游动分割窗技术在生态交错带定量判定中的应用:以四川巴郎山岷江冷杉林线为例

以样带上样方间的距离系数为指标 ,采用游动分割窗技术辨析了岷江冷杉 (Abiesfaxoniana)林线附近交错带的位置和宽度。结果表明 ,Bray_Curtis距离、相对欧氏距离、弦距离与平方欧氏距离的峰值和峰宽具有很好的重合性 ,上述距离系数均能作为判定林线交错带群落的边界和宽度的优良指标 ,其中 ,平方欧氏距离更能直观和准确地反映交错带植被的变异。样带上距离系数的峰值区和峰宽对生态交错带的位置和宽度有较为敏感的指示意义 ,游动分割窗技术是交错带判定和群落划分的有效方法。     

长白山北坡植被垂直带群落交错区的定量判定

以海拔梯度上的群落重要值和二元数据为指标,采用游动分割窗技术辨析了长白山北坡各植被带群落交错区的位置和宽度．结果表明,采用平方欧氏距离(SED)和Bray—Curtis距离函数(PD)计算的游动分割窗的峰值和峰宽有较好的重合性,其中基于灌木和草本物种重要值的平方欧氏距离更能准确地反映交错带植被的变异．依据游动分割窗的分析,判定阔叶红松林和暗针叶林的交错区为渐变类型,位于海拔1120m,宽度为200m,暗针叶林和岳桦交错区为急变类型,位于海拔1790m,宽度为50m,林线为急变类型,位于海拔2000m。宽度为40m．     

生态交错带的定量判定

生态过渡性是梯度环境的特征之一,过渡带的显著性是地理学和地植物学中长期争论的重要问题,生态交错带位置和宽度的判定是定量研究交错带生态学过程的基础。样带法是采集非连续梯度数据和研究交错带的结构,功能和格局梯度变化的有效方法。生态交错带变化最为显著的特征是植被的变化,包括植物种类组成和植被结构的变化,植被生态学群落分析中的相异系数,β多样性,梯度分析和分类排序技术等已被证明是成熟可靠的方法。介绍两种交错带定量判定的有效方法。游动分割窗技术是通过滑动求取样带上样点间相异系数,通过相异系数变化曲线判定交错带的位置和宽度。分割窗技术提供了敏感地定位非连续梯度的客观且有效的方法,它不仅可用于环境梯度上的等距离样点取样,而且可用于非等距离梯度带多元变量的分析。植被的特征是对生态环境连续体的综合反应,植被在环境梯度上的排序参数提供了一种较好的交错带定量指标,样带植被数据特征参数的变异轮廓图能够反应植被沿样带的物种组成,结构和空间变化格局,可以反应植被沿环境梯度的β多样性和植物群落的梯度分化,植被变异侧面轮廓图的间断或不连续（突变）区间就是群落边界的位置。     

植物群落类型和围栏封育对高山林线岷江冷杉幼苗成活的影响

林线树种幼苗的生长紧密关系着高山林线的形成。通过室内发芽实验测定了岷江冷杉种子萌发能力。2015年春,在川西巴郎山岷江冷杉林线之上的高山林线交错带,通过播种处理(播种和不播种),研究了不同植物群落类型(灌木和草地群落)和围栏处理(围栏和不围栏)对岷江冷杉幼苗成活率的影响,以期为进一步探讨高山林线形成机制提供科学参考。结果表明:(1)岷江冷杉室内发芽率31.4%,成活率随时间下降。(2)灌木群落的全年日平均空气温湿度显著高于草本群落,而两群落的全年日平均土壤温度无显著差异。(3)未播种样地没有发现岷江冷杉幼苗,说明林线交错带缺乏岷江冷杉种子。(4)与不围栏样地相比,围栏封育分别显著提高了岷江冷杉幼苗成活率2.0%(2015年)和2.2%(2016年);与灌木群落相比,草本群落中岷江冷杉幼苗成活率显著提高0.8%(2015年)和1.2%(2016年),说明灌木对林线交错带幼苗更新具有更强的竞争作用。围栏处理下,草本群落中岷江冷杉幼苗成活率显著高于灌木群落;不围栏处理下,草本群落中岷江冷杉幼苗成活率显著低于灌木群落,2017年在不围栏样地没有幼苗存活,说明动物干扰对林线交错带森林更新有阻碍作用。研究表明,高山林线交错带森林更新,受种子、植物竞争和动物干扰(例如,放牧)等多方面因素的共同影响,可以通过播种、植物剔除(去除竞争)和围栏等促进幼苗更新和成活。     

