Browsing by Subject "Biomass"
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Item Open Access A Comparison of Remote Sensing Methods for Estimating Above-Ground Carbon Biomass at a Wetland Restoration Area in the Southeastern Coastal Plain(2012-04-19) Riegel, BenDeveloping accurate but inexpensive methods for estimating above-ground carbon biomass is an important technical challenge that must be overcome before a carbon offset market can be successfully implemented. Previous studies have shown that full-waveform LiDAR (light detection and ranging) is well suited for modeling above-ground biomass in mature forests; however, there has been little previous research on the ability of discrete-return LiDAR to model above-ground biomass in areas with relatively sparse vegetation. This study compared the abilities of discrete-return LiDAR and high-resolution optical imagery to model above-ground carbon biomass at a wetland restoration area in eastern North Carolina. The optical imagery model explained more of the overall variation in biomass at the study site than the LiDAR model did (R2 values of 0.36 and 0.19 respectively). Moreover, the optical imagery model was better able to detect high and low biomass areas than the LiDAR model. These results suggest that the ability of discrete-return LiDAR to model above-ground biomass is rather limited in areas with relatively small trees and that high spatial resolution optical imagery may be the better tool in such areas.Item Open Access Above-ground biomass and structure of 260 African tropical forests.(Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 2013-01) Lewis, Simon L; Sonké, Bonaventure; Sunderland, Terry; Begne, Serge K; Lopez-Gonzalez, Gabriela; van der Heijden, Geertje MF; Phillips, Oliver L; Affum-Baffoe, Kofi; Baker, Timothy R; Banin, Lindsay; Bastin, Jean-François; Beeckman, Hans; Boeckx, Pascal; Bogaert, Jan; De Cannière, Charles; Chezeaux, Eric; Clark, Connie J; Collins, Murray; Djagbletey, Gloria; Djuikouo, Marie Noël K; Droissart, Vincent; Doucet, Jean-Louis; Ewango, Cornielle EN; Fauset, Sophie; Feldpausch, Ted R; Foli, Ernest G; Gillet, Jean-François; Hamilton, Alan C; Harris, David J; Hart, Terese B; de Haulleville, Thales; Hladik, Annette; Hufkens, Koen; Huygens, Dries; Jeanmart, Philippe; Jeffery, Kathryn J; Kearsley, Elizabeth; Leal, Miguel E; Lloyd, Jon; Lovett, Jon C; Makana, Jean-Remy; Malhi, Yadvinder; Marshall, Andrew R; Ojo, Lucas; Peh, Kelvin S-H; Pickavance, Georgia; Poulsen, John R; Reitsma, Jan M; Sheil, Douglas; Simo, Murielle; Steppe, Kathy; Taedoumg, Hermann E; Talbot, Joey; Taplin, James RD; Taylor, David; Thomas, Sean C; Toirambe, Benjamin; Verbeeck, Hans; Vleminckx, Jason; White, Lee JT; Willcock, Simon; Woell, Hannsjorg; Zemagho, LiseWe report above-ground biomass (AGB), basal area, stem density and wood mass density estimates from 260 sample plots (mean size: 1.2 ha) in intact closed-canopy tropical forests across 12 African countries. Mean AGB is 395.7 Mg dry mass ha⁻¹ (95% CI: 14.3), substantially higher than Amazonian values, with the Congo Basin and contiguous forest region attaining AGB values (429 Mg ha⁻¹) similar to those of Bornean forests, and significantly greater than East or West African forests. AGB therefore appears generally higher in palaeo- compared with neotropical forests. However, mean stem density is low (426 ± 11 stems ha⁻¹ greater than or equal to 100 mm diameter) compared with both Amazonian and Bornean forests (cf. approx. 600) and is the signature structural feature of African tropical forests. While spatial autocorrelation complicates analyses, AGB shows a positive relationship with rainfall in the driest nine months of the year, and an opposite association with the wettest three months of the year; a negative relationship with temperature; positive relationship with clay-rich soils; and negative relationships with C : N ratio (suggesting a positive soil phosphorus-AGB relationship), and soil fertility computed as the sum of base cations. The results indicate that AGB is mediated by both climate and soils, and suggest that the AGB of African closed-canopy tropical forests may be particularly sensitive to future precipitation and temperature changes.Item Open Access Capacity shortfalls hinder the performance of marine protected areas globally.(Nature, 2017-03-22) Gill, David A; Mascia, Michael B; Ahmadia, Gabby N; Glew, Louise; Lester, Sarah E; Barnes, Megan; Craigie, Ian; Darling, Emily S; Free, Christopher M; Geldmann, Jonas; Holst, Susie; Jensen, Olaf P; White, Alan T; Basurto, Xavier; Coad, Lauren; Gates, Ruth D; Guannel, Greg; Mumby, Peter J; Thomas, Hannah; Whitmee, Sarah; Woodley, Stephen; Fox, Helen EMarine protected areas (MPAs) are increasingly being used globally to conserve marine resources. However, whether many MPAs are being effectively and equitably managed, and how MPA management influences substantive outcomes remain unknown. We developed a global database of management and fish population data (433 and 218 MPAs, respectively) to assess: MPA management processes; the effects of MPAs on fish populations; and relationships between management processes and ecological effects. Here we report that many MPAs failed to meet thresholds for effective and equitable management