Mean Number Of Species Research Articles

Parasites, diet and stable isotopes of shorthorn sculpin (Myoxocephalus scorpius) from Frobisher bay, Canada

Shorthorn sculpin (Myoxocephalus scorpius) from Frobisher Bay, Baffin island, is a slow growing long-lived species. A wide range of diet items were present in the stomachs of the shorthorn sculpins sampled but 2-3 diet items (amphipod species) comprised 99.5% of total food consumed. These amphipods were present in the stomachs in similar proportions among all age classes of shorthorn sculpin. Several new host records for parasites were reported and mean numbers of parasite species increased with shorthorn sculpin age. The increased diversity of parasite species and higher delta15N values in older/larger individuals suggest that their diets were more diverse and the prey items consumed had higher delta15N values. By contrast, the value of delta13C in dominant diet items masked the delta13C values of minor diet items. We conclude that parasites and stable isotope values provide complementary data on feeding patterns of the shorthorn sculpin. The ubiquitous marine acanthocephalan, Echinorhynchus gadi, was found at high prevalences (87-100%) and mean intensities (28-35), and were localized in the midgut. In contrast to other studies on acanthocephalans, E. gadi did not influence fish condition as measured by condition factor, liver somatic and gonado-somatic indices.

Secondary succession in a Swiss mire after a bog burst

Severe natural disturbances can lead to the recovery of the original vegetation or the shift to new vegetation types. While post-disturbance succession is well documented for regularly disturbed ecosystems, little is known about the pathways and rapidity of vegetation dynamics after rare events such as peat mass movements in bogs. We monitored the floristic changes in a mire subject to a bog burst in 1987 for two decades through the repeated sampling of permanent plots. The mean species number per plot increased continuously, while the evenness increased only in the first decade and then slightly decreased. Declining species were mostly mire species, while colonist species were mostly wet meadow species. Species turnover was higher in the first decade after the disturbance, and was also higher in the area of peat erosion than in the area of peat accumulation. Changes in plant species composition indicate a succession towards tall-forb vegetation (Filipendulion), acidic fen vegetation (Caricion fuscae) and swamp willow forest (Salicion). We conclude that the effects of the disturbance are still ongoing, and that the mire’s potential for recovery is therefore difficult to predict.

Vertebrate diets derived from trophically transmitted fish parasites in the Bothnian Bay

Parasites that are transmitted through predator-prey interactions may be used as indicators of trophic relationships between organisms. Yet, they are rarely used as such in the construction of topological (predator-prey) food webs. We constructed food webs of vertebrate trophic interactions using observed diet alone, trophically transmitted parasites alone, and the combination of the two based on data from 31 species of fish from the Bothnian Bay, Finland. The fish food web contained 530 links derived from observed diet, 724 links inferred from parasitism, and 1,058 links calculated from a combination of both stomach contents and parasites. This sub-web constructed from stomach contents had a mean of 17.1 links per fish species, while that using parasites had 23.4 links per fish. Combining the two diet indicators yielded 34.1 links per fish species, illustrating the complementarity of the two methods. Mean number of prey species per fish species was 12.5 using observed diet items, 15.8 using parasites, and 24.5 using both measures together. Mean number of predators per fish species was 7.4 using observed diet, 11.7 using parasites and 15.0 using both. A positive correlation was found between the mean number of parasites and the number of prey taxa in the diet among the fishes. Omnivorous fish had the highest diversity of both parasite species and prey items, while benthophagous fish had among the lowest. Mean total abundance and mean total prevalence of parasites correlated positively with fish size, with piscivores being the largest with the highest abundance and prevalence, while planktivores and benthivores had the lowest. Trophically transmitted parasites may be used to help construct vertebrate sub-webs and derive information about food web processes. Parasites alone provided equivalent if not more information than observed diet. However, resolution is improved by using parasites and observed diet together.

