yield in 2003, 59–66% of sole cowpea yield in 2004, and 79–94% of sole fodder in 2005. In contrast, the 3 × 2 m spacing allowed only 17–45% of sole crop yields in these years. The better performance of intercrops in widely spaced eucalyptus was likely because of limited competition from trees for light and water. Intercropping of eucalyptus in these wider rows gave 14% greater net returns compared with intercropping in eucalyptus spaced at 3 × 2 m, 19% greater returns compared with that from sole tree woodlot and 263% greater returns compared with that from sole crops. Therefore, in regions where annual rainfall is around 1,000 mm and soils are fairly good, eucalyptus at a density of 1,666 plants per ha can be planted in uniformly spaced wide-rows (6 m) or paired rows at an inter-pair spacing of 7–11 m for improving intercrop performance without sacrificing wood production.     

Timing and intensity of precommercial thinning in Pinus sylvestris stands

The effects of timing and intensity of precommercial thinning were studied in three Scots pine artificially regenerated stands on Vaccinium forest sites in southern Finland. A two-level factorial design (3×3) was used in each stand: thinning at dominant height of 3, 6 and 9 m to 1000, 1600 and 2200 stems ha^?1. The effects of the treatments were analysed after a period of 23–25 yrs when the dominant height was 14–15 m. Early thinning resulted in the highest standing volume and amount of merchantable wood, and also in slightly accelerated height development. Thinning to 1000 stems ha^?1 caused a considerable production loss, but there were no differences between the densities of 1600 and 2200 stems ha^?1. Branches became thicker after early thinning, but the differences between the treatments were negligible for crop trees. Crown ratio was lowest as the result of early or moderate thinning (2200 stems ha^?1).     

Effects of clump spacing on nutrient distribution and root activity of <Emphasis Type="Italic">Dendrocalamus strictus</Emphasis> in the humid region of Kerala,peninsular India

The humid agroclimatic conditions of Kerala, India permit the cultivation of an array of bamboo species of which Dendrocalamus strictus Roxb. (Nees.) is an important one on account of its high growth rate and multiple uses. Stand density, a potential tool in controlling the productivity of woody ecosystems, its effect on growth and root distribution patterns may provide a better understanding of productivity optimization especially when bamboo-based intercropping options are considered. Growth attributes of 7-year-old bamboo (D. strictus) stands managed at variable spacing (4 × 4 m, 6 × 6 m, 8 × 8 m, 10 × 10 m, 12 × 12 m) were studied. Functional root activity among bamboo clumps were also studied using a radio tracer soil injection method in which the radio isotope ³²P was applied to soil at varying depths and lateral distances from the clump. Results indicate that spacing exerts a profound influence on growth of bamboo. Widely spaced bamboo exhibited higher clump diameters and crown widths while clump heights were better under closer spacing. Clump height was 30% lower and DBH 52% higher at the widest spacing (12 × 12 m) compared to the closest spacing (4 × 4 m). With increasing soil depth and lateral distance, root activity decreased significantly. Root activity near the clump base was highest (809 counts per minute, cpm; 50 cm depth and 50 cm lateral distance) at 4 × 4 m. Tracer study further showed wider distribution of root activity with increase in clump spacing. It may be concluded that the intensive foraging zone of bamboo is within a 50-cm radius around the clump irrespective of spacing. N, P and K content in the upper 20 cm was 2197, 21, and 203 kg/ha respectively for the closely spaced bamboo (4 × 4 m) which were significantly higher than corresponding nutrient content at wider spacings. About 50% of N, P and K were present within the 0–20 cm soil layer, which decreased drastically beyond the 20 cm depth. The results suggest that stand management practices through planting density regulation can modify the resource acquisition patterns of D. strictus which in turn can change growth and productivity considerably. Such information on root activities, spatial and temporal strategies of resource sharing will be helpful in deciding the effective nutrition zone for D. strictus. Further, the study throws light on the spatial distribution of non-competitive zones for productivity optimization yields, especially when intercropping practices are considered.     

Recognition of shelterbelt continuity using remote sensing and waveform recognition

Shelterbelt systems play an important and long-term role in ecological stability and food security. Today, shelterbelts are threatened by anthropogenic destruction, plant diseases, and insect pests. Determining the continuity of shelterbelts is essential for the management and maintenance of complete and stable shelterbelt systems. In this paper, we acquired SPOT 5 images with a 10 m × 10 m spatial resolution, and, based on a GIS method, we generated belt waveforms using a waveform data collector. We then developed a waveform recognition model for belt continuity based on waveform recognition theory. Finally, we identified a minimum threshold value for the identification of belt gaps, and conducted belt continuity recognition in the study area. The results were compared with data calculated from aerial images with a 0.5 m × 0.5 m spatial resolution. When belt gaps were <10 m, recognition was poor, but when belt gaps were between 10 and 20 m, the mean absolute error was 3.8 %, and when belt gaps were >20 m, the mean absolute error was 2.7 %. We propose that this method provides a powerful new tool for the investigation and management of shelterbelt systems.     

Remote estimation of shelterbelt width from SPOT5 imagery

Width is one of the key parameters of a shelterbelt. Traditional methods to acquire this width are mainly based on field measurement, which is impractical for monitoring shelterbelts at regional scale. There are many studies analyzing linear objects, but they are not directly applicable to width detection of such objects. In this paper, we analyzed relationships among vegetation fractions retrieved from SPOT5 remote sensing imagery with 10 m × 10 m spatial resolution, shelterbelt area, and shelterbelt width in one pixel. Based on this analysis, we developed a method for recognizing shelterbelt width from a remote sensing image of central western Jilin Province, China. The result was validated by field measurement data and measurement from an aerial image of 0.5 m × 0.5 m spatial resolution. Mean absolute error was 2.40 and 2.73 m respectively, suggesting that the proposed method is feasible and its accuracy is acceptable. The study provides a valuable method for monitoring shelterbelt width across large spatial scales and an accurate input parameter for the recognition of shelterbelt porosity from remote sensing data in future research.