processes, with widespread shortfalls in staff and financial resources. Although 71% of MPAs positively influenced fish populations, these conservation impacts were highly variable. Staff and budget capacity were the strongest predictors of conservation impact: MPAs with adequate staff capacity had ecological effects 2.9 times greater than MPAs with inadequate capacity. Thus, continued global expansion of MPAs without adequate investment in human and financial capacity is likely to lead to sub-optimal conservation outcomes.Item Open Access Carbon Gain and Allocation in Five Shade Intolerant Pinus Species(2021-12-08) Wang, YiPinus virginiana (Virginia pine), Pinus echinata (shortleaf pine), Pinus taeda (loblolly pine), Pinus elliottii (slash pine), and Pinus palustris (longleaf pine) are five of the most dominant shade-intolerant pine species in the southeast region. These five species have overlapping geographic ranges, tolerate poor soil conditions and low water availability conditions, and have relatively high volume growth rate. Among the five species, P. virginiana and P. echinata have the shortest needles of around 5-7 cm. P. taeda and P. elliottii have the intermediate needle length of around 15-22 cm, while P. palustris has the longest needles of around 30 cm. To compare the among species differences in biomass growth rate based on their physiology, morphology, and hydraulics related leaf traits, shoot and crown structure, and biomass allocation, we collected the data from an experimental site in Duke Forest and compared the performance of these five species when trees of the same age were grown under the same climate and soil conditions. Our study revealed distinct differences in allometric relationships and biomass allocation patterns among the five species. Analysis of leaf functional traits and crown structure showed variation in the ability to support leaf area at a given leaf mass, branch mass, and sapwood area across species. Finally, the differences in total biomass and wood production among species reflected the combined effect of leaf area index and biomass allocation pattern. We found that, when growing in one environment, species with intermediate needle length (P. taeda and P. elliottii) were more efficient in biomass production and volume growth while balancing the investment in intercepting light and maintaining hydraulic system. The results of this study indicated that growth-related functional traits, combined with biomass allocation patterns that favor stem and aboveground production, make P. taeda and P. elliottii among the fastest growing conifers with high timber values, regionally and globally.Item Open Access CARBON STOCKS IN NORTHEASTERN GABON AND POLICY IMPLICATIONS FOR RUBBER TREE CONCESSIONS(2019-04-24) Jong, Ying WeiAgricultural activities such as oil palm and rubber production have the potential to grow the economies and increase employment in tropical nations, but measures must be taken to offset the negative environmental effects of converting forests into monocultures. One approach to reconciling agricultural development with environmental degradation is to direct agricultural expansion towards low carbon landscapes such as cleared lands and secondary forests. This approach is tested by estimating carbon stocks and flux in northeastern Gabon, Central Africa at the selectively logged ORG concession that is proposed to be converted to a rubber tree plantation. Gabon is in the process of developing its agricultural sector, thus understanding the implications of converting forest into plantations is critical for implementation of best practices for estimating carbon stocks and reducing carbon emissions. This study demonstrates that even within degraded secondary forests in Gabon the mean carbon density (123.8 Mg C ha-1) remains relatively high in comparison to degraded forest in other tropical countries. This value is lower than the mean carbon density in Gabon (160-167 Mg C ha-1) (Bombelli et al., 2009; Saatchi et al., 2011), but substantially higher than the 75 Mg C ha-1 carbon threshold recommended by the High Carbon Stock protocol (HCS; HCS Steering Group Committee, 2017). The carbon density distribution within the ORG concession is related to habitat type: forests on slopes had the highest mean carbon density compared to swamps, which were dominated by low-carbon palm species, and flat terra firma forest, the majority of which had been previously cleared for subsistence agriculture. Through growth and succession, secondary forest should attain carbon densities similar to primary forest, which means there are high environmental opportunity costs of converting secondary forest to plantations. Overall, converting the ORG concession into a rubber plantation will lead to net carbon emissions. If development of the area goes forward, measures should be taken to reduce emissions and prolong carbon retention, such as minimizing soil disturbance, extending harvest rotations, making rubber wood furniture, and setting aside high carbon areas, such as slopes, as offsets.Item Open Access Climate drives the geography of marine consumption by changing predator communities.