基于改进PSO的洞庭湖水源涵养林空间优化模型

以结构化森林经营思想为理论基础,从与水源林涵养水源、保持水土功能密切相关的林分物种组成(树种混交)、种内及种间竞争、空间分布格局、垂直结构4个方面选择混交度、竞争指数、角尺度、林层指数、空间密度指数、开阔比数作为水源林健康经营和林分空间结构优化的目标函数,建立洞庭湖水源林林分多目标空间优化模型,应用改进的群智能粒子群算法求解林分空间结构优化模型,并针对模型输出的目标树空间结构单元制定周密的经营策略.研究结果表明,优化模型能准确定位林分空间关系的薄弱环节,调控措施能显著改善林分空间结构,有利于促进森林生态系统的正向演替,为恢复洞庭湖水源林生态功能和健康经营提供理论依据和技术支撑.应用优化模型进行水源涵养林健康经营突破了传统森林经营模式,为智能信息技术在森林空间经营中的应用提供了新的思路.     

基于干扰的汪清林区森林生态系统健康评价

以汪清林区60个林班为研究对象,提出基于干扰的森林生态系统健康评价模型H＝∑B2W2-∑B1W1,构建了基于干扰理论的汪清林区森林生态系统健康评价体系.其中,有害干扰指标层选取4个指标:森林病害、森林虫害、森林火险以及人为干扰,生态系统内部的增益指标层选取4个指标:树种多样性、群落层次结构、林分更新状况以及近自然度.利用层次分析法和变异系数结合的主客观赋权法计算得到各指标的权重,提出基于干扰的健康评价模型和等级划分标准.最终评价结果显示:汪清林区60个样地中,处于优质状态的样地有6块,占总样地数的10％,健康指数均大于0.2;处于健康状态的林分13块,占总样地数的21.67％,健康指数在0.1-0.2之间;处于亚健康状态的林分23块,占总样地数的38.33％,健康指数在0-0.1之间;处于不健康的林分18块,占总样地数的30％,健康指数小于0.结果表明,在天然林中,无论是针叶纯林还是针阔混交林、阔叶混交林,大多处于亚健康和健康的状况,这与他们近自然度高,物种多样性丰富、具有良好的自我调节能力有关.而在落叶松人工林分中,由于林分物种多样性低,群落结构简单,近自然度最小,林分的增益能力弱,因此不健康的占有绝大多数.该评价结果可为该林场展开相关的健康经营措施提供参考.     

辽东山区原始阔叶红松林主要树种空间结构特征

维持森林结构多样性通常被认为是确保森林生态系统稳定性和生物多样性的有效方式.本研究以辽东山区原始阔叶红松林为对象,运用相邻木空间关系构建林分空间结构参数,探究顶极群落内部主要优势乔木的空间结构特征,并以此顶极群落为借鉴,为低质量次生林改造和人工纯林结构优化经营提供参考.结果表明: 辽东山区原始阔叶红松林林分的径级分布呈倒“J”形,林下更新良好,同时保持一定比例的大径木存在;林分平均角尺度为0.507,整体呈随机分布状态,混交度平均值为0.82,混交度强;平均大小比数为0.506,反映出林分整体处于中庸状态.林分中不同优势度在极强混交维度下出现了一定程度的分化,反映出处于中下层绝对劣势的小径级被压木和主林层的绝对优势木在不同垂直空间上的优化分布与利用.林分中各优势树种的分布也随机镶嵌于总体的随机格局之中.     