阈值温度和积温对川西高原林线岷江冷杉径向生长的影响

高山林线的形成机理一直是高山生态学讨论的一个焦点问题,其中林线树木生长的阈值温度一直是研究热点。利用川西高原九寨沟弓杠岭林线岷江冷杉(Abies faxoniana)树木径向生长数据,通过树轮宽度-气候因子关系分析,探讨阈值温度和积温对林线岷江冷杉径向生长的影响。结果表明:林线岷江冷杉径向生长主要受到温度限制,其中林线岷江冷杉径向生长与当年生长季(7、8和9月)、冬季(12、1和2)及上一年9、10月温度显著正相关(P0.05),但与降水的相关性较弱。林线岷江冷杉径向生长与不同起始温度的初日负相关,与不同起始温度的终日正相关,且与9.5℃阈值温度的初日负相关最强(P0.05),与6.5℃阈值温度的终日正相关最强(P0.05)。林线岷江冷杉径向生长还与7—9.5℃的积温及9.5℃持续天数显著正相关(P0.05),说明7—9.5℃可能是形成层活动的阈值温度,尤其7℃可能是林线岷江冷杉生长的起始温度。林线岷江冷杉生长期从4月中旬开始到10月初结束,随着1980年后温度的显著升高,生长期活动积温开始增加,生长期初日提前(4.6d/10a,r~2=0.19,P=0.01),生长期终日延后(1.8 d/10a),使得生长期延长(6.4 d/10a),进而对林线岷江冷杉径向生长有显著的促进作用。未来气候变暖可能会使川西林线树木生长增加,林线可能会上移。     

RESPONSES OF PHENOLOGY AND GROWTH OF BETULA UTILIS AND ABIES FAXONIANA IN SUBALPINE TIMBERLINE ECOTONE TO SIMULATED GLOBAL WARMING, WESTERN SICHUAN, CHINA

 采用开顶式生长室(Open-top chamber, OTC)模拟增温对植被影响的研究方法, 研究了川西亚高山林线交错带糙皮桦(Betula utilis) 和岷江冷杉(Abies faxoniana)幼苗物候及生长特性对模拟增温的响应。结果表明, 温度升高使岷江冷杉幼苗芽开放时间显著提前(15.2 d); 糙 皮桦春季芽物候期变化不显著, 而落叶时间明显推迟(19.7 d), 叶寿命延长(22.8 d)。与对照(CK)相比, OTC内糙皮桦叶面积和岷江冷杉叶片长度及两者侧枝生长速率都显著加快。模拟增温对两物种基径相对生长速率都表现为正效应, 增温对两物种枝叶特性及分布格局表现为不同程度 的正效应、负效应或无影响。不同功能型两物种对模拟增温响应方式存在一定程度差异。     

岷江冷杉林线交错带的植冠三维结构

卧龙自然保护区巴郎山岷江冷杉林线交错带植冠三维结构定量分析表明：植冠明显地分化成两个叶层,两叶层间有１．４ｍ的无叶植冠区。以岷江冷杉、大叶金顶杜鹃和红毛花楸为优势,构成了林线植冠的主要成分。植冠深度较小的为低矮灌木种类,深度最大的是乔木层树种。林线植冠的物种组成较丰富,每个垂直取样冠层平均有２个以上物种。林线的植冠空间占有率最高的是高大的星毛杜鹃,其次是岷江冷杉,但植冠高度以蜕江冷杉最高,故林线交错带林相以蜕江冷杉为优势。物种的盖度与单位面积的植冠体积间有较好的线性关系,物种的植冠体积大致可用其盖度值乘以系数１．２１来计算。     