(Proceedings of the National Academy of Sciences of the United States of America, 2020-11) Whalen, Matthew A; Whippo, Ross DB; Stachowicz, John J; York, Paul H; Aiello, Erin; Alcoverro, Teresa; Altieri, Andrew H; Benedetti-Cecchi, Lisandro; Bertolini, Camilla; Bresch, Midoli; Bulleri, Fabio; Carnell, Paul E; Cimon, Stéphanie; Connolly, Rod M; Cusson, Mathieu; Diskin, Meredith S; D’Souza, Elrika; Flores, Augusto AV; Fodrie, F Joel; Galloway, Aaron WE; Gaskins, Leo C; Graham, Olivia J; Hanley, Torrance C; Henderson, Christopher J; Hereu, Clara M; Hessing-Lewis, Margot; Hovel, Kevin A; Hughes, Brent B; Hughes, A Randall; Hultgren, Kristin M; Jänes, Holger; Janiak, Dean S; Johnston, Lane N; Jorgensen, Pablo; Kelaher, Brendan P; Kruschel, Claudia; Lanham, Brendan S; Lee, Kun-Seop; Lefcheck, Jonathan S; Lozano-Álvarez, Enrique; Macreadie, Peter I; Monteith, Zachary L; O’Connor, Nessa E; Olds, Andrew D; O’Leary, Jennifer K; Patrick, Christopher J; Pino, Oscar; Poore, Alistair GB; Rasheed, Michael A; Raymond, Wendel W; Reiss, Katrin; Rhoades, O Kennedy; Robinson, Max T; Ross, Paige G; Rossi, Francesca; Schlacher, Thomas A; Seemann, Janina; Silliman, Brian R; Smee, Delbert L; Thiel, Martin; Unsworth, Richard KF; van Tussenbroek, Brigitta I; Vergés, Adriana; Yeager, Mallarie E; Yednock, Bree K; Ziegler, Shelby L; Duffy, J EmmettThe global distribution of primary production and consumption by humans (fisheries) is well-documented, but we have no map linking the central ecological process of consumption within food webs to temperature and other ecological drivers. Using standardized assays that span 105° of latitude on four continents, we show that rates of bait consumption by generalist predators in shallow marine ecosystems are tightly linked to both temperature and the composition of consumer assemblages. Unexpectedly, rates of consumption peaked at midlatitudes (25 to 35°) in both Northern and Southern Hemispheres across both seagrass and unvegetated sediment habitats. This pattern contrasts with terrestrial systems, where biotic interactions reportedly weaken away from the equator, but it parallels an emerging pattern of a subtropical peak in marine biodiversity. The higher consumption at midlatitudes was closely related to the type of consumers present, which explained rates of consumption better than consumer density, biomass, species diversity, or habitat. Indeed, the apparent effect of temperature on consumption was mostly driven by temperature-associated turnover in consumer community composition. Our findings reinforce the key influence of climate warming on altered species composition and highlight its implications for the functioning of Earth's ecosystems.Item Open Access Contingency in ecosystem but not plant community response to multiple global change factors(New Phytologist, 2012) Bradford, MA; Wood, SA; Maestre, FT; REYNOLDS, JF; Warren, RJCommunity and ecosystem responses to global environmental change are contingent on the magnitude of change and interacting global change factors. To reveal whether responses are also contingent on the magnitude of each interacting factor, multifactor, multilevel experiments are required, but are rarely conducted. We exposed model grassland ecosystems to six levels of atmospheric CO2 and six levels of nitrogen enrichment, applying the latter both chronically (simulating deposition) and acutely (simulating fertilization). The 66 treatments were maintained for 6 months under controlled growing conditions, with biomass harvested every 28 d and sorted to species. Aboveground plant productivity responses to CO2 were contingent on nitrogen amount, and the responses to nitrogen amount were dependent on whether applications were chronic or acute. Specifically, productivity responses to increasing CO2 concentrations were accentuated with higher nitrogen enrichments, and productivity was greater when higher nitrogen enrichments were applied acutely. Plant community composition was influenced only by nitrogen enrichment, where the co-dominant grass species with the greatest leaf trait plasticity increasingly dominated with higher nitrogen amounts. Community processes are considered to be unpredictable, but our data suggest that the prediction of the impacts of simultaneous global changes is more complex for ecosystem processes, given that their responses are contingent on the levels of interacting factors.Item Open Access Cooking Fuel “Stacking” Implications for Willingness to Switch to Clean Fuels in Peri-urban Kathmandu Valley, Nepal(2020) Rogers, BridgetCooking fuel “stacking,” or the use of multiple types of fuels, can be problematic in interventions when households are using both clean and dirty fuels at the same time. Dirty fuels such as firewood contribute to indoor air pollution, cause detrimental health effects, and are inefficient forms of energy. In this study, cooking fuel preference data was collected from 360 households in peripheral-urban Kathmandu, Nepal during August 2019. Respondents provided fuel information and gave economic preferences for a contingent valuation experiment on their reported primary fuel type. We explored two aims through multiple regression analyses: the relationship between fuel stacking behavior and willingness to pay (WTP), and the household characteristics associated with fuel stacking behavior. The analyses showed that stacking does not affect WTP, and household expenses are a significant factor associated with WTP only among households using LPG as their primary fuel. The secondary aim found that the main household characteristics associated with fuel stacking are household size, firewood gathering behavior, and if the household was affected by the 2015 LPG blockade. The relationships of these characteristics are complex and depend on whether the household is using more LPG or more firewood when stacking. More research is needed to better understand fuel stacking, and why most people in peri-urban Kathmandu prefer LPG as their primary fuel.
