The biogeographical peculiarity of a given geographical area is directly linked to the number of its endemic species. This paper aims to formulate an index directly linked to the biogeographical peculiarity of an area. A graphical model and an index of the biogeographical peculiarity are proposed, based on a cumulative sum (i.e., including all the amounts that were added previously). An example of the computations is proposed, based on the number of different types of geographical ranges (i.e., chorotypes) characterizing two different ecosystems; their biogeographical peculiarity of was evaluated on the basis of presence versus absence of carabid species. Both the graphical model and the index mirrored the different faunistic compositions of the ecosystems, because the index reached a higher value where more endemic species have been found. Our investigation has found a new method for evaluating the biogeographical peculiarity of a given area or biota in a simple way. The index could be used for either conservation biogeography (e.g., monitoring of biotic homogenization) or for theoretical studies integrating ecology and biogeography.
Here we document a novel phenomenon that, based on field observations in central Japan, cleistogamous flowers (or closed flowers) of an annual herb Lamium amplexicaule were dominantly expressed near an alien congener L. purpureum. The proportion of cleistogamous flowers in an individual L. amplexicaule increased with the frequency of L. purpureum occurring in the same patches but did not increase with the total density of Lamium plants and their own size. To confirm the consistency of the effect of the coexisting alien species, we assessed the cleistogamous frequency at the patch level for three other populations. In these populations as well, the proportion of L. amplexicaule producing cleistogamous flowers increased with the frequency of L. purpureum. Our transplant experiment at one site found no effect of the nearby presence of L. purpureum on the seed set of L. amplexicaule and therefore did not support the hypothesis that the adverse effect on the reproduction via interspecific pollination favored cleistogamous flowers that accepted no external pollen. Further studies must be conducted to examine the negative interactions between the related species before and after seed development.
Which factor determines animal aggressivity? Wynn-Edwards proposed the hypothesis that aggressive level increases with population density; Adams and Mesterton-Gibbons proposed the hypothesis that body weight is an indicator of animal aggressivity; however, Smith and Price hypothesized that aggression level varied with external conditions; that is, the population lived in the most unfavorable environment demonstrated the highest average aggression level, and the population that lived under the most favorable external conditions demonstrated the lowest average aggression level. In this paper, we tested these three hypotheses by manipulating enclosed root vole ( Microtus oeconomus ) populations under different food and predation treatments and observed their aggressive behavior. Aggressive behavior was measured by matching mice in a neutral arena. The experimental results supported Smith and Price’s hypothesis and Adams and Mesterton-Gibbons’s hypothesis; however, they did not support Wynn-Edwards’ hypothesis. Moreover, we found that reproductively active individuals were more aggressive. We concluded that the growth of population density did not cause or otherwise bring about increased aggressive behavior of root voles, but the external factors (predation and food supply) and physical factors (body weight and reproductive condition) were significantly correlated with aggression levels in a root vole population.
Experiments show that consumer diversity can have important effects on the control of prey diversity and abundance. However, theory also indicates that the strength of consumer effects on such properties will vary depending on system productivity and disturbance regime. Using a laboratory-based system composed of ciliate consumers and bacterial prey, I explored the interactive effects of productivity, disturbance, and consumer diversity on prey diversity and trophic-level abundance. Consumer diversity had productivity-dependent effects on bacterial prey that were consistent with theoretical expectations. At low productivity, increasing consumer diversity reduced prey abundance while at high productivity no effects were detected due to compensatory responses among bacteria. In contrast, consumer diversity had weak effects on prey diversity at low productivity but significantly depressed prey diversity at high productivity. Disturbance on consumers enhanced prey diversity but did not alter consumer diversity effects on prey. These results indicate that consumer diversity may play an important role in the regulation of prey communities, but the strength of this effect varies with system productivity.
Evaluating the structure of enemy biodiversity effects on prey in agroecosystems can provide insights into biological pest control functioning. With this aim, theoretical models that describe biological mechanisms underlying prey suppression can be developed and confronted with experimental data by means of model selection. Here, we confront multiplicative risk models to evaluate the structure of multiple predator effects on the whitefly Trialeurodes vaporariorum provided in tomatoes by two spiders ( Oxyopes lineatus and Pityohyphantes phrygianus ) and two mirids ( Nesidiocoris tenuis and Macrolophus melanotoma ). Biologically meaningful parameters retained in the best models showed that several predator traits differently affected pest control: species-specific per capita predation rates, prey use extent, different type of interactions between predators, and the response of predator species to prey density and environmental temperature. Even from a limited perspective of single-pest control and short term experiment, this study suggests that assembly of the four predator species results in predator complementarity across prey life stages and density, interactions of prey and predators with environmental conditions, and interactions between predators that do not result in whitefly control disruption. Such information about enemy biodiversity and whitefly control functioning can drive hypotheses about sustainable pest management options in local agroecosystems.