岷江冷杉精油的化学成分

岷江冷杉(Abies faxoniana Rehd. et Wils.)为我国特有树种,以产于四川省岷江流域而得名,是岷江中上游、白龙江上游和大小金川流域的主要森林树种,拥有较大蓄积量。其针叶富含精油,但至今未加以任何利用,其化学组成也未见报道。为了使这一资源得到合理利用,我们对岷江冷杉精油的化学成分进行了研究。     

高山森林林窗对凋落叶分解的影响

林窗对降水和光照等环境条件的再分配以及分解者群落的影响可能深刻作用于森林凋落物分解过程,但有关高山森林林窗大小对凋落物分解的影响尚无研究报道。采用凋落物分解袋法,研究了川西高山森林不同大小林窗对非生长季节和生长季节红桦(Betula albo-sinensis)和岷江冷杉(Abies faxoniana)凋落叶质量损失的影响。结果显示,经过1a的分解,不同生境下红桦和岷江冷杉凋落叶分别分解了27.25%—30.12%和27.04%—27.96%,其中非生长季节占53.83%—60.18%和50.23%—59.09%。林窗对红桦和岷江冷杉凋落叶质量损失的影响因物种不同而呈现季节差异。总体上,林窗加快了岷江冷杉凋落叶的分解而延缓了红桦凋落叶的分解。与郁闭林下相比,林窗显著增加了2种凋落叶非生长季节的质量损失速率,显著降低了生长季节2种凋落叶的质量损失速率;2种凋落叶质量损失速率在非生长季节随林窗面积增大而加快,在生长季节随林窗面积增大而减慢。林窗显著影响了初冻期、深冻期和融化期岷江冷杉凋落叶的质量损失率,但对红桦凋落叶质量损失率影响不显著。可见,高山森林凋落物分解过程受到林窗的显著影响,并且阔叶和针叶凋落叶在非生长季节和生长季节对林窗的响应具有明显差异。     

西藏色季拉山林线冷杉种群结构与动态

急尖长苞冷杉(Abies georgei var.smithii)是西藏东南部地区高山林线森林群落的主要建群树种,主要分布在色季拉山海拔3600～4400m区域,并成为阴坡高山林线的优势树种。通过对色季拉山林线群落交错区域的定位调查,分析了急尖长苞冷杉的个体生长、种群结构与动态以及林线特征。分析结果表明:(1)西藏色季拉山海拔4320m处为森林郁闭上限,该区域存在两种类型的高山林线,阳坡为渐变型林线,林线树种为方枝柏(Sabina saltuaria);阴坡为急变型林线,林线树种为急尖长苞冷杉。阳坡与阴坡林线分布海拔上限分别为4570m和4390m,阳坡高于阴坡180m;阳坡与阴坡林线群落交错区垂直宽度分别为250m和70m,阳坡比阴坡宽180m。(2)阴坡海拔3700～3800m属急尖长苞冷杉分布的最适范围,种群径级结构表现为典型的反"J"型,种群密度约380株/hm2;种群年龄结构表现为"金字塔"型,属于扩展型种群。(3)静态生命表和种群存活曲线反映了急尖长苞冷杉种群在形成初期的20a和生长发育的60～160a分别经历了强烈的环境筛选和竞争自疏,以及后期与环境变化相关的死亡波动,200a左右为急尖长苞冷杉的生理寿命,种群后期基本稳定,400a左右为极限寿命。     

Estimating the ecotone width in patchy ecotones using a sigmoid wave approach

Ecotones are zones of transition between two adjacent ecological systems and are characterized by a high rate of change compared to these adjacent areas. They are dynamic entities with both a spatial and temporal property, reflected in an ecotone width and location, which vary across time during succession or environmental change on both a local or global scale. Various techniques have been proposed to characterize ecotones, one of them being a sigmoid wave curve fit on the transects across the ecotone. In this paper, we test the robustness of a sigmoid wave model approach on simulated ecotone data with a varying degree of steepness, patchiness and transect length. An analysis of variance (ANOVA) provided us details on the sensitivity of the estimated ecotone width for the steepness, the transect length as well as for the patchiness of the ecotone. The statistics also allowed us to investigate the interaction between the different parameters on the resulting ecotone width. We conclude that the sigmoid wave curve-fitting algorithm provides a robust way to describe ecotones with various degrees of steepness and patchiness. Depending on the transect window size used, a sigmoid wave curve-fitting algorithm will pick up variations in ecotone steepness or in ecotone steepness and patchiness.     

