Nested Subset Analysis Research Articles

Nestedness of parasite communities of intertidal fish in central Chile: how influential is the body length of the host?

<p class="Default">La estructura de la comunidad de parásitos, determinada mediante análisis de anidamiento, varía considerablemente en función de la especie hospedera y el tamaño corporal de la misma. El patrón anidado es aquel en el que comunidades pobres en especies constituyen subunidades de comunidades de mayor riqueza, lo cual también se observa en las comunidades de parásitos. Existen grandes diferencias de riqueza y abundancia de parásitos en función del tamaño del hospedero. Por lo tanto, en este estudio determinamos, mediante análisis de anidamiento, si la estructura de la comunidad de parásitos de peces del intermareal, se relaciona con la longitud corporal de los hospederos y los descriptores parasitológicos. Se recolectaron 2 435 individuos de cinco especies de peces del intermareal rocoso de Chile central (32º02’-33º57’ S y 70º30’- 70º30’ W); <em>Helcogrammoides chilensis,</em><em> Scartichthys viridis, Auchenionchus microcirrhis, Gobiesox marmoratus </em>y<em> Sicyases sanguineus</em>. Cada especimen fue revisado con respecto a sus parásitos y medido en su longitud total (LT). Las cinco especies muestreadas fueron clasificadas en función de la longitud corporal (LT) en tres rangos, cada uno de los cuales constituye una infracomunidad del estudio, y para la que se calculó el índice de anidamiento. Se emplearon los modelos NTCP (Nestedness Temperature Calculator Program) y NODF (Nestedness metric based on the Overlap and Decreasing Fill), utilizando la presencia/ausencia de especies parásitas. También se empleó el modelo WNODF (Weighted – NODF) utilizando la abundancia de parásitos por especie. Así mismo, se calculó la riqueza total de especies, el promedio de riqueza, abundancia, diversidad y dominancia a nivel de la infracomunidad, para relacionarlos con los índices de anidamiento. Las infracomunidades de parásitos de la mayoría de las especies presentaron patrones de anidamiento, excepto en <em>G. marmoratus</em> y <em>H. chilensis,</em> en algunos de sus rangos de LT. No se encontró una relación directa entre el índice de anidamiento y la LT de los peces. Sin embargo, se observaron correlaciones directas de los índices de anidamiento con la riqueza promedio, abundancia y la diversidad infracomunitaria de parásitos, pero no con la riqueza total, que mostró una correlación inversa con la LT del hospedero. Además, se detectó anidamiento en la comunidad componente de parásitos en todas las especies de peces. Concluimos que las comunidades de parásitos de peces provenientes de la zona intermareal son estructuradas y predecibles, y se encuentran vagamente condicionadas por la LT de los hospederos y las características agregadas de los parásitos, especialmente a un nivel infracommunitario.</p>

Are There Arid Land Soilscapes in Southwestern Europe?

AbstractNo studies have proven the existence of soil assemblages typical of arid lands in Europe. This study was carried out in a representative territory of the southeastern part of the Iberian Peninsula, Almería province, which is the driest part of Europe, to determine if soils characteristic of arid lands are present. In order to analyse the spatial distribution of soils, the authors made use of mathematical tools previously developed in biodiversity and pedodiversity analysis, such as richness, entropy indices, abundance distribution models, diversity‐area relationships and nested subset analysis. The study demonstrates that the soil types or pedotaxa are typical of mountainous arid lands. Shallow and weakly developed soils (e.g. Leptosols, Regosols and Arenosols), Calcisols, Gypsisols and Solonchaks, cover most of the study area, and pedodiversity analysis demonstrates that the pedotaxa spatial patterns follow the same regularities as in other areas, environments and scales. In view of the fact that the class of landscapes identified in this study is unique in Europe, the Tarbernas desert and other arid lands sites of the study area merit preservation as part of the European geological, geomorphological and pedological heritage. Copyright © 2015 John Wiley & Sons, Ltd.

Habitat loss and mammalian extinction patterns: are the reserves in the Quadrilátero Ferrífero, southeastern Brazil, effective in conserving mammals?

