scholarly journals Sensitivity of grassland carbon pools to plant diversity, elevated CO2, and soil nitrogen addition over 19 years

2021 ◽  
Vol 118 (17) ◽  
pp. e2016965118
Author(s):  
Melissa A. Pastore ◽  
Sarah E. Hobbie ◽  
Peter B. Reich
Keyword(s):  
Species Richness ◽  
Soil Nitrogen ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Plant Species Richness ◽  
Nitrogen Addition ◽  
N Deposition ◽  
Global Changes ◽  
Soil C ◽  
C Storage

Whether the terrestrial biosphere will continue to act as a net carbon (C) sink in the face of multiple global changes is questionable. A key uncertainty is whether increases in plant C fixation under elevated carbon dioxide (CO2) will translate into decades-long C storage and whether this depends on other concurrently changing factors. We investigated how manipulations of CO2, soil nitrogen (N) supply, and plant species richness influenced total ecosystem (plant + soil to 60 cm) C storage over 19 y in a free-air CO2 enrichment grassland experiment (BioCON) in Minnesota. On average, after 19 y of treatments, increasing species richness from 1 to 4, 9, or 16 enhanced total ecosystem C storage by 22 to 32%, whereas N addition of 4 g N m−2 ⋅ y−1 and elevated CO2 of +180 ppm had only modest effects (increasing C stores by less than 5%). While all treatments increased net primary productivity, only increasing species richness enhanced net primary productivity sufficiently to more than offset enhanced C losses and substantially increase ecosystem C pools. Effects of the three global change treatments were generally additive, and we did not observe any interactions between CO2 and N. Overall, our results call into question whether elevated CO2 will increase the soil C sink in grassland ecosystems, helping to slow climate change, and suggest that losses of biodiversity may influence C storage as much as or more than increasing CO2 or high rates of N deposition in perennial grassland systems.

Anthropogenic impacts upon plant species richness and net primary productivity in California

2004 ◽  
Vol 8 (2) ◽  
pp. 127-137 ◽  
Author(s):  
John W. Williams ◽  
Eric W. Seabloom ◽  
Daniel Slayback ◽  
David M. Stoms ◽  
Joshua H. Viers
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Anthropogenic Impacts ◽  
Plant Species Richness

scholarly journals Microbial Mechanisms Mediating Increased Soil C Storage under Elevated Atmospheric N Deposition

2012 ◽  
Vol 79 (4) ◽  
pp. 1191-1199 ◽  
Author(s):  
Sarah D. Eisenlord ◽  
Zachary Freedman ◽  
Donald R. Zak ◽  
Kai Xue ◽  
Zhili He ◽  
...  
Keyword(s):  
Forest Floor ◽  
Forest Ecosystems ◽  
N Deposition ◽  
Fungal Communities ◽  
Functional Genes ◽  
Atmospheric N Deposition ◽  
Soil C ◽  
C Storage ◽  
Genes Encoding ◽  
Soil C Storage

ABSTRACTFuture rates of anthropogenic N deposition can slow the cycling and enhance the storage of C in forest ecosystems. In a northern hardwood forest ecosystem, experimental N deposition has decreased the extent of forest floor decay, leading to increased soil C storage. To better understand the microbial mechanisms mediating this response, we examined the functional genes derived from communities of actinobacteria and fungi present in the forest floor using GeoChip 4.0, a high-throughput functional-gene microarray. The compositions of functional genes derived from actinobacterial and fungal communities was significantly altered by experimental nitrogen deposition, with more heterogeneity detected in both groups. Experimental N deposition significantly decreased the richness and diversity of genes involved in the depolymerization of starch (∼12%), hemicellulose (∼16%), cellulose (∼16%), chitin (∼15%), and lignin (∼16%). The decrease in richness occurred across all taxonomic groupings detected by the microarray. The compositions of genes encoding oxidoreductases, which plausibly mediate lignin decay, were responsible for much of the observed dissimilarity between actinobacterial communities under ambient and experimental N deposition. This shift in composition and decrease in richness and diversity of genes encoding enzymes that mediate the decay process has occurred in parallel with a reduction in the extent of decay and accumulation of soil organic matter. Our observations indicate that compositional changes in actinobacterial and fungal communities elicited by experimental N deposition have functional implications for the cycling and storage of carbon in forest ecosystems.