Item Open Access Deadwood stocks increase with selective logging and large tree frequency in Gabon.(Glob Chang Biol, 2017-04) Carlson, Ben S; Koerner, Sally E; Medjibe, Vincent P; White, Lee JT; Poulsen, John RDeadwood is a major component of aboveground biomass (AGB) in tropical forests and is important as habitat and for nutrient cycling and carbon storage. With deforestation and degradation taking place throughout the tropics, improved understanding of the magnitude and spatial variation in deadwood is vital for the development of regional and global carbon budgets. However, this potentially important carbon pool is poorly quantified in Afrotropical forests and the regional drivers of deadwood stocks are unknown. In the first large-scale study of deadwood in Central Africa, we quantified stocks in 47 forest sites across Gabon and evaluated the effects of disturbance (logging), forest structure variables (live AGB, wood density, abundance of large trees), and abiotic variables (temperature, precipitation, seasonality). Average deadwood stocks (measured as necromass, the biomass of deadwood) were 65 Mg ha-1 or 23% of live AGB. Deadwood stocks varied spatially with disturbance and forest structure, but not abiotic variables. Deadwood stocks increased significantly with logging (+38 Mg ha-1 ) and the abundance of large trees (+2.4 Mg ha-1 for every tree >60 cm dbh). Gabon holds 0.74 Pg C, or 21% of total aboveground carbon in deadwood, a threefold increase over previous estimates. Importantly, deadwood densities in Gabon are comparable to those in the Neotropics and respond similarly to logging, but represent a lower proportion of live AGB (median of 18% in Gabon compared to 26% in the Neotropics). In forest carbon accounting, necromass is often assumed to be a constant proportion (9%) of biomass, but in humid tropical forests this ratio varies from 2% in undisturbed forest to 300% in logged forest. Because logging significantly increases the deadwood carbon pool, estimates of tropical forest carbon should at a minimum use different ratios for logged (mean of 30%) and unlogged forests (mean of 18%).Item Open Access Decadal biomass increment in early secondary succession woody ecosystems is increased by CO2 enrichment.(Nature communications, 2019-02) Walker, Anthony P; De Kauwe, Martin G; Medlyn, Belinda E; Zaehle, Sönke; Iversen, Colleen M; Asao, Shinichi; Guenet, Bertrand; Harper, Anna; Hickler, Thomas; Hungate, Bruce A; Jain, Atul K; Luo, Yiqi; Lu, Xingjie; Lu, Meng; Luus, Kristina; Megonigal, J Patrick; Oren, Ram; Ryan, Edmund; Shu, Shijie; Talhelm, Alan; Wang, Ying-Ping; Warren, Jeffrey M; Werner, Christian; Xia, Jianyang; Yang, Bai; Zak, Donald R; Norby, Richard JIncreasing atmospheric CO2 stimulates photosynthesis which can increase net primary production (NPP), but at longer timescales may not necessarily increase plant biomass. Here we analyse the four decade-long CO2-enrichment experiments in woody ecosystems that measured total NPP and biomass. CO2 enrichment increased biomass increment by 1.05 ± 0.26 kg C m-2 over a full decade, a 29.1 ± 11.7% stimulation of biomass gain in these early-secondary-succession temperate ecosystems. This response is predictable by combining the CO2 response of NPP (0.16 ± 0.03 kg C m-2 y-1) and the CO2-independent, linear slope between biomass increment and cumulative NPP (0.55 ± 0.17). An ensemble of terrestrial ecosystem models fail to predict both terms correctly. Allocation to wood was a driver of across-site, and across-model, response variability and together with CO2-independence of biomass retention highlights the value of understanding drivers of wood allocation under ambient conditions to correctly interpret and predict CO2 responses.Item Open Access Differential nutrient limitation of soil microbial biomass and metabolic quotients (qCO2): is there a biological stoichiometry of soil microbes?