广东象头山国家级自然保护区兰科植物垂直分布格局

于2019～2022年对广东象头山国家级自然保护区内的兰科植物进行专项调查,记录兰科植物种类、数量、生活型、海拔、生境等信息,分析保护区内兰科植物的垂直分布格局,并根据《广东高等植物红色名录》和《国家重点保护野生植物名录》对各海拔高度兰花濒危等级的物种数量进行统计。结果显示：(1)实地记录兰科植物33属48种,多数种类种群数量较少;(2)随着海拔上升,各海拔梯度的兰科植物总种数和不同生活型的种数均呈现“中间高度膨胀型”分布特点,峰值在中低海拔区域;(3)濒危物种主要集中在海拔200～500 m区间;(4)相邻海拔段的兰科植物种类相似性系数较高,垂直梯度差异越大,相似性系数越小。低海拔地区可能由于人为干扰频繁,兰科植物物种多样性较低;中海拔物种多样性最丰富;高海拔地区生长环境较苛刻,物种数量较少。     

江西武夷山黄岗山西北坡植物物种多样性沿海拔梯度的变化

武夷山脉是我国大陆东南生物多样性最为富集的关键地区,其主峰黄岗山西北坡具有典型的垂直带谱。为探讨其植物物种多样性沿海拔梯度的变化特征,依植被类型于黄岗山西北坡设置5个海拔梯度(900~2000 m,从低到高分别记为海拔梯度1、2、3、4、5),采用α和β多样性指数进行评估。结果显示:随海拔的上升,样地物种的平均科数、平均属数、平均种数和乔木的平均株数及其种数均呈下降的趋势,且海拔梯度1与海拔梯度3、4及5均呈显著性差异(P0.05)。群落α多样性指数在海拔梯度上呈减小的变化趋势,其中Gleason丰富度指数海拔梯度间差异性与物种平均种数一致,Shannon多样性指数只有海拔梯度1与海拔梯度5间呈显著性差异(P0.05),Pielou均匀度指数则差异不显著。而群落β多样性指数和物种平均密度在海拔梯度上呈先减小后增大的"V"型变化。乔木的多样性指数未表现出与群落多样性指数相同的变化趋势,但其Pielou均匀度指数在海拔梯度上的差异性表现一致。综合物种多样性和植物密度结果表明:低海拔梯度的植被群落具有较高的物种多样性,中海拔梯度的植物密度最低。     

甘肃白水江国家级自然保护区珍稀植物的垂直分布及其保护

白水江自然保护区有各类珍稀濒危植物104种,占该区总种数的5.28%。其中划归《国家重点保护野生植物名录(第一批)》的有20种,划归《中国珍稀濒危保护植物名录》的有37种,划归《国家珍贵树种名录》的有18种。该区在整个海拔梯度上均有珍稀植物分布,但很不均匀。根据珍稀植物物种丰富度的高低,大体可分为“极丰富段”“较丰富段”“丰富段”“稀少段”4段。不同类型的珍稀植物的垂直分布也有差异。根据白水江珍稀濒危植物的垂直分布格局和保护现状提出了几点建议。     

红池坝草地常见物种叶片性状沿海拔梯度的响应特征

叶片性状是决定植物光合能力和羧化能力的关键因素,研究叶片性状在海拔梯度上的变化特征是解释植物对于环境变化的适应策略的重要手段。本文以分布于红池坝(10958′E, 3130′ N)草地的5个常见物种红三叶(Trifolium pratense)、老鹳草(Geranium wilfordii)、紫菀(Aster tataricus)、火绒草(Leontopodium leontopodioides)和绣线菊(Spiraea prunifolia)为研究对象,分析了所有物种(n=56)和不同物种的叶片比叶重(LMA)、叶氮含量(单位面积氮含量Narea、单位重量氮含量Nmass)以及叶片δ13C含量沿海拔梯度(815-2545m)的变化趋势及叶片性状之间的关系。研究结果表明：所有物种样品(n=56)的比叶重(LMA)、Narea和δ13C含量沿海拔梯度的增加呈显著增加趋势;Nmass沿海拔梯度的变化趋势不明显;δ13C含量与LMA、Narea呈现极显著正相关关系;不同物种的叶片性状沿着海拔梯度的响应特征有所不同,绣线菊(S. prunifolia)和老鹳草(G. wilfordii)的叶片性状沿海拔梯度的分布规律与所有物种(n=56)样品分布规律一致,红三叶(T. pratense)、紫菀(A. tataricus)、火绒草(L. leontopodioides)的各叶片性状沿海拔梯度的分布特征有所不同。     