Status and Trends of Birds in an Extensive Western Massachusetts Forest

Abstract We report forest bird population trends from 1987–2005 at a 280.7-ha site in Chester, MA. Our study site consisted primarily of mid-successional (70–90 yr old) forest in a landscape of similar, non-fragmented forest. Using point counts at 100 stations, we detected 94 species in early June over all years. Mean numbers of species and detections/yr were 57 and 1104, respectively. Species richness and total detections were stable (P ≤ 0.05). We analyzed trends for the 36 most frequently detected species. Four species exhibited significant increasing trends and 10 significant declining trends; 22 species were stable or exhibited no significant trend (P ≤ 0.05). Whether a species was a resident, short-distance, migrant, or Neotropical migrant did not appear to be a determinative factor for trends. Trends were more readily explained by (I) areal and structural expansion of mature forest conditions and (II) forestry treatments that affected 70 ha (25%) of the study site. We report few changes in species ...

The Efficacy of 5% Povidone-Iodine for 3 Minutes Prior to Cataract Surgery

To evaluate the efficacy of 3 minutes of 5% povidone-iodine for skin and conjunctival antisepsis prior to cataract surgery as recommended by the European Society of Cataract and Refractive Surgeons. A prospective controlled study of 54 patients undergoing unilateral cataract surgery by phacoemulsification was undertaken. The eye undergoing surgery was prepared with 5% povidone-iodine for 3 minutes. The other eye served as control. Swabs were taken from both eyes prior to application of 5% povidone-iodine and 3 minutes after. Proportion of culture-positive swabs, mean number of species, and growth of isolates on culture were compared at different times and between the two groups. Coagulase-negative Staphylococcus (CoNS) was the main species isolated from culture-positive swabs. Use of 5% povidone-iodine for 3 minutes resulted in a statistically significant reduction in proportion of culture-positive swabs (87% vs 30%, p<0.001), mean number of species (0.96-/+0.47 vs 0.30-/+0.46, p<0.001), and growth of CoNS (heavy: 30% vs 0%, moderate: 23% vs 6%, light: 47% vs 94%, p=0.004). No such changes were observed in the control group. Use of 5% povidone-iodine for 3 minutes prior to cataract surgery achieves a significant reduction in organisms such as CoNS from lid and conjunctival flora.

Diversity of aquatic malacofauna within a floodplain of a large lowland river (lower Bug River, Eastern Poland)

This study analyses the composition and species richness of aquatic molluscan communities within a large sector (over 100 km) of the valley of the Bug, a large lowland river in eastern Poland. An attempt was also made to determine the number of samples sufficient to compile a representative mollusc list within the whole study area and in groups of water bodies representing different degree of permanence, as well as to test the completeness of sampling of the malacofauna. Within the study area, 54 mollusc species were found – 36 snails and 18 bivalves. Up to 27 species were recorded from individual sites with a mean of 8+ 5 species per site. Mean number of species was significantly higher in permanent water bodies than in the two other site groups. Dominance patterns in molluscan communities and frequencies of individual species showed distinct differences within three groups of habitats differing in permanence. Species composition was related to permanence, size, depth, hydrological connectivity and successional stage of water bodies, as well as to the type of bottom sediments and macrophyte abundance. The aquatic malacofauna found within the study area was rich, comprising almost 90% of potential composition based on regional species lists. Rarefaction curves for the total malacofauna confirmed the low probability of finding additional species, whereas temporary and permanent water bodies showed incomplete species lists. About 20 samples should be sufficient to collect representative data in the study area and more than 60 samples would be necessary to collect a nearly complete dataset.