(PLoS One, 2013) Hartman, Wyatt H; Richardson, Curtis JBACKGROUND: Variation in microbial metabolism poses one of the greatest current uncertainties in models of global carbon cycling, and is particularly poorly understood in soils. Biological Stoichiometry theory describes biochemical mechanisms linking metabolic rates with variation in the elemental composition of cells and organisms, and has been widely observed in animals, plants, and plankton. However, this theory has not been widely tested in microbes, which are considered to have fixed ratios of major elements in soils. METHODOLOGY/ PRINCIPAL FINDINGS: To determine whether Biological Stoichiometry underlies patterns of soil microbial metabolism, we compiled published data on microbial biomass carbon (C), nitrogen (N), and phosphorus (P) pools in soils spanning the global range of climate, vegetation, and land use types. We compared element ratios in microbial biomass pools to the metabolic quotient qCO2 (respiration per unit biomass), where soil C mineralization was simultaneously measured in controlled incubations. Although microbial C, N, and P stoichiometry appeared to follow somewhat constrained allometric relationships at the global scale, we found significant variation in the C∶N∶P ratios of soil microbes across land use and habitat types, and size-dependent scaling of microbial C∶N and C∶P (but not N∶P) ratios. Microbial stoichiometry and metabolic quotients were also weakly correlated as suggested by Biological Stoichiometry theory. Importantly, we found that while soil microbial biomass appeared constrained by soil N availability, microbial metabolic rates (qCO2) were most strongly associated with inorganic P availability. CONCLUSIONS/ SIGNIFICANCE: Our findings appear consistent with the model of cellular metabolism described by Biological Stoichiometry theory, where biomass is limited by N needed to build proteins, but rates of protein synthesis are limited by the high P demands of ribosomes. Incorporation of these physiological processes may improve models of carbon cycling and understanding of the effects of nutrient availability on soil C turnover across terrestrial and wetland habitats.Item Open Access Eco-evolutionary feedbacks in community and ecosystem ecology: interactions between the ecological theatre and the evolutionary play.(Philos Trans R Soc Lond B Biol Sci, 2009-06-12) Post, DM; Palkovacs, EPInteractions between natural selection and environmental change are well recognized and sit at the core of ecology and evolutionary biology. Reciprocal interactions between ecology and evolution, eco-evolutionary feedbacks, are less well studied, even though they may be critical for understanding the evolution of biological diversity, the structure of communities and the function of ecosystems. Eco-evolutionary feedbacks require that populations alter their environment (niche construction) and that those changes in the environment feed back to influence the subsequent evolution of the population. There is strong evidence that organisms influence their environment through predation, nutrient excretion and habitat modification, and that populations evolve in response to changes in their environment at time-scales congruent with ecological change (contemporary evolution). Here, we outline how the niche construction and contemporary evolution interact to alter the direction of evolution and the structure and function of communities and ecosystems. We then present five empirical systems that highlight important characteristics of eco-evolutionary feedbacks: rotifer-algae chemostats; alewife-zooplankton interactions in lakes; guppy life-history evolution and nutrient cycling in streams; avian seed predators and plants; and tree leaf chemistry and soil processes. The alewife-zooplankton system provides the most complete evidence for eco-evolutionary feedbacks, but other systems highlight the potential for eco-evolutionary feedbacks in a wide variety of natural systems.Item Open Access Environmental conditions influence the plant functional diversity effect on potential denitrification.(PLoS One, 2011-02-02) Sutton-Grier, Ariana E; Wright, Justin P; McGill, Bonnie M; Richardson, CurtisGlobal biodiversity loss has prompted research on the relationship between species diversity and ecosystem functioning. Few studies have examined how plant diversity impacts belowground processes; even fewer have examined how varying resource levels can influence the effect of plant diversity on microbial activity. In a field experiment in a restored wetland, we examined the role of plant trait diversity (or functional diversity, (FD)) and its interactions with natural levels of variability of soil properties, on a microbial process, denitrification potential (DNP). We demonstrated that FD significantly affected microbial DNP through its interactions with soil conditions; increasing FD led to increased DNP but mainly at higher levels of soil resources. Our results suggest that the effect of species diversity on ecosystem functioning may depend on environmental factors such as resource availability. Future biodiversity experiments should examine how natural levels of environmental variability impact the importance of biodiversity to ecosystem functioning.Item Open Access Evaluation of 11 terrestrial carbon-nitrogen cycle models against observations from two temperate Free-Air CO2 Enrichment studies.