AbstractHabitat loss is considered to be the principal cause of the local extinction of mammals worldwide. We assessed the extinction pattern of medium‐ and large‐sized mammals caused by the effects of habitat loss in reserves in the Quadrilátero Ferrífero, southeastern Brazil, and discussed the effectiveness of these natural remnants for conserving mammals. A literature review and field collections were conducted from 2006 to 2011 to estimate the composition and richness of mammals in nine remnants of different sizes, including reserves and non‐protected areas. A species–area relation and a nested subset analysis were performed, and a degree of sensitivity to habitat loss was obtained for each species according to its frequency of occurrence. Forty‐five species of mammals were recorded. There was a strong species–area relation involving the legal size of reserves. High species richness was associated with large reserves, and the z value was within the range of very isolated continental remnants. The mammalian community exhibited a nested occurrence pattern, suggesting that most species were part of a more continuous ecosystem and that non‐random extinction caused by habitat loss occurred in southeastern Brazil. The negative relation found between species frequencies and body weights suggested that selective species loss is associated with decreases in the size of the reserves. The estimated viable size required to conserve all of the sensitive species is greater than the size of the largest reserve inventoried. We recommend the aggregation of neighboring natural remnants and the creation of new reserves to reduce extinction risks.

Allele elimination recalculated: nested subset analyses for molecular biogeographical data

AbstractAimPost‐glacial colonization of species from low‐latitude refugia to high latitudes, or from lower to higher elevations, often involves repeated founder effects due to stepwise colonization. This may cause repeated population bottlenecks and the subsequent loss of alleles. Regression analyses have traditionally been used to analyse the correlation between the mean numbers of alleles and geographical distances from refugia. Here, we describe and evaluate the performance of nested subset analyses for detecting allele elimination.MethodsGenetic data sets from five butterfly and one beetle species were reanalysed using regression and nested subset analyses.ResultsThe data sets analysed here showed both congruent and divergent results under regression and nested subset analyses. Some data sets did not feature a significant correlation between the mean number of alleles and the colonization trajectory, but did show significant nested structure. Others showed the opposite effects. Using allele frequencies from the same data sets, we did not obtain significant patterns of nestedness.Main conclusionsOur results indicate that classical regression analyses are not always a suitable tool for analysing allele elimination, and nestedness analyses are much more meaningful. Local natural selection can alter allele frequencies, thereby erasing biogeographical patterns that have evolved as a result of the stochastic processes involved in colonization. Thus, an appropriate means of documenting allele elimination sensu Reinig is the joint application of nested subset and regression analyses based on presence/absence and abundance data for genetic diversity.

Regionally nested patterns of fish assemblages in floodplain lakes of the Magdalena river (Colombia).

We investigated if fish assemblages in neotropical floodplain lakes (cienagas) exhibit nestedness, and thus offer support to the managers of natural resources of the area for their decision making. The location was floodplain lakes of the middle section of the Magdalena river, Colombia. We applied the nested subset analysis for the series of 30 cienagas (27 connected to the main river and three isolated). All fish were identified taxonomically in the field and the matrix for presence–absence in all the lakes was used for the study of the pattern of nestedness. The most diverse order was Characiformes (20 species), followed by Siluriformes (19 species). Characidae and Loricaridae were the richest families. The species found in all the lakes studied were migratory species (17), and sedentary species (33). Two species (Caquetaia kraussii and Cyphocharax magdalenae) were widespread across the cienagas archipelago (100% of incidence). Nestedness analysis showed that the distribution of species over the spatial gradient studied (840 km) is significantly nested. The cienagas deemed the most hospitable were Simiti, El Llanito, and Canaletal. Roughly, 13 out of the 50 species caught show markedly idiosyncratic distributions. The resulting dataset showed a strong pattern of nestedness in the distribution of Magdalenese fishes, and differed significantly from random species assemblages. Out of all the measurements taken in the cienagas, only the size (area) and local richness are significantly related to the range of order of nested subset patterns (r=–0.59 and –0.90, respectively, at p < 0.01). Differential species extinction is suggested as the cause of a nested species assemblage, when the reorganized matrix of species occurring in habitat islands is correlated with the island area. Our results are consistent with this hypothesis.

