Importance Of Local Environmental Factors Research Articles

Observations of Satellite Land Surface Phenology Indicate That Maximum Leaf Greenness Is More Associated With Global Vegetation Productivity Than Growing Season Length

AbstractVegetation green leaf phenology directly impacts gross primary productivity (GPP) of terrestrial ecosystems. Satellite observations of land surface phenology (LSP) provide an important means to monitor the key timing of vegetation green leaf development. However, differences between satellite‐derived LSP proxies and in situ measurements of GPP make it difficult to quantify the impact of climate‐induced changes in green leaf phenology on annual GPP. Here, we used 1,110 site‐years of GPP measurements from eddy‐covariance towers in association with time series of satellite LSP observations from 2000 to 2014 to show that while satellite LSP explains a large proportion of variation in annual GPP, changes in green‐leaf‐based growing season length (GSL, leaf development period from spring to autumn) had less impact on annual GPP by ∼30% than GSL changes in GPP‐based photosynthetic duration. Further, maximum leaf greenness explained substantially more variance in annual GPP than green leaf GSL, highlighting the role of future vegetation greening trends on large‐scale carbon budgets. Site‐level variability contributes a substantial proportion of annual GPP variance in the model based on LSP metrics, suggesting the importance of local environmental factors altering regional GPP. We conclude that satellite LSP‐based inferences regarding large‐scale dynamics in GPP need to consider changes in both green leaf GSL and maximum greenness.

Contrasting Effects of Local Environmental and Biogeographic Factors on the Composition and Structure of Bacterial Communities in Arid Monospecific Mangrove Soils.

ABSTRACTMangrove forests are important biotic sinks of atmospheric CO2 and play an integral role in nutrient-cycling and decontamination of coastal waters, thereby mitigating climatic and anthropogenic stressors. These services are primarily regulated by the activity of the soil microbiome. To understand how environmental changes may affect this vital part of the ecosystem, it is key to understand the patterns that drive microbial community assembly in mangrove forest soils. High-throughput amplicon sequencing (16S rRNA) was applied on samples from arid Avicennia marina forests across different spatial scales from local to regional. Alongside conventional analyses of community ecology, microbial co-occurrence networks were assessed to investigate differences in composition and structure of the bacterial community. The bacterial community composition varied more strongly along an intertidal gradient within each mangrove forest, than between forests in different geographic regions (Australia/Saudi Arabia). In contrast, co-occurrence networks differed primarily between geographic regions, illustrating that the structure of the bacterial community is not necessarily linked to its composition. The local diversity in mangrove forest soils may have important implications for the quantification of biogeochemical processes and is important to consider when planning restoration activities.IMPORTANCE Mangrove ecosystems are increasingly being recognized for their potential to sequester atmospheric carbon, thereby mitigating the effects of anthropogenically driven greenhouse gas emissions. The bacterial community in the soils plays an important role in the breakdown and recycling of carbon and other nutrients. To assess and predict changes in carbon storage, it is important to understand how the bacterial community is shaped by its environment. Here, we compared the bacterial communities of mangrove forests on different spatial scales, from local within-forest to biogeographic comparisons. The bacterial community composition differed more between distinct intertidal zones of the same forest than between forests in distant geographic regions. The calculated network structure of theoretically interacting bacteria, however, differed most between the geographic regions. Our findings highlight the importance of local environmental factors in shaping the microbial soil community in mangroves and highlight a disconnect between community composition and structure in microbial soil assemblages.

Local factors drive bacterial and microeukaryotic community composition in lake surface sediment collected across an altitudinal gradient.

Lake surface sediments are dominated by microorganisms that play significant roles in biogeochemical cycling within lakes. There is limited knowledge on the relative importance of local environmental factors and altitude on bacterial and microeukaryotic community richness and composition in lake sediments. In the present study, surface sediment samples were collected from 40 lakes along an altitude gradient (2-1215m). Microbial communities were characterized using 16S (bacteria) and 18S (microeukaryotes) rRNA gene metabarcoding. Bacterial and microeukaryotic richness were not correlated with altitude but instead to environmental variables (e.g. area of water in the catchment (bacteria: R = -0.43). For both bacteria and microeukaryotes, dissimilarity in the community structure had a higher correlation to combined environmental variables (without altitude) (bacteria: R = 0.53; microeukaryotes: R = 0.55) than altitude alone (bacteria: R = 0.34; microeukaryotes: R = 0.47). Sediment sulfur and productive grassland were important variables in determining the relative abundance of sulfate reducing bacteria. Nitrospira, was positively related to altitude but negatively to water column total organic carbon and the proportion of productive grassland in the catchment. Little overlap in amplicon sequence variants was shown amongst lakes. This has important considerations for management decisions, suggesting that to protect biodiversity, conservation of numerous lakes and lake types is required.

