Agricultural silica harvest: have humans created a new loop in the global silica cycle?

Vandevenne, Floor; Struyf, Eric; Clymans, Wim; Meire, Patrick

doi:10.1890/110046

Cited by 149 publications

(121 citation statements)

References 27 publications

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“…Human transformations of the landscape are strongly impacting on ecosystem Si processing, yet the processes and underlying mechanisms are still poorly understood. Changes in riverine DSi fluxes along a temperate European watershed [24] as well as lowered BSi soil stocks under sustained agricultural conditions have already been observed [25][26][27]. Grasslands in particular play an important role in global Si cycling, showing a high capacity to store BSi as well as moving Si from relatively inert mineral silicate soil layers to biologically active soil horizons, by enhancing mineral weathering [28].…”

Section: Introductionmentioning

confidence: 92%

Grazers: biocatalysts of terrestrial silica cycling

et al. 2013

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Silica is well known for its role as inducible defence mechanism countering herbivore attack, mainly through precipitation of opaline, biogenic silica (BSi) bodies (phytoliths) in plant epidermal tissues. Even though grazing strongly interacts with other element cycles, its impact on terrestrial silica cycling has never been thoroughly considered. Here, BSi content of ingested grass, hay and faeces of large herbivores was quantified by performing multiple chemical extraction procedures for BSi, allowing the assessment of chemical reactivity. Dissolution experiments with grass and faeces were carried out to measure direct availability of BSi for dissolution. Average BSi and readily soluble silica numbers were higher in faeces as compared with grass or hay, and differences between herbivores could be related to distinct digestive strategies. Reactivity and dissolvability of BSi increases after digestion, mainly due to degradation of organic matrices, resulting in higher silica turnover rates and mobilization potential from terrestrial to aquatic ecosystems in non-grazed versus grazed pasture systems (2 versus 20 kg Si ha 21 y 21). Our results suggest a crucial yet currently unexplored role of herbivores in determining silica export from land to ocean, where its availability is linked to eutrophication events and carbon sequestration through C-Si diatom interactions.

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Section: Introductionmentioning

confidence: 92%

Grazers: biocatalysts of terrestrial silica cycling

et al. 2013

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“…We neglect processes that can be responsible for ASi losses but do not result in increased Si delivery to rivers such as (re-)precipitation of dissolved ASi as secondary clays (e.g. koalinite and gibbsite) (Lucas et al, 1993), bio-mineralization (Van Cappellen, 2003), direct removal of ASi by annual crop harvest, timber logging and grazing ( Vandevenne et al, 2011) and losses due to soil erosion (Triplett, 2008;Smis et al, 2011). We also assume that our Swedish data are representative for the whole temperate region, which comprises 70 % of the Earth's land surface and varies strongly in climate, geology, pedology and vegetation.…”

Section: Historical Deforestation: An Estimate For Temperate Regions mentioning

confidence: 99%

Anthropogenic impact on amorphous silica pools in temperate soils

et al. 2011

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Abstract. Human land use changes perturb biogeochemical silica (Si) cycling in terrestrial ecosystems. This directly affects Si mobilisation and Si storage and influences Si export from the continents, although the magnitude of the impact is unknown. A major reason for our lack of understanding is that very little information exists on how land use affects amorphous silica (ASi) storage in soils. We have quantified and compared total alkali-extracted (PSi a ) and easily soluble (PSi e ) Si pools at four sites along a gradient of anthropogenic disturbance in southern Sweden. Land use clearly affects ASi pools and their distribution. Total PSi a and PSi e for a continuous forested site at Siggaboda Nature Reserve (66 900 ± 22 800 kg SiO 2 ha −1 and 952 ± 16 kg SiO 2 ha −1 ) are significantly higher than disturbed land use types from the Råshult Culture Reserve including arable land (28 800 ± 7200 kg SiO 2 ha −1 and 239 ± 91 kg SiO 2 ha −1 ), pasture sites (27 300 ± 5980 kg SiO 2 ha −1 and 370 ± 129 kg SiO 2 ha −1 ) and grazed forest (23 600 ± 6370 kg SiO 2 ha −1 and 346 ± 123 kg SiO 2 ha −1 ). Vertical PSi a and PSi e profiles show significant (p < 0.05) variation among the sites. These differences in size and distribution are interpreted as the long-term effect of reduced ASi replenishment, as well as changes in ecosystem specific pedogenic processes and increased mobilisation of the PSi a in disturbed soils. We have also made a first, though rough, estimate of the magnitude of change in temperate continental ASi pools due to human disturbance. Assuming that our data are representative, we estimate that total ASi storage in soils has declined by ca. 10 % since the onset of agricultural development (3000 BCE). Recent agricultural expansion (after 1700 CE) may have resulted in an average additional export of 1.1 ± 0.8 Tmol Si yr −1 from the soil reservoir to aquatic ecosystems. This is ca. 20 % to the global land-ocean SiCorrespondence to: W. Clymans (wim.clymans@ees.kuleuven.be) flux carried by rivers. It is necessary to update this estimate in future studies, incorporating differences in pedology, geology and climatology over temperate regions, but data are currently not sufficient. Yet, our results emphasize the importance of human activities for Si cycling in soils and for the land-ocean Si flux.

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“…Li et al (2006) described the annual Si cycle of uptake, retention, and return in a moso bamboo (Phyllostachys pubescens) community in China. Bamboo also contributes to carbon bio-sequestration within silica phytoliths (Parr et al 2010;Song et al 2013;Huang et al 2014), and harvesting substantially changes terrestrial Si export fluxes to rivers and oceans, because reconstitution of biogenic Si in litter fall is prevented (Vandevenne et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Biological cycle of silicon in moso bamboo (Phyllostachys pubescens) forests in central Japan

Umemura

Takenaka

2014

Ecological Research

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Silicon (Si) has various biogeochemical functions, such as regulating soil formation and species composition, not only in terrestrial ecosystems but also in aquatic ones. Bamboo stands accumulate large quantities of amorphous Si. Evaluating Si dynamics in moso bamboo (Phyllostachys pubescens) forests, which are currently spreading through eastern Asia, is important in understanding their biogeochemical function as a supply source of phytoliths. We conducted a study on the organic accumulation and biological cycle of Si in three P. pubescens stands in central Japan with different site characteristics. The amounts of Si accumulation aboveground and underground were 200-360 and 180-460 kg/ha, respectively. These values indicate that Si accumulation underground was comparable to that aboveground. Silicon supply to the forest floor through litterfall was 77-330 kg/ha/year corresponding to 165-706 kg/ha/year as phytoliths (SiO 2 ), and 72-88 % was supplied as leaf litter. These results showed that a huge biogenic Si pool derived from bamboo plants exists in the floor of bamboo forests. Furthermore, we estimated the Si turnover time in P. pubescens forests as being 1.3-12.2 years, although this variation may depend on forestry conditions such as soil water content or stem density.

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Agricultural silica harvest: have humans created a new loop in the global silica cycle?

Abstract: The agricultural silica loop F Vandevenne et al. 244 www.frontiersinecology.org

Cited by 149 publications

References 27 publications

Grazers: biocatalysts of terrestrial silica cycling

Grazers: biocatalysts of terrestrial silica cycling

Anthropogenic impact on amorphous silica pools in temperate soils

Biological cycle of silicon in moso bamboo (Phyllostachys pubescens) forests in central Japan

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