Plant growth and reproduction on a toxic alpine ultramafic soil: adaptation to nutrient limitation

Abstract

SUMMARYThe ultramafic sites at Meikle Kilrannoch, Scotland, have small sparsely colonized patches with soils which have highly toxic (to many non-indigenous plants) concentrations of Mg and Ni. These toxic metals are unlikely to be the main cause of the open vegetation as the indigenous plants are at least partially tolerant of them. The hypothesis that low soil nutrients were a likely cause of the open vegetation was tested by a fertilization experiment in which major nutrients and Ca were added in August 1991 and July 1992 to replicated quadrats which initially had 5-3-6-6% plant cover. There was a large increase in plant cover on major nutrient addition. The increase in rosette size, flowering, seed production, and recruitment of the dominant semelparous Cochlearia pyrenaica DC. ssp, alpina (Bab.) Dalby was studied in detail. The increased growth of Cochlearia (and some other native species at the site) on nutrient addition strengthens the argument that a major nutrient deficiency rather than a metal toxicity limits plant growth at Meikle Kilrannoch and shows that at least some stress tolerators respond with rapid growth and reproduction when nutrient limitation is removed. A small-scale experiment set up in June 1993, in which the major nutrients were added separately, suggested that P and not N, or K was the limiting element. The effects of P seem to be unrelated to any possible reduction in the availability of the toxic ions Mg^* and Ni*^, Key words: Cochlearia pyrenaica, fertilizer addition, functional type, P, population dynamics, ultramafic (serpentine).by P fertilization. The low vegetation cover of INTRODUCTION fellfieids cannot be ascribed to toxicity generally The ultramafic sites at Meikle Kilrannoch in Angus, since they often lack elevated metal concentrations. Scotland have an unusual flora whose presence and Nutrient addition experiments made on ultramafic local pattern are at least partly related to the effects sites in the field have shown a marked response, of Mg and Ni toxicities (Nagy & Proctor, 1997). The which could be ascribed to P in those cases where the distinctive feature of the vegetation as a whole is the added nutrients were studied separately, but in none low plant cover in which it resembles that found in of these cases were the soils so toxic as those at other habitats including metal mine spoil heaps and Meikle Kilrannoch (Ferreira & Wormell, 1971; fellfieids (Spence, 1957). Metal toxicities in Meikle Turitzin, 1982; Carter, Proctor & SUngsby, 1987a; Kilrannoch soil have been demonstrated for non- Hobbs et al., 1988;Looney & Proctor, 1989; indigenous plants (e.g. Proctor, 1971; Goodwin-Huenneke e( a/., 1990), Bailey, Woodell & Loughman, 1992;Nagy & In this paper we report an experiment at Meikle Proctor, 1997), but they are unlikely to explain the Kilrannoch designed as a direct test of the hypothesis low plant cover since the indigenous (tolerant) plants that low nutrients rather than metal toxicities cause should be able to colonize the site in the absence of low plant cov...

Abiotic and biotic resistance to grass invasion in serpentine annual plant communities

“…Native biomass also had a strong positive response to the addition of N, but not to P, H 2 O, or Ca alone. N and P limitation have been previously documented for serpentine grasslands (Turitzin 1982;Huenneke et al 1990;Nagy and Proctor 1997) and several of these studies have reported that the increase in plant biomass from nutrient addition was greatest when N and P were provided together (Turitzin 1982; Huenneke et al 1990). In the absence of competition, N addition never more than doubled the biomass and fecundity of Avena, Bromus, and Hordeum (Fig.…”

Edaphic influences of ophiolitic substrates on vegetation in the Western Italian Alps

“…The role of heavy metals in influencing serpentine vegetation is unclear. Some researchers have reported that Ni has strong negative effects on plant cover on serpentine (Lee 1992;Chardot et al 2007), whereas others have reported little to no effect (Nagy and Proctor 1997;Chiarucci et al 2001).…”

“…Although this vegetation is typically sparse and stunted, plant diversity is often high with abundant endemic plant species (Kruckeberg 1984;Brooks 1987). Many studies have examined the numerous edaphic stresses of the serpentine syndrome to identify the primary factor influencing plant community species composition and cover (Carter et al 1987;Chiarucci et al 1998Chiarucci et al , 2001Kayama et al 2005;Kràm et al 1997;Nagy and Proctor 1997;Roberts 1992;Robinson et al 1996;Verger et al 1993). The relative strength and role of each edaphic factor has been found to vary greatly depending upon plant community and local climate (Proctor and Nagy 1991;Lazarus et al 2011).…”

Plant mineral accumulation, use and transport during the life cycle of plants: A review

“…Various factors affect nutrient uptake, including soil nutrient limitations (Lauter et al 1996;Nagy and Proctor 1997), translocation and use of the nutrients by the transplant during transplant production in the greenhouse (Basoccu and Nicola 1995;Dufault 1998) and during crop establishment in the field (Dufault 1998). Transplants for field crop establishment are produced in greenhouses, in growing medium, usually peat moss, in multi-celled trays.…”