Abstract
Wetland soils are the greatest source of nitrous oxide (N
2
O), a critical greenhouse gas and ozone depleter released by microbes. Yet, microbial players and processes underlying the N
2
O ...emissions from wetland soils are poorly understood. Using in situ N
2
O measurements and by determining the structure and potential functional of microbial communities in 645 wetland soil samples globally, we examined the potential role of archaea, bacteria, and fungi in nitrogen (N) cycling and N
2
O emissions. We show that N
2
O emissions are higher in drained and warm wetland soils, and are correlated with functional diversity of microbes. We further provide evidence that despite their much lower abundance compared to bacteria, nitrifying archaeal abundance is a key factor explaining N
2
O emissions from wetland soils globally. Our data suggest that ongoing global warming and intensifying environmental change may boost archaeal nitrifiers, collectively transforming wetland soils to a greater source of N
2
O.
Native biodiversity decline and non-native species spread are major features of the Anthropocene. Both processes can drive biotic homogenization by reducing trait and phylogenetic differences in ...species assemblages between regions, thus diminishing the regional distinctiveness of biotas and likely have negative impacts on key ecosystem functions. However, a global assessment of this phenomenon is lacking. Here, using a dataset of >200,000 plant species, we demonstrate widespread and temporal decreases in species and phylogenetic turnover across grain sizes and spatial extents. The extent of homogenization within major biomes is pronounced and is overwhelmingly explained by non-native species naturalizations. Asia and North America are major sources of non-native species; however, the species they export tend to be phylogenetically close to recipient floras. Australia, the Pacific and Europe, in contrast, contribute fewer species to the global pool of non-natives, but represent a disproportionate amount of phylogenetic diversity. The timeline of most naturalisations coincides with widespread human migration within the last ~500 years, and demonstrates the profound influence humans exert on regional biotas beyond changes in species richness.
Abstract
Although species with larger body size and slow pace of life have a higher risk of extinction at a global scale, it is unclear whether this global trend will be consistent across ...biogeographic realms. Here we measure the functional diversity of terrestrial and freshwater vertebrates in the six terrestrial biogeographic realms and predict their future changes through scenarios mimicking a gradient of extinction risk of threatened species. We show vastly different effects of extinctions on functional diversity between taxonomic groups and realms, ranging from almost no decline to deep functional losses. The Indo-Malay and Palearctic realms are particularly inclined to experience a drastic loss of functional diversity reaching 29 and 31%, respectively. Birds, mammals, and reptiles regionally display a consistent functional diversity loss, while the projected losses of amphibians and freshwater fishes differ across realms. More efficient global conservation policies should consider marked regional losses of functional diversity across the world.
Locally observed biodiversity always consists of only a fraction of its site‐specific species pool. Why some suitable species are absent, shaping dark diversity of that site, is a basic yet ...increasingly crucial question in the face of global biodiversity degradation. The ultimate processes underlying dark diversity associate with either dispersal or persistence limitations, or both. These two limitations in turn link to several characteristics of individual species and sites, making it challenging to detect the exact factors contributing to dark diversity in a particular metacommunity.
Here, we propose a metric, dark diversity affinity (DDA), which measures the tendencies of individual species to be absent from suitable sites and of individual sites to miss suitable species. We developed a Bayesian model interrelating four types of datasets: metacommunity matrix of species presences in sites, species‐sites suitability matrix, species functional traits and site characteristics. In the model, DDA operates as an adjustment bridging the disparity between site‐specific suitability and observed presence/absence of each species at each site. Furthermore, DDA can be related to individual properties of species and sites through logistic regression sub‐models. We demonstrated our framework using nine empirical datasets of vertebrate, invertebrate and vascular plant metacommunities.
We show the decomposed roles of species traits and site characteristics in defining DDA and, therefore, dark diversity in metacommunities. In the empirical datasets, various functional traits, which related to morphology, reproduction, dispersal ability, population attributes, resource specificity and life history, significantly affected species‐level DDA, while site characteristics regarding habitat types and attributes, resource availability, pollution, and edaphic and water conditions influenced DDA at the site level.
Our framework provides a concept and methodological toolbox that allows identification of the processes underlying dark diversity and advances both the theory of community ecology and biodiversity conservation. Conservation actions can be more successful by knowing whether species loss in a particular metacommunity is associated to some species traits or site characteristics and what their relative contributions are.
Plant species richness: the world records Wilson, J. Bastow; Peet, Robert K.; Dengler, Jürgen ...
Journal of vegetation science,
August 2012, Letnik:
23, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Questions: The co-existence of high numbers of species has always fascinated ecologists, but what and where are the communities with the world records for plant species richness? The species—area ...relationship is among the best-known patterns in community ecology, but does it give a consistent global pattern for the most saturated communities, the global maxima? Location: The world. Methods: We assembled the maximum values recorded for vascular plant species richness for contiguous areas from 1 mm2 up to 1 ha. We applied the power function to relate maximal richness to area and to make extrapolations to the whole Earth. Results: Only two community types contain global plant species maxima. The maxima at smaller spatial grain were from oligo- to meso-trophic, managed, semi-natural, temperate grasslands (e.g. 89 species on 1 m 2 ), those at larger grains were from tropical rain forests (e.g. 942 species on 1 ha). The maximum richness values closely followed a power function with z = 0.250: close to Preston's 'canonical' value of 0.262. There was no discernable difference between maxima using rooted presence (i.e. including only plants rooted in the plot) vs shoot presence (i.e. including any plant with physical cover over the plot). However, shoot presence values must logically be greater, with the curves flattening out at very small grain, and there is evidence of this from point quadrats. Extrapolating the curve to the terrestrial surface of the Earth gave a prediction of 219 204 vascular plant species, surprisingly close to a recent estimate of 275 000 actual species. Conclusions: Very high richness at any spatial grain is found only in two particular habitat/community types. Nevertheless, these high richness values form a very strong, consistent pattern, not greatly affected by the method of sampling, and this pattern extrapolates amazingly well. The records challenge ecologists to consider mechanisms of species co-existence, answers to the 'Paradox of the Plankton'.