scholarly journals Worldwide patterns in species richness of falconiformes: analytical null models, geometric constraints, and the mid-domain effect

2004 ◽  
Vol 64 (2) ◽  
pp. 209-308
Author(s):  
T. F. L.V. B. Rangel ◽  
J. A. F. Diniz-filho
Keyword(s):  
Species Richness ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Empirical Support ◽  
Null Models ◽  
Geometric Constraints ◽  
Global Level ◽  
Spatial Gradients ◽  
Available Energy ◽  
Surrogate Variable

Recently, the hypothesis that the geographic distribution of species could be influenced by the shape of the domain edges, the so-called Mid-Domain Effect (MDE), has been included as one of the five credible hypotheses for explaining spatial gradients in species richness, despite all the unsuccessful current attempts to prove empirically the validity of MDE. We used data on spatial worldwide distributions of Falconiformes to evaluate the validity of MDE assumptions, incorporated into two different sorts of null models at a global level and separately across five domains/landmasses. Species richness values predicted by the null models of the MDE and those values predicted by Net Primary Productivity, a surrogate variable expressing the effect of available energy, were compared in order to evaluate which hypothesis better predicts the observed values. Our tests showed that MDE continues to lack empirical support, regardless of its current acceptability, and so, does not deserve to be classified as one possible explanation of species richness gradients.

Net primary productivity and seasonality of temperature and precipitation are predictors of the species richness of the Damselflies in the Amazon

2019 ◽  
Vol 35 ◽  
pp. 45-53 ◽  
Author(s):  
Leandro Schlemmer Brasil ◽  
Divino Vicente Silverio ◽  
Helena Soares Ramos Cabette ◽  
Joana Darc Batista ◽  
Thiago Bernardi Vieira ◽  
...  
Keyword(s):  
Species Richness ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Temperature And Precipitation

scholarly journals More individuals but fewer species: testing the ‘more individuals hypothesis’ in a diverse tropical fauna

2010 ◽  
Vol 6 (4) ◽  
pp. 490-493 ◽  
Author(s):  
Terrence P. McGlynn ◽  
Michael D. Weiser ◽  
Robert R. Dunn
Keyword(s):  
Species Richness ◽  
Primary Productivity ◽  
Large Scale ◽  
Positive Relationship ◽  
Tropical Rainforest ◽  
Net Primary Productivity ◽  
Resource Abundance ◽  
Monotonic Increase ◽  
Ant Diversity ◽  
Unimodal Relationship

A positive relationship between species richness and productivity is often observed in nature, but the causes remain contentious. One mechanism, the ‘more individuals hypothesis’ (MIH), predicts richness increases monotonically with density, as a function of resource flux. To test the MIH, we manipulated resource abundance in a community of tropical rainforest litter ants and measured richness and density responses. A unimodal relationship between richness and density most closely fitted the control and disturbance (resource removal) treatments in contrast to expectations of the MIH. Resource addition resulted in a monotonic increase in richness relative to density, a shift from the pattern in the control. In the disturbance treatment, richness was greater than in the control, opposite to expectations of the MIH. While large-scale correlations between ant diversity and net primary productivity or temperature are reconcilable with the MIH, key elements of the hypothesis are not supported.

scholarly journals Microbial Mechanisms Mediating Increased Soil C Storage under Elevated Atmospheric N Deposition

2013 ◽  
Vol 79 (8) ◽  
pp. 2847-2847 ◽  
Author(s):  
Sarah D. Eisenlord ◽  
Zachary Freedman ◽  
Donald R. Zak ◽  
Kai Xue ◽  
Zhili He ◽  
...  
Keyword(s):  
N Deposition ◽  
Atmospheric N Deposition ◽  
Soil C ◽  
C Storage ◽  
Soil C Storage

scholarly journals Effects of nutrient availability and other elevational changes on bromeliad populations and their invertebrate communities in a humid tropical forest in Puerto Rico