Realistic plant species losses reduce invasion resistance in a California serpentine grassland

Summary1. The majority of experiments examining effects of species diversity on ecosystem functioning have randomly manipulated species richness. More recent studies demonstrate that realistic species losses have dramatically different effects on ecosystem functioning than those of randomized losses, but these results are based primarily on microcosm experiments or modelling efforts.2. We conducted a field‐based experiment directly comparing the consequences of realistic and randomized plant species losses on invasion resistance and productivity in a native‐dominated serpentine grassland in California, USA. The realistic species loss order was based on nested subset analysis of long‐term presence/absence data from our research site and reflects differing species sensitivities to prolonged drought.3. Biomass of exotic invasive plant species was inversely related to native species richness in the realistic loss order. In contrast, invader biomass was consistently low across species richness levels in the randomized species loss order, with no effect of native species richness on invader biomass among randomized assemblages. Although total above‐ground plant biomass increased with soil depth (a proxy for resource availability) in both realistic and randomized assemblages, soil depth influenced invader biomass only in the randomized assemblages.4. Synthesis. Our results illustrate that the functional consequences of realistic species losses can differ distinctly from those of randomized species losses and that incorporation of realistic species loss scenarios can increase the relevance of experiments linking biodiversity and ecosystem functioning to conservation in the face of anthropogenic global change.

Invasion Prediction on Alaska Trails: Distribution, Habitat, and Trail Use

AbstractLittle is known about the relationship between frequency of occurrence and the expected maximum distance a nonnative species might spread along a trail once introduced to an ecological system with high native species integrity. Understanding how colonization and invasive plant habitat degradation occur in largely intact ecosystems is challenging. Determining which nonnative species are most likely to spread might be possible, given a suite of environmental or trail conditions. Spread may be linked to a particular set of environmental conditions, or to type and level of trail use. A field study conducted on trails in Forest Service and State Park lands on the Kenai Peninsula, Alaska, was designed to determine frequency and spread distance of all nonnative vascular plant species per 100-m segments keyed to vegetation type, canopy cover class, aspect, trail use level, and trail use type. Although the maximum total number of nonnative species decreased with increased distances from trailheads, the average number of species remained nearly constant. Common dandelion, broadleaf plantain, and annual bluegrass exhibited consistent presence per canopy cover class or vegetation type. A nested subset analysis revealed a significant reduction in nonnative species presence beyond a 500-m distance from a trailhead and a moderately strong nestedness pattern. High-use trails exhibited the greatest numbers of nonnative species at the farthest distances from the trailhead and contained a greater number of less common nonnative species. Alaska and other northern biomes have relatively few widespread invasive problems, offering an opportunity to limit ecosystem degradation by invasion. Results suggest that control strategies might focus on high-use trails with open-canopy habitats to prevent spread.

Nestedness of desert bat assemblages: species composition patterns in insular and terrestrial landscapes

Nested patterns of community composition exist when species at depauperate sites are subsets of those occurring at sites with more species. Nested subset analysis provides a framework for analyzing species occurrences to determine non-random patterns in community composition and potentially identify mechanisms that may shape faunal assemblages. We examined nested subset structure of desert bat assemblages on 20 islands in the southern Gulf of California and at 27 sites along the Baja California peninsula coast, the presumable source pool for the insular faunas. Nested structure was analyzed using a conservative null model that accounts for expected variation in species richness and species incidence across sites (fixed row and column totals). Associations of nestedness and island traits, such as size and isolation, as well as species traits related to mobility, were assessed to determine the potential role of differential extinction and immigration abilities as mechanisms of nestedness. Bat faunas were significantly nested in both the insular and terrestrial landscape and island size was significantly correlated with nested structure, such that species on smaller islands tended to be subsets of species on larger islands, suggesting that differential extinction vulnerabilities may be important in shaping insular bat faunas. The role of species mobility and immigration abilities is less clearly associated with nestedness in this system. Nestedness in the terrestrial landscape is likely due to stochastic processes related to random placement of individuals and this may also influence nested patterns on islands, but additional data on abundances will be necessary to distinguish among these potential mechanisms.