(The New phytologist, 2014-05) Zaehle, Sönke; Medlyn, Belinda E; De Kauwe, Martin G; Walker, Anthony P; Dietze, Michael C; Hickler, Thomas; Luo, Yiqi; Wang, Ying-Ping; El-Masri, Bassil; Thornton, Peter; Jain, Atul; Wang, Shusen; Warlind, David; Weng, Ensheng; Parton, William; Iversen, Colleen M; Gallet-Budynek, Anne; McCarthy, Heather; Finzi, Adrien; Hanson, Paul J; Prentice, I Colin; Oren, Ram; Norby, Richard JWe analysed the responses of 11 ecosystem models to elevated atmospheric [CO2 ] (eCO2 ) at two temperate forest ecosystems (Duke and Oak Ridge National Laboratory (ORNL) Free-Air CO2 Enrichment (FACE) experiments) to test alternative representations of carbon (C)-nitrogen (N) cycle processes. We decomposed the model responses into component processes affecting the response to eCO2 and confronted these with observations from the FACE experiments. Most of the models reproduced the observed initial enhancement of net primary production (NPP) at both sites, but none was able to simulate both the sustained 10-yr enhancement at Duke and the declining response at ORNL: models generally showed signs of progressive N limitation as a result of lower than observed plant N uptake. Nonetheless, many models showed qualitative agreement with observed component processes. The results suggest that improved representation of above-ground-below-ground interactions and better constraints on plant stoichiometry are important for a predictive understanding of eCO2 effects. Improved accuracy of soil organic matter inventories is pivotal to reduce uncertainty in the observed C-N budgets. The two FACE experiments are insufficient to fully constrain terrestrial responses to eCO2 , given the complexity of factors leading to the observed diverging trends, and the consequential inability of the models to explain these trends. Nevertheless, the ecosystem models were able to capture important features of the experiments, lending some support to their projections.Item Open Access Experimental evaluation of evolution and coevolution as agents of ecosystem change in Trinidadian streams.(Philos Trans R Soc Lond B Biol Sci, 2009-06-12) Palkovacs, EP; Marshall, MC; Lamphere, BA; Lynch, BR; Weese, DJ; Fraser, DF; Reznick, DN; Pringle, CM; Kinnison, MTEvolution has been shown to be a critical determinant of ecological processes in some systems, but its importance relative to traditional ecological effects is not well known. In addition, almost nothing is known about the role of coevolution in shaping ecosystem function. Here, we experimentally evaluated the relative effects of species invasion (a traditional ecological effect), evolution and coevolution on ecosystem processes in Trinidadian streams. We manipulated the presence and population-of-origin of two common fish species, the guppy (Poecilia reticulata) and the killifish (Rivulus hartii). We measured epilithic algal biomass and accrual, aquatic invertebrate biomass, and detrital decomposition. Our results show that, for some ecosystem responses, the effects of evolution and coevolution were larger than the effects of species invasion. Guppy evolution in response to alternative predation regimes significantly influenced algal biomass and accrual rates. Guppies from a high-predation site caused an increase in algae relative to guppies from a low-predation site; algae effects were probably shaped by observed divergence in rates of nutrient excretion and algae consumption. Rivulus-guppy coevolution significantly influenced the biomass of aquatic invertebrates. Locally coevolved populations reduced invertebrate biomass relative to non-coevolved populations. These results challenge the general assumption that intraspecific diversity is a less critical determinant of ecosystem function than is interspecific diversity. Given existing evidence for contemporary evolution in these fish species, our findings suggest considerable potential for eco-evolutionary feedbacks to operate as populations adapt to natural or anthropogenic perturbations.Item Open Access Experimental evidence that phenotypic divergence in predators drives community divergence in prey.(Ecology, 2009-02) Palkovacs, EP; Post, DMStudies of adaptive divergence have traditionally focused on the ecological causes of trait diversification, while the ecological consequences of phenotypic divergence remain relatively unexplored. Divergence in predator foraging traits, in particular, has the potential to impact the structure and dynamics of ecological communities. To examine the effects of predator trait divergence on prey communities, we exposed zooplankton communities in lake mesocosms to predation from either anadromous or landlocked (freshwater resident) alewives, which have undergone recent and rapid phenotypic differentiation in foraging traits (gape width, gill raker spacing, and prey size-selectivity). Anadromous alewives, which exploit large prey items, significantly reduced the mean body size, total biomass, species richness, and diversity of crustacean zooplankton relative to landlocked alewives, which exploit smaller prey. The zooplankton responses observed in this experiment are consistent with patterns observed in lakes. This study provides direct evidence that phenotypic divergence in predators, even in its early stages, can play a critical role in determining prey community structure.Item Open Access Four-decade responses of soil trace elements to an aggrading old-field forest: B, Mn, Zn, Cu, and Fe.