Pre-climax epiphyte communities of bryophytes and lichens in Mediterranean forests from the Central Plateau (Spain)

The pre-climax epiphytic communities of forests from the Spanish Mediterranean region (Central Plateau) were studied by numerical and traditional floristic methods. One hundred phytosociological relevés were analyzed through a classical numerical approach based on hard partitions improved by PCoA — Principal Coordinates Analysis — ordinations. Two groups easily related to two different suballiances included in Frullanion dilatatae Lecointe 1975, Ulotenion crispae (Barkman 1958) Lecointe 1975 and Fabronienion pusillae Barkman 1958 were detected. Two new syntaxa within the ass. Ortotrichetum lyellii (Allorge 1922) Lecointe 1975 are proposed. Phytogeography, syntaxonomy and ecology of these communities are discussed.     

Benthic bacterial diversity from freshwater tufas of the Iberian Range (Spain)

Aiming to characterize the bacterial diversity of modern tufa systems of the Iberian Range (Spain), we surveyed the 16S rRNA gene sequence diversity from 24 sites within three rivers (A?amaza, Mesa and Piedra). These tufas record substantial calcareous growth under different physicochemical conditions and are part of an important, regional landscape-building system. The bacterial community structure and composition, richness and diversity were quantified from denaturing gradient gel electrophoresis fingerprints. Retrieved DNA sequences could be assigned to 10 bacterial phyla and included a variety of phototrophic and heterotrophic groups. Cyanobacteria, mainly filamentous taxa, constituted 43% of all the retrieved sequences, followed by Firmicutes (11%), Gammaproteobacteria (10%), Alphaproteobacteria (7%), Acidobacteria (6%), Bacteroidetes (5%), Betaproteobacteria (4%), Planctomycetes (4%), Actinobacteria (3%) and Deltaproteobacteria (2%). Diatom and Xanthophyceae chloroplast sequences were also detected. Physicochemical variables measured at each site were modelled with multivariate statistics. Principal component analyses yielded the highest variance for salinity-related variables (conductivity; Na(+) , Cl(-) and SO4(2-) concentrations), which correlated negatively and significantly with diversity indices. However, the highest variance explained by individual principal components was relatively low (< 34%). Overall, we show that these young fluvial tufas are inhabited by a large variety of bacteria in diverse and widespread communities.     

The halophilous vegetation of the Po Delta (northern Italy)

The halophilous vegetation in the Po Delta region (north Adriatic) has been studied with the Braun-Blanquet method. Vegetation types have been defined by numerical classification of vegetation data. Their ecology has been studied by indirect gradient analysis. The following three main groups of phytocoena have been recognized. (1) Perennial halophytic vegetation (class Puccinellio-Salicornietea) including 7 associations: Spartinetum maritimae, Puccinellietum palustris, Salicornietum radicantis, Salicornietum fruticosae, Agropyro-Inuletum crithmoidis, Halimionetum portulacoidis, are quoted according to an approximate gradient of decreasing soil moisture. The Juncetum maritimi is conditioned by soil erosion. (2) Therophytic vegetation settled on soils subject to natural or artificial disturbance (class Thero-Salicornietea), including 3 associations: Suaedo-Kochietum hirsutae, Salicornietum herbaceae s.1. and the Aster tripolium-Suaeda maritima community. (3) Halotolerant vegetation (class Artemisietea vulgaris), including only the Atripliceto-Elytrigietum pungentis settled on soils with a low salt content.Nomenclature of species follows Pignatti (1982).The research was supported by a grant of the Istituto per i Beni Artistici, Culturali e Naturali, Regione Emilia-Romagna (Italy) and by a grant of the Italian C.N.R. (Research Group for Naturalistic Biology).     

Effect of long-term cutting versus abandonment on the vegetation of a mountain hay meadow (Polygono-Trisetion) in Central Europe

The aim of this study was to identify changes in the plant species richness, diversity and composition of a mountain hay meadow (alliance Polygono bistortae-Trisetion flavescentis) after abandonment in comparison with a control cut once per year. The experiment was carried out from 1999 to 2008 in a mountain hay meadow in the Bukovec nature reserve in the north-eastern part of the Jizera Mountains (Jizerské hory, Góry Izerskie, Isergebirge), Czech Republic.The number of vascular plants species with cover greater than or equal to 1% remained almost the same throughout the study period; however, the total number of vascular plants was higher in the cut treatment after the first four years of the study. The cover of Festuca rubra, Agrostis capillaris, Anthoxanthum odoratum, Briza media and Trifolium repens was positively affected by cutting. On the other hand, the cover of Cirsium heterophyllum, Geranium sylvaticum, Hypericum maculatum, Trisetum flavescens and Luzula luzuloides was higher on the abandoned treatment plots.The main effect of the abandonment on plant species composition was the shift in cover of the dominant species. Despite ten years of contrasting management, changes in the vegetation were relatively small with no shift to a different plant community. Therefore the cutting regime combined with several years of no management may be a suitable management strategy for the maintenance of Polygono-Trisetion grasslands and will not be detrimental to the preservation of the target vegetation.     

