Vertical stratification of Neotropical leaf-nosed bats (Chiroptera: Phyllostomidae) revealed by stable carbon isotopes

2011 ◽  
Vol 27 (03) ◽  
pp. 211-222 ◽  
Author(s):  
Katja Rex ◽  
Robert Michener ◽  
Thomas H. Kunz ◽  
Christian C. Voigt
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Species Interactions ◽  
Rain Forest ◽  
Stable Carbon Isotopes ◽  
Stable Carbon Isotope ◽  
The Body ◽  
Vertical Stratification ◽  
Forest Site ◽  
Stable Carbon

Abstract:Tropical rain forests harbour the most diverse plant and animal assemblages known to science, but our understanding of assemblage structure and species interactions is limited. Bats, as the only flying mammals, have the potential to exploit resources from all strata in forest communities. Thus, fruit-eating phyllostomid bats often have been categorized into canopy-, subcanopy- and understorey-foraging species, based largely upon the height at which they were most frequently captured. Here we challenge this classification and use stable carbon isotopes to assess foraging height of bat species at an Amazonian rain-forest site in Ecuador and at a Caribbean lowland rain-forest site in Costa Rica for comparison with data from mist-net captures. The proportion of the heavy stable carbon isotope13C in relation to the lighter12C isotope increases in plants from ground level to the canopy (0.12‰ m−1–0.18‰ m−1), and these differences in stable carbon isotope signatures are reflected in the body tissue of phytophagous bats. We used the stable carbon isotope ratio (δ13C) of wing tissue to estimate the foraging heights of 54 phyllostomid species in two Neotropical bat assemblages. Based on stable isotope data, phyllostomid species exploit food resources at all vertical strata of the forest. Capture height was not a reliable predictor of foraging height and suggests that bats most likely use lower strata to commute between foraging sites to avoid predators. Vertical stratification is likely to be a key factor promoting niche partitioning, thus promoting high local species richness in many tropical animal assemblages.

scholarly journals Degradation changes stable carbon isotope depth profiles in palsa peatlands

2014 ◽  
Vol 11 (1) ◽  
pp. 1383-1412 ◽  
Author(s):  
J. P. Krüger ◽  
J. Leifeld ◽  
C. Alewell
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Stable Carbon Isotopes ◽  
Stable Carbon Isotope ◽  
Stable Carbon ◽  
Δ13c Values ◽  
Depth Profiles ◽  
Degradation Rates ◽  
Aerobic Decomposition ◽  
Permafrost Thawing

Abstract. Palsa peatlands are a significant carbon pool in the global carbon cycle and are projected to change by global warming due to accelerated permafrost thaw. Our aim was to use stable carbon isotopes as indicators of palsa degradation. Depth profiles of stable carbon isotopes generally reflect organic matter dynamics in soils with an increase of δ13C values during aerobic decomposition and stable or decreasing δ13C values with depth during anaerobic decomposition. Stable carbon isotope depth profiles of undisturbed and degraded sites of hummocks as well as hollows at three palsa peatlands in northern Sweden were used to investigate the degradation processes. The depth patterns of stable isotopes clearly differ between intact and degraded hummocks at all sites. Erosion and cryoturbation at the degraded sites significantly changes the stable carbon isotope depth profiles. At the intact hummocks the uplifting of peat material by permafrost is indicated by a turning in the δ13C depth trend and this assessment is supported by a change in the C / N ratios. For hollows isotope patterns were less clear, but some hollows and degraded hollows in the palsa peatlands show differences in their stable carbon isotope depth profiles indicating enhanced degradation rates. We conclude that the degradation of palsa peatlands by accelerated permafrost thawing could be identified with stable carbon isotope depth profiles. At intact hummocks δ13C depth patterns display the uplifting of peat material by a change in peat decomposition processes.

scholarly journals Stable carbon isotopes as indicators for environmental change in palsa peats

2011 ◽  
Vol 8 (7) ◽  
pp. 1769-1778 ◽  
Author(s):  
C. Alewell ◽  
R. Giesler ◽  
J. Klaminder ◽  
J. Leifeld ◽  
M. Rollog
Keyword(s):  
Environmental Change ◽  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Climate Warming ◽  
Anaerobic Degradation ◽  
Stable Carbon Isotopes ◽  
Stable Carbon Isotope ◽  
Stable Carbon ◽  
Depth Profiles ◽  
Water Saturated