(Ecology, 2008-10) Li, Jianwei; Richter, Daniel D; Mendoza, Arlene; Heine, PaulIn the ancient and acidic Ultisol soils of the Southern Piedmont, USA, we studied changes in trace element biogeochemistry over four decades, a period during which formerly cultivated cotton fields were planted with pine seedlings that grew into mature forest stands. In 16 permanent plots, we estimated 40-year accumulations of trace elements in forest biomass and O horizons (between 1957 and 1997), and changes in bioavailable soil fractions indexed by extractions of 0.05 mol/L HCl and 0.2 mol/L acid ammonium oxalate (AAO). Element accumulations in 40-year tree biomass plus O horizons totaled 0.9, 2.9, 4.8, 49.6, and 501.3 kg/ha for Cu, B, Zn, Mn, and Fe, respectively. In response to this forest development, samples of the upper 0.6-m of mineral soil archived in 1962 and 1997 followed one of three patterns. (1) Extractable B and Mn were significantly depleted, by -4.1 and -57.7 kg/ha with AAO, depletions comparable to accumulations in biomass plus O horizons, 2.9 and 49.6 kg/ha, respectively. Tree uptake of B and Mn from mineral soil greatly outpaced resupplies from atmospheric deposition, mineral weathering, and deep-root uptake. (2) Extractable Zn and Cu changed little during forest growth, indicating that nutrient resupplies kept pace with accumulations by the aggrading forest. (3) Oxalate-extractable Fe increased substantially during forest growth, by 275.8 kg/ha, about 10-fold more than accumulations in tree biomass (28.7 kg/ha). The large increases in AAO-extractable Fe in surficial 0.35-m mineral soils were accompanied by substantial accretions of Fe in the forest's O horizon, by 473 kg/ha, amounts that dwarfed inputs via litterfall and canopy throughfall, indicating that forest Fe cycling is qualitatively different from that of other macro- and micronutrients. Bioturbation of surficial forest soil layers cannot account for these fractions and transformations of Fe, and we hypothesize that the secondary forest's large inputs of organic additions over four decades has fundamentally altered soil Fe oxides, potentially altering the bioavailability and retention of macro- and micronutrients, contaminants, and organic matter itself. The wide range of responses among the ecosystem's trace elements illustrates the great dynamics of the soil system over time scales of decades.Item Open Access Is there foul play in the leaf pocket? The metagenome of floating fern Azolla reveals endophytes that do not fix N2 but may denitrify.(The New phytologist, 2018-01) Dijkhuizen, LW; Brouwer, P; Bolhuis, H; Reichart, G; Koppers, N; Huettel, B; Bolger, AM; Li, F; Cheng, S; Liu, XDinitrogen fixation by Nostoc azollae residing in specialized leaf pockets supports prolific growth of the floating fern Azolla filiculoides. To evaluate contributions by further microorganisms, the A. filiculoides microbiome and nitrogen metabolism in bacteria persistently associated with Azolla ferns were characterized. A metagenomic approach was taken complemented by detection of N2 O released and nitrogen isotope determinations of fern biomass. Ribosomal RNA genes in sequenced DNA of natural ferns, their enriched leaf pockets and water filtrate from the surrounding ditch established that bacteria of A. filiculoides differed entirely from surrounding water and revealed species of the order Rhizobiales. Analyses of seven cultivated Azolla species confirmed persistent association with Rhizobiales. Two distinct nearly full-length Rhizobiales genomes were identified in leaf-pocket-enriched samples from ditch grown A. filiculoides. Their annotation revealed genes for denitrification but not N2 -fixation. 15 N2 incorporation was active in ferns with N. azollae but not in ferns without. N2 O was not detectably released from surface-sterilized ferns with the Rhizobiales. N2 -fixing N. azollae, we conclude, dominated the microbiome of Azolla ferns. The persistent but less abundant heterotrophic Rhizobiales bacteria possibly contributed to lowering O2 levels in leaf pockets but did not release detectable amounts of the strong greenhouse gas N2 O.Item Open Access Long-term thermal sensitivity of Earth's tropical forests.(Science (New York, N.Y.), 2020-05-21) Sullivan, Martin JP; Lewis, Simon L; Affum-Baffoe, Kofi; Castilho, Carolina; Costa, Flávia; Sanchez, Aida Cuni; Ewango, Corneille EN; Hubau, Wannes; Marimon, Beatriz; Monteagudo-Mendoza, Abel; Qie, Lan; Sonké, Bonaventure; Martinez, Rodolfo Vasquez; Baker, Timothy R; Brienen, Roel JW; Feldpausch, Ted R; Galbraith, David; Gloor, Manuel; Malhi, Yadvinder; Aiba, Shin-Ichiro; Alexiades, Miguel N; Almeida, Everton C; de Oliveira, Edmar Almeida; Dávila, Esteban Álvarez; Loayza, Patricia Alvarez; Andrade, Ana; Vieira, Simone Aparecida; Aragão, Luiz EOC; Araujo-Murakami, Alejandro; Arets, Eric JMM; Arroyo, Luzmila; Ashton, Peter; Aymard C, Gerardo; Baccaro, Fabrício B; Banin, Lindsay F; Baraloto, Christopher; Camargo, Plínio Barbosa; Barlow, Jos; Barroso, Jorcely; Bastin, Jean-François; Batterman, Sarah A; Beeckman, Hans; Begne, Serge K; Bennett, Amy C; Berenguer, Erika; Berry, Nicholas; Blanc, Lilian; Boeckx, Pascal; Bogaert, Jan; Bonal, Damien; Bongers, Frans; Bradford, Matt; Brearley, Francis Q; Brncic, Terry; Brown, Foster; Burban, Benoit; Camargo, José Luís; Castro, Wendeson; Céron, Carlos; Ribeiro, Sabina Cerruto; Moscoso, Victor Chama; Chave, Jerôme; Chezeaux, Eric; Clark, Connie J; de Souza, Fernanda Coelho; Collins, Murray; Comiskey, James A; Valverde, Fernando Cornejo; Medina, Massiel Corrales; da Costa, Lola; Dančák, Martin; Dargie, Greta C; Davies, Stuart; Cardozo, Nallaret Davila; de Haulleville, Thales; de Medeiros, Marcelo Brilhante; Del Aguila