Highly anomalous accumulation rates of C and N recorded by a relic, free-floating peatland in Central Italy

Abstract

Floating islands mysteriously moving around on lakes were described by several Latin authors almost two millennia ago. These fascinating ecosystems, known as free-floating mires, have been extensively investigated from ecological, hydrological and management points of view, but there have been no detailed studies of their rates of accumulation of organic matter (OM), organic carbon (OC) and total nitrogen (TN). We have collected a peat core 4 m long from the free-floating island of Posta Fibreno, a relic mire in Central Italy. This is the thickest accumulation of peat ever found in a free-floating mire, yet it has formed during the past seven centuries and represents the greatest accumulation rates, at both decadal and centennial timescale, of OM (0.63 vs. 0.37 kg/m2/yr), OC (0.28 vs. 0.18 kg/m2/yr) and TN (3.7 vs. 6.1 g/m2/yr) ever reported for coeval peatlands. The anomalously high accretion rates, obtained using 14C age dating, were confirmed using 210Pb and 137Cs: these show that the top 2 m of Sphagnum-peat has accumulated in only ~100 years. As an environmental archive, Posta Fibreno offers a temporal resolution which is 10x greater than any terrestrial peat bog, and promises to provide new insight into environmental changes occurring during the Anthropocene.

Soil degradation determines release of nitrous oxide and dissolved organic carbon from peatlands

“…Peat degradation leads to the mineralization of organic carbon and relative enrichment of N (Krüger et al 2015). In contrast to bogs ( figure 1(a)), fens have lower C/N ratios in peat soils with BD<0.2 g cm -3 ( figure 1(b)), indicating lower C and higher N accumulation in fens than bogs (Wang et al 2014, Zaccone et al 2017. The lower C/N ratios (less than 30) in fens occurred at almost all peat degradation stages.…”

Paleoenvironment change and its impact on carbon and nitrogen accumulation in the Zoige wetland, northeastern Qinghai‐Tibetan Plateau over the past 14,000 years

“…Normally, the C/N ratio of hydrobiont is lower than 10, and that of algae ranges from 4 to 12, and submerged and floating aquatic macrophytes generally have C/N ratio between 10 and 20 [Meyers, 2003]. The C/N ratio of the mixture of aquatic and terrestrial plants fluctuate from 12 to 20 and that of the terrestrial plant ranges from approximately 20 to 40 and even can rise to greater than 100, due to the high carbohydrate content [Dean, 1999;Meyers and Ishiwatari, 1993;Zaccone et al, 2017]. The C/N ratio of the mixture terrestrial and marsh vascular plants range from minima of 10 to 20 to maxima of 40 2 100 [Cloern et al, 2002], and the C/N ratio of modern freshwater marsh plants are usually >13, and even can reach to 26 [Atanassova and Mills, 2016;Khan et al, 2015].…”

“…Therefore, more intensive research on the interactions between environmental change and C and N accumulation and on environmental condition during the Holocene in the Zoige wetland is needed. In this paper, we report records for the δ 13 C in OM (δ 13 C org ), TOC, TN, C/N ratio, humification, and loss on ignition (LOI) in a 4.5 m Hongyuan peat profile from the southern Zoige wetland to reconstruct the history of the paleoenvironment, to evaluate the long‐term C and N sedimentation fluxes (SFs) [ Chen et al ., ; Zaccone et al ., ] in combination with their controlling factor, to monitor changes in the OM source and primary productivity, and to clarify the relationship between environmental conditions and SFs. Other influencing factors of SFs, such as the decomposition rate and nutrient supply, are also investigated.…”

Grasping at straws: a re‐evaluation of sweepstakes colonisation of islands by mammals

“…Floating islands can form in bogs, wetlands, lakes and rivers worldwide [MacMillan, ; Brewster, ; Hughes & Gaudet, ; Trivedy et al, ; Oliver & Mckaye, ; Spruce, 1908 and Wallace, 1876 (both cited in Simons, )]. The thickest floating mire ever recorded (400 cm) was observed in central Italy (Zaccone et al, , ). Such floating islands are created by (mostly Sphagnum ) mosses that reach out into the water from the banks.…”