Contrasting dynamics and trait controls in first-order root compared with leaf litter decomposition

Decomposition is a key component of the global carbon (C) cycle, yet current ecosystem C models do not adequately represent the contributions of plant roots and their mycorrhizae to this process. The understanding of decomposition dynamics and their control by traits is particularly limited for the most distal first-order roots. Here we followed decomposition of first-order roots and leaf litter from 35 woody plant species differing in mycorrhizal type over 6 years in a Chinese temperate forest. First-order roots decomposed more slowly (k = 0.11 ± 0.01 years−1) than did leaf litter (0.35 ± 0.02 years−1), losing only 35% of initial mass on average after 6 years of exposure in the field. In contrast to leaf litter, nonlignin root C chemistry (nonstructural carbohydrates, polyphenols) accounted for 82% of the large interspecific variation in first-order root decomposition. Leaf litter from ectomycorrhizal (EM) species decomposed more slowly than that from arbuscular mycorrhizal (AM) species, whereas first-order roots of EM species switched, after 2 years, from having slower to faster decomposition compared with those from AM species. The fundamentally different dynamics and control mechanisms of first-order root decomposition compared with those of leaf litter challenge current ecosystem C models, the recently suggested dichotomy between EM and AM plants, and the idea that common traits can predict decomposition across roots and leaves. Aspects of C chemistry unrelated to lignin or nitrogen, and not presently considered in decomposition models, controlled first-order root decomposition; thus, current paradigms of ecosystem C dynamics and model parameterization require revision.

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Rapid evolution at the Drosophila telomere: transposable element dynamics at an intrinsically unstable locus

Genetics ◽

10.1093/genetics/iyaa027 ◽

2020 ◽

Vol 217 (2) ◽

Author(s):

Michael P McGurk ◽

Anne-Marie Dion-Côté ◽

Daniel A Barbash

Keyword(s):

Copy Number ◽

Large Scale ◽

Insertion Site ◽

Rapid Evolution ◽

Interspecific Variation ◽

High Rate ◽

Evolutionary Strategy ◽

Control Mechanisms ◽

Genetic Conflict ◽

Number Variation

AbstractDrosophila telomeres have been maintained by three families of active transposable elements (TEs), HeT-A, TAHRE, and TART, collectively referred to as HTTs, for tens of millions of years, which contrasts with an unusually high degree of HTT interspecific variation. While the impacts of conflict and domestication are often invoked to explain HTT variation, the telomeres are unstable structures such that neutral mutational processes and evolutionary tradeoffs may also drive HTT evolution. We leveraged population genomic data to analyze nearly 10,000 HTT insertions in 85 Drosophila melanogaster genomes and compared their variation to other more typical TE families. We observe that occasional large-scale copy number expansions of both HTTs and other TE families occur, highlighting that the HTTs are, like their feral cousins, typically repressed but primed to take over given the opportunity. However, large expansions of HTTs are not caused by the runaway activity of any particular HTT subfamilies or even associated with telomere-specific TE activity, as might be expected if HTTs are in strong genetic conflict with their hosts. Rather than conflict, we instead suggest that distinctive aspects of HTT copy number variation and sequence diversity largely reflect telomere instability, with HTT insertions being lost at much higher rates than other TEs elsewhere in the genome. We extend previous observations that telomere deletions occur at a high rate, and surprisingly discover that more than one-third do not appear to have been healed with an HTT insertion. We also report that some HTT families may be preferentially activated by the erosion of whole telomeres, implying the existence of HTT-specific host control mechanisms. We further suggest that the persistent telomere localization of HTTs may reflect a highly successful evolutionary strategy that trades away a stable insertion site in order to have reduced impact on the host genome. We propose that HTT evolution is driven by multiple processes, with niche specialization and telomere instability being previously underappreciated and likely predominant.

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Revisiting the ‘direct mineral cycling’ hypothesis: arbuscular mycorrhizal fungi colonize leaf litter, but why?

The ISME Journal ◽

10.1038/s41396-019-0403-2 ◽

2019 ◽

Vol 13 (8) ◽

pp. 1891-1898 ◽

Cited By ~ 18

Author(s):

Rebecca A. Bunn ◽

Dylan T. Simpson ◽

Lorinda S. Bullington ◽

Ylva Lekberg ◽

David P. Janos

Keyword(s):

Arbuscular Mycorrhizal Fungi ◽

Leaf Litter ◽

Mycorrhizal Fungi ◽

Arbuscular Mycorrhizal ◽

Mineral Cycling

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Meiofauna in stream habitats: temporal dynamics of abundance, biomass and secondary production in different substrate microhabitats in a first-order stream

Aquatic Ecology ◽

10.1007/s10452-020-09795-5 ◽

2020 ◽

Vol 54 (4) ◽

pp. 1079-1095

Author(s):

Henrike Brüchner-Hüttemann ◽

Christoph Ptatscheck ◽

Walter Traunspurger

Keyword(s):

