Increasing biomass demand enlarges negative forest nutrient budget areas in wood export regions

Abstract

Energy production from biomass is one of the adopted strategies in different European countries to limit global warming to within the 1.5–2° targets after the 2015 UN climate agreement. This will motivate enhanced forest harvest rates and whole tree harvest to supply the increasing biomass demand. Negative nutrient budgets for certain timberland areas where geogenic nutrient supply cannot cope with harvesting rates will be one consequence. A spatially explicit analysis for a U.S. timberland area of 33,570 km2 reveals that for a minimum nutrient loss and supply scenario, negative nutrient budgets occur in 17, 20, 16, and almost 94% of the studied areas for Ca, K, Mg, and P, respectively. For a maximum nutrient loss (considering intensive harvesting) and supply assumptions, the affected areas increase to 50, 57, 45 and 96% for Ca, K, Mg, and P, respectively. In general, atmospheric nutrient deposition is of minor importance for the high weathering supply cases. Increasing global woody biomass demand may cause additional pressure on forested ecosystems, enlarging negative nutrient budget areas. If woody biomass demand rises, strategies to counterbalance nutrient gaps might be needed, for example, by preparing harvested areas with rock products, designed to replenish growth limiting nutrients, and/or implementing forest management strategies to minimize nutrient export.

Repply RC2

“…No, according to Christman and Rogan (2012) the nearest-neighbor scaling method can keep with the overall proportions of the original fine resolution map. This is because the interpolant exhibits the smallest variation of the interpolant function while meeting the measured data.…”

Ideas and perspectives: Synergies from co-deployment of negative emission technologies

“…The main reason is the higher mobility of most exchangeable metals at low pH, which decreases logarithmically with increasing pH (Kabata-Pendias, 2010;Robinson et al, 1996;Tack et al, 1996;Harter, 1983). Levels of pH 6 and higher generally ensure very low levels of exchangeable harmful metals, with the exception of arsenic, depending on the oxidation state (Dixit and Hering, 2003). The release of base cations from rock flour leads to a soil pH increase.…”

Base cations in the soil bank. Non-exchangeable pools may sustain centuries of net loss to forestry and leaching

“…We are not aware of any other studies of ecosystem mass-balance of base cations that have attempted to explore the sizes of nonexchangeable nutrient pools in relation to net ecosystem losses over time. Those that have compared HCl-or HNO 3extractable base cation contents in similar soils have commonly found acid-extractable pools to be many fold larger than salt-extractable exchangeable pools (Olofsson et al, 2016;Nezat et al, 2007;Simard et al, 1989;Moritsuka et al, 2002;Lucash et al, 2012).…”

“…These practices may severely impact soil fertility, especially in forest ecosystems where nutrient availability may be low (Feller, 2005;Kreutzweiser et al, 2008;Thiffault et al, 2011;Achat et al, 2015). For example, in the USA it has been projected that increased biomass harvest for biofuels will markedly increase the area of managed forest that will experience net nutrient losses due to biomass export: from 17 to 50% of the total forest area for Ca, 20 to 57% for K and 16 to 45% for Mg (de Oliveira Garcia et al, 2018). Similar concerns have been raised in other countries, including Sweden (Akselsson et al, 2007a), Belgium (Vangansbeke et al, 2015), Finland (Aherne et al, 2012) and Germany (Knust et al, 2016).…”

“…The nutrient mass balance (i.e. input-output budget) approach is commonly used to estimate the net gain or loss of nutrient elements in the soil or ecosystems under different management and climate scenarios (Akselsson et al, 2007a;Knust et al, 2016;de Oliveira Garcia et al, 2018). This mass-balance approach typically accounts for inputs via atmospheric deposition and the weathering of primary minerals as well as secondary clay minerals, and exports occur via leaching and biomass removals (Nilsson et al, 1982;Van Breemen et al, 1984).…”