Effects of an experimentally applied increase in ammonium on growth and amino‐acid metabolism of Sphagnum cuspidatum Ehrh. ex. Hoffm. from differently polluted areas

Abstract

SUMMARYSphagnum cuspidatum Ehrh. ex. HofFm. was removed from a relatively remote moorland site at the Migneint, N. Wales and from Holme Moss, S. Pennines -a site that has been subjected to atmospheric pollution deposition for a period of at least the last 200 yr.When exposed to elevated ammonium (NHj"") concentrations {0-1 and 10 mM) under laboratory conditions for a period of 30 d, S. cuspidatum from N. Wales showed a marked reduction in growth, whereas in the S. Pennine population, growth was stimulated above that of the untreated control tissue at both 0-1 and 1-0 mM NH,~. The largest growth stimulation, however, was seen at 0-1 mM.The effects of increased NH^' in the growth medium on tissue total chlorophyll concentration after 30 d exposure were similar in nnoss from both study sites. There -was a small linear decline in chlorophyll concentration with increasing ammonium concentration.Moss from both sites was exposed to 0-1 mM NH^"" for a period of 20 d. There was a marked difference in the response of the different moss populations as indicated by changes in the concentrations of the individual ammo acids; notably a dramatic transient increase in glutamine (three-fold), arginine (19-fold), and asparagine (fourfold) in the moss from N. Wales. In contrast, in the S. Pennine moss, changes in tissue amino-N concentration were very mucb smaller. Possible mechanisms to account for the intraspecific differences in response of the moss from the two stud>' sites ro increased ammonmm concentrations are discussed.

Growth, production and interspecific competition in Sphagnum: effects of temperature, nitrogen and sulphur treatments on a boreal mire

“…(Granberg et al, 2001). Sphagnum species retain much of the N added (Malmer, 1988;Li & Vitt, 1997) and store much of the excess N as free amino acids, which have been found to accumulate with the addition of N (Baxter et al, 1992;Nordin & Gunnarsson, 2000). The Sphagnum plants in the high N plots in our study site had 70 -80% more N stored in the top 5 cm than untreated plots after 2 yr of applications (Granberg et al, 2001), indicating N accumulation.…”

Effects of different ammoniacal nitrogen sources on N-metabolism of the atmospheric bromeliad Tillandsia pohliana Mez

“…In addition, plants give off N-NH 3 , through the stomata, as has been observed in rice (Oryza sativa L.) (Silva & Stutte 1981), wheat (Triticum aestivum L.) (Parton et al 1988), and pea (Pisum sativum L.) (Betelsen & Jensen 1992), as well as in several wild species, such as Mercurialis perennis L., Rubus fruticosus L., and Trientalis europaea L. (Pearson et al 1998). There is strong evidence that increased N level in the atmosphere is beneficial to epiphytic plants up to a certain limit (Baxter et al 1992). Levels above a limit can poison epiphytes; this particularly applies to lower plants such as lichens and mosses (Baxter et al 1992).…”

“…There is strong evidence that increased N level in the atmosphere is beneficial to epiphytic plants up to a certain limit (Baxter et al 1992). Levels above a limit can poison epiphytes; this particularly applies to lower plants such as lichens and mosses (Baxter et al 1992).…”

The deposition of atmospheric ammonia and its effects on plants

“…However, with increased concentrations of sulphur and nitrogen in the atmosphere there is strong evidence that these cease to be beneficial to such plants and in fact 'poison' them. This applies particularly to lower plants such as lichens and mosses (Ferguson & Lee, 1983;Farmer, Bates & Bell, 1991;Baxter, Emes & Lee, 1992). Baxter et al (1992) have shown that the growth and physiology of Sphagnum cuspidatum when treated with ammonium at 01 or 1-0 mM, can depend markedly on the pollution history of the moss.…”