Avian Biogeography and Conservation on Hainan Island, China

The aim of this study was to perform a biogeographical and conservation analysis of avian distribution on Hainan Island, China using quantitative approaches. I employed cluster analysis with a statistical test to examine the biogeographical zonation of birds on Hainan Island, and then employed an optimization criterion approach to detect candidate areas of endemism. Three biogeographical regions were diagnosed based on the statistical tests. One area of endemism was identified in the southwestern part of the island, principally in the western limestone areas and the central mountainous areas. Canonical variate analysis showed significant separation among the three biogeographic regions correlated with climatic variables. Nested subset analysis using two null models indicated that there was a good nested pattern in the avian assemblage on Hainan Island. In addition, complementarity analysis identified six top species-rich provinces for conservation. The present study is one of the first attempts to use integrative quantitative approaches to analyze bird diversity patterns on this island, and the effectiveness of the methodologies employed is discussed.

Nestedness patterns of container-dwelling mosquitoes: effects of larval habitat within variable terrestrial matrices

Distributions of mosquito larvae likely are a consequence of multiple factors, although two commonly studied factors (quality of the larval environment and the terrestrial matrix in which these habitats reside) have rarely and simultaneously been varied in the field to understand distributions of larvae. We monitored aquatic containers of two leaf detritus levels within a forest, prairie, and industrial habitat across five months to understand the temporal and spatial colonization of aquatic invertebrates in Northcentral Illinois, USA. Data were collected monthly on mosquito populations and the composition of other invertebrates colonizing containers. Overall, six species of mosquitoes colonized containers, with Culex restuans and Aedes triseriatus having the highest relative abundances. There were strong seasonal abundance patterns for these two mosquito species, with the dominant species changing over time in the forest habitat. The responses of other mosquito taxa were more variable, with abundances reflective of either the terrestrial matrix or larval habitat quality. High detritus containers supported the highest abundances of most species encountered, regardless of habitat. Non-mosquito taxa were less common numerically, but analyses suggested that some taxa, such as syrphid larvae, often co-occurred with mosquitoes. Nested subset analysis indicated communities were strongly nested, and that both habitat type and detritus level were important in explaining nested patterns of aquatic invertebrates. Our data show that both the larval habitat and the surrounding terrestrial matrix shape patterns of container mosquitoes, and that other container invertebrates vary in similar ways as mosquitoes.

Floodplain lake fish assemblages in the Amazon River: directions in conservation biology

The Neotropical region is renowned for its high biodiversity, and the Amazon River basin contains the highest number of fish species of any river system in the world. In recent years, habitat fragmentation and exploitation of biotic resources have threatened biological integrity and provoked to need for sustainable management and conservation of the Amazon River system. We studied 36 floodplain lakes along 2000 km of the Amazon River. The fish assemblages associated with flood forests are moderately diverse, with low species dominance and reduced populations. To detect nestedness of fish assemblage composition in floodplain lakes, a nested subset analysis was performed on species presence–absence. The incidence matrix (species × lakes) was maximally packed using the Nestedness Temperature Calculator software. The results of ranking lakes and species allow us to establish targets for conservation. Such strategy for sustainable management should be focused on maintaining the Amazonian biodiversity.

Spatial and temporal predictability of the parasite community structure of a benthic marine fish along its distributional range

The search for consistent patterns of organisation in parasite communities remains a central theme in parasite community ecology. However, to date, much evidence comes from studies without replication in both space and time; when replicate communities are examined, repeatable patterns are rarely observed. Here we determine, using nested subset analyses, whether the infracommunities of ectoparasites and endoparasites of a benthic marine fish ( Sebastes capensis) show non-random structure. Then we examine the spatial repeatability of parasite community structure across the host's distribution in the southern Pacific, and the temporal repeatability of ectoparasite community structure from one locality. In total, 537 fish were captured from different latitudes (between 11°S and 52°S) along the Pacific coast of South America; a further 122 specimens were captured in two other years from one of the sampling localities, Valdivia (40°S). In spite of variation in fish sizes among samples, fish size generally did not correlate with either ecto- or endoparasite species richness. The ecto- and endoparasite species richness of the component communities were also not correlated with fish sample size across the nine localities. Significant nested patterns were found in the ectoparasite communities of S. capensis at all eight localities, except at latitude 52°S. Significant nested patterns were also found in the endoparasite infracommunities of S. capensis at seven of the nine localities, the exceptions being those from latitudes 11°S and 20°S. On a temporal scale, significant nestedness was observed in the ectoparasite infracommunities of S. capensis during each of the 3 years of sampling at Valdivia. In general, the same parasite species are responsible for the repeatability of nested patterns, though their importance varies among localities. The spatial and temporal predictability of the parasite community structure in S. capensis may be associated with the fish's benthic habitat and territorial behavior, suggesting that host biology may be a key determinant of the structure of parasite communities.