2000 ◽  
Vol 16 (2) ◽  
pp. 167-188 ◽  
Author(s):  
Barbara A. Richardson ◽  
M. J. Richardson ◽  
F. N. Scatena ◽  
W. H. Mcdowell
Keyword(s):  
Species Richness ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Plant Density ◽  
Nutrient Concentrations ◽  
Forest Types ◽  
Nutrient Inputs ◽  
Nitrogen And Phosphorus ◽  
Faunal Abundance ◽  
High Plant Density

Nutrient inputs into tank bromeliads were studied in relation to growth and productivity, and the abundance, diversity and biomass of their animal inhabitants, in three forest types along an elevational gradient. Concentrations of phosphorus, potassium and calcium in canopy-derived debris, and nitrogen and phosphorus in phytotelm water, declined with increasing elevation. Dwarf forest bromeliads contained the smallest amounts of debris/plant and lowest concentrations of nutrients in plant tissue. Their leaf turnover rate and productivity were highest and, because of high plant density, they comprised 12.8% of forest net primary productivity (0.47 t ha−1 y−1), and contained 3.3 t ha−1 of water. Annual nutrient budgets indicated that these microcosms were nutrient-abundant and accumulated < 5% of most nutrients passing through them. Exceptions were K and P in the dwarf forest, where accumulation was c. 25% of inputs. Animal and bromeliad biomass/plant peaked in the intermediate elevation forest, and were positively correlated with the debris content/bromeliad across all forest types. Animal species richness showed a significant mid-elevational peak, whereas abundance was independent of species richness and debris quantities, and declined with elevation as forest net primary productivity declined. The unimodal pattern of species richness was not correlated with nutrient concentrations, and relationships among faunal abundance, species richness, nutrient inputs and environment are too complex to warrant simple generalizations about nutrient resources and diversity, even in apparently simple microhabitats.

scholarly journals Comment on Pescott & Jitlal 2020: Failure to account for measurement error undermines their conclusion of a weak impact of nitrogen deposition on plant species richness

2020 ◽  
Author(s):  
SM Smart ◽  
CJ Stevens ◽  
SJ Tomlinson ◽  
LC Maskell ◽  
PA Henrys
Keyword(s):  
Species Richness ◽  
Measurement Error ◽  
Plant Species ◽  
Large Scale ◽  
Plant Species Richness ◽  
N Deposition ◽  
Spatial Gradient ◽  
Spatial Gradients ◽  
Deposition Effect ◽  
Time Substitution

AbstractEstimation of the impacts of atmospheric nitrogen (N) deposition on ecosystems and biodiversity is a research imperative. Analyses of large-scale spatial gradients, where an observed response is correlated with measured or modelled deposition, have been an important source of evidence. A number of problems beset this approach. For example, if responses are spatially aggregated then treating each location as statistically independent can lead to biased confidence intervals and a greater probably of false positive results.Using sophisticated methods that account for residual spatial autocorrelation Pescott & Jitlal (2020) re-analysed two large-scale spatial gradient datasets from Britain where modelled N deposition at 5×5km resolution had been previously correlated with species richness in small quadrats. They found that N deposition effects were weaker than previously demonstrated leading them to conclude that “..previous estimates of Ndep impacts on richness from space-for-time substitution studies are likely to have been over-estimated”. We use a simple simulation study to show that their conclusion is flawed. They failed to recognise that an influential fraction of the residual spatially structured variation could itself be attributable to N deposition. This arises because the covariate used was modelled N deposition at 5×5km resolution leaving open the possibility that measured or modelled N deposition at finer resolutions could explain more variance in the response. Explicitly treating this as spatially auto-correlated error ignores this possibility and leads directly to their unreliable conclusion. We further demonstrate the plausibility of this scenario by showing that significant variation in N deposition at the 1km square resolution is indeed averaged at 5×5km resolution.Further analyses are required to explore whether estimation of the size of the N deposition effect on plant species richness and other measures of biodiversity is indeed dependent on the accuracy and hence measurement error of the N deposition covariate. Until then the conclusions of Pescott & Jitlal (2020) should be considered premature and not proven.

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