人工杉木林林分空间结构参数分析及相关性研究

基于南平松溪林场九个人工杉木林标准地的实测数据, 对人工杉木林林分空间结构参数进行了评价和相关性分析, 为制定杉木林和其他纯林林分空间结构优化和调整措施奠定基础。采用n=4确定林木的空间结构单元, 用大小比数、角尺度和竞争指数等3个林分空间结构参数分析杉木林的林分空间结构特征。结果表明, 9个标准地的杉木林大小比数都接近中庸状态, 林木个体差异不大, 林木分化不严重; 角尺度处于均匀和随机分布状态之间, 与水平分布理想模式存在一定差距; 竞争指数较为稳定, 没有因为年龄的不同而出现大幅度的变动。大小比数U和竞争指数H间为中度相关, 大小比数U和角尺度W, 以及角尺度W和竞争指数H间几乎不相关。研究结果有助于杉木人工林的可持续经营。     

珠江口淇澳岛红树林湿地生态系统健康评价

基于湿地生态系统健康理论和压力-状态-响应模型,以珠江口淇澳岛红树林湿地生态系统为研究对象,构建了红树林湿地生态系统健康评价指标体系,并确定了具体的评价指标、评价标准、指标权重、评价等级和评价方法,对珠江口淇澳岛红树林湿地生态系统健康状况进行了评价.结果表明:2008年,淇澳岛红树林湿地生态系统总健康指数为0.6580,评价等级为Ⅱ级(健康);压力、状态和响应指标的健康指数分别为0.3469、0.8718和0.7554,说明该评价系统存在一定的压力,而状态和响应方面较好.作为省级自然保护区,珠江口淇澳岛红树林湿地生态系统健康水平有待进一步提升.红树林湿地生态系统健康评价研究目前尚不成熟,进一步研究需重点关注针对红树林特征的评价因子筛选、相关数据的长期定位监测、生态系统健康与生态系统功能的定量关系研究等.     

京西油松生态公益林空间结构评价

分析油松生态公益林空间结构并进行经营迫切性评价,为油松生态公益林空间结构的优化调整奠定理论基础。基于北京九龙山油松生态公益林的实测数据,选取混交度、大小比数、角尺度、密集度、林层指数、开敞度和竞争指数7个空间结构参数分析油松生态公益林的空间结构特征,并从密度、格局、竞争和混交等方面选取10个指标构建了经营迫切性评价指标体系并确定评价标准,进而对油松林进行了经营迫切性评价。结果表明:(1)油松纯林和油松混交林都接近随机分布,但油松纯林空间结构较为简单,树种组成单一,以零度和弱度混交为主,呈现单种聚集趋势;(2)林木大小分化不明显,主要树种油松与华北落叶松的优势度较大;(3)林木之间较为密集,处于密集的林木比例较高;(4)绝大部分林木都分布在中林层与上林层,林层结构不太明显;(5)两种林分处于中度竞争状态,与油松纯林相比,油松混交林的开敞度较小,生长空间较为不足;(6)油松纯林与混交林的经营迫切性指数分别为0.6与0.5,经营迫切性等级为特别迫切和十分迫切,说明油松生态公益林多数状态特征不符合标准,急需通过采取有效的经营措施优化林分配置,改善森林状况,以实现油松生态公益林可持续发展。     

北京通州平原生态林空间结构特征

林分空间结构直接反映林木间资源竞争情况和生长空间分配状况,对掌握生态林生长状况、制定林分结构调控措施,提升森林质量和生态服务具有重要作用。本文以北京市通州区油松林、白蜡林、旱柳林、毛白杨林、国槐林、刺槐林和垂柳林7种平原生态林为对象,采用聚集度、角尺度、大小比数、开敞度、树冠指数、竞争指数、边缘效益和空间结构综合指数评价了平原生态林的空间结构特征。结果表明: 研究区林分水平分布格局良好,聚集度处于0.32～1.41,角尺度都分布在0.4左右,大小比数主要分布在0.5附近。林分垂直分布格局有待改善,开敞度介于0.19～0.52,大部分树冠指数在0.7左右,竞争指数均大于50,整体居于高位状态。除刺槐林空间结构综合评价指数为Ⅲ级外,其他6种林分均为Ⅱ级,林分开阔程度较低,生活力一般,各林分空间结构综合评价指数从大到小为刺槐林>垂柳林>油松林>旱柳林>白蜡林>国槐林>毛白杨林。     