Freshwater Bacterioplankton Metacommunity Structure Along Urbanization Gradients in Belgium.

Urbanization is transforming and fragmenting natural environments worldwide, driving changes in biological communities through alterations in local environmental conditions as well as by changing the capacity of species to reach specific habitats. While the majority of earlier studies have been performed on higher plants and animals, it is crucial to increase our insight on microbial responses to urbanization across different spatial scales. Here, using a metacommunity approach, we evaluated the effects of urbanization on bacterioplankton communities in 50 shallow ponds in Belgium (Flanders region), one of the most urbanized areas in Northwest Europe. We estimated the relative importance of local environmental factors (35 abiotic and biotic variables), regional spatial factors and urbanization (built-up area) quantified at two spatial scales (200 m × 200 m and 3 km × 3 km). We show that urbanization at local or regional scales did not lead to strong changes in community composition and taxon diversity of bacterioplankton. Urbanization at regional scale (3 km × 3 km) explained only 2% of community composition variation while at local scale (200 m × 200 m), no effect was detected. Local environmental factors explained 13% (OTUs with relative abundance ≥ 0.1%) to 24% (12 dominant OTUs -≥ 1%) of community variation. Six local environmental variables significantly explained variation in bacterioplankton community composition: pH, alkalinity, conductivity, total phosphorus, abundance of Daphnia and concentration of copper (Cu), of which pH was partly mediated by urbanization. Our results indicate that environmental rather than spatial factors accounted for the variation in bacterioplankton community structure, suggesting that species sorting is the main process explaining bacterioplankton community assembly. Apparently, urbanization does not have a direct and strong effect on bacterioplankton metacommunity structure, probably due to the capacity of these organisms to adapt toward and colonize habitats with different environmental conditions and due to their fast adaptation and metabolic versatility. Thus, bacterioplankton communities inhabiting shallow ponds may be less affected by environmental conditions resulting from urbanization as compared to the impacts previously described for other taxa.

Genetics of the patella.

We review genetic diseases with identified molecular bases that include abnormal, reduced(hypoplasia), or absent (aplasia)patellae as a significant aspect of the phenotype. The known causal genes can be broadly organized according to three major developmental and cellular processes, although some genes may act in more than one of these: limb specification and pattern formation; DNA replication and chromatin structure; bone development and differentiation. There are also several genes whose phenotypes in mice indicate relevance to patellar development, for which human equivalent syndromes have not been reported. Developmental studies in mouse and chick embryos, as well as patellar involvement in human diseases with decreased mobility, document the additional importance of local environmental factors in patellar ontogenesis. Patellar anomalies found in humans can be an important clue to a clinical genetic diagnosis, and a better knowledge of the genetics of patellar anomalies will improve our understanding of limb development.

Environmental effects on fine-scale spatial genetic structure in four Alpine keystone forest tree species.

Genetic responses to environmental changes take place at different spatial scales. While the effect of environment on the distribution of species' genetic diversity at large geographical scales has been the focus of several recent studies, its potential effects on genetic structure at local scales are understudied. Environmental effects on fine-scale spatial genetic structure (FSGS) were investigated in four Alpine conifer species (five to eight populations per species) from the eastern Italian Alps. Significant FSGS was found for 11 of 25 populations. Interestingly, we found no significant differences in FSGS across species but great variation among populations within species, highlighting the importance of local environmental factors. Interannual variability in spring temperature had a small but significant effect on FSGS of Larix decidua, probably related to species-specific life history traits. For Abies alba, Picea abies and Pinus cembra, linear models identified spring precipitation as a potentially relevant climate factor associated with differences in FSGS across populations; however, models had low explanatory power and were strongly influenced by a P.cembra outlier population from a very dry site. Overall, the direction of the identified effects is according to expectations, with drier and more variable environments increasing FSGS. Underlying mechanisms may include climate-related changes in the variance of reproductive success and/or environmental selection of specific families. This study provides new insights on potential changes in local genetic structure of four Alpine conifers in the face of environmental changes, suggesting that new climates, through altering FSGS, may also have relevant impacts on plant microevolution.

Predicting local malaria exposure using a Lasso-based two-level cross validation algorithm.