금강 유역의 수변 식생 현황과 분포

Riparian vegetation gives basic habitats for animal and other biological organisms. It is one of essential landscapes in river ecosystem. This floral study was conducted to give basic information for management of the Geum river ecosystem. We discovered total 69 plant communities out of 40 sites studied and mean 8 plant communities were analysed per study site. Salix koreensis and Salix subfragilis community were dominant of all communities at tree layer and Salix gracilistyla and Rubus parvifolius were dominant communities at shrub layer. Phalaris arundinacea, Phragmites japonica, Miscanthus sacchariflorus and Artemisia princeps var. orientalis appeared most as perennial grasses and Humulus japonicus, Persicaria thunbergii and Persicaria hydropiper appeared most as annual grasses. Robinia pseudoacacia, Amorpha fruticosa and Bidens frondosa were frequently present as exotic species. Grass communities were higher than tree communities because of human disturbance by artificial banks. The number of species was 182 appeared as 53 families 144 species, 34 varieties and 4 forma and mean species number was 25.5 per site. The most abundant site was Yanggang bridge site (14 vegetation association, 49 species) and the least abundant site was Namdaechon, Muju site (3 vegetation association, 12 species). We suggest that continuous riparian vegetation monitoring should be carried out to manage water environment ecologically.

The response of ash-alder swamp forest to increasing stream water level caused by damming by the European beaver (Castor fiber L.)

The response of an ash-alder swamp forest to water damming was studied in the Łutownia stream running in Bialowieza Forest. The Łutownia stream with artificial dam existing from 2001 for small water retention purposes was the test object. The first observation of vegetation was done in 2004, when small retention construction started to influence surrounding forest, but beavers had not built their dam yet. After one year of experiments (2005) the beaver dam was constructed close to man-made dam and its influence was most significant for further studies. So, the first observation refers to the status of ash-alder swamp forest before beaver damming. Water table level was measured from the beginning of 2004. The main goal of presented studies was to determine changes of terrestrial vegetation and its habitat after increasing of the water level in the stream. One square metre plots in a frame 5 x 5m were localized in a transect close to the stream upstream and downstream artificial dam. Within 104 such plots ground vegetation (growing up to 0.5 m above ground) was described using Braun-Blanquet scale of abundance. The vegetation studies were conducted twice in 2004 and repeated in 2007. The list of species and their abundance were determined twice: in spring and in summer. Changes of species richness and coverage by species characteristic for floodplain and swamp forest site were evaluated. Ecological indices of soil moisture and fertility determined as the means weighed by percent cover by plant species were calculated for two periods of observation. Calculated indicator values showed that water retention increased the number of swamp forest species by 8 times, but the area of swamp habitat increased 16 times compared with 2004. The mean number of species per sample plot was the same before and after water damming by beavers. The plant association (ash-alder riparian forest) changed its floristic composition to swampier variant. Obtained results showed real impact of beavers’ activity on ground vegetation and its habitat in ashalder swamp forest. Observed increased number of swamp species close to the beaver dam is positive from ecological point of view. Presented results indicate also, that species richness is strongly controlled by beaver damming. The population dynamics of beavers could also potentially affect species richness by altering the age distribution of beaver dams and abandoned ponds across the river valley landscape. Generally, this point of view could have adverse social effects because beavers’ activity brings losses to forestry and agriculture. Therefore, we should try to find a balance between economy and wildlife management. Monitoring of the beaver sites should be continued to evaluate ecological consequences and to find best solution of these problems. DOI: 10.2478/v10025-010-0032-7 Unauthenticated Download Date | 6/13/16 9:14 AM 250 J. CZEREPKO et al.

Changes over three decades in the floristic composition of nutrient-poor grasslands in the Swiss Alps

To investigate recent changes in the floristic composition and nature conservation value of nutrient-poor, semi-natural grasslands of the Swiss Alps, we resurveyed 151 phytosociological releves in four regions, originally recorded between 1975 and 1985. In the original surveys, the mean number of plant species per plot (25–100 m2) ranged from 47.1 to 58.1 according to region. The flora included a total of 18 species that are protected in Switzerland and a high proportion of habitat specialists of nutrient-poor grasslands (NPG-species). In the second survey, conducted between 2002 and 2004, both mean species number per plot (−3.2 to +11.4) and species evenness (−0.05 to +0.07) were higher in most regions. However, the data revealed clear shifts in community composition, with a higher proportion of nutrient-demanding species (mean nutrient indicator value increased by +0.07 to +0.24 units) and a lower proportion per plot of NPG-species (−3.6 to −11.6%). These changes were greatest in pastures, and in meadows converted to sheep pastures, while the NPG-species were maintained in unfertilized meadows that were managed as ecological compensation areas. To prevent continuing decline in the conservation value of these grasslands, it is important to support low-intensity management, especially mowing, and to prevent further eutrophication.

