Do soil organisms affect aboveground litter decomposition in the semiarid Patagonian steppe, Argentina?

Araujo, Patricia I.; Yahdjian, Laura; Austin, Amy T.

doi:10.1007/s00442-011-2063-4

Cited by 42 publications

(28 citation statements)

References 79 publications

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“…Previous studies indicated plant litter decomposition is a key process in terrestrial ecosystems, including carbon turnover and nutrient releasing [56]. Soil microorganisms affect aboveground litter decomposition and represent a biotic component affecting nutrient releasing [57]. In this study, the below-ground interactions were also discussed.…”

Section: Discussionmentioning

confidence: 88%

The Impact of Microbial Biotransformation of Catechin in Enhancing the Allelopathic Effects of Rhododendron formosanum

Wang

Jhan

et al. 2013

PLoS ONE

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Rhododendron formosanum is distributed widely in the central mountains in Taiwan and the major allelopathic compound in the leaves has been identified as (-)-catechin, which is also a major allelochemical of an invasive spotted knapweed in North America. Soil microorganisms play key roles in ecosystems and influence various important processes, including allelopathy. However, no microorganism has been identified as an allelochemical mediator. This study focused on the role of microorganisms in the allelopathic effects of R. formosanum. The microorganism population in the rhizosphere of R. formosanum was investigated and genetic analysis revealed that the predominant genera of microorganisms in the rhizosphere of R. formosanum were Pseudomonas, Herbaspirillum, and Burkholderia. The dominant genera Pseudomonas utilized (-)-catechin as the carbon source and catalyzed the conversion of (-)-catechin into protocatechuic acid in vitro. The concentrations of allelochemicals in the soil were quantified by liquid chromatography-electrospray ionization/tandem mass spectrometry. The concentration of (-)-catechin in the soil increased significantly during the extreme rainfall in the summer season and suppressed total bacterial populations. Protocatechuic acid accumulation was observed while total bacterial populations increased abundantly in both laboratory and field studies. Allelopathic interactions were tested by evaluating the effects of different allelochemicals on the seed germination, radicle growth, and photosynthesis system II of lettuce. Protocatechuic acid exhibited higher phytotoxicity than (-)-catechin did and the effect of (-)-catechin on the inhibition of seed germination was enhanced by combining it with protocatechuic acid at a low concentration. This study revealed the significance of the allelopathic interactions between R. formosanum and microorganisms in the rhizosphere. These findings demonstrate that knowledge regarding the precise biotransformation process of (-)-catechin by microorganisms in the environment is necessary to increase our understanding of allelopathy.

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Section: Discussionmentioning

confidence: 88%

The Impact of Microbial Biotransformation of Catechin in Enhancing the Allelopathic Effects of Rhododendron formosanum

Wang

Jhan

et al. 2013

PLoS ONE

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“…On the one hand, the asynchrony between soil water availability and temperatures favourable to decomposition in the Patagonian region (Paruelo et al 1995) may constrain the abundance and activity of soil organisms (Henegan et al 1999). Additionally, low concentrations of soil organic matter in bare soil and open areas (Gonzalez-Polo & Austin 2009), and a minor role of soil fauna in surface litter decomposition in the Patagonian steppe (Araujo, Yahdjian & Austin 2012) all suggest that biotic activity may be highly constrained at the arid end of the precipitation gradient, either by low temperatures, drought or labile C availability. Photodegradation thus overrides the biotic control on litter decomposition in these sites , and its relative importance on surface litter decomposition is directly linked to changes in plant cover at the ecosystem scale.…”

Section: N T E G R a T I N G R A I N F A L L L I T T E R Q U A L mentioning

confidence: 99%

A shady business: pine afforestation alters the primary controls on litter decomposition along a precipitation gradient in Patagonia, Argentina

