Long-term nitrogen deposition increases phosphorus limitation of bryophytes in an ombrotrophic bog

Abstract

Here we investigate the effect of 4 years simulated atmospheric deposition of ammonium (NH 4 ) and nitrate (NO 3 ), applied alone or in combination with phosphorus and potassium (PK), on the surface phosphatase activities and nutrient acquisition behaviour of two species of moss (Sphagnum capillifolium and Hypnum jutlandicum) from an ombrotrophic peatland. Phosphatase activity was significantly enhanced by both the NH 4 and NO 3 treatments, particularly for Sphagnum, but the activity decreased when exposed to additions of PK. Regression analysis revealed that phosphatase activity on Sphagnum was positively related with tissue N and negatively related to tissue P concentrations. For Hypnum, a negative relationship between shoot P concentration and phosphatase activity was observed. Using a 32 P tracer, mosses removed from plots receiving PK in combination with NH 4 maintained their affinity for increased phosphorus uptake. These findings suggest that enhanced nutrient supply, even at modest doses, significantly alter the nutrient recycling behaviour of bryophytes.

Fate of N in a peatland, Whim bog: immobilisation in the vegetation and peat, leakage into pore water and losses as N<sub>2</sub>O depend on the form of N

“…Rowe et al (2008) showed that N deposition led to higher phosphatase activity and thus could improve the P supply and acquisition. We measured increased surface phosphatase activity in S. capillifolium and H. jutlandicum, in proportion to their N concentration (Phuyal et al, 2007).…”

Nitrogen fixation by associative cyanobacteria in the Canadian Arctic.

“…Both epiphytic and terricolous cyanolichens have shown higher rates of N 2 -fixation under P fertilization treatments and in some cases higher thallus N concentrations Weiss et al, 2005). Enhanced nutrient supply even at modest doses can significantly alter productivity and nutrient recycling behaviours of bryophytes (Crews, 1993;Gordon et al 2001;Phuyal et al, 2008). However, increases in NA with the addition 17 of P may also be due to an increase in host plant biomass rather than a direct effect of P on N 2 -fixation rates (Gordon et al 2001).…”

“…Ayres et al (2006) demonstrated direct uptake of N from the soil by mosses, which suggests mosses may have access to multiple N pools and are likely highly competitive at acquiring N. Bryophytes have adapted to nutrient poor environments and are extremely efficient both in their use of N and their ability to retain N and may exert control over the N retention efficiency of the ecosystem (Bowden, 1991;Aldous, 2002;Phuyal et al, 2008). Weber & Van Cleve (1984) found that isotopically enriched feather moss mats released very little available N to underlying vascular plant roots, and suggest that bryophyte mats function as a major ecosystem sink for available N. However, under some circumstances, stored N pools can be released from moss mats.…”

“…Liverwort mats, the main component of Hollow BSC, may be more effective at retaining nutrients than the Hummock BSC making them less available to soils below. Bryophytes have adapted to nutrient-poor environments and are extremely efficient both in their use of N and their ability to retain N and may exert control over the N retention efficiency of the ecosystem (Aldous, 2002;Bowden, 1991;Phuyal et al, 2008). N released from bryophytes may be in less biologically available forms and bryophytes may reduce nutrient turnover rates through the production of acidic nutrient-poor organic matter, retention of N in recalcitrant compounds and by reducing soil temperatures and hence lowering decomposition rates (Eckstein, 2000;Lagerstrom et al, 2007;Turetsky, 2003).…”

Effects of different nitrogen:phosphorus levels on the growth and ecological stoichiometry of Glycyrrhiza uralensis

“…, 从而提高 土壤N和磷(P)的有效性。 随着长期或过多N沉降, 不 仅生态系统N输入增加, 而且N:P失衡、系统N饱和 甚至P压力增加 (Bobbink et al, 2010;Wardle et al, 2013), 以及植物生长P受限性增强 (Yu et al, 2012 (Phoenix et al, 2004)。在其他一些生态 系统, 如热带森林生态系统 (Zhu et al, 2013)、温带 森林生态系统 (Naples & Fisk, 2010)和沼泽生态系统 (Phuyal et al, 2008) …”