TROPICAL COASTAL HABITATS AS SURROGATES OF FISH COMMUNITY STRUCTURE, GRAZING, AND FISHERIES VALUE

Habitat maps are frequently invoked as surrogates of biodiversity to aid the design of networks of marine reserves. Maps are used to maximize habitat heterogeneity in reserves because this is likely to maximize the number of species protected. However, the technique's efficacy is limited by intra-habitat variability in the species present and their abundances. Although communities are expected to vary among patches of the same habitat, this variability is poorly documented and rarely incorporated into reserve planning. To examine intra-habitat variability in coral-reef fishes, we generated a data set from eight tropical coastal habitats and six islands in the Bahamian archipelago using underwater visual censuses. Firstly, we provide further support for habitat heterogeneity as a surrogate of biodiversity as each predefined habitat type supported a distinct assemblage of fishes. Intra-habitat variability in fish community structure at scales of hundreds of kilometers (among islands) was significant in at least 75% of the habitats studied, depending on whether presence/absence, density, or biomass data were used. Intra-habitat variability was positively correlated with the mean number of species in that habitat when density and biomass data were used. Such relationships provide a proxy for the assessment of intra-habitat variability when detailed quantitative data are scarce. Intra-habitat variability was examined in more detail for one habitat (forereefs visually dominated by Montastraea corals). Variability in community structure among islands was driven by small, demersal families (e.g., territorial pomacentrid and labrid fishes). Finally, we examined the ecological and economic significance of intra-habitat variability in fish assemblages on Montastraea reefs by identifying how this variability affects the composition and abundances of fishes in different functional groups, the key ecosystem process of parrotfish grazing, and the ecosystem service of value of commercially important finfish. There were significant differences in a range of functional groups and grazing, but not fisheries value. Variability at the scale of tens of kilometers (among reefs around an island) was less than that among islands. Caribbean marine reserves should be replicated at scales of hundreds of kilometers, particularly for species-rich habitats, to capture important intra-habitat variability in community structure, function, and an ecosystem process.

Traditional Home Gardens Of Petén, Guatemala: Resource Management, Food Security, And Conservation

Abstract Conservation and development agencies in Peten, Guatemala have been promoting home gardens among migrant families in order to improve the welfare of these families and to conserve natural resources. The agencies have not been successful. However, native Peteneros do have a productive gardening system that is compatible with resource conservation. This essay describes the structure, management, and economic and social benefits of 23 traditional Peten home gardens, which have over 180 useful plant species. Traditional gardens in Peten are highly diverse, rich, and productive (mean number of species per garden is 54; mean number of plants is 392). In addition, the gardens can contribute up to 15 percent of household income, improve family nutrition, and strengthen social networks. However, for reasons described in this essay, traditional home gardening is declining in Peten.

