Modelling the biogeochemical cycle of silicon in soils: Application to a temperate forest ecosystem

Gérard, Frédéric; Mayer, K. Ulrich; Hodson, Martin J.; Ranger, Jacques

doi:10.1016/j.gca.2007.11.010

Cited by 148 publications

(124 citation statements)

References 81 publications

(136 reference statements)

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“…H 0 : µ forest = µ human = (µ urban + µ cropland + µ grassland )/3 versus H 1 : µ forest > µ human (1) H 0 : µ forest = µ agricultural = (µ cropland + µ pasture )/2 versus H 1 : µ forest > µ agricultural (2) H 0 : µ forest = µ urban versus H 1 : µ forest > µ urban (3) H 0 : µ forest = µ grassland versus H 1 : µ forest > µ grassland (4) H 0 : µ forest = µ cropland versus H 1 : µ forest > µ cropland (5) Here, µ forest , µ urban , µ cropland and µ pasture represent the regression coefficients of the proportions of forested area, urban area, cropland and grasslands, respectively. We used a right-sided t-test and constructed the corresponding one-sided confidence interval for each of the contrasts µ forest − µ human (forest versus human), µ forest − µ agricultural (forest versus agriculture), µ forest − µ urban (forest versus urban), µ forest − µ grassland (forest versus grassland) and µ forest − µ cropland (forest versus cropland).…”

Section: Methodsmentioning

confidence: 99%

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Historical land use change has lowered terrestrial silica mobilization

et al. 2010

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Continental export of si to the coastal zone is closely linked to the ocean carbon sink and to the dynamics of phytoplankton blooms in coastal ecosystems. Presently, however, the impact of human cultivation of the landscape on terrestrial si fluxes remains unquantified and is not incorporated in models for terrestrial si mobilization. In this paper, we show that land use is the most important controlling factor of si mobilization in temperate European watersheds, with sustained cultivation ( > 250 years) of formerly forested areas leading to a twofold to threefold decrease in baseflow delivery of si. This is a breakthrough in our understanding of the biogeochemical si cycle: it shows that human cultivation of the landscape should be recognized as an important controlling factor of terrestrial si fluxes.

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Section: Methodsmentioning

confidence: 99%

“…I t has recently been shown that intense biogeochemical cycling of silica occurs in soils 1,2 . The annual ecosystem biogeochemical cycling of Si exceeds the annual export from continents to the ocean by two orders of magnitude 3,4 and effectively buffers bedrockweathering Si fluxes 5 .…”

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confidence: 99%

Historical land use change has lowered terrestrial silica mobilization

et al. 2010

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“…Alexandre et al 1997;Melzer et al 2012;Gerard et al 2008;Blecker et al 2006). Depth distributions of BSi suggest the presence of a refractory pool of ASi which may include aged BSi (Saccone et al 2006;Cornelis et al 2011).…”

Section: Evidence For Continental Dsi Retention From River Geochemistrymentioning

confidence: 99%

Lack of steady-state in the global biogeochemical Si cycle: emerging evidence from lake Si sequestration

et al. 2014

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Weathering of silicate minerals releases dissolved silicate (DSi) to the soil-vegetation system. Accumulation and recycling of this DSi by terrestrial ecosystems creates a pool of reactive Si on the continents that buffers DSi export to the ocean. Human perturbations to the functioning of the buffer have been a recent research focus, yet a common assumption is that the continental Si cycle is at steadystate. However, we have no good idea of the timescales of ecosystem Si pool equilibration with their environments. A review of modelling and geochemical considerations suggests the modern continental Si cycle is in fact characterised in the longterm by an active accumulation of reactive Si, at least partially attributable to lakes and reservoirs. These lentic systems accumulate Si via biological conversion of DSi to biogenic silica (BSi). An analysis of new and published data for nearly 700 systems is presented to assess their contribution to the accumulating continental pool. Surface sediment BSi concentrations (n = 692) vary between zero and [60 % SiO 2 by weight, apparently independently of lake size, location or water chemistry. Using sediment core BSi accumulation rates (n = 109), still no relationships are found with lake or catchment parameters. However, issues associated with single-core accumulation rates should in any case preclude their use in elemental accumulation calculations. Based on lake/reservoir mass-balances (n = 34), our best global-scale estimate of combined lake and reservoir Si retention is 1.53 TMol year -1 , or 21-27 % of river DSi export. Again, no scalable relationships are apparent, suggesting Si retention is a complex process that varies from catchment to catchment. The lake Si sink has implications for estimation of weathering flux generation from river chemistry. The size of the total continental Si pool is poorly constrained, as is its accumulation rate, but lakes clearly contribute substantially. A corollary to this emerging understanding is that the flux and isotopic composition of DSi delivered to the ocean has likely varied over time, partly mediated by a fluctuating continental pool, including in lakes.

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“…and pedological processes. Uptake of DSi in the vegetation and dissolution of ASi in soils has been shown to be an important factor for the DSi export to rivers from catchments dominated by boreal wetlands (Struyf et al, 2010a), forests (Gérard et al, 2008) and grasslands (Blecker et al, 2006).…”

Section: Introductionmentioning

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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Modelling the biogeochemical cycle of silicon in soils: Application to a temperate forest ecosystem

Cited by 148 publications

References 81 publications

Historical land use change has lowered terrestrial silica mobilization

Historical land use change has lowered terrestrial silica mobilization

Lack of steady-state in the global biogeochemical Si cycle: emerging evidence from lake Si sequestration

Anthropogenic impact on amorphous silica pools in temperate soils

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