Statistical Efficiency in Distance Sampling

Distance sampling is a technique for estimating the abundance of animals or other objects in a region, allowing for imperfect detection. This paper evaluates the statistical efficiency of the method when its assumptions are met, both theoretically and by simulation. The theoretical component of the paper is a derivation of the asymptotic variance penalty for the distance sampling estimator arising from uncertainty about the unknown detection parameters. This asymptotic penalty factor is tabulated for several detection functions. It is typically at least 2 but can be much higher, particularly for steeply declining detection rates. The asymptotic result relies on a model which makes the strong assumption that objects are uniformly distributed across the region. The simulation study relaxes this assumption by incorporating over-dispersion when generating object locations. Distance sampling and strip transect estimators are calculated for simulated data, for a variety of overdispersion factors, detection functions, sample sizes and strip widths. The simulation results confirm the theoretical asymptotic penalty in the non-overdispersed case. For a more realistic overdispersion factor of 2, distance sampling estimation outperforms strip transect estimation when a half-normal distance function is correctly assumed, confirming previous literature. When the hazard rate model is correctly assumed, strip transect estimators have lower mean squared error than the usual distance sampling estimator when the strip width is close enough to its optimal value (± 75% when there are 100 detections; ± 50% when there are 200 detections). Whether the ecologist can set the strip width sufficiently accurately will depend on the circumstances of each particular study.     

华北农牧交错带农田-草地界面土壤水分影响域分析

在华北农牧交错区,选择线状边界的农田与草地典型区进行调查与土壤水分测定,采用移动窗口法,对农田-草地景观界面表层（0～20 cm）土壤水分影响域进行研究.结果表明：界面水分的影响域为草地6 m到农田4 m,总宽度10 m,属急变型界面;将农田-草地景观界面划分为3个功能区：农田功能区、草地功能区和农田-草地复合功能区.其中农田-草地复合功能区的土壤含水量变化剧烈,而草地功能区与农田功能区内土壤水分基本呈线性分布;草地生态系统土壤平均含水量比农田高约1 g·g^-1,这主要是由于草地开垦为农田后风蚀等作用而引起的土壤毛管持水力下降所致.作为植被覆盖不同的两个生态系统,不同的植物蒸腾和地表蒸发,可使不同功能区的土壤含水量产生明显差异,从而使土壤水势发生变化,使水分跨生态系统运移成为可能.     

岷江上游花椒地/林地边界土壤水分影响域的定量判定

在岷江上游干旱河谷区,选取典型的花椒地/林地边界,利用TDR仪测定干旱条件下、雨后和每月0～15 cm土层水分含量,并用移动窗口法判定土壤水分的边界影响域.结果表明,若用移动窗口法对土壤水分的边界影响域进行判定,当窗口宽度为8～12时,边界影响域较易判定.年内土壤水分随时间变化而变化.这种变化可分为土壤水分上升期、高峰期和消退期3个时期.干旱条件下土壤水分的边界影响域较小,其宽度约从花椒地6 m到林地2 m;雨后土壤水分的边界影响域有较大增加,其宽度约从花椒地12 m到林地2 m;年内土壤水分的边界影响域宽度约从花椒地10 m到林地2 m之间变化.不同季节土壤水分的边界影响域不同,并随着季节的变化呈动态变化.从生态学意义上讲,岷江上游地区目前进行的将花椒地退耕成林地、栽植树苗的措施是不可取的,该区退耕还林的最好方法应该是退耕,使其灌木林或草本植物自然生长.     