부산광역시 온천변 식물상의 군집구조에 관한 연구

군집구조란 군집에서 종 수와 이들 종 간 개체들의 분포 양상을 말한다. 본 연구는 다른 지점에서 생태학적 생물종다양성의 통계학적 방법으로 종이 임의로 분포하는지 평가하였다. 이를 위해 부산광역시 도심을 관류하는 온천천의 상, 중, 하류의 다섯 개의 지점을 선정하여 각 지점당 양쪽에 위치한 10개 정점에서 종수를 파악하였다. 95분류군(85종, 9변종, 1품종)이 온천천변에 분포하였다. 다섯 지점에 대해 종수는 유의하게 차이를 나타내었다(F=7.75, P<0.01). Shannon-Wiener의 정보지수는 정점간 유의한 차이를 나타내었으며(F=4.12, p<0.05), 지점 St.1이 다른 지점(St. 2는 2.206, St. 3는2.116, St. 4는 2.069, St. 5는 0.637)에 비해 가장 높았다(2.380). 풍부도 지수에서 R1값은 온천천의 상류에서 하류로 갈수록 낮았다. 공존하는 근연속내 식물종의 풍부도를 근연관계가 먼 그룹과 낮은 그룹 간 분석하는 새로운 군집구조 분석법을 시도하였다. 근연속과 그렇지 않은 속의 쌍 분포도에서 정점 간 유의한 차이를 역시 나타내었다. 축적값은 x=0.85일 때 가장 유의한 차이를 나타내었다. Community structure refers to the number of species in a community and the pattern of distribution of individuals among those species. The purpose of this paper was to describe a statistical analysis for detecting a ecological biodiversity which is valid even though the assumption at the different sampling points is not violated spatial randomness of species. Counts and cover were determined from 10 (<TEX>$20\;m{\times}20\;m$</TEX>) plots in five sites of the Oncheon River which is located in Busan, Korea. Total 95 taxa (85 species, 9 varieties, and one form) were identified and measured in edge sides of this river. These were a total of present in the five sites. Overall across the fragments, mean number of species per plot differed significantly among the five sites (F=7.75, p<0.01). Shannon-Wiener functions differed significantly among plots (F=4.12, p<0.05), with the St. 1 having significantly higher value (2.380) than the others (2.206 for St. 2, 2.116 for St. 3, 2.069 for St. 4, and 0.637 for St. 5). The richness indices, R1 decreased from the upper stream of the Oncheon River to the lower stream. We used a novel way of representing community structure to show that abundance within closely related pairs of co-occurring species in the Oncheon River. The differences between the distributions for of congeners and pairs of non-congeners showed at the largest difference of the cumulative fractions of the data sets (x=0.85).

Time-consistent rearrangement of carabid beetle assemblages by an urbanisation gradient in Hungary

To examine the impact of urbanisation on arthropod biodiversity, carabid (Coleoptera: Carabidae) assemblages were studied over 2 years along a rural–urban gradient representing increasing levels of human disturbance. Carabids were collected by pitfall trapping during their whole activity period in lowland oak forest patches in and near the city of Debrecen, Eastern Hungary, over two seasons (2001–2002). Carabid activity density was significantly higher in the rural than in the two other areas, but there was no significant difference in species richness (measured as mean number of species caught/trap). The proportion of forest specialists significantly decreased from the rural towards the urban area, and the proportion of forest specialist species was significantly higher in the rural and suburban areas than in the urban one. In contrast, the relative activity density of generalist species significantly increased along the rural–urban gradient. Both the relative number of open-habitat species and their activity density were significantly higher in the urban forest fragments than in the suburban and rural ones. The patterns found were consistent between the 2 years. Multidimensional scaling indicated pronounced changes in species composition along the gradient; the assemblages in urban forest fragments were more variable than in the other areas. A large proportion of the variation in overall activity density, species richness and the proportion of carabids with different habitat affinities could be explained by structural habitat variables (percentage cover by canopy, leaf litter, herbs and decaying wood), and prey availability.

Partial cutting as a conservation alternative for oak ( Quercus spp.) forest—Response of bryophytes and lichens on dead wood

Semi-open oak-rich forests may support many species adapted to large trees and coarse woody debris. Currently many oak-rich forests in northern Europe have more or less closed canopies due to lack of natural and cultural disturbances. In these forests, conservation oriented partial harvesting of biofuel may restore a desired forest structure and light regime that potentially may favour many species that have declined during the last century. We quantified effects of such cutting on lichens and bryophytes living on dead wood in southern Sweden, using a design with paired cutting and control plots (each 1 ha) in 15 forests. In each plot we surveyed the same five logs and three stumps before and after harvest (25% of the tree basal area removed). The epixylic species composition shifted towards a flora typical for dryer dead wood. The mean species number of lichens per stump increased (clear effect) and the mean number of bryophytes per stump decreased (nearly significantly) due to harvesting. The species composition, but not species richness, on logs was affected. No increases or decreases in species of conservation concern could be detected. Since the overall negative effects were weak, we suggest that partial harvesting of dense oak forests is compatible with maintenance of the diversity of lichens and bryophytes on dead wood. However, the amount of such forest harvested needs to be carefully assessed in relation to demands of other taxa.