Ambrosia artemisiifolia L., native to North America, is a problematic invasive species, because of its highly allergenic pollen. The species is expected to expand its range due to climate change. By means of ecological niche modelling (ENM), we predict habitat suitability for A. artemisiifolia in Europe under current and future climatic conditions. Overall, we compared the performance and results of 16 algorithms commonly applied in ENM. As occurrence records of invasive species may be dominated by sampling bias, we also used data from the native range. To assess the quality of the modelling approaches we assembled a new map of current occurrences of A. artemisiifolia in Europe. Our results show that ENM yields a good estimation of the potential range of A. artemisiifolia in Europe only when using the North American data. A strong sampling bias in the European Global Biodiversity Information Facility (GBIF) data for A. artemisiifolia causes unrealistic results. Using the North American data reflects the realized European distribution very well. All models predict an enlargement and a northwards shift of potential range in Central and Northern Europe during the next decades. Climate warming will lead to an increase and northwards shift of A. artemisiifolia in Europe.
Succession following deforestation in Neotropical forests has been investigated extensively, yet rarely have studies connected nutrient dynamics with vegetation. This study was conducted in lowland wet forests of Maquenque, Costa Rica. The objectives were (1) to compare carbon (C), nitrogen (N), and phosphorus (P) characteristics and understory vegetation diversity between regenerating forests and primary forests; and (2) to use these variables to evaluate P. macroloba’s successional role. Four 300 m2 plots were established in primary and secondary forests where P. macroloba was the dominant N-fixing tree. Soil and vegetation data were collected from 2008 to 2010. Values of indicators of C, N, and P cycle activity were generally greater in primary than in secondary forest soils. Efficiency of organic C use and the relative contribution of respiration and organic C to soil biomass were also greater in the primary forest. These trends corresponded with greater richness, biomass, and cover of total and leguminous plant species, greater volume of P. macroloba in primary stands, and greater density of P. macroloba in secondary stands. As cleared regions of former primary forest regenerate, P. macroloba is the important dominant N-fixing tree and a critical driver of C, N, and P recuperation and ecosystem recovery.
Study Aim . To assess species diversity and tree regeneration patterns of different vegetation types of Western Ghats, India. Rarefaction was used to estimate species diversity of different vegetation types. One-way ANOVA was used to test for differences in tree density and basal area of different vegetation types. Sorenson index of similarity was used to calculate change in species composition between mature trees and regenerating individuals. Results showed that species diversity and regeneration pattern of trees differ in different vegetation types of the forest landscape. Species-area and species-individual accumulation curve (rarefaction) against equal-sized sampling area in different vegetation types showed that species heterogeneity was higher in vegetation types at mid elevations while their abundance was higher in vegetation types at higher elevations. All the vegetation types of the study area were heterogeneously distributed. Tree regeneration was higher in species rich vegetation type with no sign of human disturbances. Change in species composition across mature and regenerating phase was more frequent in disturbed forest as compared to undisturbed or less disturbed forests. New entry species occur in all the vegetation types.
Ripley’sKfunction is the classical tool to characterize the spatial structure of point patterns. It is widely used in vegetation studies. Testing its values against a null hypothesis usually relies on Monte-Carlo simulations since little is known about its distribution. We introduce a statistical test against complete spatial randomness (CSR). The test returns thePvalue to reject the null hypothesis of independence between point locations. It is more rigorous and faster than classical Monte-Carlo simulations. We show how to apply it to a tropical forest plot. The necessary R code is provided.
Distribution patterns of alien species in nonnative ranges might be driven by a combination of various mechanisms, including phylogenetic history, competition for resource, environmental filtering, and so on. Both phylogenetic and functional limitations might work synergistically to determine the distribution of alien species. In this report, by utilizing the information of provincial distribution, functional attributes, and phylogeny for 95 alien species of China, the corresponding phylogenetic and functional community structures are evaluated. The results show that introduction pathway, life form, and flowering time of alien plants of China processed significant phylogenetic clustering patterns, while both the origin of distribution and reproduction mode of alien species showed phylogenetic overdispersion patterns, as revealed by NRI/NTI indices. The phylogenetic signal tests using Pagel’s statistic and Blomberg et al.’s statistic further verified the previous patterns, even though there are some inconsistencies. Through partial Mantel test, it is found that compositional patterns of alien plant community were mainly affected by phylogenetic limitation but not functional limitation. Conclusively, phylogeny plays a more important role in structuring provincial distribution of alien plants in China.