Dataset of Passerine bird communities in a Mediterranean high mountain (Sierra Nevada,Spain)

In this data paper, a dataset of passerine bird communities is described in Sierra Nevada, a Mediterranean high mountain located in southern Spain. The dataset includes occurrence data from bird surveys conducted in four representative ecosystem types of Sierra Nevada from 2008 to 2015. For each visit, bird species numbers as well as distance to the transect line were recorded. A total of 27847 occurrence records were compiled with accompanying measurements on distance to the transect and animal counts. All records are of species in the order Passeriformes. Records of 16 different families and 44 genera were collected. Some of the taxa in the dataset are included in the European Red List. This dataset belongs to the Sierra Nevada Global-Change Observatory (OBSNEV), a long-term research project designed to compile socio-ecological information on the major ecosystem types in order to identify the impacts of global change in this area.     

Grassland dynamics under sheep grazing in an Australian Mediterranean type climate

Grassland dynamics in a degraded disclimax grassland dominated by Danthonia caespitosa Gaudich. are examined using both demographic and multivariate approaches in an experiment designed to determine the effect of grazing intensity and exclosure on pasture dynamics. The experiment ran for 20 years from 1949 to 1968, using permanent quadrats at 3 grazing intensities and within exclosures. Demographic studies of some perennial grass species demonstrated markedly different responses to grazing; Danthonia caespitosa was unaffected by grazing but responsive to seasonal rainfall differences. Enteropogon acicularis survived only on protected sites. Numerical classification of total species set (121 species) for six observation periods demonstrated that community types were sensitive to differences in winter rainfall, and time since the start of experiment. Principal component analysis of permanent quadrat observations for individual years demonstrates quadrat trajectories which confirm this and indicate progressive divergence of the successional trends of the grazed and ungrazed quadrats. Repeated analysis on grazed quadrats only, shows that three components of pasture dynamics can be recognized; these are trend (succession?) and seasonal differences, each of which account for about 20% of the variance, and differences due to soil heterogeneity in the experimental paddock (8% of variance accounted for). No effect of grazing intensity was detected. Multivariate techniques can provide a clear partitioning of types of dynamic behaviour present in grassland communities. It is concluded that partitioning of environmental heterogeneity prior to demographic studies would increase their sensitivity.

     

A numerical phytosociological study of the summits of the majella massive (Italy)

Summary A phytosociological study of Majella's summits by the use of multivariate methods has allowed to discover the following new associations:Gnaphalio-Plantaginetum atratae on humocarbonatic soils in snowy depressions,Leontopodio-Elynetum on rendzina in wind exposed and stony places,Saxifrago-Papaveretum julici andCrepidi-Leontodontetum montani on protorendzina with gravel.Gnaphalio-Plantaginetum atratae andLeontopodio-Elynetum might be classified inElyno-Seslerietea, although the former presents character species ofSalicetea herbaceae; Saxifrago-Papaveretum julici andCrepidi-Leontodontetum montani are classified inThlaspidion stylosi (foeder. nova) ofThlaspidietea.Comparisons between some clustering methods and between ordination methods based on the mathematics of principal component analysis are discussed. The efficiency of sum of squares agglomeration when the plant communities vary in a continuum and the importance of a linearizing transformation in principal component analysis are stressed.The research was supported by a grant from the Italian CNR to Prof. D. Lausi. We wish to thank also Prof. L. Orlóci, Dr. E. van der Maarel and Prof. S. Pignatti for reading and discussing the text, and Mr. A. Zampar, S. Sedmak and T. Ubaldini for technical assistance.     

Middle and Upper Jurassic bivalve associations from the Iberian Range (Spain)

The four sections richest in bivalves from the Middle and Upper Jurassic of the Iberian Range (Spain) were selected for a quantitative palaeoecological analysis of the bivalve fraction of the macrobenthos. Five bivalve associations and two assemblages were recognized with the help of a Q-mode hierarchical cluster analysis (Ward method). The main environmental factors controlling bivalve associations are thought to be substrate, water energy and distribution of organic matter. The bivalves exhibit a distinct spatial and temporal distribution pattern within the Aragonian Branch of the Iberian Range. Four of the bivalve associations occur in the Upper Oxfordian (Sot de Chera Fm) and one association in the Lower Callovian (Chelva Fm). In the Sot de Chera and Loriguilla formations, the abundance of bivalves decreases from NW to SE i.e., from relatively close to the shore line towards the distal-most part of the carbonate platform. In the Chelva Fm, bivalves are abundant in the Ariño region, interpreted as a palaeogeographic high. The spatial distribution of bivalves might have been largely controlled by the availability of nutrients.     