Abstract. Palsa peats are unique northern ecosystems formed under an arctic climate and characterized by a high biodiversity and sensitive ecology. The stability of the palsas are seriously threatened by climate warming which will change the permafrost dynamic and induce a degradation of the mires. We used stable carbon isotope depth profiles in two palsa mires of Northern Sweden to track environmental change during the formation of the mires. Soils dominated by aerobic degradation can be expected to have a clear increase of carbon isotopes (δ13C) with depth, due to preferential release of 12C during aerobic mineralization. In soils with suppressed degradation due to anoxic conditions, stable carbon isotope depth profiles are either more or less uniform indicating no or very low degradation or depth profiles turn to lighter values due to an enrichment of recalcitrant organic substances during anaerobic mineralisation which are depleted in 13C. The isotope depth profile of the peat in the water saturated depressions (hollows) at the yet undisturbed mire Storflaket indicated very low to no degradation but increased rates of anaerobic degradation at the Stordalen site. The latter might be induced by degradation of the permafrost cores in the uplifted areas (hummocks) and subsequent breaking and submerging of the hummock peat into the hollows due to climate warming. Carbon isotope depth profiles of hummocks indicated a turn from aerobic mineralisation to anaerobic degradation at a peat depth between 4 and 25 cm. The age of these turning points was 14C dated between 150 and 670 yr and could thus not be caused by anthropogenically induced climate change. We found the uplifting of the hummocks due to permafrost heave the most likely explanation for our findings. We thus concluded that differences in carbon isotope profiles of the hollows might point to the disturbance of the mires due to climate warming or due to differences in hydrology. The characteristic profiles of the hummocks are indicators for micro-geomorphic change during permafrost up heaving.

scholarly journals Degradation changes stable carbon isotope depth profiles in palsa peatlands

2014 ◽  
Vol 11 (12) ◽  
pp. 3369-3380 ◽  
Author(s):  
J. P. Krüger ◽  
J. Leifeld ◽  
C. Alewell
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Stable Carbon Isotopes ◽  
Stable Carbon Isotope ◽  
Stable Carbon ◽  
Δ13c Values ◽  
Depth Profiles ◽  
Degradation Rates ◽  
Aerobic Decomposition ◽  
Permafrost Thawing

Abstract. Palsa peatlands are a significant carbon pool in the global carbon cycle and are projected to change by global warming due to accelerated permafrost thaw. Our aim was to use stable carbon isotopes as indicators of palsa degradation. Depth profiles of stable carbon isotopes generally reflect organic matter dynamics in soils with an increase of δ13C values during aerobic decomposition and stable or decreasing δ13C values with depth during anaerobic decomposition. Stable carbon isotope depth profiles of undisturbed and degraded sites of hummocks as well as hollows at three palsa peatlands in northern Sweden were used to investigate the degradation processes. The depth patterns of stable isotopes clearly differ between intact and degraded hummocks at all sites. Erosion and cryoturbation at the degraded sites significantly changes the stable carbon isotope depth profiles. At the intact hummocks the uplifting of peat material by permafrost is indicated by a turning in the δ13C depth trend, and this assessment is supported by a change in the C / N ratios. For hollows isotope patterns were less clear, but some hollows and degraded hollows in the palsa peatlands show differences in their stable carbon isotope depth profiles indicating enhanced degradation rates. We conclude that the degradation of palsa peatlands by accelerated permafrost thawing can be identified with stable carbon isotope depth profiles. At intact hummocks δ13C depth patterns display the uplifting of peat material by a change in peat decomposition processes.

scholarly journals An observational constraint on stomatal function in forests: evaluating coupled carbon and water vapor exchange with carbon isotopes in the Community Land Model (CLM4.5)

