Showing papers on "Species richness published in 1970"

Annual Cycles of Species Occurrence, Abundance, and Diversity in Georgia Estuarine Fish Populations

Abstract: A total of 31,637 individuals, comprising 70 fish species and 37 families, were trawled in a Georgia estuary. Population structure was influenced by seasonal changes in taxa, numbers of species and individuals, and average size of fishes. Species-numbers diversity was studied in regard to seasonal variation and three zones. Four indices were compared. Seasonal variation was found with "equitability" and "evenness" but not with the ShannonWiener index or species "richness." A seasonal change in relative abundance resulted primarily from the influx of juveniles in the late summer and autumn. An apparent increase in diversity from sounds to small creeks based on three indices was not statistically significant. INTRODUCTION Trawl samples of fish collected throughout one annual cycle from three zones in a Georgia salt marsh estuary are analyzed in terms of seasonal cycles and four contrasting diversity indices. Establishing the normal cycle of diversity in this undisturbed estuarine system is part of an inventory designed to establish bases for the future detection, evaluation, and control of pollution that might result from new industries. Species-numbers diversity is generally a more sensitive and reliable index of environmental health than are individual "indicator" organisms. For example, Wilhm (1967) found that diversity of benthic stream invertebrates decreased with the degree of pollution. However. diversity may also be affected by normal downstream trends related to stream order (size) (Harrel and Dorris, 1968). It is important, therefore, that the pattern of diversity in time and space be determined, if possible, prior to the advent of stress. The behavior of diversity indices needs to be understood, since the various ratios proposed measure different components of diversity. As the indices are variously affected by sample size and seasonal phenomena, it is also necessary to analyze population dynamics, seasonal changes in taxa, numbers of species and individuals, and growth. METHODS Fishes were sampled at approximately three-week intervals from January 1967 to February 1968 at 14 stations in the -estuarine system of Sapelo and St. Catherines sounds. The Marine Inistitute's R/V Kit Jones sampled with a 20 ft (6 m) wide otter trawl having 1 ,4 in (32 mm) mesh in the bag. Each station was trawled for 15 minutes. 1 Contribution No. 182 of the Marine Institute, University of Georgia, Sapelo Island 31327. 382 This content downloaded from 157.55.39.83 on Sun, 09 Oct 2016 05:13:42 UTC All use subject to http://about.jstor.org/terms 1970 DAHLBERG AND ODUM: ANNUAL CYCLES IN FISH 383 A representative fish collection is maintained at the Marine Institute. To compare habitats the study area was arbitrarily divided into three ecological areas according to the size of tidal waters: (1) sounds -stations 1, 2, 3, 7, and 8; (2) larger creeks-stations 4, 5, 6, 9, and 14; and (3) smaller upper creeks-stations 10, 11, 12, and 13 (Fig. 1). The sounds are the widest and deepest of the aquatic habitats compared and have, primarily, sandy bottoms. The lumps of clay occasionally trawled are exposed by erosion of the bottom. The "upper creeks" are relatively narrow and shallow with sand bottom, and drain the extensive Spartina salt marshes characteristic of Georgia estuaries. A considerable amount of organic detritus, settles here, and sticks and logs are commonly found on the bottom. The "large creeks" are generally intermediate in location and physical characteristics. Four diversity indices were calculated. The Shannon-Wiener function is: H =-X Pi logPi (1) i=n where Pi is the proportion of individuals in the i-th species. This -J H 9 SAPELO ~~SOUNUND 0 I < X 1~~~~~~~~~~~~~2 #< jW Fig. 1.-Collecting stations in estuarine system of Sapelo and St. Catherines sounds. This content downloaded from 157.55.39.83 on Sun, 09 Oct 2016 05:13:42 UTC All use subject to http://about.jstor.org/terms 384 THE AMERICAN MIDLAND NATURALIST 83(2) formula has been used widely as a species diversity index, as suggested by Margalef (1957). The Shannon-Wiener function increases as both the number of species and the equitability of species abundance increase. It is desirable to consider indices that treat these aspects separately since the two components of diversity may react differently to certain types of stresses. For the "species richness" component of diversity we selected the following: D = (S-1)/log N (2) where S is the number of species and N is the number of individuals. Tbhis index was also used by Margalef (1969) in diversity studies. Relative species abundance was measured by two indices. Lloyd and Ghelardi's (1964) equitability index is:

A first inventory of gypsum flora in the Palearctic and Australia

Abstract: Gypseous substrates are well-recognised as supporting distinctive and unique flora assemblages, including numerous gypsum endemic (gypsophile) species. Along with these, others are also frequent although their presence is not restricted to gypsum; they show a clear preference for them (gypsocline). While this phenomenon (gypsophily) has been studied regionally, and various hypotheses put forward to explain it, there has been little global synthesis. We present a preliminary check-list on the gypsophile and gypsocline flora of the Palaearctic and Australian areas as a part of a project to develop a global checklist of the World’s gypsophytes, which can broaden our ecological and biogeographical understanding of these unique environments. The database contains 935 taxa spanning 54 countries. The Irano-Turanian region —and to a lesser extent the Mediterranean region— emerged as the richest territories in terms of gypsophile species; this richness was much reduced in the Saharo-Arabian and, especially in the Eurosiberian regions. The factors that can modulate the richness of gypsophytes in a region are discussed and have been distributed into four groups: a) geological and edaphic factors; b) factors linked to the insular nature of outcrops; c) climatic variables and their interaction with the soil; d) biogeographical factors. The importance of those factors linked to insularity and, especially, to water availability is emphasized. Because the soil structure of many gypsum outcrops reduces water ability to plants, such outcrops can be regarded as “dry-islands” surrounded by less xeric substrates. The fact that gypsophytes can be grouped within a few major flowering plant clades across continents, confirms their pre-adaptations to these harsh and unique environments. Our work provides a preliminary database for exploring ecological and biogeographic issues relating to gypsophily, and we hope it will stimulate global interest in these valuable ecosystems.

Diversity of butterflies in four different forest types in Mount Slamet, Central Java, Indonesia.

Abstract: Widhiono I. 2015. Diversity of butterflies in four different forest types in Mount Slamet, Central Java, Indonesia.Biodiversitas 16: 196-204. The study was carried out in four different habitat types (secondary forest, plantation forest, agroforest, andtourist area) on the southern slope of Mount Slamet, Baturaden Forest, Central Java, Indonesia from July 2009 to August 2010. A totalof 99 species belonging to eight families showed a dominance of Nymphalidae (30 species) followed by Pieridae (17 species),Lycaenidae (15 species), Papilionidae (13 species), Satyridae (11 species), Danaidae (6 species), Amathusidae (4 species), andRiodinidae (3 species). From the 99 butterflies species found on the southern slope of Mount Slamet, 32 species (30%) were specific tothe forest, whereas 63 species (60.6%) were common to all habitats sampled, and the last 10 species (9.4%) were endemics species withone protected species (Troides helena). The present results was showed that butterflies diversity, abundance, and endemism is stillrelatively high, representing 18% of all butterfly species found in Java and supporting 71.4% endemic species found in Central Java.The plantation forest were contributed the highest diversity and abundance of butterfly species, whereas the agroforest showed thelowest diversity, abundance, and endemism. Among all habitats surveyed, the secondary forest represented the most suitable habitat forbiodiversity conservation and maintenance of rare and endemic species.