南岭国家级自然保护区兰科植物物种多样性的海拔梯度格局

兰科是单子叶植物最大的科和被子植物中的第二大科.兰科植物物种多样性的海拔梯度格局因地域或坡向不同而呈不同趋势.南岭国家级自然保护区地处南岭山脉中段南坡,植物资源丰富.作者对南岭国家级自然保护区兰科植物进行了为期4年的调查,记录了其种类、数量、生活型、海拔、生境,分析了其区系成分,并依据IUCN(2001)濒危物种红色名录及保护区的具体情况对其濒危等级进行了评估.从海拔230-1,902m,每200 m分段,共划分为9个海拔段分析其垂直分布格局.结果显示:(1)实地记录兰科植物38属70种,大多数种类数量较少,乳阳管理处的种类最为丰富;(2)随着海拔的上升,总体兰科植物以及不同生活型的兰科植物物种数量均呈现"中间高度膨胀型"而峰值偏向低海拔的特点;(3)濒危物种主要集中在600-1,000 m人为活动稀少、环境好的小生境中;(4)800-1,000 m的区系成分最丰富,热带性质的兰花多数分布在海拔1,600 m以下;(5)相邻海拔段的兰科植物种类的相似性系数较高;海拔段相隔越远,相似性系数越小.小生境和水分条件对于兰科植物的生长非常重要,中海拔具有良好的水热条件,因此物种多样性最高;而低海拔地区的人为破坏使得该海拔段兰科植物物种的多样性显著降低.     

三江并流地区干旱河谷植物物种多样性海拔梯度格局比较

在滇西北三江并流地区典型干旱河谷段, 在怒江、澜沧江和金沙江的东、西坡共设置了6条海拔梯度样带, 通过标准样地的植物群落调查, 分析各条样带植物的物种丰富度、物种更替率的海拔梯度格局, 并比较了地理和植被变量对分布格局的解释。干旱河谷植被带位于海拔3,000 m以下, 以灌丛和灌草丛为主, 其在各河谷的分布上限自西向东依次升高。植物物种丰富度的分布主要与海拔、流域、经纬度和植被带有关, 沿纬度和海拔梯度升高而显著增加的格局主要表现在草本层和灌木层, 灌木物种丰富度还呈现自西向东显著增加的趋势。怒江的灌木和草本种物种丰富度显著高于金沙江和澜沧江, 三条江的乔木种丰富度差异则不显著。森林带的样方草本物种丰富度显著低于灌草丛带样方, 并且还拥有后者没有的乔木种。不同样带的植物物种更替速率呈现了不一致的海拔梯度格局, 但均在样带海拔下部的灌草丛群落与海拔上部森林群落之间的交错带出现峰值。森林-灌草丛植被交错带在怒江样带处于海拔1,900-2,100 m处, 在澜沧江河谷位于海拔2,300-2,400 m, 在金沙江河谷位于海拔2,700-2,900 m。所有海拔样带的森林段或灌草丛段相对于同一样带不同植被段之间的物种更替程度为最小, 不仅小于同一流域不同样带相同植被段之间物种更替率的均值, 更小于所有样带相同植被段之间的更替率均值。在三条河流6条海拔样带的12个植被带段之间的物种更替变化中, 空间隔离因素可以解释34.2%, 而植被类型差异仅能解释不到0.5%。本研究结果显示了环境差异对不同植被类型物种丰富度的首要影响, 和各河流之间的空间隔离对植物群落构建和物种构成的主要作用。     

高寒草地植物生存策略地理分布特征及其影响因素

植物性状能够反映植物的生存策略,是植物生态学的研究热点之一。植物CSR策略模型将植物物种分为3类:在资源丰富环境中能够最大程度提高生物量的物种(竞争型物种:C策略);在干扰频率较高的环境中能够快速摄取资源并繁殖的物种(投机取巧型物种:R策略);在资源贫瘠环境中能够保持个体生存的物种(耐受型物种:S策略)。植物叶片性状对环境梯度具有适应性的改变,性状的改变对植物生存策略产生影响,但是青藏高原植物叶片性状是如何影响植物CSR生存策略的,其机制尚不清楚。该研究探究了高寒草地植物CSR生存策略的分布特征,以及环境因子对CSR生存策略的影响机制。2020年7–8月,对青藏高原高寒草地53个样点进行了调查,测定植物叶片叶面积、叶片鲜质量和叶片干质量等性状,并计算C、S、R值。然后,分析关键地理环境要素对植物CSR策略影响的主要因子和作用机理。结果表明:(1)在青藏高原高寒草地,植物的生存策略主要以S策略(41.6%–96.7%)为主。(2)随着经度的增加,青藏高原高寒草地C策略植物所占比例自西向东逐渐上升;在海拔梯度上,高寒草地C策略植物所占比例随着海拔的升高而降低。(3)随机森林分析结果显示降水...     