2016 ◽  
Vol 13 (18) ◽  
pp. 5183-5204 ◽  
Author(s):  
Brett Raczka ◽  
Henrique F. Duarte ◽  
Charles D. Koven ◽  
Daniel Ricciuto ◽  
Peter E. Thornton ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Nitrogen Limitation ◽  
Carbon Isotope Discrimination ◽  
Stable Carbon Isotope ◽  
Atmospheric Co2 ◽  
Stable Carbon ◽  
Isotope Discrimination ◽  
Community Land Model

Abstract. Land surface models are useful tools to quantify contemporary and future climate impact on terrestrial carbon cycle processes, provided they can be appropriately constrained and tested with observations. Stable carbon isotopes of CO2 offer the potential to improve model representation of the coupled carbon and water cycles because they are strongly influenced by stomatal function. Recently, a representation of stable carbon isotope discrimination was incorporated into the Community Land Model component of the Community Earth System Model. Here, we tested the model's capability to simulate whole-forest isotope discrimination in a subalpine conifer forest at Niwot Ridge, Colorado, USA. We distinguished between isotopic behavior in response to a decrease of δ13C within atmospheric CO2 (Suess effect) vs. photosynthetic discrimination (Δcanopy), by creating a site-customized atmospheric CO2 and δ13C of CO2 time series. We implemented a seasonally varying Vcmax model calibration that best matched site observations of net CO2 carbon exchange, latent heat exchange, and biomass. The model accurately simulated observed δ13C of needle and stem tissue, but underestimated the δ13C of bulk soil carbon by 1–2 ‰. The model overestimated the multiyear (2006–2012) average Δcanopy relative to prior data-based estimates by 2–4 ‰. The amplitude of the average seasonal cycle of Δcanopy (i.e., higher in spring/fall as compared to summer) was correctly modeled but only when using a revised, fully coupled An − gs (net assimilation rate, stomatal conductance) version of the model in contrast to the partially coupled An − gs version used in the default model. The model attributed most of the seasonal variation in discrimination to An, whereas interannual variation in simulated Δcanopy during the summer months was driven by stomatal response to vapor pressure deficit (VPD). The model simulated a 10 % increase in both photosynthetic discrimination and water-use efficiency (WUE) since 1850 which is counter to established relationships between discrimination and WUE. The isotope observations used here to constrain CLM suggest (1) the model overestimated stomatal conductance and (2) the default CLM approach to representing nitrogen limitation (partially coupled model) was not capable of reproducing observed trends in discrimination. These findings demonstrate that isotope observations can provide important information related to stomatal function driven by environmental stress from VPD and nitrogen limitation. Future versions of CLM that incorporate carbon isotope discrimination are likely to benefit from explicit inclusion of mesophyll conductance.

Basketmaker II Subsistence: Carbon Isotopes and Other Dietary Indicators from Cedar Mesa, Utah

1991 ◽  
Vol 56 (3) ◽  
pp. 444-459 ◽  
Author(s):  
R. G. Matson ◽  
Brian Chisholm
Keyword(s):  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Stable Carbon Isotope ◽  
Isotope Analysis ◽  
Settlement Pattern ◽  
Skeletal Remains ◽  
Stable Carbon ◽  
Stable Carbon Isotope Analysis ◽  
Carbon Isotope Analysis ◽  
Lines Of Evidence

Four separate lines of evidence show that the Cedar Mesa Basketmaker II were dependent on maize horticulture: the settlement pattern of the mesa-top Basketmaker II; stable carbon-isotope analysis of Basketmaker and other skeletal remains from the Cedar Mesa area; and two different analyses of coprolites and midden constituents from the Turkey Pen Cave site (a Basketmaker II site in Grand Gulch, which drains parts of Cedar Mesa). All of these analyses concur with a dependence on maize horticulture for the Cedar Mesa Basketmaker II, a dependence not differing significantly from later Pueblo inhabitants of Cedar Mesa and elsewhere. Whether other Basketmaker II variants were as reliant on maize is uncertain, but there are good indications that at least some, and probably all, were. By 2,000 years ago the Basketmaker II peoples on Cedar Mesa were not modified hunters and gatherers, but relied on maize.

scholarly journals Stable carbon isotopes as indicators for micro-geomorphic changes in palsa peats

