Anthropogenic changes to the Holocene nitrogen cycle in Ireland

Abstract

Chemical signatures from Bronze Age animal bones show that prehistoric humans had a major impact on the nitrogen cycle in Ireland.

Complexities of Stable Carbon and Nitrogen Isotope Biogeochemistry in Ancient Freshwater Ecosystems: Implications for the Study of Past Subsistence and Environmental Change

“…This may ultimately lead to increased δ 13 C values for respired CO 2 (coming from metabolized terrestrially-derived nutrients; see section Variation in Carbon Sources) that are passed up the food web (Nordt et al, 1994;Street-Perrott et al, 2004). Likewise, similar climatic trends that cause a transition from forests to open grasslands could promote a regime shift in prevalence of different kinds of mycorrhizal-plant relationships, which play an important role in the fractionation of nitrogen isotopes in nutrients taken up by terrestrial plants, potentially resulting in higher δ 15 N for nitrogenous nutrients (Szpak et al, 2014;Guiry et al, 2018) that are transported to adjacent aquatic ecosystems. Another important impact can come more directly from the influence of temperature and aridity on terrestrial nitrogen-cycle openness with warmer conditions potentially favoring higher levels of denitrification and ammonia volatilization (Austin and Vitousek, 1998;Handley et al, 1999;Szpak, 2014).…”

“…In comparison with sediments, archaeological fauna record environmental change from a different ecological perspective and data interpretation are subject to a different set of strengths and weaknesses, making them potentially complementary (Guiry et al, submitted). For instance, variability associated with short term intra-annual oscillations in environmental conditions, sediment mixing, and diagenesis that may complicate interpretations of time series composed from sediment isotopic compositions (Lehmann et al, 2002;Lu et al, 2014) may not present a significant issue when analyzing bone collagen isotopic compositions (which provide an inter-annual average) from longer-lived fauna-a quality which can lend a degree of temporal stability to a data set (Guiry et al, 2018). In this context, the prospect for exploring past climate change through isotopic analyses of time series of aquatic fauna, such as fish and birds from archaeological sources, is worthy of closer consideration.…”

Quality control for modern bone collagen stable carbon and nitrogen isotope measurements

“…Burton et al., 2001; Guiry, Needs‐Howarth, et al, 2016; Guiry, Orchard, Royle, Cheung, & Yang, 2020; Misarti, Finney, Maschner, & Wooller, 2009; Szpak, Orchard, McKechnie, & Gröcke, 2012). These studies are particularly important because they can allow for more accurate reconstructions of preindustrial environmental conditions as well as provide detailed insights into how humans have altered ecosystem dynamics throughout the Anthropocene (Braje et al., 2017; Guiry, Beglane, et al, 2018; Guiry, Buckley, et al, 2020; Szpak, Buckley, Darwent, & Richards, 2018; Szpak et al., 2019)—both of which, in turn, can provide context for guiding future conservation policy and environmental restoration efforts (Rick & Lockwood, 2013; Swetnam, Allen, & Betancourt, 1999).…”

Deforestation caused abrupt shift in Great Lakes nitrogen cycle

“…Within the context of debate about the onset of the Anthropocene (Lewis and Maslin 2015), there is a growing consensus that "pristine environments" probably did not exist where humans were present, because there was always some form of impact from human activities (Heckenberger et al 2003). This perspective has been supported by archaeological research showing that ancient societies, particularly those that used agriculture, had significant impacts at both local and regional scales on terrestrial and aquatic nutrient cycles for millennia (Curtis et al 1998;Hadley et al 2010;Guiry et al 2018). Evaluating the role of past human activities as drivers of ecological change has been a priority for archaeologists (Kintigh et al 2014), but is complicated by the fact that ancient anthropogenic impacts on the environment are spatiotemporally heterogeneous and occur along a continuum of intensity (from very significant to ephemeral).…”

“…In the context of recent debate about the timing of the origins of the Anthropocene (Lewis and Maslin 2015), in which past societies are considered as potential architects of the first broad-scale environmental changes, the role of humans as drivers of biogeochemical processes such as the nitrogen cycle is becoming increasingly important (Hadley et al 2010;Kintigh et al 2014;Guiry et al 2018).…”