The Peace Parkland, Alberta, Canada is part of a continentally important region for breeding and migrating aquatic birds. As a result of resource development and agricultural conversion, many wetlands have been lost. Road construction in the area results in the creation of borrow pits, <3 ha ponds created when soil is removed to form the road bed. We surveyed 200 borrow pits for aquatic birds in May through August 2007. We examined patterns of occurrence and richness, categorizing ponds based on surrounding landscape type: agriculture (0–33.3% forest within 500 m), mixed habitat (33.4–66.6% forest), and forested (66.7–100% forest). Principal Component Analysis indicated that pond environments differed based on local and landscape features. Twenty-seven species of aquatic birds used borrow pits, with 13 nesting. Nonmetric Multidimensional Scaling and Indicator Species Analysis of birds observed in each month revealed assemblages characteristic of agricultural ponds, including horned grebe, lesser scaup, American coot, and mallard, and of ponds with >33.3% forest, including bufflehead, ring-necked duck, green-winged teal, and American wigeon. Because borrow pits were used by a variety of dabbling and diving aquatic birds in repeatable assemblages across the breeding season, we propose that these wetlands be integrated into avian conservation strategies.
Phylogenetic analyses of 18S rDNA sequences from environmental clones and culture strains revealed a widespread distribution of two subaerial green algal lineages, Jenufa and Xylochloris, recently described from rainforests in southeast Asia. A new lineage of Jenufa (Chlorophyceae), most closely related to or even conspecific with J. minuta, was formed by sequences of European origin. Two more lineages of Jenufa were formed by three additional sequences from Ecuador and Panama. The other lineage was a close relative of Xylochloris irregularis (Trebouxiophyceae), probably representing a new species of the genus and distinct from the only so far described species, X. irregularis. It comprised two distinct clades each containing almost identical sequences from Germany and Ecuador. Analyses of the new sequences for both genera allowed to presume a preference of J. minuta to subaerial growth on rock or artificial hard substrates combined with a remarkable adaptation to extended periods of darkness, whereas Xylochloris may preferably occur on tree bark or in the soil.
The relationship between vegetation functional characteristics of production, stability and descriptive characteristic of species diversity or dominance, and other possible compositional invariants were investigated in 2400 micro-plot sward of 20 species at randomly assigned positions and using different matrix sizes of adjacent plots and four harvest to derive a combination of “vegetations” of differing species configurations.Within the highest frequency section of the data there was little relationship between productivity and stability (deviance) and either species diversity or dominance (% contribution of 1st ranked species). However, considering all data, productivity increased with increasing dominance and was unrelated to species diversity, while stability increased with diversity. Of single parameters combining diversity and dominance, the gradient of the log abundance/rank relationship was superior to Shannon H, with both showing productivity increasing with dominance rather than diversity. The fate of individual micro-plots from a mixed species stand through successive harvests was consistent with the −3/2 thinning rule, though with species cumulative yields. The abundance/rank relationship was compared with many models. Where there was simultaneous fitting to both density and biomass relationships, self-thinning random particle packing models were best and offered an explanation of the process. The positive correlation between regional and local frequency was related to sample area in a random placement model. Observed species composition and mortality was simulated by consideration of plant size related growth and mortality, initial establishment, growth potential and variation in plant size.
The patterns of uptake and distribution of Co, Ni, Cu, Zn, Cd, and Pb in the soil-mycelium-sporocarps compartments in various transfer steps are presented. I attempted to find out whether there is a difference between the uptake of metals from soil to fungi (mycelium/soil ratio) and transport within fungal thalli (sporocarps/mycelium ratio). The concentration of Cu, Zn, and Cd increased in the order bulk soil < soil-root interface (or rhizosphere) < fungal mycelium < fungal sporocarps. The concentration of Co, Ni, and Pb decreased in the order bulk soil (or rhizosphere) < fungal mycelium < soil-root interface < fungal sporocarps. The uptake of Cu, Zn, and Cd during the entire transfer process in natural conditions between soil and sporocarps occurred against a concentration gradient. Mycorrhizal fungi (mycelium and sporocarps) only absorbed Co, Ni, and Pb but did not accumulate these elements in their thalli. Metal accumulation within fungal mycelium biomass in the top forest soil layer (0–5 cm) may account for about 5% of the total amount of Co, 4% Ni, 7% Cu, 8% Zn, 24% Cd, and 3% Pb.
According to the ideal free distribution hypothesis, the density of organisms is expected to remain constant across a range of habitat availability, provided that organisms are ideal, selecting habitat patches that maximize resource access, and free, implying no constraints associated with patch choice. The influence of the amount of habitat on moose (Alces alces) pellet group density as an index of moose occurrence was assessed within the Foothills Natural Region, Alberta, Canada, using a binary patch-matrix approach. Fecal pellet density was compared across 45 sites representing a gradient in habitat amount. Pellet density in moose habitat increased in a linear or quadratic relationship with mean moose habitat patch size. Moose pellet density decreased faster thanwhatwould be expected from a decrease in habitat amount alone. This change in pellet group density with habitat amount may be because one or both of the assumptions of the ideal free distribution hypothesis were violated.