Araujo

Austin

2015

Journal of Ecology

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1. Our understanding of the principal controls on litter decomposition is critical for our capacity to predict how global changes will impact terrestrial ecosystems. Although climate, litter quality and soil organisms clearly modulate carbon (C) and nutrient turnover, land-use change affecting plant species composition and structure can alter the relative importance of such controls. 2. We took advantage of prior land-use changes of intentional planting of exotic forest species along a broad precipitation gradient [250-2200 mm mean annual precipitation (MAP)] in Patagonia, South America, where we established five paired sites in natural vegetation and adjacent 35-year-old pine plantations. We explored direct and interactive effects of precipitation and plant community structure on litter decomposition with in situ decomposition, common litters and reciprocal transplants, in addition to an evaluation of microenvironmental changes. 3. Surface litter decomposition in natural vegetation (NV) was similar in all sites along the gradient, independent of litter quality, MAP or soil characteristics, while mass loss demonstrated a significant positive linear relationship with MAP in pine plantations (PP). 4. Decomposition of common litters in PP was markedly reduced with respect to NV, which was > 50% faster at the arid extreme of the gradient. C:N ratios predicted decomposition only in PP, and differences in decomposition were highly correlated with impacts of vegetative cover on incident solar radiation. 5. Synthesis. Concurrent changes in plant cover in NV with increasing MAP resulted in reduced incident solar radiation at the soil surface and decreased the relative importance of photodegradation as a control on surface mass loss. These changes eclipsed direct effects of water availability, litter quality and soil nutrients. In contrast, increased shade and recalcitrant litter with afforestation in PP sites combined such that photodegradation was entirely eliminated as a control and biotic decomposition was much reduced. While afforestation projects are promoted as a strategy to mitigate increased atmospheric carbon dioxide due to human activity, our results highlight that primary controls of litter decomposition were substantially altered with unexpected consequences for the C balance of these ecosystems.

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“…While we detected some impacts of digging mammals on litter decomposition, most likely due to soil infiltration, the impacts were limited to the early stages of decomposition. Above‐ground decomposition processes therefore might be driven more strongly by abiotic factors, such as solar radiation (Austin & Vivanco, ), especially in arid environments, without significant impacts of invertebrates (Araujo, Yahdjian, & Austin, ) or digging mammals over a long time period.…”

Section: Discussionmentioning

confidence: 99%

Rainfall‐dependent impacts of threatened ecosystem engineers on organic matter cycling

2019

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Species loss is often associated with a decline in ecosystem functions. Globally, digging mammals (or ecosystem engineers) are functionally important, altering soil processes at local scales. However, their effects on the process of decomposition are poorly understood, particularly at larger scales, where the environment may moderate the magnitude of effects. We tested the landscape‐scale effects of reintroducing ecologically extinct digging mammals on two aspects of nutrient cycling over a large environmental gradient in Australia, where many digging mammals became extinct or ecologically extinct following the arrival of Europeans. We measured the impacts of digging mammals on soil organic matter content and plant litter decomposition over a 3,000 km transect, where annual average rainfall varied between 166 and 877 mm. We set up paired study plots (n = 8–10) inside and outside five reintroduction reserves. We took soil samples to assess soil organic matter content and set up litter bags to measure plant litter decomposition over 4 and 12 months. We used macroinvertebrate exclusion and macroinvertebrate access treatments to determine the relative importance of macroinvertebrates in decomposition with and without digging mammals. Soil organic matter was greater in reintroduction areas, but the magnitude of the effect was driven by productivity (average annual rainfall as a proxy), with little effect of digging activity at the wettest sites. Short‐term plant matter decomposition was greater in the presence of digging mammals, and their effect was dependent on the amount of rain that fell during the study period. Long‐term litter decomposition increased with annual rainfall, independent of digging mammals. Unexpectedly, macroinvertebrate exclusion increased decomposition rates over 12 months. Reintroduction of digging mammals substantially alters soil processes and organic matter decomposition, but impacts are rainfall‐dependent. Restoring native digging mammals to their historical distribution is likely to reverse degradation of ecosystem processes, but the magnitude of this effect depends on the environment. A free Plain Language Summary can be found within the Supporting Information of this article.

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Do soil organisms affect aboveground litter decomposition in the semiarid Patagonian steppe, Argentina?

Cited by 42 publications

References 79 publications

The Impact of Microbial Biotransformation of Catechin in Enhancing the Allelopathic Effects of Rhododendron formosanum

The Impact of Microbial Biotransformation of Catechin in Enhancing the Allelopathic Effects of Rhododendron formosanum

A shady business: pine afforestation alters the primary controls on litter decomposition along a precipitation gradient in Patagonia, Argentina

Rainfall‐dependent impacts of threatened ecosystem engineers on organic matter cycling

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