Nested communities, invasive species and Holocene extinctions: evaluating the power of a potential conservation tool

General ecological methods and models that require a minimum amount of information yet are still able to inform conservation planning are particularly valuable. Nested subset analysis has been advocated as such a tool for the prediction of extinction-prone species and populations. However, such advocacy has not been without skepticism and debate, and in the majority of published examples assessing extinction vulnerability, actual extinctions are based on assumptions rather than direct evidence. Here, we empirically test the power of nested subset analysis to predict extinction-prone species, using documented Holocene insular mammal extinctions on three island archipelagos off the west coast of North America. We go on to test whether the introduction of invasive mammals promotes nestedness on islands via extinction. While all three archipelagos were significantly nested before and after the extinction events, nested subset analysis largely failed to predict extinction patterns. We also failed to detect any correlations between the degree of nestedness at the genus-level with area, isolation, or species richness and extinction risk. Biogeography tools, such as nested subset analysis, must be critically evaluated before they are prescribed widely for conservation planning. For these island archipelagos, it appears detailed natural history and taxa-specific ecology may prove critical in predicting patterns of extinction risk.

Nested subset analysis and taxa-range size distributions of pedological assemblages: implications for biodiversity studies

A common pattern of taxa distribution has been termed nested subsets by ecologists. Species present in any particular biological assemblage tend also to be present in larger assemblages. The same is true for the so called species–range size distribution: locally abundant species tend to be widespread, whereas locally rare species tend to be narrowly distributed. According to several ecologists, this pattern could be described by a power law. In this paper we show that regularities tested with our data (soil types = pedotaxa, and soilscapes = pedological assemblages) are surprisingly similar to those in ecological literature. For this purpose several soil data sets, as well as techniques utilised in mathematical ecology, including Atmar and Patterson’s Nested Calculator Program have been used. Many of these common patterns appear at different spatial scales suggesting that mechanisms such as nestedness, taxa-range size distributions and species–area relationships among others could be scale invariant, as some ecologists claim. Our results show that nestedness and scale-independent taxa-range size distributions are not exclusive properties of biological assemblages, but can be found in a broader class of earth systems. Pedodiversity analysis also has practical implications for designing reserves for biological and pedological conservation.

Nested subset analysis and taxa-range size distributions of pedological assemblages: implications for biodiversity studies

A common pattern of taxa distribution has been termed nested subsets by ecologists. Species present in any particular biological assemblage tend also to be present in larger assemblages. The same is true for the so called species–range size distribution: locally abundant species tend to be widespread, whereas locally rare species tend to be narrowly distributed. According to several ecologists, this pattern could be described by a power law. In this paper we show that regularities tested with our data (soil types = pedotaxa, and soilscapes = pedological assemblages) are surprisingly similar to those in ecological literature. For this purpose several soil data sets, as well as techniques utilised in mathematical ecology, including Atmar and Patterson’s Nested Calculator Program have been used. Many of these common patterns appear at different spatial scales suggesting that mechanisms such as nestedness, taxa-range size distributions and species–area relationships among others could be scale invariant, as some ecologists claim. Our results show that nestedness and scale-independent taxa-range size distributions are not exclusive properties of biological assemblages, but can be found in a broader class of earth systems. Pedodiversity analysis also has practical implications for designing reserves for biological and pedological conservation.

