Long-distance pollen transport from North America to Greenland in spring

International audienceIn the Arctic domain there is evidence for very long distance transport of pollen grains from boreal forests to tundra environments. However, the sampling protocol used in earlier studies did not allow the determination of the precise timing of the deposition of exotic grains. The ongoing "Epilobe" project monitors the deposition of exotic grains on both western and eastern coasts of Greenland utilizing wind filters, which are changed weekly throughout the entire year. A combination of the identification of tree pollen grains, the dates of deposition of the pollen on the filters, and the distribution map of the trees identified, allows the selection of modeled backward trajectories of air parcels responsible for the capture of the grains in the growing area of northeastern North America, and their long distance transport to Greenland. A survey of data obtained from four stations, analyzed during 2004 and 2005, indicates the occurrence of a general pattern, every spring, which follows the main cyclone tracks reaching this Arctic regio

Litter quality - physical properties

This file provides the chemical quality data for the litter of Potentilla verna and Bromopsis erecta, sampled in the various land use treatments used in the study. Data presented are litter thickness (µm) and litter structural resistance (J.m-1). For each litter species and each land use treatments, eight replcates were measured

Distinct microbial limitations in litter and underlying soil revealed by carbon and nutrient fertilization in a tropical rainforest

Key message Molecular markers were used for paternity recovery in a maritime pine (Pinus pinasterAit.) polycross trial, facilitating forward selection. Different breeding strategies for seed orchard establishment were evaluated by comparing genetic gains and diversity. This work opens up new perspectives in maritime pine breeding.Context Polycross mating designs are widely used in forest tree breeding to evaluate parental breeding values for backward selection. Alternatively, polycross progeny trials may be used to select the best trees on the basis of individual breeding values and molecular pedigree analysis.Aims This study aimed to test such a forward selection strategy for the maritime pine breeding program.Methods In a maritime pine polycross trial, progeny with higher breeding values for growth and stem straightness was first preselected with or without relatedness constraints. After paternity recovery, the preselected trees were ranked on the basis of their breeding values, estimated from the recovered full pedigree. Finally, the best candidates were selected with three different strategies (forward, backward, mixed) and three levels of coancestry constraints to establish a virtual clonal seed orchard.Results Complete pedigrees were successfully recovered for most of the preselected trees. There was no major difference in expected genetic gains between the two preselection strategies which differed for relatedness constraints. Genetic gains were slightly higher for forward selection than for classical backward selection.Conclusion This seminal study opens up new perspectives for using forward selection within the French maritime pine breeding program

Reconstruction of the Grande Pile Eemian using inverse modeling of biomes and delta C-13

International audienceA new method to reconstruct past climatic conditions between 130 and 100 ka BP from pollen and isotopic data is applied to a previously unanalyzed Grande Pile core, GPXXI. We applied the inverse mode to the Biome4 vegetation model. The method utilizes delta C-13, measured in parallel to the pollen samples as a constraint for the model. First the biomes and the delta C-13 simulated by the model are compared with the biome allocation of the pollen data. The delta C-13 to be simulated takes into account the degradation effect on the preserved organic matter. This procedure allows the reconstruction of the mean annual temperature and precipitation as well as the mean temperatures of the warmest and coldest months. We show that during the Eemian sensu stricto, the reconstructed precipitation is similar to modern values with low variability. The cold stadials and the penultimate glaciation are characterized by very low precipitation amounts. The temperature estimates, however, indicate differences with several oscillations identified. The peak values are reached at about 124-125 ka BP, but two other warm intervals are also identified. The variations in temperature appear to be related to sea-surface temperature oscillations in the North Atlantic region and are also in agreement with the timing of ice sheet build-up in the Northern Hemisphere. Seasonal variations are also identified in the estimated temperatures of the warmest and coldest months. (c) 2006 Elsevier Ltd. All rights reserved

Modern pollen rain in savanna and forest ecosystems of Gabon and Cameroon, Central Atlantic Africa

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Mass loss and consumption data

This file provides the mass loss (including control microcosms without detritivores) and the litter consumption (logically with NAs for control microcosms without detritivores), as well as the individual body mass of the detritivores. Mass loss unit = mg.day-1) and consumption unit = mg.g.day-1). Since the experiment was made with binary choices, each microcosm is constituted of 2 litter types(called A and B for clarity). A litter type is a litter species collected in a given land use treatment (fertilization - grazing). Mass loss was recorded for three millipede species (GM = Glomeris marginata, OR = Ommatoiulus rutilans, CC = Cylindroiulus caerulocinctus) and two litter species (Bromopsis erecta ex Bromus erectus and Potentilla verna). The land use treatments are exposed in detail in the article