Recent studies have highlighted the importance of local environmental factors to determine the fine-scale heterogeneity of malaria transmission and exposure to the vector. In this work, we compare a classical GLM model with backward selection with different versions of an automatic LASSO-based algorithm with 2-level cross-validation aiming to build a predictive model of the space and time dependent individual exposure to the malaria vector, using entomological and environmental data from a cohort study in Benin. Although the GLM can outperform the LASSO model with appropriate engineering, the best model in terms of predictive power was found to be the LASSO-based model. Our approach can be adapted to different topics and may therefore be helpful to address prediction issues in other health sciences domains.

The roles of elevation and local environmental factors as drivers of diatom diversity in subarctic streams

Summary High latitude and altitude freshwater systems are highly sensitive to the effects of global warming and associated environmental changes. Diatoms are widely used as sentinels of environmental change, yet knowledge of diatom community patterns in high latitude and altitude streams remains limited. The aim of this study was to examine alpha and beta diversity of diatoms in subarctic streams in Finland and Norway, and to determine the importance of local environmental factors and elevation in shaping their community patterns. We also aimed at testing, for the first time, whether microbes conform to Rapoport's elevational rule, which states that species occurring at higher elevations have generally larger elevational ranges than species at lower elevations. Three streams (44 sites in total) with an altitudinal gradient of 21–877 m a.s.l. were sampled. Generalized linear models, hierarchical partitioning, and a boosted regression tree method were used to identify drivers of diatom species richness. We ran Mantel tests, and calculated initial similarities and elevational halving distances to examine beta diversity. There were no apparent richness–elevation relationships within streams. Across all study streams, the water depth was the most important factor for richness, with additional influences by stone size, conductivity, pH and elevation. Diatoms in subarctic streams did not conform to Rapoport's elevational rule. Community similarity decreased significantly with elevational distance while distance decay was weaker with environmental distance. Our results suggest that diatom alpha and beta diversity along stream elevational gradients are shaped by interacting local environmental factors such as water depth and substrate size, indicating vulnerability of diatoms to physical disturbances, and regional factors such as dispersal and geographical variables. Diatom diversity patterns do not seem to concur with patterns often observed for larger organisms as no consistent elevational patterns in richness or range sizes were found.

High temperatures and absence of light affect the hatching of resting eggs of Daphnia in the tropics.

Temperature and light are acknowledged as important factors for hatching of resting eggs. The knowledge of how they affect hatching rates of this type of egg is important for the comprehension of the consequences of warming waters in recolonization of aquatic ecosystems dependent on dormant populations. This study aimed at comparing the influence of different temperature and light conditions on hatching rates of Daphnia ambigua andDaphnia laevis resting eggs from tropical environments. The ephippia were collected in the sediment of three aquatic ecosystems, in southeastern Brazil. For each lake, the resting eggs were exposed to temperatures of 20, 24, 28 and 32 °C, under light (12 h photoperiod) and dark conditions. The results showed that the absence of light and high temperatures have a negative influence on the hatching rates. Statistical differences for hatching rates were also found when comparing the studied ecosystems (ranging from 0.6 to 31%), indicating the importance of local environmental factors for diapause and maintenance of active populations.

The life-history traits of widespread freshwater fish species: the case of Roach Rutilus rutilus (Linnaeus, 1758) (Pisces: Teleostei) in water bodies at the southern limits of distribution

The Roach Rutilus rutilus (Linnaeus, 1758) (Pisces: Teleostei) is a widespread Eurasian cyprinid freshwater fish. Although numerous studies have investigated the species’ life history traits across its main native range of distribution, little is known from water bodies located beyond the southern limits of the latter, especially where the species has been introduced. Between July 2010 and April 2011, a total of 949 R. rutilus specimens was collected from Porsuk Reservoir (NW Turkey), and life-history traits of age, growth, fecundity and egg size were studied and compared to six other R. rutilus populations (including Caspian Roach R. r. caspicus) from the southern limits of distribution. The Porsuk population was characterised by relatively shorter lifespan, slower growth and lower fecundity. These findings support previous studies emphasising the importance of local environmental factors in shaping the life-history traits of widespread fish species. These must be taken into consideration especially in view of the potential value of R. rutilus as an economic resource for in-land fisheries.

Dispersal ability determines the role of environmental, spatial and temporal drivers of metacommunity structure.