Putting floodplain hyperdiversity in a regional context: an assessment of terrestrial–floodplain connectivity in a montane environment

Abstract Aim and location Alluvial flood plains support higher levels of vascular plant species richness than other terrestrial ecosystems. Whereas the spatial and temporal heterogeneity of these ecosystems has been considered the local determinant of high plant richness, regional influences, such as regional species pools have received little attention. In this study we surveyed plant species richness across the entire Nyack catchment (c. 21,000 ha), in Glacier National Park, USA, to determine the relation of upland ecosystem community structure to biodiversity patterns on montane floodplains that are relatively extensive and flood‐scoured ecosystems.Method We surveyed floodplain and other terrestrial ecosystems within the Nyack catchment using 50 × 2 m plots to record species present and visual estimates of percentage cover. Species pools from flood plains and three other terrestrial ecosystems (low elevation forests, sub‐Alpine forests and alpine) were analysed with nested subset analysis, detrended correspondence analysis (DCA), and an index of beta diversity to identify dissimilarity in species composition and richness, and the separate contributions of generalists (species occurring in more than one ecosystem) and specialists to richness in each ecosystem. Analysis of variance and post hoc Tukey–Kramer tests were used to identify where in the Nyack catchment each species was most abundant. Species life form and dispersal strategies were analysed to better understand influences on beta diversity.Results Our data show that in this pristine system, floodplain ecosystems host 202 (63%) of the 320 vascular plants identified within Nyack catchment. Of these species, the nested subset analysis showed that 146 (72%) are found in at least one adjacent upland ecosystem. While the DCA ordination scatter plots show statistically significant separations of ecosystems on the first two axes, values of beta diversity showed that substantial similarity exists between floodplain and all upland species pools. Further, of the 146 floodplain species shared with upland ecosystems, 61% were more frequent in upland ecosystems, whereas 55% were more abundant in uplands than flood plains (Tukey–Kramer P ≤ 0.05). Significant numbers of specialists were found on flood plains (24% of floodplain species), but also within upland ecosystems, where 23% and 40% of low elevation forest and alpine species were found to be specialists, respectively. Whereas 83% of herb generalists were wind dispersed, &lt;70% of specialists were animal dispersed, indicating that similarity in species pools may be driven by wind dispersal.Main conclusions These results suggest a re‐evaluation of the contribution of floodplain ecosystems to regional plant species richness. While flood plains host specialists, other ecosystems had equal or higher levels of regional ‘endemism’. Furthermore, these data suggest that conservation of high levels of biodiversity on floodplain ecosystems may require consideration of upland ecosystems throughout the catchment as the majority of species were relatively rare on flood plains, indicating they may be sink habitats for some species.

The Mammals of Coastal Texas: A Comparison between Mainland and Barrier Island Faunas

Biodiversity patterns of non-volant mammals on oceanic and land-bridge islands have been well documented, but little information is available about the biodiversity of barrier islands. We compared the mammalian fauna of the barrier islands of Texas with the adjacent mainland by using historical trapping records and recent field work. The barrier islands of Texas have a depauperate mammalian fauna when compared to that of the Texas coast. A number of factors have influenced this, including hurricane events, mainland species pool for the island to draw upon, and the degree of isolation of the island from the mainland. Differences in species richness and composition among islands can be attributed to the biotic province to which an island is adjacent and island area. Differences in species richness among island complexes can be attributed to island complex length. Regression analysis demonstrates a significant correlation between species richness and island area, and a highly correlated relationship between richness and island complex length. Two similarity indices indicate that the mammalian fauna of islands within each complex is more similar than the fauna between complexes. Two nested subset analyses reveal the islands contain a nested distribution of mainland species. It appears that the dearth of mammals on the islands has not resulted from a lack of colonization events, but rather the inability of mammals to survive in the harsher island environments.

Breeding bird species diversity in the Negev: effects of scrub fragmentation by planted forests

Summary Afforestation of the Northern Negev, Israel, from 1956 resulted in patches of primarily coniferous trees that fragmented large scrubland areas. This alteration in landscape pattern was followed by immigration of mediterranean bird species to the Negev. We counted breeding birds, and measured various environmental variables in scrubland and planted forest patches, to test whether bird assemblages were random subsets of the regional species pool, and whether area or habitat structure was the major correlate with species abundance and distribution. Of 22 bird species recorded, only three appeared in both scrub and forest, showing that these two habitats were occupied by different species assemblages. In both habitats, species richness increased with area at a rate greater than that expected by random sampling. In the scrub this increase was related to area per se, while in the forest it was related to habitat diversity in terms of stand age and tree type. The density of forest species was unaffected by area, but specialist scrubland species declined as area decreased. We suggest that edge effects might reduce species abundance in small scrubland patches. Nested subset analysis indicated that, at the community level, species composition was not random. However, at the species level, the distribution of three forest‐dwelling species appeared as random, as it was associated with habitat rather than with patch size. Our results indicate that increased diversity of breeding birds in the Northern Negev will require scrub patches larger than 50 ha among the increasingly forested landscape. In contrast, increasing forest area would hardly increase species diversity in the whole landscape. Future forest management regimes should also aim to increase habitat diversity by adding foliage layers, especially in the understorey. Exotic coniferous forests support fewer species than deciduous forests in mediterranean zones around the world. The suggested management regime may improve such forests as habitat for species‐rich bird communities.

