Abundance,biomass and diversity of ground-beetles (Col. Carabidae) as indicators of climatic change effects over elevation strata in Tenerife (Canary Islands)

Species relative importance distribution pattern changes of the ground-beetle assemblages were analyzed along elevation strata of Tenerife Island. The species importance estimates were expressed in terms of (i) activity density, as total catching of ground-beetle adults obtained with pitfall traps over each elevation stratum for one year, and (ii) biomass, as the total number of specimens caught multiplied by a mean dry weight in milligrams for the species. The K-dominance curves indicated moderate or insignificant perturbances, and patterns were sigmoidal following a truncated log-normal slightly skewed to the right, by using the Kolmogoroff–Smirnov test. The results also showed perceptible deviations from the truncated log-normal pattern (p < 0.05) mainly with biomass data. The disturbance through successional progress and perturbances by environmental warming and cooling could be assumed by deviations from the log-normal distribution among species. Thus, assuming that the assemblages of strata exhibited generally low similarity, the results will be arranged around the following four tracks: (1) the assemblage progressed toward highest abundances, dominance and a low-diversity equilibrium state in the cloud montane stratum, (2) the assemblage was subject to severe warming and dryness, lowest abundances with dominance in biomass, such that log-normal pattern was not shown in the basal stratum, (3) a non-equilibrium state in summer-xeric montane stratum maintained the highest diversity and an archetypical log-normal pattern was described for assemblage, and (4) assemblage stressed by cold semi-arid climate showed a certain tendency to log-normality and decrease in the diversity for the summit stratum. These results indicate that variation in ground-beetle assemblages by way of advanced evolutionary and adaptive trade-offs can best be understood as consequences of selective pressures by adverse climatic changes – perturbances – or seasonal climatic fluctuations and population dynamics – disturbances – according to the elevation stratum, which can generate different deviations from the log-normal pattern; these are more directly related to magnitude and frequency of local natural disturbance regimes and the productivity of the ecosystem.     

Diatoms from surface sediments of the northern part of Lake Tanganyika

227 Diatom taxa were observed in the surface sediments of the northern part of Lake Tanganyika, including 1 new to science: Amphora tanganyikae. The diatom community of these sediments is mainly composed of benthic organisms while planktonic diatoms are rather rare. Many brackish-water and a few marine organisms were observed. Cosmopolitan organisms (77.1%) dominate the diatom flora but tropical, tropical African and African taxa are also well represented (22.9%)Deceased.Deceased.     

Indicating assemblage vulnerability and resilience in the face of climate change by means of adult ground beetle length–weight allometry over elevation strata in Tenerife (Canary Islands)

Adaptive trade-offs in length–weight allometry might reduce vulnerability under climate change of adult ground beetle (Col., Carabidae) assemblages in their original elevation stratum on Tenerife. In particular this study shows that the predictive values for simple log-linear regression parameters were high in all strata and also the F-tests were statistically significant (p < 0.0001). Ground beetle assemblage on upper stratum had smaller coefficients and higher intercepts than did lower ones, indicating that the ground-beetle assemblages may be trading off higher powers for higher resilience via water and thermal efficiency in the face of environmental warming, in opposition to strategies adopted in cool and wet climates. Adults of ground beetle assemblages from warm and dry lower strata might have to be heftier, with encapsulation of bodies and heavily sclerotized exoskeleton, than those from cloudy, cool and wet strata; the latter group, freed from this constraint, would thus be characterized by more elongated, thinner and softer-bodied species. The outlined methodology could become a useful tool for the vulnerability and resilience assessment of natural assemblages, and could theoretically be applied to any latitudinal and altitudinal assemblage.     

Sedimentary pigments as an index of the trophic status of Lake Mead

Sedimentary pigment data were analysed from 6 cores from Lake Mead, the reservoir resulting from the impoundment of the Colorado River by Boulder (now Hoover) Dam in 1935. Surficial sedimentary pigments correlated well with contemporaneously measured primary productivity of the water column at the 6 coring stations. For the coring station nearest the sewerage inflow from the City of Las Vegas, the historical record of pigments closely paralleled the increase in human population, sewerage loading to the reservoir, and the associated phosphorus loadings. For three of the cores, pigments were closely correlated with total nitrogen from the same levels in the cores. Pigment concentrations in cores from different parts of the reservoir corroborate findings of other studies which indicate major differences in productivity of the upper and lower basins of Lake Mead (the lower basin having higher primary productivity). The pigment data from the cores provide some indications of the effect of the damming of the Colorado River above the Grand Canyon in 1963 to form Lake Powell, which significantly reduced phosphorus loading downstream to Lake Mead, and which may have adversely affected the largemouth bass fishery.     

基于13C、15N和C/N识别南岳小流域沉积有机质的来源

农业流域有机质流失造成水体富营养化和土地退化,不仅威胁水质和粮食安全,而且会导致温室气体排放等潜在环境问题.本研究用13C、15N和C/N作为指纹标志物,分析了南岳小流域出口沉积有机质的来源及其在林地、稻田和菜地等典型土地利用类型土壤的空间分布特征,并结合贝叶斯稳定同位素混合模型定量估算了各土地利用类型的贡献率.结果 ...     

湖南新化下石炭统遗迹化石及其沉积环境

鉴定了产自湖南新化地区早石炭世碳酸岩沉积中的遗迹化石6属(Zoophycus, Chondrites, Phycodes, Planolites, Palaeophycus, Skolithos)16种.并根据岩性实体与遗迹化石以及沉积构造等特征,划分为2个沉积亚相、21个微相、19个遗迹相.     