Recently, community ecologists are focusing on the relative importance of local environmental factors and proxies to dispersal limitation to explain spatial variation in community structure. Albeit less explored, temporal processes may also be important in explaining species composition variation in metacommunities occupying dynamic systems. We aimed to evaluate the relative role of environmental, spatial and temporal variables on the metacommunity structure of different organism groups in the Upper Paraná River floodplain (Brazil). We used data on macrophytes, fish, benthic macroinvertebrates, zooplankton, periphyton, and phytoplankton collected in up to 36 habitats during a total of eight sampling campaigns over two years. According to variation partitioning results, the importance of predictors varied among biological groups. Spatial predictors were particularly important for organisms with comparatively lower dispersal ability, such as aquatic macrophytes and fish. On the other hand, environmental predictors were particularly important for organisms with high dispersal ability, such as microalgae, indicating the importance of species sorting processes in shaping the community structure of these organisms. The importance of watercourse distances increased when spatial variables were the main predictors of metacommunity structure. The contribution of temporal predictors was low. Our results emphasize the strength of a trait-based analysis and of better defining spatial variables. More importantly, they supported the view that “all-or- nothing” interpretations on the mechanisms structuring metacommunities are rather the exception than the rule.

Modeling the Influence of Local Environmental Factors on Malaria Transmission in Benin and Its Implications for Cohort Study

Malaria remains endemic in tropical areas, especially in Africa. For the evaluation of new tools and to further our understanding of host-parasite interactions, knowing the environmental risk of transmission—even at a very local scale—is essential. The aim of this study was to assess how malaria transmission is influenced and can be predicted by local climatic and environmental factors.As the entomological part of a cohort study of 650 newborn babies in nine villages in the Tori Bossito district of Southern Benin between June 2007 and February 2010, human landing catches were performed to assess the density of malaria vectors and transmission intensity. Climatic factors as well as household characteristics were recorded throughout the study. Statistical correlations between Anopheles density and environmental and climatic factors were tested using a three-level Poisson mixed regression model. The results showed both temporal variations in vector density (related to season and rainfall), and spatial variations at the level of both village and house. These spatial variations could be largely explained by factors associated with the house's immediate surroundings, namely soil type, vegetation index and the proximity of a watercourse. Based on these results, a predictive regression model was developed using a leave-one-out method, to predict the spatiotemporal variability of malaria transmission in the nine villages.This study points up the importance of local environmental factors in malaria transmission and describes a model to predict the transmission risk of individual children, based on environmental and behavioral characteristics.

The Predictability of Phytophagous Insect Communities: Host Specialists as Habitat Specialists

The difficulties specialized phytophagous insects face in finding habitats with an appropriate host should constrain their dispersal. Within the concept of metacommunities, this leads to the prediction that host-plant specialists should sort into local assemblages according to the local environmental conditions, i.e. habitat conditions, whereas assemblages of host-plant generalists should depend also on regional processes. Our study aimed at ranking the importance of local environmental factors and species composition of the vegetation for predicting the species composition of phytophagous moth assemblages with either a narrow or a broad host range. Our database consists of 351,506 specimens representing 820 species of nocturnal Macrolepidoptera sampled between 1980 and 2006 using light traps in 96 strict forest reserves in southern Germany. Species were grouped as specialists or generalists according to the food plants of the larvae; specialists use host plants belonging to one genus. We used predictive canonical correspondence and co-correspondence analyses to rank the importance of local environmental factors, the species composition of the vegetation and the role of host plants for predicting the species composition of host-plant specialists and generalists. The cross-validatory fit for predicting the species composition of phytophagous moths was higher for host-plant specialists than for host-plant generalists using environmental factors as well as the composition of the vegetation. As expected for host-plant specialists, the species composition of the vegetation was a better predictor of the composition of these assemblages than the environmental variables. But surprisingly, this difference for specialized insects was not due to the occurrence of their host plants. Overall, our study supports the idea that owing to evolutionary constraints in finding a host, host-plant specialists and host-plant generalists follow two different models of metacommunities: the species-sorting and the mass-effect model.