Pasquel, Jhon; Derroire, Géraldine; Di Fiore, Anthony; Doucet, Jean-Louis; Dourdain, Aurélie; Droissart, Vincent; Duque, Luisa Fernanda; Ekoungoulou, Romeo; Elias, Fernando; Erwin, Terry; Esquivel-Muelbert, Adriane; Fauset, Sophie; Ferreira, Joice; Llampazo, Gerardo Flores; Foli, Ernest; Ford, Andrew; Gilpin, Martin; Hall, Jefferson S; Hamer, Keith C; Hamilton, Alan C; Harris, David J; Hart, Terese B; Hédl, Radim; Herault, Bruno; Herrera, Rafael; Higuchi, Niro; Hladik, Annette; Coronado, Eurídice Honorio; Huamantupa-Chuquimaco, Isau; Huasco, Walter Huaraca; Jeffery, Kathryn J; Jimenez-Rojas, Eliana; Kalamandeen, Michelle; Djuikouo, Marie Noël Kamdem; Kearsley, Elizabeth; Umetsu, Ricardo Keichi; Kho, Lip Khoon; Killeen, Timothy; Kitayama, Kanehiro; Klitgaard, Bente; Koch, Alexander; Labrière, Nicolas; Laurance, William; Laurance, Susan; Leal, Miguel E; Levesley, Aurora; Lima, Adriano JN; Lisingo, Janvier; Lopes, Aline P; Lopez-Gonzalez, Gabriela; Lovejoy, Tom; Lovett, Jon C; Lowe, Richard; Magnusson, William E; Malumbres-Olarte, Jagoba; Manzatto, Ângelo Gilberto; Marimon, Ben Hur; Marshall, Andrew R; Marthews, Toby; de Almeida Reis, Simone Matias; Maycock, Colin; Melgaço, Karina; Mendoza, Casimiro; Metali, Faizah; Mihindou, Vianet; Milliken, William; Mitchard, Edward TA; Morandi, Paulo S; Mossman, Hannah L; Nagy, Laszlo; Nascimento, Henrique; Neill, David; Nilus, Reuben; Vargas, Percy Núñez; Palacios, Walter; Camacho, Nadir Pallqui; Peacock, Julie; Pendry, Colin; Peñuela Mora, Maria Cristina; Pickavance, Georgia C; Pipoly, John; Pitman, Nigel; Playfair, Maureen; Poorter, Lourens; Poulsen, John R; Poulsen, Axel Dalberg; Preziosi, Richard; Prieto, Adriana; Primack, Richard B; Ramírez-Angulo, Hirma; Reitsma, Jan; Réjou-Méchain, Maxime; Correa, Zorayda Restrepo; de Sousa, Thaiane Rodrigues; Bayona, Lily Rodriguez; Roopsind, Anand; Rudas, Agustín; Rutishauser, Ervan; Abu Salim, Kamariah; Salomão, Rafael P; Schietti, Juliana; Sheil, Douglas; Silva, Richarlly C; Espejo, Javier Silva; Valeria, Camila Silva; Silveira, Marcos; Simo-Droissart, Murielle; Simon, Marcelo Fragomeni; Singh, James; Soto Shareva, Yahn Carlos; Stahl, Clement; Stropp, Juliana; Sukri, Rahayu; Sunderland, Terry; Svátek, Martin; Swaine, Michael D; Swamy, Varun; Taedoumg, Hermann; Talbot, Joey; Taplin, James; Taylor, David; Ter Steege, Hans; Terborgh, John; Thomas, Raquel; Thomas, Sean C; Torres-Lezama, Armando; Umunay, Peter; Gamarra, Luis Valenzuela; van der Heijden, Geertje; van der Hout, Peter; van der Meer, Peter; van Nieuwstadt, Mark; Verbeeck, Hans; Vernimmen, Ronald; Vicentini, Alberto; Vieira, Ima Célia Guimarães; Torre, Emilio Vilanova; Vleminckx, Jason; Vos, Vincent; Wang, Ophelia; White, Lee JT; Willcock, Simon; Woods, John T; Wortel, Verginia; Young, Kenneth; Zagt, Roderick; Zemagho, Lise; Zuidema, Pieter A; Zwerts, Joeri A; Phillips, Oliver LThe sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (-9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per °C in the hottest forests (>32.2°C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth's climate.Item Open Access Low concentrations of silver nanoparticles in biosolids cause adverse ecosystem responses under realistic field scenario.(PLoS One, 2013) Colman, Benjamin P; Arnaout, Christina L; Anciaux, Sarah; Gunsch, Claudia K; Hochella, Michael F; Kim, Bojeong; Lowry, Gregory V; McGill, Bonnie M; Reinsch, Brian C; Richardson, Curtis J; Unrine, Jason M; Wright, Justin P; Yin, Liyan; Bernhardt, Emily SA large fraction of engineered nanomaterials in consumer and commercial products will reach natural ecosystems. To date, research on the biological impacts of environmental nanomaterial exposures has largely focused on high-concentration exposures in mechanistic lab studies with single strains of model organisms. These results are difficult to extrapolate to ecosystems, where exposures will likely be at low-concentrations and which are inhabited by a diversity of organisms. Here we show adverse responses of plants and microorganisms in a replicated long-term terrestrial mesocosm field experiment following a single low dose of silver nanoparticles (0.14 mg Ag kg(-1) soil) applied via a likely route of exposure, sewage biosolid application. While total aboveground plant biomass did not differ between treatments receiving biosolids, one plant species, Microstegium vimeneum, had 32 % less biomass in the Slurry+AgNP treatment relative to the Slurry only treatment. Microorganisms were also affected by AgNP treatment, which gave a significantly different community composition of bacteria in the Slurry+AgNPs as opposed to the Slurry treatment one day after addition as analyzed by T-RFLP analysis of 16S-rRNA genes. After eight days, N2O flux was 4.5 fold higher in the Slurry+AgNPs treatment than the Slurry treatment. After fifty days, community composition and N2O flux of the Slurry+AgNPs treatment converged with the Slurry. However, the soil microbial extracellular enzymes leucine amino peptidase and phosphatase had 52 and 27% lower activities, respectively, while microbial biomass was 35% lower than the Slurry. We also show that the magnitude of these responses was in all cases as large as or larger than the positive control, AgNO3, added at 4-fold the Ag concentration of the silver nanoparticles.