鄂西南天然林主要乔木树种物种组成及林分空间结构动态变化研究

该研究以鄂西南木林子国家级自然保护区内天然林为研究对象,以森林内胸径≥5 cm的乔木个体为具体分析对象,通过乔木树种重要值及其角尺度、大小比、混交度等林分空间结构参数的一元分布,阐述林分空间分布格局、大小分化程度、林木混交程度及变化,并通过分析林分空间结构参数的二元分布,探究各参数之间的联系,揭示5年间其林分空间结构特征及动态变化,为该林分类型的森林可持续经营提供准确的数据,以促进林分结构理想化,维持该区域物种多样性。结果显示:(1)2014年与2019年林分中主要建群种均为青冈(Cyclobalanopsis glauca),该种在群落中处于优势地位,鹅耳枥(Carpinus turczaninowii)重要值提高0.63%,其在林分中的相对重要性超过杉木(Cunninghamia lanceolata)位居第二,说明在该群落中鹅耳枥具有稳定的种群结构。(2)林分整体依然处于轻微团状分布状态,且各树种强度混交,平均混交度增长0.02,大小比均值降低0.01,林分生长依然处于中庸状态,5年来林分整体空间结构变化较小,但处于由当前林分结构向理想结构的过渡阶段。(3)结构参数两两组合的各组林分空间结构二元分布中,各参数不同取值等级的变化趋势基本不变,但大小比和混交度的二元分布结果显示林分中处于绝对劣势、劣势且零度混交、弱度混交的林木个体减少,林分稳定性得到提高。研究表明,研究区内天然林分空间结构动态变化虽不明显,但处于向更好、更稳定的结构发展中。     

基于空间结构指数的不同森林群落稳定性研究

以长白山杨桦次生林、云冷杉针阔混交林、云冷杉近原始林为研究对象,基于微观经济学中的柯布—道格拉斯生产函数相关理论,以3个常用的空间结构指标(混交度、大小比数、角尺度)为"投入",林分整体空间结构为"产出",构建林分空间结构生产函数,定义了林分空间结构指数(FSSI)并计算了林分空间结构距离(FSSD)。利用这5个指标分析比较不同演替阶段森林群落的空间结构特点,从而评价各演替阶段的稳定性。结果表明:不同演替阶段森林群落的混交度值均不相同,云冷杉近原始林平均混交度最大,云冷杉针阔混交林次之,杨桦次生林最小;大小比数对不同森林群落空间结构影响较小,其值基本为0.49~0.52;3种森林群落水平分布状态为云冷杉针阔混交林和云冷杉近原始林随机分布,杨桦次生林聚集分布;其空间结构指数大小及与理想结构接近程度排序为:云冷杉近原始林云冷杉针阔混交林杨桦次生林。因此,云冷杉近原始林空间结构较好,稳定性最佳。     

2001-2010年洞庭湖生态系统质量遥感综合评价与变化分析

生态系统质量能够反映生态系统的重要特征,是表征生态环境质量和服务功能的重要指标。在生态系统质量的理论框架指导下,结合GIS综合指数法,利用遥感数据和土地覆被数据,对2001—2010年洞庭湖区域各生态系统类型进行生态系统质量综合评价和变化分析。以NPP年均值和变异系数构建生态系统生产能力指数(EPI)和稳定性指数(ESI),结合PSR模型和AHP层次分析法构建生态系统承载力指数(EBCI),并基于熵值权重法,构建生态系统质量遥感综合评价模型,实现对生态系统生产能力、稳定性和承载力三方面的综合评价。结果表明,洞庭湖区域生态系统质量综合评价分数达到59.81(总分100),而且在三项指数评价中,各指数均值分别为72.79、52.21和71.86,可见洞庭湖区域生态系统稳定性略差。三项指数在2001—2010年期间变化表现不同,EPI和EBCI分别下降8.85%和9.11%,ESI小幅度上升3.09%;整体生态系统质量在2001—2010年呈现逐年降低趋势,下降5.97%,平均变化率为-0.508/年。针对各生态系统类型的分析可知,森林生态系统质量高于其他生态系统类型,湿地生态系统质量最低,同时在这十年间,湿地生态系统质量下降最明显,降幅达12.97%,森林生态系统质量变化较小,降幅只有2.26%。     