Bacterial ‘cosmopolitanism’ and importance of local environmental factors for community composition in remote high‐altitude lakes

In October 2004, plankton samples were collected from six permanent lakes located between 4960 and 5440 m a.s.l. in the Mount Everest region (Nepal) to assess how spatial and local environmental factors affect natural bacterial community composition. Fingerprinting analysis of the bacterial 16S rRNA gene fragment was done by denaturing gradient gel electrophoresis (DGGE).The number of DGGE bands (range: 12-23) was not correlated with lake area or remoteness, but there was a strong negative correlation with the ratio of catchment to lake area (r = -0.826, P < 0.05), suggesting that hydraulic retention time affects the establishment of the bacterial community in these seepage lakes.Most dominant sequences belonged to Betaproteobacteria except in two lakes where members of Bacteroidetes made the largest relative contribution. Up to 81% of the phylotypes had high similarity (>98 to 100%) in partial 16S rRNA gene sequence to those reported from other alpine lakes and glaciers around the world, suggesting the presence of 'cosmopolitan' bacteria.An analysis based on dissimilarity matrices and the Mantel test revealed the existence of dissimilarities in bacterial community composition related to geographical distance over a small spatial scale (<6 km), but determined by local environmental constraints.Our results suggest that several bacterial phylotypes are ubiquitous in the freshwater aquatic realm, but taxon sorting by local environmental constraints is important.

Biogeography of Bacterioplankton in Inland Waters

Bacteria are among the most abundant groups of organisms. They mediate key ecological processes. Recent molecular advances have provided greater insight into bacterial diversity as well as allowing a more thorough examination of patterns in the spatial and temporal distribution of bacteria. Thus, the study of bacterial biodiversity and biogeographical distribution has stimulated considerable interest and dispute over the last decade.This review summarises the findings obtained from studies on the biogeography of bacterioplankton in inland waters. We examine factors and processes that may determine and maintain bacterial diversity and biogeography, and relate these to the theoretical metacommunity framework.We conclude that the importance of local environmental factors (such as lake character) for local bacterioplankton community compositions (BCC) is much more intensively studied than the importance of regional factors, such as dispersal. Further, few attempts have been made to evaluate simultaneously the relative importance of the two types of factors for BCC. Finally, we summarise gaps in knowledge, delineate challenges and put forward possible future research directions.

Scale‐related patterns in the spatial and environmental components of stream macroinvertebrate assemblage variation

ABSTRACTAim We examined the relative contributions of spatial gradients and local environmental conditions to macroinvertebrate assemblages of boreal headwater streams at three hierarchical extents: bioregion, ecoregion and drainage system. We also aimed to identify the environmental variables most strongly related to assemblage structure at each study scale, and to assess how the importance of these variables is related to regional context and spatial structuring at different scales.Location Northern Finland (62–68° N, 25–32° E).Methods Variation in macroinvertebrate data was partitioned using partial canonical correspondence analysis into components explained by spatial variables (nine terms from the cubic trend surface regression), local environmental variables (15 variables) and spatially structured environmental variation.Results The strength of the relationship between assemblage structure and local environmental variables increased with decreasing spatial extent, whereas assemblage variation related to spatial variables and spatially structured environmental variation showed the opposite pattern. At the largest extents, spatial variation was related to latitudinal gradients, whereas spatial autocorrelation among neighbouring streams was the likely mechanism creating spatial structure within drainage systems. Only stream size and water acidity were consistently important in explaining assemblage structure at all study scales, while the importance of other environmental variables was more context‐dependent.Main conclusions The importance of local environmental factors in explaining macroinvertebrate assemblage structure increases with decreasing spatial extent. This scale‐related pattern is not caused solely by changes in study extent, however, but also by variable sample sizes at different regional extents. The importance of environmental gradients is context‐dependent and few factors are likely to be universally important correlates of macroinvertebrate assemblage structure. Finally, our results suggest that bioassessment should give due attention to spatial structuring of stream assemblages, because important assemblage gradients may not only be related to local factors but also to biogeographical constraints and neighbourhood dispersal processes.

Heliotropium europaeum poisoning of sheep with low liver copper concentrations and the preventive efficacy of cobalt and antimethanogen.

In a field experiment in the Mallee district of Victoria, Merlno xBorder Leicester ewes and wethers grazed Heliotropium europaeum (heliotrope) over periods of 3 to 4 months in 4 successive years. By the end of the second year 12% (14 of 120) of the sheep had died; after 4 years the loss attributable to heliotrope was between 18% and 35%. Mortality was not affected by intraruminal treatment with cobalt or antimethanogen. At the end of the experiment the highest concentration of copper in the liver was 1.95 mmol/kg wet weight (approximately 413 micrograms/g dry weight). The relatively low mortality from primary heliotrope poisoning and the low concentration of copper in the liver of sheep grazing the plant are discussed in relation to the contrasting situation that prevails in the Riverina area of New South Wales. The importance of local environmental factors in the management of heliotrope grazing by sheep is emphasised, particularly in relation to the number of seasons in which the plant may be a major component of the diet.