西藏米拉山植物资源的垂直分异

通过野外调查和现有文献资料的分析,研究了西藏米拉山东坡不同海拔带内植物资源的构成特征.结果表明:米拉山区有维管植物86科324属765种,其中蕨类植物15科20属37种,裸子植物有3科7属12种.种类组成趋向于集中在少数科内,区系优势现象明显,反映出米拉山自然环境的特殊性和区系的过渡性.米拉山的植物物种多样性和地理成分多样性都有随海拔升高而减小的变化趋势.海拔3 100～4 100 m是本山区中植物分布相对集中的高度带.海拔3 500～3 700 m是物种资源最为丰富的地段.海拔3 700 m以下地段和海拔5 100 m以上地段的植物物种资源构成与其他各海拔带的相似性较低.     

秦岭小陇山保护区维管植物丰富度和种域海拔梯度格局及其对Rapoport法则验证

物种丰富度和种域的海拔梯度格局及其形成机制一直是生物地理学和生物多样性研究的重点.海拔Rapoport法则认为,物种丰富度随海拔升高而逐渐降低,种域逐渐变宽.本文分析了秦岭小陇山国家级自然保护区维管植物物种丰富度及其种域宽度的海拔梯度格局;采用4种常用方法,验证不同类群、不同生长型和不同阶元的物种丰富度与其分布中点间的关系,并检验其是否支持海拔Rapoport法则.结果表明: 除窄域种外,秦岭小陇山维管植物物种丰富度随海拔升高呈先升后降的单峰分布格局;狭域种主要分布在低海拔和高海拔段,低海拔段的丰富度高于高海拔段;物种海拔分布宽度与海拔关系因不同类群和验证方法而异,随分类阶元的增大更容易支持Rapoport法则,这可能与不同分类阶元所占据的生态位不同有关;被子植物的平均种域呈单峰分布格局,蕨类植物和裸子植物的种域海拔梯度格局无明显规律;藤本植物平均种域随海拔升高而变宽,灌木能适应不同的环境条件,因此,灌木分布对海拔梯度的变化不敏感.Pagel验证方法最容易支持Rapoport法则,Stevens方法次之,中点法受中域效应的影响物种平均种域分布呈单峰分布格局而不支持Rapoport法则,逐种法受散点图分布格局的影响线性模型拟合结果解释力很低.
     

地形对七姊妹山自然保护区植物丰富度及分布格局的影响

该研究以七姊妹山自然保护区40个(20×20m2)植物群落调查样方为基础,并采用回归分析和典型对应分析(CCA)的方法研究该区地形对植物物种丰富度及植物分布格局的影响,以明确海拔、坡度、坡向、坡位等地形因子的相对重要性,为该区植物多样性的保护和管理提供理论依据。结果表明:(1)七姊妹山自然保护区40个调查样地共有植物633种,隶属133科,316属,其中乔木118种,灌木150种,草本365种。(2)曲线回归方程拟合结果显示,七姊妹山自然保护区植物物种丰富度分别与海拔、坡度具有显著相关性,物种丰富度沿海拔梯度升高而增大,沿坡度梯度先减少后增大之后又减小。(3)从植物的生活型来看,在所有海拔段,乔木物种丰富度始终低于灌木和草本植物;在低、中低海拔地带,灌木物种丰富度均高于乔木和草本植物;而在中、高海拔地带草本植物物种丰富度较大且高于乔木和灌木。(4)CCA排序结果表明,地形因子对植物物种的分布具有显著影响按其影响强度排序为海拔坡度坡位坡向,说明海拔是影响该区植物物种分布最重要的地形因子。     

Temporal changes in floral resource availability and flower visitation in a butterfly