Cold storing bareroot southern pine (Pinus spp.) seedlings for greater than one week after lifting in the fall can lead to poor outplanting survival when compared to seedlings that are lifted and stored in winter. In contrast, container-grown seedlings typically do not experience adverse effects from storing for periods greater than one week. The practice of lifting bareroot seedlings can cause wounds to root systems, which could allow soil-borne pathogens such as Pythium species to be used as infection sites. Once seedlings are placed in storage, the cool, moist environment may be conducive for zoospore activity, leading to root disease and outplanting failure. Bareroot and container-grown longleaf pine (Pinus palustris), loblolly pine (Pinus taeda), and slash pine (Pinus elliottii) and container-grown shortleaf pine (Pinus echinata) were inoculated with either Pythium dimorphum or Pythium irregulare, cold-stored for 3, 4, 6, or 12 weeks, and outplanted. Both Pythium species reduced survival of bareroot longleaf pine but not bareroot slash pine. Length of storage decreased survival for both seedling stock types. Pythium species did not affect the survival of container-grown seedlings. These results suggest that P. dimorphum and P. irregulare are more virulent to bareroot longleaf pine than the other pine species tested.
We examined models for population growth curves, contrasting integrated versions with various other forms. A sizable number of data sets for birds and mammals were considered, but the main comparisons were based on 27 data sets that could be fit to the generalized logistic curve. Akaike's information criterion was used to rank fits of those data sets to 5 integrated models. We found that the integrated models gave the best fits to the data examined. The difference equations examined gave much poorer fits as judged by AICc and coefficients of variation. We conclude that the integrated models should be used when possible.
In order to reduce the amounts of pesticides used, and thereby their associated risks, new generations of less environmentally dangerous molecules with lower weight are currently being used in the mixtures sprayed on crops. Few studies have been made, however, to analyse their impact on the soil, and more particularly on the microorganisms living in the soil which maintain the essential functions of this ecosystem. By taking a microcosmic approach, we were able to assess the impact of the maize herbicides “cocktail” Mesotrione and S-metolachlor on global soil microbial activity, biomass, and structures, by using the formulated compounds, respectively, Callisto and Dual Gold (both registered brands of Syngenta). Our results highlighted a synergetic effect in “cocktail” microcosms resulting in an increase in the Mesotrione herbicide dissipation time and in an impact on the microbial community at onefold field rate equally to more than a single herbicide used at tenfold field rate.
The responses of the soil microbial community features associated to the legume tree Acacia senegal (L.) Willd. including both arbuscular mycorrhizal fungal (AMF) diversity and soil bacterial functions, were investigated under contrasting environmental conditions. Soil samples were collected during dry and rainy seasons in two contrasting rainfall sites of Senegal (Dahra and Goudiry, in arid and semiarid zone, resp.). Soils were taken from the rhizosphere of A. senegal both in plantation and natural stands in comparison to bulk soil. A multiple analysis revealed positive correlations between soil physicochemical properties, mycorrhizal potential and enzyme activities variables. The positive effects of A. senegal trees on soil mycorrhizal potential and enzyme activities indicates that in sahelian regions, AMF spore density and diversity as well as soil microbial functions can be influenced by land-use systems (plantation versus natural population of A. senegal) and environmental conditions such as moisture and soil nutrient contents. Our study underlines the importance of prior natural AMF screening for better combinations of A. senegal seedlings with AMF species to achieve optimum plant growth improvement, and for restoration and reforestation of degraded lands.
Coastal wetlands of eastern Georgian Bay provide critical habitat for a variety of wildlife, especially spawning and nursery habitat for Great Lakes fishes. Although the eastern shoreline has been designated a World Biosphere Reserve by UNESCO, a complete inventory is lacking. Prior effort by the Great Lakes Coastal Wetland Consortium (GLCWC) was unable to fully identify coastal wetland habitat in eastern Georgian Bay due to limited data coverage. Here we outline the methodology, analyses, and applications of the McMaster Coastal Wetland Inventory (MCWI) created from a comprehensive collection of satellite imagery from 2002–2008. Wetlands were manually delineated in a GIS as two broad habitat types: coastal marsh and upstream wetland. Coastal marsh was further subdivided into low marsh (LM; permanently inundated) and high marsh (HM; seasonally inundated) habitat. Within the coastal zone of eastern and northern Georgian Bay there are 12629 distinct wetland units comprised of 5376 ha of LM, 3298 ha of HM and 8676 ha of upstream habitat. The MCWI identifies greater total wetland area within the coastal zone than does the GLCWC inventory (17350 ha versus 3659 ha resp.). The MCWI provides the most current and comprehensive inventory of coastal wetlands in eastern Georgian Bay.