Correspondence of vegetation boundaries to redox barriers in a Northern European moraine plain

Little attention has been devoted to the investigation of the formation and functioning of ecotones at the interfaces between the upland and riparian zones. The margins of riparian mires act as redox geochemical barriers. Such biogeochemical hot spots retain elements that have leached from upland soils, favouring the growth of mesomorphic plants in hydromorphic soils. This paper aims to clarify the correspondence of vegetation borders to horizontal redox barriers of a Northern European moraine plain in Estonia.24 random transects were surveyed on the moraine plain, sampled across sharp soil moisture boundaries as proxies of redox barriers. The shifts in vegetation perpendicular to the boundaries were investigated. Curves of Euclidean distance were computed by moving a 20 m split-window along transects. The curves showed peaks of high dissimilarity a few metres below the redox barriers in the sites of natural soil moisture. In artificially drained sites, the relict redox barriers poorly corresponded to the vegetation borders. We conclude that in the studied moraine plain, the vegetation boundaries between riparian mires and uplands correspond to the redox barriers. The same can be set as a hypothesis for Northern European moraine plains. Related ecotones can be observed on the footslopes, revealing redox barrier in the landscape and related hot spots in cultural landscapes. In field margins, the redox barriers and corresponding ecotones occur below cultivation terraces. The ecotones may represent functional boundaries for delineating wetlands. Man-made drainage removes soil redox barriers and corresponding vegetation boundaries, making the landscape uniform and therefore vulnerable to disturbances. As a management implication, footslope ecotones should be preserved in their natural condition.     

A study on the community analysis using three-factorial data (time x site x species)

1. This study is to demonstrate that the analysis of biological communities using scaling unstandardized squared Euclidean distance is extremely effective to deal with data which are quite generally collected by 3 factors (time x site x species).
2. The main part of this study has been explained in detail byWilliams andStephenson (1973). We have conducted some discussion introducing mathematic complementary explanation as well as expansive interpretation.
3. The dissimilarity measure based on squared Euclidean distance is used to classify clusters from a dendrogram obtained by cluster analysis. The outline of the community structure can be known by comparing the values of mean variance per comparison and interaction.
4. The table of mutual comparison among clusters introduces dynamic pattern expression for community. Contributions by species to time and site are capable of expressing a concrete role of the species.
5. We apply the technique above to the demersal fish community in Shijiki Bay, Hirado Island, Nagasaki Pref. Number of individuals caught with Gochi trawls at 11 fixed stations in 1975–1984 are used as material for analysis. 84 species is accounted.

     

群体遗传学研究中的数据处理方法I．RAPD数据的AMOVA分析

近年来,RAPD数据和AMOVA分析广泛地应用于群体遗传学和保护遗传学研究。然而,由于RAPD标记具显性特点。加上目前进行AMOVA分析所依赖的RAPDistance软件不完善,使得对RAPD数据进行AMOVA分析时存在许多不足。本文介绍了AMOVA分析的基本过程,同时引入一个新的程序DCFA用以替代RADistance并详述了将DCFA与WINAMOVA联用,对RAPD数据进行AMOVA分析的具体步骤与注意事项,最后,以产自中国和巴西8个普通野生稻（Oryza furipogon)天然群体为例,演示了对RAPD表型数据进行AMOVA分析的过程,讨论了AMOVA分析结果在群体遗传结构上的意义。通过对AMOVA算法的分析,同时比较4种距离系数所得AMOVA结果,我们认为在进行AMOVA分析时选择NEI－LI距离和欧氏距离平方较为合适,而目前国内使用较多的JACCARD系数不适合AMOVA分析。     

Relationship between 17 Venezuelan counties estimated through communality of surnames

The coefficients of relationship and the Euclidean distances between 17 Venezuelan counties were estimated based on the frequency distribution of surnames obtained from the 1984 Venezuelan register of electors. In general, the coefficients of relationship between counties within the same state were higher than those between counties from different states. Euclidean distances exhibited the opposite relationship. Spearman's correlation coefficients for 136 pairs of counties were estimated between geographic and Euclidean distances (r = 0.41), geographic distance and coefficient of relationship (r = -0.44) and between Euclidean distance and coefficient of relationship (r = -0.48). The effect of partial geographic isolation on the frequency distribution of surnames is shown in the State of Falcón, where an isthmus separates two counties of the peninsula from two others on the mainland, and in Mérida, where the Venezuelan Andes separates three counties from the rest of the country. Our results suggest that Euclidean distances are less influenced by common surnames than the coefficients of relationship. They also indicate that in Venezuela a high proportion of the population has remained sedentary until recently, and this gives rise to the focal distribution of some surnames.