2011 ◽  
Vol 8 (1) ◽  
pp. 527-548 ◽  
Author(s):  
C. Alewell ◽  
R. Giesler ◽  
J. Klaminder ◽  
J. Leifeld ◽  
M. Rollog
Keyword(s):  
Carbon Isotope ◽  
Climate Warming ◽  
Anaerobic Degradation ◽  
Turning Point ◽  
Stable Carbon Isotopes ◽  
Stable Carbon Isotope ◽  
Stable Carbon ◽  
Depth Profiles ◽  
The Stability ◽  
Water Saturated

Abstract. Palsa peats are unique northern ecosystems formed under an arctic climate and characterized by an unique biodiversity and ecology. The stability of the palsas are seriously threatened by climate warming which will change the permafrost dynamic and results in degradation of the mires. We used stable carbon isotope depth profiles in two palsa mires of Northern Sweden to track environmental change during the formation of the mires. Carbon isotope (δ13C) depth profile of the yet undisturbed mire Storflaket indicated very low to no degradation of the peat in the water saturated depressions (hollows) but increased rates of anaerobic degradation at the Stordalen site. The latter might be induced by degradation of the permafrost cores in the uplifted areas (hummocks) and subsequent braking and submerging of the hummock peat into the hollows due to climate warming. Carbon isotope depth profiles of hummocks indicated a turn from aerobic mineralisation to anaerobic degradation at a peat depth between 4 to 25 cm. The age of these turning point was 14C dated between 150 and 670 years and could thus not be caused by anthropogenically induced climate change. We found the uplifting of the hummocks due to permafrost heave the most likely explanation for our findings. We thus concluded that differences in carbon isotope profiles of the hollows might point to the disturbance of the mires due to climate warming or due to differences in hydrology. The characteristic profiles of the hummocks are indicators for micro-geomorphic change during permafrost up heaving.

Seedling growth, leaf water status and signature of stable carbon isotopes in C3 perennials exposed to natural phytochemicals

2012 ◽  
Vol 60 (8) ◽  
pp. 676 ◽  
Author(s):  
M. Iftikhar Hussain ◽  
Manuel J. Reigosa
Keyword(s):  
Water Use Efficiency ◽  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Water Use ◽  
Stable Carbon Isotopes ◽  
Carbon Isotope Discrimination ◽  
Water Status ◽  
Perennial Species ◽  
Stable Carbon ◽  
Use Efficiency

In the present study, we evaluated the seedling growth, water status and signature of stable carbon isotopes in C3 perennial species exposed to natural phytochemicals. Three perennial species, cocksfoot (Dactylis glomerata), perennial ryegrass (Lolium perenne) and common sorrel (Rumex acetosa), were grown for 30 days in perlite, watered with Hoagland solution and exposed to the phytochemicals benzoxazolin-2(3H)-one (BOA) and cinnamic acid (CA) at 0, 0.1, 0.5, 1.0 and 1.5 mM concentrations. BOA markedly decreased the leaf and root fresh weights of D. glomerata and L. perenne in a concentration-dependent manner. The leaf fresh weight (LFW) of plants treated with CA (1.5 mM) was similarly affected by showing a decrease of LFW, being the lowest in L. perenne (56%) followed by D. glomerata (46%). The relative water contents of L. perenne, D. glomerata and R. acetosa were decreased while maximum RWC reduction was observed in L. perenne. Carbon isotope discrimination in L. perenne, D. glomerata and R. acetosa were reduced following treatment with BOA and CA at 1.5 mM. BOA at 1.5 mM decreased the ratio of intercellular to ambient CO2 concentration relative to control in L. perenne, D. glomerata and R. acetosa. There was an increase in water-use efficiency in L. perenne, D. glomerata and R. acetosa after treatment with BOA and CA. The dry weight of plants treated with CA (1.5 mM) showed different patterns of variation, being lowest in L. perenne (33%) followed by D. glomerata (3%) and R. acetosa (2%). Phytotoxicity was higher for the perennial grass than for the perennial broadleaf. These results clearly demonstrate a widespread occurrence of phytotoxicity among the three species, their tolerance and relationship between carbon isotope discrimination and intrinsic water-use efficiency.

