Forecasting tillage and soil warming effects on earthworm populations

Abstract

Healthy soils are crucial for sustainable food production, but tillage limits the biological regulation of essential ecosystem services. Better understanding of the mechanisms driving management effects on soil ecosystem engineers is needed to support sustainable management under environmental change. This paper presents the Energy–Environment–Earthworm (EEEworm) model, a mechanistic individual‐based model of Lumbricus terrestris populations. Lumbricus terrestris is a dominant earthworm species in undisturbed habitats and is closely associated with numerous ecosystem services such as water flow regulation, soil structure and crop production. In reduced tillage agriculture, a decline in mechanical disturbance allows for L. terrestris proliferation, whilst the activities of L. terrestris can replace many of the soil functions provided by tillage. Extensive EEEworm validation with eight published studies (average R2 = .84) demonstrates a mechanistic approach which can extrapolate between diverse soil, management and weather conditions. EEEworm simulation experiments elucidate that a combination of direct and indirect tillage effects leads to population declines in tilled fields, with litter removal from the soil surface being the main driver. We investigate the effects of different tillage intensities under historical and projected soil warming conditions and find that future warmer and drier soils in our simulation exacerbate the effects of deep ploughing on L. terrestris population declines. These effects result from warmer and drier soil conditions increasing individual metabolic rates and tillage reducing food availability to meet energy demands. Synthesis and applications. Pre‐emptive strategies to mitigate climate change impacts on soil health in agroecosystems should focus on decreasing tillage intensity and retention of crop residues following tillage. Energy–Environment–Earthworm (EEEworm) has the potential to benefit land managers, policy makers, risk assessors and regulators by providing a tool to forecast how soil systems respond to combinations of land management and environmental change. To allow better cost–benefit analysis of contrasting land management systems, a future aim of mechanistic models like EEEworm is to incorporate the links between earthworm populations, soil functions and ecosystem services.

Land management modulates the environmental controls on global earthworm communities

“…Earthworm species richness and total abundance were highest in temperate and lowest in mediterranean climates, while abundance was comparable in tropical and boreal but species richness higher in boreal than tropical climates (Figure ). Climate thus strongly influences global earthworm communities, as hypothesized, through individual physiological and behavioural responses to temperature and soil water extremes (Johnston et al, ). Interestingly, this study indicates nonlinear latitudinal shifts in earthworm species richness, previously thought to increase from high to low latitudes (Lavelle, ).…”

“…Earthworms are typically classified into three broad ecological groups (epigeic, anecic and endogeic), which play different roles in ecosystem functioning and display different responses to management and environmental changes (Blouin et al, 2013). Epigeic (surface-living) and anecic (vertical burrowing) earthworms rely on leaf litter for habitat and food, and when this is disturbed by management practices such as tillage, their numbers are largely reduced (Briones & Schmidt, 2017;Johnston, Sibly, & Thorbek, 2018). Thus, managed soils are often dominated by endogeic species, which live in temporary horizontal burrows in the mineral soil (Riley, Pommeresche, Eltun, Hansen, & Korsaeth, 2008).…”

Predicting population responses to environmental change from individual-level mechanisms: towards a standardized mechanistic approach

“…Because physiological and biochemical properties are widely shared across taxa and/or species, energy budgets also provide a general framework for representing individual life cycles [71]. When coupled with heterogeneous landscapes, energy budgets integrated into population models are useful for predicting population responses to changing resource distributions and temperature regimes [48,49]. However, current energy budget approaches are limited to describing life cycles in response to a small number of abiotic drivers (temperature, resource amount, and energy contents).…”

“…Bocedi et al[47], Galic et al[48], Johnston et al[49], Boyd et al[50] royalsocietypublishing.org/journal/rspb Proc. R. Soc.…”

Long Term Effects of Ploughing and Conservation Tillage Methods on Earthworm Abundance and Crumb Ratio

“…Authors referred to the quality of habitat, e.g., soil looseness or structure, temperature, water content, shading of surface, and supplying with food material [13,14]. Evaluation of the relationships among tillage, soil condition, and earthworm abundance has been widely published [4,10,11,14,15], but it is needed to highlight that year weather effects in long-term experiments on their habitat required more knowledge.…”