Building for the future: Abandoned beaver ponds promote bird diversity

We examined beaver (Castor canadensis) pond dynamics and associated riparian bird communities, based on call- response surveys. Following water disappearance, abandoned beaver ponds were invaded by grassy areas and alder shrubs and supported higher bird species numbers than nearby riparian areas. We detected a total of 49 species. At abandoned beaver ponds, the mean number of species was 6.4, whereas it ranged between 2.4 and 3.1 species for active beaver ponds, rivers, and lakes. Density of deciduous shrubs and graminoid cover, higher in abandoned beaver ponds, was positively associated to the number of species of birds. However, riparian avian diversity was lower near clearcuts and large water areas. Beaver population control or geographic confinement may suppress both spatial and temporal dynamics of beaver pond creation and abandonment, and could impact riparian vegetation and birds.

Insect biogeography in the south‐western Sea of Korea with comments on the insect fauna of Kwanmae Island

AbstractThe insect species richness of each island in the south‐western Sea of Korea was considered on the background of the equilibrium theory. The species number of insects on Kwanmae Island in the present study (140 species) was much higher compared with a previous survey. Based on a literature survey of island biota surveys published in the 1980s, of 47 islands, the lowest species number (12 species) was on Kwanmae Island, and the most diverse insect fauna (254 species) was on Baekryong Island. The mean species number of surveyed islands was approximately 54 (53.96 with a standard deviation of 46.95). The median species number was 38 with a skew of +2.56. Insects, including the orders Odonanta, Orthoptera, Hemiptera, Lepidoptera, Coleoptera, Hymenoptera and Diptera, occurred on 32 of the 47 surveyed islands, and had an occurrence rate of more than 0.68. This indicates that these insects are distributed widely on the islands in the south‐western Sea of Korea. The species number showed a significant linear relationship with both area of an island and its distance from the mainland (P &lt; 0.05), with an extremely low determinant coefficient (r2 = 0.13 for area vs species number and r2 = 0.28 for distance vs species number). Other factors tested in the study failed to show a significant relationship with species number. A multiple‐regression model established using area and distance as independent variables showed significant relationship with species number, with a relatively higher determinant coefficient (r2 = 0.70, P &lt; 0.05). We present possible explanations to explain the difference between estimated and observed species number in Kwanmae Island.

Macrophytes of the Ipel’ River: effect of flood to species composition and distribution

Effects of spring and summer floods on macrophyte vegetation were studied along the Ipel' River - a typical submontane river with regular winter/spring floods and with occasional summer floods. If we compare macrophyte vegetation in July 2000 (three months after spring flood) and July 2006 (one month after flood) then (i) total and mean number of species decreased, (ii) length of river sections without any macrophytes increased, (iii) mean mass total (MMT) of typical hydrophytes (e.g. Potamogeton crispus and Ranunculus aquatile), some helophytes (e.g. Alisma lanceolatum, Leersia oryzoides, Persicaria hydropiper) as well as Algae fil. decreased, (iv) MMT of bryophytes (Chiloscyphus pallescens, Fontinalis antipyretica, Rhynchostegium riparioides) remained similar in both years, (v) MMT of Phalaroides arundinaceae and Lemna minor increased. Decline in the mentioned species was probably due to disturbance of fine sediment. These species grew mostly in this sediment type; after summer flood it was replaced by coarser sediment and poorly rooted plants were removed. Bryophytes were not damaged by summer flood because they grew mainly on harder substrates in fast-flowing water. Generally, Lemna minor was frequent in running waters during the year and migration was typical for this pleustophyte species. In case of Phalaroides arundinacea, our results differ from those published by other authors, where this species is considered to be sensitive to floods.

