Extensive forest grazing and hay-making on mires - vegetation changes in south-central Sweden due to land use since Medieval times

Segerström, Ulf; Emanuelsson, Marie

doi:10.1007/s003340200021

Cited by 40 publications

(45 citation statements)

References 24 publications

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“…Pollen studies in the region show a similar timing for the expansion of this type of landscape utilization around A.D. 1300-1500 (41,42), and historical documents mention summer farms in the direct vicinity of Lång-Älgsjön for the first time around A.D. 1650 (Swedish National Heritage Board database, www.fmis.raa.se/cocoon/fornsok/ search.html). The increased presence of humans is further supported by a higher abundance of larger charcoal particles (>25 μm) in the sediment record (Fig.…”

Section: Significancementioning

confidence: 87%

“…This evidence occurs mainly in the form of disturbance indicators, resulting from the gradual opening and alteration of the forest vegetation (40)(41)(42)(43). However, the region underwent more fundamental changes in agricultural practices after the medieval agrarian crisis.…”

Section: Significancementioning

confidence: 99%

“…Activities at these sites included the grazing of the livestock in the forest, production and processing of milk, haymaking on mires for fodder, and occasionally also cultivation of cereals (e.g., barley and rye) (40). To improve forest grazing, the canopy cover was opened and unwanted field-layer vegetation such as dwarf shrubs and mosses was grazed, removed, or burned, leading to an altered, more open forest composition (42).…”

Section: Significancementioning

confidence: 99%

“…Three important effects of summer grazing and farming on OC dynamics in the boreal forest are the following: First, opening of the forest canopy, haymaking on mires, and grazing reduce the aboveground biomass and litter production (42,44). This consequently decreases the labile soil OC pool, which codetermines OC concentrations in surface waters (45).…”

Section: Significancementioning

confidence: 99%

“…This consequently decreases the labile soil OC pool, which codetermines OC concentrations in surface waters (45). Second, the regular removal of biomass lowers the depth to the water table on mires (42,46), reducing the possible OC generation in the soil solution upon rehydration (47). Third, the exposure of fresh, less weathered mineral-soil horizons, associated with soil disturbance by the livestock, facilitates an enhanced adsorption of DOC to mineral surfaces (48).…”

Section: Significancementioning

confidence: 99%

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Early land use and centennial scale changes in lake-water organic carbon prior to contemporary monitoring

Meyer-Jacob

Tolu

Bigler

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Organic carbon concentrations have increased in surface waters across parts of Europe and North America during the past decades, but the main drivers causing this phenomenon are still debated. A lack of observations beyond the last few decades inhibits a better mechanistic understanding of this process and thus a reliable prediction of future changes. Here we present past lake-water organic carbon trends inferred from sediment records across central Sweden that allow us to assess the observed increase on a centennial to millennial time scale. Our data show the recent increase in lake-water carbon but also that this increase was preceded by a landscape-wide, long-term decrease beginning already A.D. 1450-1600. Geochemical and biological proxies reveal that these dynamics coincided with an intensification of human catchment disturbance that decreased over the past century. Catchment disturbance was driven by the expansion and later cessation of widespread summer forest grazing and farming across central Scandinavia. Our findings demonstrate that early land use strongly affected past organic carbon dynamics and suggest that the influence of historical landscape utilization on contemporary changes in lake-water carbon levels has thus far been underestimated. We propose that past changes in land use are also a strong contributing factor in ongoing organic carbon trends in other regions that underwent similar comprehensive changes due to early cultivation and grazing over centuries to millennia.lake-water quality | carbon cycling | land use | Holocene | paleoecology O ver the past three decades, monitoring programs have recorded a widespread increase of organic carbon (OC) concentrations in surface waters in parts of Europe and North America (1-4). OC in lakes and rivers plays a major role in the global carbon cycle by transporting carbon from terrestrial to freshwater and marine environments (5), determining drinking water quality and associated treatment costs (6), and affecting aquatic ecosystem functioning. In aquatic ecosystems, OC influences energy mobilization, light conditions (7), water acidity (8), as well as the transport of metals and pollutants (9). The widespread occurrence of this increase in surface water OC, also referred to as browning or brownification due to an associated increase in color, suggests that regional rather than local factors are the drivers behind this phenomenon, but at present the underlying mechanisms are still controversial.Several hypotheses have been proposed to explain this recent OC increase, from climate change to changes in anthropogenic forcing such as declining atmospheric acid deposition or alterations in landscape utilization. A number of climate-sensitive mechanisms have been suggested to cause an increase in OC export from the terrestrial to the aquatic environment; for example, increased temperatures enhance decomposition rates in organic-rich soils (10) and promote vegetation cover (11). Changes in the amount and timing of precipitation potentially lead to alteration...

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Section: Significancementioning

confidence: 87%

Section: Significancementioning

confidence: 99%

Section: Significancementioning

confidence: 99%

Section: Significancementioning

confidence: 99%

Section: Significancementioning

confidence: 99%

See 3 more Smart Citations

Early land use and centennial scale changes in lake-water organic carbon prior to contemporary monitoring

Meyer-Jacob

Tolu

Bigler

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Investigating molecular changes in organic matter composition in two Holocene lake‐sediment records from central Sweden using pyrolysis‐GC/MS

et al. 2017

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Organic matter (OM) is a key component of lake sediments, affecting carbon, nutrient, and trace metal cycling at local and global scales. Yet little is known about long‐term (millennial) changes in OM composition due to the inherent chemical complexity arising from multiple OM sources and from secondary transformations. In this study we explore how the molecular composition of OM changes throughout the Holocene in two adjacent boreal lakes in central Sweden and compare molecular‐level information with conventional OM variables, including total carbon, total nitrogen, C:N ratios, δ13C, and δ15N. To characterize the molecular OM composition, we employed a new method based on pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS), which yields semiquantitative data on >100 organic compounds of different origin and degradation status. We identify large changes in OM composition after deglaciation (circa 8500 ± 500 B.C.), associated with early landscape development, and during the most recent 40–50 years, driven by degradation processes. With molecular‐level information we can also distinguish between natural landscape development and human catchment disturbance during the last 1700 years. Our study demonstrates that characterization of the molecular OM composition by the high‐throughput Py‐GC/MS method is an efficient complement to conventional OM variables for identification and understanding of past OM dynamics in lake‐sediment records. Holocene changes observed for pyrolytic compounds and compound classes known for having different reactivity indicate the need for further paleo‐reconstruction of the molecular OM composition to better understand both past and future OM dynamics and associated environmental changes.

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Disturbance in Boreal Peatlands

Turetsky

Louis

Ecological Studies

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Extensive forest grazing and hay-making on mires - vegetation changes in south-central Sweden due to land use since Medieval times

Cited by 40 publications

References 24 publications

Early land use and centennial scale changes in lake-water organic carbon prior to contemporary monitoring

Early land use and centennial scale changes in lake-water organic carbon prior to contemporary monitoring

Investigating molecular changes in organic matter composition in two Holocene lake‐sediment records from central Sweden using pyrolysis‐GC/MS

Disturbance in Boreal Peatlands

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