长白山阔叶红松林结构多样性的初步研究

在林业可持续发展的背景下,对森林实施生态系统管理,必须保护和维持森林的生物多样性。这就要求在森林调查和经营过程中增加林分结构多样性方面的内容,因此必须充分认识森林结构包括的内容,并研究制订简便实用的结构多样性指标。本文采用目测分层盖度结合无样地点四分法取样进行林分结构因子调查,设计了一套简便的林分结构指标体系,并对长白山红松阔叶混交林及其次生林进行了林分结构多样性的测定研究。结果表明：基于分层盖度构建的林分垂直多样性指数和水平结构异质性指数,可以较好地表示林分的基本结构特征,同时借助点四分法测定的物种多样性指数和对倒木、站干、林隙等的统计,可以较全面地描述阔叶红松林的林分结构因素。应用该方法测定不同的原始林样地的林分结构,得到的林分结构指标与其他林分结构因素的描述,同常规林学调查结论一致并更全面;同时对不同采伐方式的林分结构进行了测定,结合相应的常规指标测定对比,表明该结构指数不但能较好地表示群落的空间结构特征,同时也能对比不同经营方式对林分结构造成的影响,如择伐方式比皆伐方式对林分的结构影响相对较小而且结构恢复时间较短,从而说明对阔叶红松林这种复层异龄混交林的森林类型而言,择伐是一种更适合的通过结构调控进行生态系统管理的方式。在对生态系统进行经营管理过程中,采用该方法能有效地说明林分的垂直结构复杂性和水平结构异质性及重要的林分结构因子存在状况,因而更适合当前森林生态系统管理的要求。文章进一步分析了林分结构指标待改进的部分与研究方向。     

The effect of stand age and microhabitat on soil seed banks in Mediterranean Aleppo pine forests after fire

Soil samples from three microhabitats (gaps, beneath shrubs and beneath trees) in five stands of various post-fire ages (6–55 years) were collected in an east Mediterranean Aleppo pine Pinus halepensis forest. Total germinable seed bank densities varied between 300 and 1300 seeds per m². Herbaceous taxa were the major constituents of the germinable seed bank in gaps, regardless of stand age. Perennials were the major components beneath shrubs in all stands except the youngest stand where herbaceous species were the major components in all microhabitats. Important tree and shrub species (e.g., Pinus halepensis, Quercus calliprinos, Pistacia lentiscus, Phillyrea latifolia) of the mature pine forest were not an important component of the soil seed bank and therefore, little resemblance was observed between the above-ground plant species composition and soil seed bank composition. This is consistent with the fact that these species regenerate by resprouting rather than by germination from the seed bank. Both microhabitats and forest-stands, which were of different ages, contributed to the variation in taxa richness, germinable seed density and diversity among samples. The effect of small-scale spatial heterogeneity (among microhabitats) was much more pronounced. In contrast to other studies, species richness, species diversity, and density of seed banks did not decrease with post-fire age. Moreover, stand age was a poor predictor for these attributes of the soil seed bank in an Aleppo pine forest. The heterogeneity plays an important role in conservation and management of this ecosystem.     

基于Voronoi图的林分空间模型及分布格局研究

以南洞庭湖龙虎山次生林为研究对象,建立林分Voronoi图模型,通过该模型表示林分空间结构特征,提取林木空间量化信息。在此基础上,引入变异系数量化Voronoi多边形面积的变化率,将林木空间格局分析转化为计算Voronoi图变异系数,并将计算结果与角尺度作相关性比较。结果表明:林分Voronoi图模型能准确表达林木邻接关系、相邻木距离及角度、空间密度等重要空间信息;大尺度取样时(76m以上),变异系数趋于稳定,林分整体空间格局呈接近随机分布的轻度聚集;Voronoi图变异系数和角尺度存在显著的正相关关系,进一步说明本研究格局分析方法的可行性和有效性;受多种因素影响,乔木层主要树种在不同发育阶段的空间格局表现出强烈的时间和空间动态特性,且小径木多为聚集分布,大径木呈轻度聚集或随机分布。基于Voronoi图的林分空间模型及格局分析方法,从空间上表征林木的生长繁育特性、种内种间关系、资源及环境分布特征,为计算几何方法应用于林分空间经营提供了新的思路。     