Assessing habitat utilization by neotropical primates: a new approach

This study aims to ascertain habitat utilization, in relation to forest structural variation, by a multi-species group of primates in tropical lowland rainforest in Southeast Peru during dry season. A new approach to assessing habitat utilization was used. Habitat variation was described by structural and indicator variables collected in quadrats along transects through a study area within Terra Firme and Floodplain forest. Variables were grouped into ‘factors’ accounting for most of the variation by means of a Principal Components Analysis (PCA). Presence or absence of the primates within the quadrats, assessed by repeat transect surveys, was taken to indicate habitat preferences. Discrimination between the habitat and forest structure in areas of primate presence as opposed to absence was carried out by means of Discriminant Function Analysis (DFA). This highlighted patterns in most utilized habitat. Vertical utilization of the forest was also assessed along with presence in bamboo and general activity on encounter. Suggestions of habitat preference and utilization are made for each of the six sympatric species studied, based on significantly discriminating habitat factors, vertical stratification on encounter and relationships with bamboo.Saguinus fuscicollis andCebus moloch appeared as habitat generalists.Cebus apella, Saimiri sciureus, andAotus spp., exhibited varying degrees of preference for habitat factors suggesting disturbed forest,Cebus albifrons was more generalistic but with a possible association with primary, naturally disturbed forest.C. appella was encountered in Terra Firme forest significantly more than in Floodplain. ForS. sciureus, C. moloch, andC. apella, upper understory was the most utilized forest layer, forC. albifrons, middle canopy and forS. sciureus andAotus spp., lower understory. Both positive and negative relationships with bamboo were highlighted. Significant positive relationships betweenAotus spp., and bamboo suggest dense bamboo stands provide important daytime resting sites for this nocturnal species.C. moloch was also shown to utilize bamboo whereasS. fuscicollis appeared to actively avoid it. High levels of conformity with past studies in terms of habitat utilization patterns described for the species studied supports the conclusion that the methods used in this study provide an effective means of assessing primate habitat utilization within complex habitat.     

Nutrient-limited biodegradation of PAH in various soil strata at a creosote contaminated site

The effects of nutrient addition on the in situ biodegradation of polycyclic aromatic hydrocarbons in creosote contaminated soil were studied in soil columns taken from various soil strata at a wood preserving plant in Norway. Three samples were used: one from the topsoil (0–0.5 m), one from an organic rich layer (2–2.5 m) and one from the sandy aquifer (4.5–5 m). The addition of inorganic nitrogen and phosphorous stimulated the degradation of polycyclic aromatic hydrocarbons (PAHs) in the top soil and the aquifer sand. These two soils, which differed strongly in contamination levels, responded similarly to nutrient addition with the corresponding degradation of 4-ring PAHs. The ratio between available nitrogen (N) and phosphorous (P) might explain the degree of degradation observed for the 4-ring PAHs. However, the degree of degradation of 3-ring PAHs did not significantly increase after nutrient addition. An increase in the respiration rate, after nutrient addition, could only be observed in the topsoil. In the aquifer sand, 4-ring PAH degradation was not accompanied by an increase in the respiration rate or the number of heterotrophic micro-organisms. PAH degradation in the organic layer did not respond to nutrient addition. This was probably due to the low availability of the contaminants for micro-organisms, as a result of sorption to the soil organic matter. Our data illustrate the need for a better understanding of the role of nutrients in the degradation of high molecular weight hydrocarbons for the successful application of bioremediation at PAH contaminated sites.     

The Role of Revegetation for Rehabilitation of Sodic Soils in Semiarid Subtropical Forest, India

A 40‐year‐old rehabilitated forest developed on a sodic wasteland at Banthra, Lucknow, north India, was studied for the performance of various species in different vegetation strata as well as their overall impact in soil amelioration. The plant communities of the three selected stands (S1, S2, and S3) of this forest were categorized into three vegetation strata: overstory trees, understory trees and shrubs, and a ground layer with scattered herbs and tree seedlings. The three stands contained 44, 19, and 8 species in each stratum, respectively, and three climber species. Importance value index (IVI) and basal area/cover did not show a clear dominance for particular species, and this is identified as a mixed forest with deciduous as well as evergreen species. Therefore, dominant species in each layer were categorized according to an IVI value of 10 and greater than 10% relative basal area. Within each stratum, species richness and plant population density decreased with an increase in plant size. Both species diversity and productivity were relatively high compared to the reference site because of protection from biotic disturbances, which cannot be controlled on the reference site. Creation of new forest on the barren land has contributed significant soil amelioration in the degraded sodic soil of the Indogangetic plains. The soil properties of the three stands did not vary much, although different tree species dominated the stands. Maximum soil amelioration was recorded for total N, followed by mineralized N, available N, and organic carbon contents for the nutritional properties. With regard to chemical properties, exchangeable sodium was greatly reduced in comparison to other properties viz pH, electrical conductivity, cation exchange capacity, and exchangeable Ca content. During 40 years of growth and development of the diverse vegetation in the revegetated forest, microbial C increased to about five times that of the surrounding barren sodic soils. There were no significant changes in soil structure even though the water‐holding capacity of the soil improved to about 53% of the once barren land due to a 7‐fold increase in organic carbon content.