Foraging affects survival and reproductive success in animals, including flower-visiting insects. Plant-derived floral food resources (i.e. nectar and pollen) may be rapidly changing in space and time and pollinators may need to quickly switch to new resources. Butterflies are suitable model organisms to investigate foraging behaviour of insect pollinators, because they can be easily monitored under natural conditions. We studied flower visitation patterns in the Clouded Apollo butterfly Parnassius mnemosyne in relation to the abundance of available floral resources. We recorded flower visitation daily in individually marked butterflies, listed flowering species and estimated flower abundance categories every 3 days in a single meadow, during five consecutive flight periods. Butterflies visited 35 nectar plants from the 71 species available. Few nectar plants were frequently visited (visit ratios for the annually most visited species: 37–60%), many were scarcely visited and no visits were observed on several abundant species. Flower abundance and visit ratio varied among years and within flight periods. The number of visits increased with flower abundance in the seven most frequently visited plant species, but not in the occasionally visited ones. Beside their choosiness, Parnassius mnemosyne butterflies were able to adjust foraging behaviour to rapidly changing resource distributions. Diet selectivity in adults might increase the vulnerability of this species. However, visitation plasticity may mitigate the effect of the lack of some nectar plants, as complementary resources can be used as alternatives.     

Factors influencing the distributional abundance of two trophic guilds of Peruvian cricetid rodents

The distributional abundance of 13 species of southern Peruvian rodents is significantly correlated with altitude and patterns of vegetation but vegetation is a better predictor than altitude. Coincidental reversals in the altitudinal trends of both vegetation and rodents demonstrate that rodents are responding to vegetation patterns. Abundance and diversity of rodents are greatest around 4000 m elevation which coincides with the region of greatest vegetational abundance and seasonally heavy rainfall.
The rodent communities consist of two separate feeding guilds, omnivores and insectivores and these guilds show distinctly different distributional patterns. Insectivorous species are strongly associated with the zone of seasonally heavy rainfall (4000 m) whereas omnivorous rodents are relatively abundant over a broader spectrum of elevations and habitats. In a previous study of these same communities, we showed a correspondence between rodent morphology and their diets. This study reveals a correspondence between distributional abundance of the various species and their diets. We conclude that the distributional abundance of southern Peruvian rodents is related to the physiological constraints imposed by altitude (climate) and the distributional abundance of food resources.     

The vertical distribution and abundance of gastropods and bivalves from rocky beaches of Cuastecomate Bay, Jalisco, México

The vertical distribution and abundance of conspicuous gastropod and bivalve species were studied at five rocky beaches in Cuastecomate Bay, Jalisco. Sampling was done from September, 1993 through March, 1994 with 0.75 m2 quadrants placed along replicate transect lines (10 m long) in the supralittoral and mesolittoral (upper, middle and lower intertidal) zones. A total of 6,643 mollusks were collected. Gastropods dominated the samples (6,272 individuals, 44 species); the bivalves were less abundant and diverse (371 individuals, five species). Seventeen species comprised 89.8% of all individuals collected. The gastropods Nodilittorina aspera and Nerita scabricosta were the most abundant with 637.8 and 71.43 individuals/m2, respectively. The most abundant bivalves were Brachidontes adamsianus and Chloromytilus palliopunctatus with 60.7 and 61.3 individuals/m2 respectively. The abundance of gastropods decreased from the supralittoral to the lower tidal zones while the number of species increased in the same direction. The number of species of bivalves also increased from the supralittoral to the lower intertidal zone; the abundance of individuals was higher at the middle intertidal zone. Affinities between groups of species among sampling stations were identified by computing Pearson's correlation coefficient using abundance values (ind./m2) and Jaccard's dissimilarity index using species presence or absence in the lower intertidal zone. Affinity among stations was not dependent upon their vicinity but on the high dominance of few species, the occurrence of many secondary species and beach characteristics.     