Phytogeography of parasteppic vegetation in the high Friulian Plain (NE Italy)

The vascular flora of pedologically conditioned, extensive dry grasslands occurring in a very rainy area of northeastern Italy, was submitted to phytogeographic analysis. The distributional ranges of 144 species were digitized into two presence-absence matrices of species and Operational Geographic Units (quadrants), one covering Europe, the other, limited to 56 species with extra-European distributions, extended to the Northern Hemisphere north of the Tropic of Cancer. These matrices were submitted to numerical classification, obtaining clusters of species with similar distributional patterns (chorotypes). For each cluster of species, the percent occurrencies in each quadrant were processed by a program of automatic mapping, producing a series of isoporic maps showing the joint distribution of the species of each cluster. The species can be subdivided into six main phytogeographical groups: (1) Narrow-ranging (34% of the total), including the endemic, subendemic, Illyrian-Balcanic and NW submediterranean elements, (2) Southern European-Submediterranean (18.8%), (3) Wide-ranging European (16.6%), (4) Eastern-Pontic (7.6%), (5) Southern Eurasiatic (10.5%), (6) Northern Eurasiatic (12.5%). The phytogeographic originality of the investigated grasslands is high, with more than one third of the species having narrow distributional ranges. Particularly relevant are the connections with the Balkanic-Illyrian and the eastern Alpine regions.Nomenclature: Pignatti (1982).     

Composition and ecology of the Quercus coccifera L. communities along the eastern Adriatic coast (NE Mediterranean)

The aim of this study is to classify and describe all plant communities with Quercus coccifera covering the entire eastern Adriatic coast and islands from north Croatia to south Albania, and to relate their species composition, chorotypes and life forms to environmental factors using Pignatti ecological indicator values. From total 70 phytosociological relevés, we identified and described four floristically and ecologically distinctive vegetation communities (two new proposed subassociations, one association and stand each) using TWINSPAN and the Braun-Blanquet classification scheme. In Croatia and Montenegro, Q. coccifera is forming macchia within the Fraxino orni–Quercetum cocciferae pistacietosum lentisci. Quercus coccifera occurs only sparsely in south Croatia as a shrubland within Fraxino orni–Quercetum cocciferae nerietosum oleandri subassociation or macchia within the Erico arboreae–Arbutetum unedonis association. Despite the difference in biogeographic position and bioclimates, low shrubby Albanian Q. coccifera stands are more closely related to the Q. coccifera communities from the western Mediterranean. Eastern Adriatic communities appear exclusively within the Querceta ilicis vegetation zone and spread within the meso-Mediterranean belt. They nevertheless are an important part of the region's natural heritage and management plans must ensure that all forms of land are used in a sustainable way.     

Structural and floristic diversity of shrublands and woodlands in Northern Israel and other Mediterranean areas

Summary Between 1974 and 1978 structure and diversity of shrublands and woodlands of northern Israel were studied along climatic and human-disturbance gradients using 0.1 ha vegetation samples. Diversity increased along the moisture gradient, with highest woody and herb species richness in open Pistacia shrubland on the xeric border of the Mediterranean region, and highest equitability and lowest dominance concentration in sub-humid, moderately grazed, open oak woodlands. Semi-open disturbed shrublands were rich in herbs and had much higher structural, plant species, and animal species diversities than the closed, mature, climax maquis. Diversity showed a two-slope response to grazing with highest species numbers in heavily (but not the most severely) grazed woodlands and shrublands. These communities have some of the highest plant alpha diversities in the world; the richness of their floras (especially in annual plants) is the product of relatively rapid evolution under stress by drought, fire, grazing, and cutting.Comparative data on diversity and growth-form composition are compiled for mediterranean communities: Israeli' shrublands and woodlands, California chaparral and woodlands, Chilean matorral, South African fynbos, and Australian heath and mallee. Communities of three of these areas are of more recent (primarily Pleistocene) development and share some similarities; these threc form a sequence (California, Chile, and Old World Mediter-ranean) of increasing length of human disturbance and consequent species diversity. The southwest Australian heath or kwongan and the South African fynbos are, in contrast, derived from ancient Gondwanan heath like communities and are adapted to very old, nutrient-poor soils. The Gondwanan communities are quite different in growth-form structure and soil and nutrient relationships from communities of the three more recent mediterranean areas; the Gondwanan communities are almost lacking in annual species and are exceedingly rich in woody species. The richest temperate plant communities known — grazed Mediterranean pastures vs. fynbos and Australian heath — are in almost polar contrast in their growth-form structures and the bases of their species diversities.This study, sponsored by the U.S.-Israel Binational Science Foundation (No. 450), was carried out by Z. Naveh as principal investigator with R.H. Whittaker as American collaborator. We thank Mr. A. Mann, S. Burmil, Mrs. Chaim, and Mrs. A. Kleen for botanical field work and statistical computations, Mr. D. Feigin and S. Ben Ezrah for technical assistance, Mr. S. Asherow for identification of young plants, and the Nature Reserve Authorities, the Neve Yaar Experimental Station, the Agricultural School Kfar Hanoar Hadati, and Kibbutzim Allonim and Allone Abba for allowing us to use their land for this study. The work by R.H. Whittaker was supported by the U.S. National Science Foundation, Australian National University, and Canberra Botanic Gardens; and we thank all the collaborators in this work.Nomenclature follows Zohary et al. (1948).     