Tree diversity and population structure in undisturbed and human-impacted stands of tropical wet evergreen forest in Arunachal Pradesh, Eastern Himalayas, India

Tree species richness, tree density, basal area, population structure and distribution pattern were investigated in undisturbed, mildly disturbed, moderately disturbed and highly disturbed stands of tropical wet evergreen forests of Arunachal Pradesh. The forest stands were selected based on the disturbance index (the basal area of the cut trees measured at ground level expressed as a fraction of the total basal area of all trees including felled ones): (i) undisturbed stand (0% disturbance index), (ii) mildly disturbed (20% disturbance index), (iii) moderately disturbed (40% disturbance index), and (iv) highly disturbed stand (70% disturbance index). Tree species richness varied along the disturbance gradient in different stands. The mildly disturbed stand showed the highest species richness (54 of 51 genera). Species richness was lowest (16 of 16 genera) in the highly disturbed stand. In the undisturbed stand, 47 species of 42 genera were recorded while in the moderately disturbed stand 42 species of 36 genera were found. The Shannon–Wiener diversity index for tree species ranged from 0.7 to 2.02 in all the stands. The highest tree diversity was recorded in the undisturbed stand and the lowest in the highly disturbed stand. The stands differed with respect to the tree species composition at the family and generic level. Fagaceae, Dipterocarpaceae and Clusiaceae dominated over other families and contributed 53% in the undisturbed, 51% in the mildly disturbed, 42% in the moderately disturbed and 49% in the highly disturbed forest stands to the total density of the respective stand. Stand density was highest (5452 stems ha^–1) in the undisturbed stand, followed by the mildly disturbed stand (5014), intermediate (3656) in the moderately disturbed stand and lowest (338) in the highly disturbed stand. Dominance, calculated as the importance value index of different species, varied greatly across the stands. The highest stand density and species richness were represented in the medium girth class (51–110 cm) in all the stands. In the undisturbed stand, the highest density was found in the 111–140 cm girth class, while in the mildly disturbed stand the 51–80 cm girth range recorded the highest density. About 55, 68 and 52% species were found to be regenerating in the undisturbed, mildly disturbed and moderately disturbed stands, respectively. No regeneration was recorded in the highly disturbed stand. Variation in species richness, distribution pattern and regeneration potential is related to human interference and the need for forest conservation is emphasized.     

宝天曼地区栓皮栎林恢复过程中高等植物物种多样性变化

对宝天曼地区不同恢复阶段栓皮栎林的高等植物物种多样性特征进行了初步分析。结果表明,各层物种丰富度和多样性指数在不同恢复阶段栓皮栎林表现出草本层＞灌木层＞乔木层的趋势。乔木层物种丰富度和多样性指数基本上随恢复时间的增加而增加;灌木层在未破坏的栓皮栎林内较低,而在其他恢复阶段的栓皮栎林内基本相同;草本层在恢复５年、１５年和２５年的栓皮栎林中较高,而在恢复４５年和未破坏的栓皮栎林内较低。乔木层物种均匀度指数在未破坏的栓皮栎林中较高,在恢复２５年的栓皮栎林中较低;灌木层在恢复４５年的栓皮栎林中较高,在恢复１５年的栓皮栎林较低;草本层在恢复５年的栓皮栎林中较高,在恢复１５年的栓皮栎林中较低。不同恢复阶段栓皮栎林各层次间的物种多样性差异大多不显著,只有乔木层和草本层及灌木层和草本层之间的物种丰富度指数有显著差异。不同恢复阶段栓皮栎林在乔木层物种多样性特征上的差异最大,在灌木层物种多样性特征上有一定差异,在草本层物种多样性特征上没有明显的差异。     

Communities of ground-living spiders in deciduous forests: Does tree species diversity matter?

