Inorganic and organic nitrogen uptake by nine dominant subtropical tree species

Abstract

(1)We explored inorganic and organic N uptake patterns by dominant tree species in a subtropical plantation of southern China to improve understanding of nitrogen (N) cycling in these forests. We labeled intact roots by brief 15 N exposures in field hydroponic experiments. Nine dominant tree species were examined to compare the effects of functional plant group (conifers versus broadleaves), mycorrhizal types, and forest successional stages on N uptake. . All investigated species absorbed ammonium for more than 80% of total N uptake. Nitrate acquisition by these species was about 14% of total N uptake, with only 6% for glycine. Conifers showed significantly higher uptake rates of glycine, but lower uptake of nitrate than broadleaves. Arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) tree species showed significant difference in nitrate uptake, with higher rates by AM tree species. Tree species at late-successional forest stages showed higher uptake rates of nitrate than those in earlier successional stages. Our findings indicate that ammonium is the dominant N source and glycine is a minor N source throughout forest succession.

Variations in Soil Functional Fungal Community Structure Associated With Pure and Mixed Plantations in Typical Temperate Forests of China

“…mandshurica , with lower soil nutrients, which may indicate the existence of a mechanism enabling the regulation of soil low in nutrients. ECM fungi can excrete extracellular enzymes that degrade complex organic nitrogen compounds, thereby providing benefits to forest trees by enhancing the mobilization and uptake of soil nutrients (Nygren et al, 2007; Courty et al, 2010; Li et al, 2016; Luo et al, 2018). Additionally, ECM symbiosis is usually viewed as promoting nutritional mutualism and providing resources for host trees to withstand harsh conditions (Peay, 2016; Karst et al, 2018).…”

Relationship of plant diversity with litter and soil available nitrogen in an alpine meadow under a 9‐year grazing exclusion

“…However, legume species (including Gueldenstaedtia diversifolia and Medicago ruthenica) have strong nitrogen fixation ability, but weak absorption efficiency for NH 4 + and NO 3 À (Wang et al 2012). The different uptake patterns of different species have been demonstrated by many studies in alpine meadows and other ecosystems (McKane et al 2002;Gao et al 2014;Jiang et al 2015;Li et al 2015). Thus, a decrease in the diversity of the functional groups might enhance the contents of different nitrogen forms in the soil.…”

Soil microbes promote complementarity effects among co‐existing trees through soil nitrogen partitioning

“…However, these two types of mycorrhiza are functionally distinct with respect to N-acquisition (Smith & Read, 2008;Taylor & Alexander, 2005). EM fungi are capable of producing extracellular enzymes that degrade complex organic N and take up dissolved organic N such as amino acids (Chalot & Brun, 1998;Courty et al, 2010;Endo, Norisada, Kogawara, Hogetsu, & Kojima, 2009;Li et al, 2016). Unlike EM fungi that have access to organic N, AM fungi have no known saprotrophic capacity and function as an extension of roots to acquire inorganic N (but see Hodge, Campbell, & Fitter, 2001;Leigh, Hodge, & Fitter, 2009;Smith & Read, 2008;Smith & Smith, 2011).…”