La familia Cactaceae en Argentina: patrones de diversidad y prioridades políticas para su conservación

Abstract: The Cactaceae family in Argentina: diversity patterns and political priorities for their conservation. In this paper we used species richness and endemism of Argentine cacti to select those provinces with highest priority for the conservation of this plant family in the country. The role of cactus diversity as a surrogate for dicot diversity was further analyzed. Species richness (number of species) and endemism (number of endemic species) were determined for each of the 24 provinces of Argentina. Fifteen provinces were selected as priority based on the number of species and 14 provinces were selected based on the number of endemic species. Salta province presents the highest species richness and endemism. Endemic species are a good surrogate for cactus diversity. Similarly, cactus diversity is a good surrogate for dicot diversity

Overall Diversity of Fruit-Feeding Butterflies (Lepidoptera: Nymphalidae) Along Vertical Gradient in a Peat Swamp Forest, Kota Samarahan, Sarawak

Abstract: A study which aims to investigate the vertical distribution pattern of nymphalids had been conducted in a peat swamp forest of Kota Samarahan, Sarawak. This 60-day sampling period which utilised baited traps as the main sampling method, had resulted to 104 individuals from both ground and canopy levels. The lower stratum revealed a higher diversity index (H’= 1.17466) in comparison with the canopy stratum. Nymhalinae represents the most diverse subfamily at both levels, dominating almost half of the total individuals respectively. In general, species richness and abundance decrease with the increasing strata height, and was observed in all subfamilies. Analyses on the relationship between forewing length and strata revealed significant result for both male and female of Satyrinae, while for body design, it was only significant for male Nymphalinae and female Satyrinae. Overall, the study on strata preference of the nymphalids had led to a better understanding on their dependence on microclimatic conditions, as well as the status of their habitat.

Diversidad diferencial de esporas de Glomeromycota en la rizosfera de bromeliáceas nativas del Parque Nacional Sierra de las Quijadas (San Luis, Argentina)

Abstract: Differential diversity of Glomeromycota in relation to host species in the rhizosphere of native bromeliads from Sierra de las Quijadas National Park (San Luis, Argentina). Arbuscular mycorrhizal fungi (AMF) are associated with most of the plants, forming arbuscular mycorrhizas. Bromeliaceae is an American family living from the tropics to temperate and arid zones. Sierra de las Quijadas has species of terrestrial Bromeliaceae colonized by AMF with different degree of association. The aim of this work was to study the AMF spore diversity (richness and density) in the rhizospheric soil of three native species of Bromeliaceae from Sierra de las Quijadas. Richness and density of spores differed significantly between the Bromeliaceae species studied, with the lowest values in Bromelia urbaniana. Meanwhile, Deuterocohnia longipetala and Dyckia floribunda showed the highest values and only differed between them in richness of spores. This AMF differential diversity between the three bromeliads species may be related to the host species and also due to different levels of root colonization that were previously reported. Moreover, the low richness and density of AMF in the rhizosphere of B. urbaniana may be either due to anallelopathic effect of this plant or due to its particular root morphology.

Are Wildland Fires Threatening The MediterraneanFlora And Vegetation

Abstract: Fire is an ancient and universal ecological force which has shaped most of plant communities and landscapes of the Mediterranean basin. Associated with climate and topography, fire has contributed to create, but not always predominantly, the types of vegetation growing around the Mediterranean Sea. In any study dealing with plant dynamics after fire, qualitative and quantitative aspects should be considered. Immediately after fire (first months to first year) floristic richness is lower than in unbumed sites; then during the second to fifth years it becomes higher. This is due to a progressive recovery of communities and also an invasion of many annuals attempting to occupy the burned open sites. But towards the fifth year after fire the floristic richness reaches a composition similar to the prefire one. In the same way, as communities get older, their structure becomes more and more complex, with numerous strata depending on the original complexity. Present ecological systems of the Mediterranean area are the result of an ancient historical influence during which species have used mechanisms to overcome fire effects but also to resist to other disturbances. To-day, fire is really not a factor of change of Mediterranean ecosystems. Present species have developed several survival traits the best adapted to survive the disturbances. Management strategies that ignore the fundamental instability of ecological systems are totally unsound and ultimately lead to surprises. Depending on fire regime and frequency the Mediterranean vegetation has reach an equilibrium. In any elaboration of management plan of natural areas, fire must be considered as an integral part of fire-fighting planification.