Density Distribution ◽

Leaf Litter ◽

Secondary Production ◽

Dead Wood ◽

Temporal Dynamics ◽

Seasonal Patterns ◽

Order Stream ◽

First Order ◽

Relative Contribution ◽

Meiofaunal Abundance

Abstract Meiofaunal abundance, biomass and secondary production were investigated over 13 months in an unpolluted first-order stream. Four microhabitats were considered: sediment and the biofilms on dead wood, macrophytes and leaf litter. The relative contribution of the microhabitats to secondary production and the influence of environmental factors on meiofaunal density distribution were estimated. We expected (1) meiofaunal abundance and biomass to exhibit seasonal patterns, with more pronounced seasonal fluctuations on macrophytes and leaf litter than in the other microhabitats, (2) annual secondary production to be highest in sediment; however, the relative contribution of the microhabitats to monthly secondary production would change during the year, and (3) a bottom-up driven influence on meiofaunal density distribution in the microhabitats. Meiofaunal annual mean abundance, biomass and secondary production were 7–14 times higher in sediment and on dead wood than on macrophytes and leaf litter. Significant seasonal patterns described the meiofaunal abundance in sediment and on leaf litter as well as the biomass in sediment, on macrophytes and leaf litter. Organisms in sediment and on dead wood contributed 48 and 43%, respectively, to secondary production m−2, but in regard to the stream area covered by the microhabitats, sediment had the highest share (80%). Significant determinants of the density distribution were AFDM, protozoans, bacteria and Chl-a, which influenced all meiofaunal groups. Our study clearly indicates that meiofaunal organisms in sediment and on dead wood have a remarkable share on total secondary production of lotic systems which is especially relevant for forested low-order streams.

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Dynamics and Control Mechanisms in Maintenance of Regional Cerebral Blood Flow

Stroke ◽

10.1161/01.str.5.4.461 ◽

1974 ◽

Vol 5 (4) ◽

pp. 461-469 ◽

Cited By ~ 7

Author(s):

YURI E. MOSKALENKO ◽

IVAN T. DEMCHENKO ◽

ALEXANDER I. KRIVCHENKO ◽

INNA P. FEDULOVA

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Regional Cerebral Blood Flow ◽

Control Mechanisms ◽

Regional Cerebral Blood ◽

Dynamics And Control ◽

And Control

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Long-term effects of canopy opening and liming on leaf litter production, and on leaf litter and fine-root decomposition in a European beech (Fagus sylvatica L.) forest

Forest Ecology and Management ◽

10.1016/j.foreco.2014.11.029 ◽

2015 ◽

Vol 338 ◽

pp. 183-190 ◽

Cited By ~ 10

Author(s):

Na Lin ◽

Norbert Bartsch ◽

Steffi Heinrichs ◽

Torsten Vor

Keyword(s):

Leaf Litter ◽

Fine Root ◽

European Beech ◽

Root Decomposition ◽

Litter Production ◽

Long Term Effects ◽

Canopy Opening ◽

Fagus Sylvatica L ◽

Leaf Litter Production

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Impacts of earthworms on nitrogen acquisition from leaf litter by arbuscular mycorrhizal ash and ectomycorrhizal beech trees

Environmental and Experimental Botany ◽

10.1016/j.envexpbot.2015.06.013 ◽

2015 ◽

Vol 120 ◽

pp. 1-7 ◽

Cited By ~ 8

Author(s):

Nan Yang ◽

Klaus Schützenmeister ◽

Diana Grubert ◽

Hermann F. Jungkunst ◽

Dirk Gansert ◽

...

Keyword(s):

Leaf Litter ◽

Arbuscular Mycorrhizal ◽

Nitrogen Acquisition

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Dynamics and control of loop reactors - a review

Mathematical Modelling of Natural Phenomena ◽

10.1051/mmnp/2021035 ◽

2021 ◽

Author(s):

Moshe Sheintuch ◽

Olga Nekhamkina

Keyword(s):

Infinite Number ◽

Front Propagation ◽

Complex Frequency ◽

Periodic Operation ◽

Arrhenius Kinetics ◽

First Order ◽

Dynamics And Control ◽

Moving Coordinate ◽

And Control ◽

Propagation Velocities

In loop reactors the system is composed of several reactor units that are organized in a loop and the feeding takes place at one of several ports with switching of the feed port. In its simplest operation a pulse is formed and rotates around it, producing high temperatures which enable combustion of dilute streams. A limiting model with infinite number of units was derived. Rotating pulses, steady in a moving coordinate, emerge in both models when the switching to front propagation velocities ~1. But this behavior exists over a narrow domain. Simulations were conducted with generic first order Arrhenius kinetics. Experimental observations are reviewed. Outside the narrow frozen rotating pattern domain the system may exhibit multi- or quasi-periodic operation separated by domains of inactive reaction. The bifurcation set incorporates many 'finger'-like domains of complex frequency-locked solutions that allow to extend the operation domain with higher feed temperatures. Control is necessary to attain stable simple rotating frozen pattern within the narrow domains of active operation. Various tested control approaches are reviewed. Actual implementation of combustion in LR will involve several reactants of different ignition temperatures. Design and control should be aimed at producing locked fronts and avoid extinction of slower reactions.

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