Spatial patterns in the distribution of damselfishes on a fringing coral reef

Damselfishes are an important element of the fauna of coral reefs. This study describes spatial patterns in the distribution of 15 species of damselfishes at Lizard Island, northern Great Barrier Reef (GBR). The aim of the work was to identify the spatial scales at which major changes in the composition and abundance of the fauna occurred. These patterns were then compared with previous studies in an attempt to determine if distributions followed general patterns at a range of localities. The assemblage found at Lizard Island was similar to that of reefs in the central GBR. The most important changes in the composition of the fauna occurred among reef zones. Shallow zones (the reef flat and crest) were dominated by herbivorous species while planktivorous and omnivorous species were most abundant in deeper zones (the reef slope). Densities of herbivorous damselfishes in shallow reef zones at Lizard Island averaged 45.5 individuals per 80 m², a value comparable to densities found in similar zones on reefs in the central and southern GBR and at one locality in the Caribbean. Comparisons of relative distributions suggested that abundant species tend to be widely distributed among zones and habitats, while rare species have restricted distributions at Lizard Island. However, computer simulation of the sampling program suggested that the ability of our study to describe the distribution patterns of rare species was limited, despite intensive sampling. Correlations between breadth of distribution and abundance may have occurred simply because rare species were less likely to be recorded within a transect. Our results suggest that it will be difficult to compare the distribution patterns of species among studies. Furthermore, the interpretation of relative patterns of distribution at a single locality in terms of ecological specialization or partitioning may first require an assessment of the ability of the sampling program to accurately record spatial patterns.     

Decline in lizard species diversity,abundance and ectoparasite load across an elevational gradient in the Australian alps

The rapid changes in altitude, and associated habitat, of mountain ecosystems make them ideal natural laboratories for testing the effect of environmental heterogeneity on species assemblage. Our understanding of the sensitivity of Australian reptiles to elevational clines is limited. We examined lizard distribution across three elevation zones (montane, subalpine and alpine), spanning from 900 to 1840 m above sea level, in the Australian alps. We aimed to examine how elevation influences species diversity and abundance, and ectoparasite load, and whether species alter their habitat use amongst different elevational zones. Active searches were conducted across the elevation zones to identify lizard community structure (at least 16 species) across elevational zones, along with skink habitat preferences and the ectoparasite load. Skink diversity and abundance were negatively correlated with increased elevation. The alpine zone had significantly lower diversity and abundance of skinks. Habitat use differed amongst both elevations and species. Ectoparasite prevalence was also significantly diminished in the alpine zone. Ectoparasites only infected a subset of the skink community, with ectoparasite load increasing as the active season progressed. This study provides evidence of the complex interplay between elevation and species diversity, as well as the differences in ectoparasite pressure along elevational gradients in the Australian alps.     

Colonisation of pitcher plant leaves at several spatial scales

Abstract.  1. The effect of meso-scale (zone within bog and local plant density) and fine-scale (leaf length and resource availability) factors on the colonisation of pitcher plant leaves by arthropods was examined in an eastern Canadian bog.
2. In spring, the abundances of three arthropods, the mosquito Wyeomyia smithii , the midge Metriocnemus knabi , and the mite Sarraceniopus gibsoni , were determined for plots with low, moderate, and high densities of pitcher plants. All overwintering inhabitants were then removed from the plots. Newly opening leaves were colonised from outside the plots, and arthropod abundances were assessed again in autumn.
3. Pitcher plant fauna varied in their response to the meso-scale factors. In autumn (soon after colonisation), midges were more abundant in areas with high densities of pitcher plants. The relationship between mosquito abundance and plant density, and the variation in abundance among zones within the bog in the spring, were probably due to overwintering mortality.
4. All taxa responded to the fine-scale factors, leaf length, and capture rate, in the autumn, but the strength of the responses frequently depended on a meso-scale factor (plant density), in which responses were usually strongest where plants were sparse. Thus, the interaction between meso- and fine-scale processes needs to be considered when interpreting patterns of species abundance within arthropod assemblages in pitcher plant leaves.     

山西庞泉沟自然保护区步甲物种组成及多样性格局

利用巴氏罐诱法,对山西庞泉沟国家自然保护区的不同功能区——核心区（绿色长廊）、缓冲区（八道沟）、远离农田实验区（神尾沟）及靠近农田实验区（八水沟）——林地地表甲虫步甲物种多样性进行了调查和比较,目的在于探明该保护区有代表性林地步甲物种的组成及受不同程度人为干扰下的多样性格局。结果表明：（1）本研究共捕获步甲物种42种,38种是该保护区的新记录种类,其中粗皱步甲Carabus crassesculptus和沟步甲C. canaliculatus 为优势种,与尖角通缘步甲Pterostichus eschscholtzii,强足通缘步甲P. fortipes,罕丽步甲C. manifestus和长叶步甲C. vladimirskyi一起构成研究地的常见种。（2）不同功能区物种组成和数量分布各不相同,多样性各项指标均是靠近农田的实验区最高,核心区最低。（3）各功能区具有特有的指示性种类,其中黄条春步甲Notiophilus reitteri为核心区指示种; 凹唇春步甲N. impressifrons 为缓冲区指示种; 粒步甲C．granulatus,刻翅步甲C．sculptipennis 和中华通缘步甲P．chinensis为实验区指示种。（4）群落相似性分析表明缓冲区与核心区及远离农田实验区之间具有较高的相似性,靠近农田实验区与其他3个地点相似性较低。结果提示适度干扰可提高物种丰富度,但降低人为干扰（如旅游和交通压力）有利于步甲多样性的保护。     