The relationships between species diversity and ecosystem functions are in the focus of recent ecological research. However, until now the influence of species diversity on ecosystem processes such as decomposition or mineral cycling is not well understood. In deciduous forests, spiders are an integral part of the forest floor food web. In the present study, patterns of spider diversity and community structure are related to diversity of deciduous forest stands in the Hainich National Park (Thuringia). In 2005, pitfall trapping and quantitative forest floor sampling were conducted in nine plots of forest stands with one (Diversity Level 1), three (DL 2) and five (DL 3) major deciduous tree species. Species richness, measured with both methods, as well as spider abundance in forest floor samples were highest in stands with medium diversity (DL 2) and lowest in pure beech stands (DL 1). The Shannon-Wiener index and spider numbers in pitfall traps decreased from DL 1 to DL 3, while the Shannon-Wiener index in forest floor samples increased in the opposite direction. Spider community composition differed more strongly between single plots than between diversity levels. Altogether, no general relationship between increasing tree species diversity and patterns of diversity and abundance in spider communities was found. It appears that there is a strong influence of single tree species dominating a forest stand and modifying structural habitat characteristics such as litter depth and herb cover which are important for ground-living spiders.     

Variability in Leaf Area and Stemwood Increment Along a 300-year Lodgepole Pine Chronosequence

Large disturbances such as the 1988 Yellowstone fires produce considerable spatial heterogeneity in ecosystem processes across landscapes, in part by affecting vegetation structure. However, the persistence of this heterogeneity with time since disturbance, and thus the role of large disturbances in shaping the heterogeneity of ecosystem processes over large spatial and temporal scales, remains unclear. Such an inquiry requires that variability as well as mean conditions of forest structure and growth be examined if changes are to be projected for heterogeneous postdisturbance landscapes. We studied a chronosequence of unburned, mature lodgepole pine stands (stand ages ranging from 50 to 300 or more years) to examine the variability in stand density, leaf-area index (LAI), and stem growth [basal area increment (BAI), a surrogate for aboveground net primary productivity (ANPP)] with stand age, the relationships between these factors, and how these factors were related to stand and site characteristics. Variation in LAI and BAI was explained primarily by differences in stand density and age (r²=0.51 for both LAI and BAI), and both LAI and BAI were most variable in the youngest age class [coefficient of variation (CV), 38% and 41% for LAI and BAI]. The relationship between LAI or BAI and stand density was significantly weaker (r² < 0.20) at stand ages characterized by canopy closure (50–175 years), suggesting that stand structure and production are closely linked. Thus, the spatial variability of stand production, which is initially very high following large fires in this landscape, is detectable for over a century before successional changes in forest structure greatly affect the initial postdisturbance landscape pattern of stand production. Given the recent focus on spatial heterogeneity of ecosystem processes across large landscapes, projecting changes in postdisturbance patterns of stand production has very strong significance for ecosystem science.     

不同林龄马尾松人工林优势种径级结构及物种多样性分析

采用空间代替时间的方法,以黔中山地孟关林场10a、20a、30a和36a的马尾松人工林为研究对象,通过设置12块20 m×20 m的典型样地,分析了马尾松人工林发育过程中径级结构与物种多样性的动态特征。结果表明:(1)马尾松人工林不同林龄阶段,优势种径级结构存在一定差异,10a林分呈单峰型结构,20a、30a、36a林分呈多峰型结构。(2)林下共有植物种类35科53属53种,其中灌木16科24属24种,草本20科29属29种,物种较丰富;不同林龄林分物种组成种类为:20a林分10a林分30a林分36a林分。(3)随林龄增加,马尾松人工林物种丰富度指数先增大后减小,Shannon-Wiener指数和Simpson指数以及Pielou均匀度指数和Alatalo均匀度指数在10a～30a之间变化趋势相反,30a～36a之间变化趋势一致。