Data from: Intraspecific variation in litter palatability to macroarthropods in response to grazing and soil fertility

1. Clarifying the functional consequences of intraspecific trait variability in response to interacting trophic levels would provide a significant improvement in our understanding of aboveground-belowground linkages. In particular, the effects of grazing on plant traits may translate into altered litter quality, with potentially important consequences for litter-feeding decomposers. Plant and litter variability in response to grazing is expected to depend on soil fertility levels, with tolerance and defensive strategies more commonly expressed on fertile and poorer soils, respectively. However, how grazing and fertility interactively alter litter quality and palatability to detritivores has not been explored yet. 2. We conducted a cafeteria experiment with three common millipede (Diplopoda) species feeding on leaf litter from two plant species, the grass Bromopsis erecta and the forb Potentilla verna. Each millipede was offered a binary choice between litter types produced by the same plant species, but sampled in plots with distinct herbivory and fertilization status: litter originating from grazed areas or from one-year sheep exclosures, both in native areas and in adjacent paddocks that received chemical N and P fertilization, as well as litter from a 25-year sheep exclusion in the native area. 3. We found that fertilization and herbivore exclusion interactively affected Bromopsis litter quality and palatability, whereas Potentilla was much less affected. Bromopsis litter palatability was not affected by grazing when litter was collected in native plots, except for the long-term exclosure which led to a very low palatability. In contrast, and in line with our expectations, herbivory was associated with much higher palatability in fertilized plots. The changes in palatability were associated with important alterations of litter quality. 4. Overall, our study demonstrates that intraspecific variation in litter can have profound consequences for soil functioning. It emphasizes the role of grazing as a key, but plant species-specific factor controlling litter intraspecific variability, and its complex interaction with soil fertility level. Moreover, our results advocate for a better understanding of the response of the different organisms involved in the decomposition process, in particular litter-feeding macro-detritivores. We encourage future studies aiming at disentangling the various and complex relationships between aboveground processes such as herbivory and soil functioning

Litter quality - chemistry

This file provides the chemical quality data for the litter of Potentilla verna and Bromopsis erecta, sampled in the various land use treatments used in the study. Data presented are CN, CP, NP, polyphenols (%) and condensed tannins (%). For each litter species in each land use treatments, 3 replicates were measured, except for polyphenols (only one replicate)

15. Estimates of temperature and precipitation variations during the Eemian interglacial: New data from the grande pile record (GP XXI)

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Intraspecific variation in litter palatability to macroarthropods in response to grazing and soil fertility

The data associated with this paper are available from the Dryad Digital Repository https://doi.org/10.5061/dryad.s458b5n (Coq et al., 2018).1 - Clarifying the functional consequences of intraspecific trait variability in response to interacting trophic levels would provide a significant improvement in our understanding of above‐ground–below‐ground linkages. In particular, the effects of grazing on plant traits may translate into altered litter quality, with potentially important consequences for litter‐feeding decomposers. Plant and litter variability in response to grazing is expected to depend on soil fertility levels, with tolerance and defensive strategies more commonly expressed on fertile and poorer soils, respectively. However, how grazing and fertility interactively alter litter quality and palatability to detritivores has not been explored yet.2 - We conducted a cafeteria experiment with three common millipede (Diplopoda) species feeding on leaf litter from two plant species, the grass Bromopsis erecta and the forb Potentilla verna. Each millipede was offered a binary choice between litter types produced by the same plant species, but sampled in plots with distinct herbivory and fertilization status: litter originating from grazed areas or from 1‐year sheep exclosures, both in native areas and in adjacent paddocks that received chemical N and P fertilization, as well as litter from a 25‐year sheep exclosures in the native area.3 - We found that fertilization and herbivore exclusion interactively affected Bromopsis litter quality and palatability, whereas Potentilla was much less affected. Bromopsis litter palatability was not affected by grazing when litter was collected in native plots, except for the long‐term exclosure which led to low palatability. In contrast, and in line with our expectations, herbivory was associated with much higher palatability in fertilized plots. The changes in palatability were associated with important alterations of litter quality.4 - Overall, our study demonstrates that intraspecific variation in litter can have profound consequences for soil functioning. It emphasizes the role of grazing as a key, but plant species‐specific factor controlling litter intraspecific variability, and its complex interaction with soil fertility level. Moreover, our results advocate for a better understanding of the response of the different organisms involved in the decomposition process, in particular litter‐feeding macro‐detritivores. We encourage future studies aiming at disentangling the various and complex relationships between above‐ground processes such as herbivory and soil functioning