Abundance–occupancy relationships

1.  The abundance and distribution of species tend to be linked, such that species declining in abundance often tend also to show declines in the number of sites they occupy, while species increasing in abundance tend also to be increasing in occupancy. Therefore, intraspecific abundance–occupancy relationships are commonly positive.
2.  The intraspecific pattern is mirrored by more general positive interspecific abundance–occupancy relationships: widespread species tend to be abundant, and narrowly distributed species rare.
3.  Here, we review recent research on these patterns based on the flora and fauna of the British Isles. We assess their generality, describe what is currently known about their structure, and summarize the results of tests of the several hypotheses proposed to explain their existence.
4.  The positive form generally exhibited by abundance–occupancy relationships, intraspecific or interspecific, has consequences for several areas of applied ecology, including conservation, harvesting, biological invasions and biodiversity inventorying. These implications are discussed briefly.     

山东半岛潮上带沙草地的物种多度格局及其对人为干扰的响应

沿海岸线分布的潮上带沙滩是受风暴潮影响的独特生境, 蕴含着独特的植物群落与植物资源。很多沙滩已受到不同程度的人为干扰。人们尚未了解潮上带沙滩植物群落的构建方式, 也忽视了各种人为干扰对它的影响。该文以几何级数模型、分割线段模型、重叠生态位模型和中性理论模型, 剖析了山东半岛潮上带3处典型沙草地的物种多度格局, 同时研究了滩涂养殖和旅游践踏两种最重要的干扰方式对潮上带沙滩植物群落的影响。对于这3处植被, 中性理论模型的拟合效果最好, 其次是几何级数模型, 而分割线段模型和重叠生态位模型的拟合效果不够理想。旅游践踏和沙滩养殖使潮上带沙草地的植被盖度降低, 不利于珍稀特有植物的生存。在潮上带沙滩上很多植物具有不少相似的特征, 导致它们在个体水平上的空间替代有强烈的随机性, 服从群落中性理论。然而, 它们的性状毕竟存在或多或少的差异, 这些差异难免对各种植物的资源分配或竞争能力产生微弱的影响, 经过很多年的积累, 这种影响必然在群落水平上逐渐显现出来, 以至于用几何级数模型也可拟合物种的多度格局。作者建议应控制人为干扰对潮上带沙滩珍稀植物的不利影响。     

Spatio-temporal distribution patterns and conservation of fish assemblages in a Chilean coastal river

River environments are characterized by extreme spatial and temporal variation in the physical environment. The relationship of fish assemblages to environmental variation is poorly understood in many systems. In Chile zonation patterns of fish assemblages have been documented in several Andean river drainages. Coastal river drainages are comparatively small, but inordinately important because of their highly endemic flora and fauna and their proximity to major human populations. For conservation purposes it is important to understand what environmental factors affect assemblage structure of fishes especially in the comparatively high diversity coastal drainages. We studied patterns of fish distribution and abundance in three rivers of the coastal, Andalien drainage near Concepción, Chile. We used multi-dimensional scaling analyses to compare patterns among zones (rithron, transition and potamon) and high and low flow seasons. Species assemblages differed by zone, but not with season. Assemblages consisted of nested subsets of species characterized by their range of distribution among zones. One species group was composed of widespread species that occurred in all three zones, another species group consisted of species found only in transitional and potamal zones, and a final group was comprised of species found only in the potamal zone. The potamal zone contained the most diverse and abundant fish assemblage. Fish assemblages were related to both water quality and habitat structure variables. This study suggests that the key to conserving the diversity of native fish communities in coastal Chilean rivers is in the conservation of potamal regions. Unfortunately, most protected areas in Chile are in the depauperate headwaters of drainages. Protection of only headwaters is clearly inadequate and will not contribute to the conservation of this unique freshwater fish fauna.