Conservation value of forest plantations for bird communities in western Kenya

Tree plantations of native and exotic species are frequently used to compensate for forest loss in the tropics. However, these plantations may support lower species diversity and different communities than natural forest. We therefore investigated bird communities in stands of natural forest, different types of tree plantations and secondary forest in Kakamega Forest, western Kenya. We compared birds differing in habitat specialisation, i.e. forest specialists, generalists, and visitors. We recorded significant differences in mean species richness and number of individuals among the different forest types. Stands of natural forest and plantations of indigenous tree species comprised more species and individuals than plantations of exotic tree species and secondary forest. This was caused by a significant decline of forest specialists and generalists from natural forest and indigenous plantations to exotic plantations and secondary forest. Species composition of the bird communities did not differ between natural forest stands and plantations of a mixture of indigenous tree species, but clearly changed between natural forest and plantations of single tree species. These findings demonstrate that natural forest areas are needed for the conservation of forest bird diversity, but that plantations with a mixture of indigenous tree species can have similarly high conservation value.

Lichen diversity on stumps in relation to wood decay in subalpine forests of Northern Italy

Although several studies demonstrated the importance of dead wood for lichen conservation in N-Europe and N-America, the lichen biota on dead wood was poorly studied in the Alps, where stumps represent one of the main available dead wood type. This work aims at evaluating species richness and composition of lichens in relation to the decay of stumps in subalpine forests of the Italian Alps. Differences in species richness between three decay stages were tested using a one-way ANOVA, while the pattern of species composition was evaluated with non-metric multidimensional scaling and an Indicator Species Analysis. Overall, 69 species were found and wood decay proved to be an important factor influencing lichen communities on stumps in our subalpine forests. Despite the fact that the mean number of species per stump did not differ between the three decay stages and lichen communities broadly overlapped, a main pattern of species turnover was identified across wood decay process as well as some indicator species for each decay stage. During the decay process, lichen communities change functional and ecological composition as an adaptive response to the continuous change of substrate. Since stumps host several nationally rare species, which are related to different stages of decay, they could have a relevant role in lichen conservation in managed forests where other types of dead wood are normally absent.

High tropical net diversification drives the New World latitudinal gradient in palm (Arecaceae) species richness

AbstractAim Species richness exhibits striking geographical variation, but the processes that drive this variation are unresolved. We investigated the relative importance of two hypothesized evolutionary causes for the variation in palm species richness across the New World: time for diversification and evolutionary (net diversification) rate. Palms have a long history in the region, with the major clades diversifying during the Tertiary (65–2 Ma).Location Tropical and subtropical America (34° N–34° S; 33–120° W).Methods Using range maps, palm species richness was estimated in a 1° × 1° grid. Mean lineage net diversification was estimated by the mean phylogenetic root distance (MRD), the average number of nodes separating a species from the base of the palm phylogeny for the species in each grid cell. If evolutionary rate limits richness, then richness should increase with MRD. If time limits richness, then old, relict species (with low root distance) should predominantly occur in long‐inhabited and therefore species‐rich areas. Hence, richness should decrease with MRD. To determine the influence of net diversification across different time frames, MRD was computed for subtribe, genus and species levels within the phylogeny, and supplemented with the purely tip‐level measure, mean number of species per genus (MS/G). Correlations and regressions, in combination with eigenvector‐based spatial filtering, were used to assess the relationship between species richness, the net diversification measures, and potential environmental and geographical drivers.Results Species richness increased with all net diversification measures. The regression models showed that richness and the net diversification measures increased with decreasing (absolute) latitude and, less strongly, with increasing energy/temperature and water availability. These patterns therefore reflect net diversification at both deep and shallow levels in the phylogeny. Richness also increased with range in elevation, but this was only reflected in the MS/G pattern and therefore reflects recent diversification.Main conclusions The geographical patterns in palm species richness appear to be predominantly the result of elevated net diversification rates towards the equator and in warm, wet climates, sustained throughout most of the Tertiary. Late‐Tertiary orogeny has caused localized increases in net diversification rates that have also made a mark on the richness pattern.