Population analysis of white grubs (Coleoptera: Melolonthidae) throughout the Brazilian Pampa biome

The replacement of natural grassland by cultivated areas might favor the increase in abundance of some root-feeding species such as the white grubs, which may become a constraint for field crop production. This research aimed to assay the population density and geographical distribution of white grubs pest and other species in natural grassland and cultivated areas throughout the Brazilian Pampa biome. White grubs were sampled in 18 locations in both landscape use types and identified. Population density (number of larvae m^?2) was calculated for each recorded species and sorted within two groups (pest species and other species), compared between natural grasslands and cultivated areas, as well as among locations. A dendrogram to evaluate species similarity among locations was built based on combined data obtained from both landscape use types throughout the region. In total, 31 species were found in the Brazilian Pampa, and four of them are considered as crop pests: Diloboderus abderus (Sturm, 1826), Euetheola humilis (Burmeister, 1847), Lyogenys fusca (Blanchard, 1830), and Phyllophaga triticophaga Morón & Salvadori, 1998. The average population density of pest species in cultivated areas was less than five larvae m^?2, at most of locations. Some species had a wide geographical distribution (e.g. D. abderus and Cyclocephala modesta Burmeister), while other melolontids occurred at only one location. The knowledge of which white grub species are present in a field and its population densities assist farmers to take proper management decisions.     

Fire,canopy cover and seedling dynamics in Mediterranean shrubland of northeastern Spain

Abstract. Seedling establishment and survival of the main woody species of early-successional shrubland in northeastern Spain were studied from 1992 to 1995 with emphasis on the importance of vegetation cover (existence of open areas and the situation beneath the plant canopy) and microhabitat (occurrence of stones, litter and bare soil). In the absence of fire, vegetation cover (measured at a scale of 30cm × 30 cm) was not correlated with seedling emergence of most species, nor with growth and survival of seedlings up to one year old. Seedlings older than one year showed a similar pattern: their density was not significantly different in both kinds of habitats. The emergence of seedlings was mainly associated with the presence of mature plants – which can provide seeds – and with the absence of unsuitable microhabitats (large stones, deep litter and bare soil). In April 1994 a wildfire burned the study area. This enabled a study of the pattern of post-fire establishment. After the wildfire, seedling emergence of several species increased and most species produced seedlings with higher survival and growth rates than in the period before the fire. Pre-fire cover, however, did not show significant effects on post-fire seedling dynamics in most cases.     

On the dynamics of vegetation: Succession in model communities

Summary Successional change is thought to be at least partially driven by forees originating from within the community, namely by reaction and competition. Both processes operate through changes in the environment, but from the literature on the subject it is not clear how they differ.To clarify these issues successiens of model communities are studied. This leads us to conclude that competition represent an instantaneous interaction, whereas reaction has historical aspects since it relies on cumulative changes in the environment. The three models considered-one relying on reaction to cause vegetational change, one relying on competition and differential growth rates, and a hybrid third one-yield very similar predictions: roughly bell-shaped curves displaced along the time axis. This shows that the mere fit of a certain model to successional data may easily be spurious (recently some workers have empirically fitted models identical to one derived here from first principles). The three models do behave radically different under perturbation, however: any model relying completely or partially on historical interactions cannot account for the well known possibility of artificially arresting succession. Even if the importance of historical interactions in succession (i.e. the Markovian character of succession) cannot easily be ascertained, one can nevertheless ask whether historical interactions are at all necessary for the explanation of successional change. It is argued here that succession can be entirely understood in terms of instantaneous interactions, notably competition. The argument rests upon the well known relationship between colonizing and competitive ability, and on the fact, proven here, that stress, defined as expressing itself in severe random fluctuations in the growth parameters, is negatively correlated with competition intensity.The author gratefully acknowledges the critical support be received from Professor László Orlóci. This paper forms part of a wider research program supported by a NCR grant to Proc. Orlóci.