Many studies have shown plant species' dispersal distances to be strongly related to life-history traits, but how well different traits can predict dispersal distances is not yet known. We used ...cross-validation techniques and a global data set (576 plant species) to measure the predictive power of simple plant traits to estimate species' maximum dispersal distances. Including dispersal syndrome (wind, animal, ant, ballistic, and no special syndrome), growth form (tree, shrub, herb), seed mass, seed release height, and terminal velocity in different combinations as explanatory variables we constructed models to explain variation in measured maximum dispersal distances and evaluated their power to predict maximum dispersal distances. Predictions are more accurate, but also limited to a particular set of species, if data on more specific traits, such as terminal velocity, are available. The best model (
R
2
= 0.60) included dispersal syndrome, growth form, and terminal velocity as fixed effects. Reasonable predictions of maximum dispersal distance (
R
2
= 0.53) are also possible when using only the simplest and most commonly measured traits; dispersal syndrome and growth form together with species taxonomy data. We provide a function (dispeRsal) to be run in the software package R. This enables researchers to estimate maximum dispersal distances with confidence intervals for plant species using measured traits as predictors. Easily obtainable trait data, such as dispersal syndrome (inferred from seed morphology) and growth form, enable predictions to be made for a large number of species.
When restoring habitat for biodiversity, the most effective outcome will be achieved by restoration projects which target several organism groups or ecosystem types. Such integrated approaches ...require direct comparisons among different ecological communities while evaluating success of restoration. The Community Completeness Index (CCI) is a recently developed metric that allows such comparisons by accounting for both present and absent but otherwise suitable taxa. We empirically evaluated the applicability of CCI for assessing the outcome of ecological restoration. We analyzed how species richness and the completeness of ecological communities recover after restoration, for different ecological groups and ecosystem types, and how it develops over time after restoration. Analyses were performed on 18 datasets with per site presence-absence data from Northern Europe. Each dataset represented one of the three habitat types (mire, forest, grassland) and different ecological groups (plants, flying insects, epigeic invertebrates). Datasets contained pristine, degraded and restored sites. We calculated the dark diversity and subsequently CCI based on species co-occurrences. Our multiple-study analyses revealed that CCI of grassland plant communities increased faster after restoration than invertebrate communities or plant communities in forests and mires. In addition, flying insect communities demonstrated significantly highest CCI in pristine mires. Some results were significant only for richness but not for CCI indicating species pool effect. Finally, completeness and species richness of restored communities increased with time since restoration. As such, our study demonstrated that CCI is a useful tool in evaluating restoration success across different organism groups and ecosystem types.
Plant traits determine how individual plants cope with heterogeneous environments. Despite large variability in individual traits, trait coordination and trade-offs
result in some trait combinations ...being much more widespread than others, as revealed in the global spectrum of plant form and function (GSPFF
) and the root economics space (RES
) for aboveground and fine-root traits, respectively. Here we combine the traits that define both functional spaces. Our analysis confirms the major trends of the GSPFF and shows that the RES captures additional information. The four dimensions needed to explain the non-redundant information in the dataset can be summarized in an aboveground and a fine-root plane, corresponding to the GSPFF and the RES, respectively. Both planes display high levels of species aggregation, but the differentiation among growth forms, families and biomes is lower on the fine-root plane, which does not include any size-related trait, than on the aboveground plane. As a result, many species with similar fine-root syndromes display contrasting aboveground traits. This highlights the importance of including belowground organs to the GSPFF when exploring the interplay between different natural selection pressures and whole-plant trait integration.
Although experiments show a positive association between vascular plant and arbuscular mycorrhizal fungal (AMF) species richness, evidence from natural ecosystems is scarce. Furthermore, there is ...little knowledge about how AMF richness varies with belowground plant richness and biomass. We examined relationships among AMF richness, above‐ and belowground plant richness, and plant root and shoot biomass in a native North American grassland. Root‐colonizing AMF richness and belowground plant richness were detected from the same bulk root samples by 454‐sequencing of the AMF SSU rRNA and plant trnL genes. In total we detected 63 AMF taxa. Plant richness was 1.5 times greater belowground than aboveground. AMF richness was significantly positively correlated with plant species richness, and more strongly with below‐ than aboveground plant richness. Belowground plant richness was positively correlated with belowground plant biomass and total plant biomass, whereas aboveground plant richness was positively correlated only with belowground plant biomass. By contrast, AMF richness was negatively correlated with belowground and total plant biomass. Our results indicate that AMF richness and plant belowground richness are more strongly related with each other and with plant community biomass than with the plant aboveground richness measures that have been almost exclusively considered to date.
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