scholarly journals Stable Carbon Isotopes in Zea mays

2018 ◽  
Author(s):  
Robert J. Twohey ◽  
Lucas M. Roberts ◽  
Anthony J. Studer
Keyword(s):  
Zea Mays ◽  
Carbon Isotopes ◽  
Water Use ◽  
Stable Carbon Isotopes ◽  
Carbon Fixation ◽  
Isotope Composition ◽  
Stable Carbon Isotope ◽  
Climate Change Scenarios ◽  
Transpiration Efficiency ◽  
Stable Carbon

SummaryThe increasing demand for food production and predicted climate change scenarios highlight the need for improvements in crop sustainability. The efficient use of water will become increasingly important for rainfed agricultural crops even in fertile regions that have historically received ample precipitation. Improvements in water-use efficiency in Zea mays have been limited, and warrants a renewed effort aided by molecular breeding approaches. Progress has been constrained by the difficulty of measuring water-use in a field environment. The stable carbon isotope composition (δ13C) of the leaf has been proposed as an integrated signature of carbon fixation with a link to stomatal conductance. However, additional factors affecting leaf δ13C exist, and a limited number of studies have explored this trait in Z. mays. Here we present an extensive characterization of leaf δ13C in Z. mays. Significant variation in leaf δ13C exists across diverse lines of Z. mays, which we show to be heritable across several environments.Furthermore, we examine temporal and spatial variation in leaf δ13C to determine the optimum sampling time to maximize the use of leaf δ13C as a trait. Finally, our results demonstrate the relationship between transpiration and leaf δ13C in the field and the greenhouse. Decreasing transpiration and soil moisture are associated with decreasing leaf δ13C. Taken together these results outline a strategy for using leaf δ13C and reveal its usefulness as a measure of transpiration efficiency under well-watered conditions rather than a predictor of performance under drought.Significance StatementThis study identifies sources of variation in stable carbon isotopes of maize leaves and establishes the framework for connecting leaf δ13C and transpiration efficiency.

scholarly journals Anaerobic methane oxidation by nitrate: kinetic isotope effect

2018 ◽  
Vol 10 (1) ◽  
Author(s):  
Vasiliy A. Vavilin
Keyword(s):  
Dynamic Model ◽  
Carbon Isotope ◽  
Carbon Isotopes ◽  
Isotope Effect ◽  
Isotope Fractionation ◽  
Kinetic Isotope Effect ◽  
Stable Carbon Isotopes ◽  
Stable Carbon ◽  
Fractionation Factor ◽  
Kinetic Isotope

The ratio of stable carbon isotopes (13C/12C) in different environments serves as a significant limitation in estimating the global balance of methane [Hornibrook et al., 2000]. In this case, the value of 13C/12C largely depends on the kinetic isotope effect associated with the metabolism of microorganisms that produce and consume CH4. The article suggests a dynamic model of the processes of methane formation and its anaerobic oxidation with nitrate by methanotrophic denitrifying microorganisms (DAOM), which allowed estimating the fractionation factor of stable carbon isotopes. In the experiment with peat from the minerotrophic bog [Smemo, Yavitt, 2007], the dynamics of the amount of methane and was measured. The dynamic model showed that the introduction of nitrate leads to a slow decrease in the partial pressure of methane. Since methane in the DAOM process is a substrate, methane is enriched with heavier carbon 13C in the system under study. This leads to an increase in the value . The carbon isotope fractionation factor during methane oxidation with nitrate was equal to 1.018 and comparable with the fraction of carbon isotope fractionation in the process of acetoclastic methanogenesis (1.01). Model calculations have shown that during incubation the apparent fractionation factor of carbon isotopes with the simultaneous formation of methane and DAOM slowly decreases. The ratio of 13C/12C isotopes in dissolved and gaseous methane practically does not differ. The model showed that an increase in the initial concentration of nitrate increases the rate of DAOM, which leads to a decrease in the concentration of dissolved methane. In this case, the value of 13C/12C increases. In field studies, Shi et al. (2017) showed that the presence of DAOM in peat bogs in which fertilizers penetrate can be controlled by the amount of nitrate used and the depth of penetration into the anoxic layer. Two MATLAB files describing DAOM are attached to the article.

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