Uncommon vascular plant species in an East‐Central Swedish forest area‐a comparison between young and old stands

Abundance of uncommon vascular plant species (indicator species and red‐listed species) was recorded in 120 circular (12.6 m2) random plots in young (10–24 years after deal‐cutting) and old (&gt;80 years) forest stands, respectively, in the forest area of Vällen (2 600 ha), ca. 80 km north of Stockholm, Sweden. Factors describing stand density, field‐layer and soil moisture were recorded. A total of 16 species were observed and of these 14 were found in old and 9 in young stands. Seven species occurred exclusively in the old stands and two in the young stands. The total number of species records was significantly higher in young than in old stands, 80 and 71, respectively. Mean number of records per ha was ca. 530 for the young stands and ca. 470 for the old. Of the five species common enough to be tested, a difference was only found for Paris quadrifolia, which was significantly more frequent in young than old stands. Galium odoratum, Hepatica nobilis, Lathyrus vernus and Paris quadrifolia grew in significantly more sheltered sites, e.g. beneath other herbs and grasses or close to shrubs and trees in young compared to old stands. Nested subset analysis showed that the whole data‐set had a nested structure. Galium odoratum was significantly nested and thus indicated rich plant assemblages. In this calcareous area with nutrient‐rich forest soils, there evidently is a potential for at least some uncommon vascular plant species to survive the phases following clearcutting. The study indicates that green‐tree retention at final fellings and avoidance of heavy shrub removal during cleaning are beneficial to the flora.

Contrasting patterns of elevational zonation for birds and mammals in the Andes of southeastern Peru

Abstract. To determine the generality of avian diversity patterns, we investigated patterns of elevational zonation shown by birds and mammals along the eastern slope of the Andes Mountains in southeastern Peru. The strong environmental gradient sampled, entirely within Peru's Manu National Park and Biosphere Reserve, supports highly diverse faunas. Elevational distributions of 901 bird species, 129 bat species, and twenty‐eight species of native mice exhibit contrasting patterns in species richness, species composition, and species turnover. Birds and bats showed smooth declines of species richness with elevation, whereas the richness of mouse assemblages was unrelated to elevation. For all three groups, the greatest differences were between lowland and highland faunas, although cutoff points for this contrast varied among groups (≈ 500 m for birds, 750 m for bats, and 1000 m for mice). Differences in composition also separated bird and bat faunas on either side of c. 1400 m (the boundary between montance forest and cloud forest); for mice, this faunal transition may take place nearer to 2000 m. Bird and bat faunas lacked the more discrete zonations suggested for mouse assemblages, as indicated by elevational range profiles and nested subset analyses. Distinct highland assemblages are apparent in two‐dimensional histograms of range limits of birds and mice, but not for bats. Highland bat species occupy broader elevational ranges than lowland bat species, but for both birds and mice, species at intermediate elevations had the broadest amplitudes. Finally, clumping of range maxima and minima along the gradient identified zones of pronounced species turnover in each group, but these were generally not strongly associated with the locations of ecotones.Differences in zonation of these groups appear to reflect their different biological attributes and phylogenetic histories. Such differences obviously complicate discussions of ‘general’ diversity patterns, and limit the usefulness of birds to forecast or predict diversity patterns in other more poorly known groups—other groups may show elevated diversity and endemism in areas where avian diversity patterns appear unremarkable. The pronounced contrasts between bats and mice, and the generally intermediate character of avian patterns, suggest that future analyses might profitably partition birds into finer, more homogeneous groups of historically and/or ecologically similar species. Group differences in zonation may ultimately prove explicable with information on both species‐abundance patterns and resource distributions.