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Complementarity in mineral nitrogen use among dominant plant species in a subalpine community
Author(s) -
Por André,
Escaravage Nathalie,
Lamaze Thierry
Publication year - 2007
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.94.11.1778
Subject(s) - vaccinium myrtillus , biology , growing season , plant community , botany , ecology , species richness , festuca , ericaceae , poaceae , agronomy
The underlying mechanisms that enable plant species to coexist are poorly understood. Complementarity in resource use is among the major mechanisms proposed that could favor species coexistence but is insufficiently documented. In alpine soil, low temperatures are a major constraint for the supply of plant nitrogen. We carried out 15 N labeling of soil mineral N to determine to what extent four major species of a subalpine community compete for N, or develop ionic (NH 4 + vs. NO 3 − ) or temporal complementarity. The Poaceae took up much more 15 N per soil area unit than the ericaceous species, and all species displayed three major strategies in exploiting 15 N: (1) uptake mainly early in the growing season ( Vaccinium myrtillus ), (2) uptake at a slow and similar rate throughout the growing season ( Rhododendron ferrugineum ), and (3) uptake at high rates over the growing season ( Festuca eskia and Nardus stricta ). However , while F. eskia used 15 NH 4 + mainly early and 15 NO 3 − mainly late in the growing season, the reverse was observed for N. stricta . Taking into account 15 N dilution in soil NH 4 + and NO 3 − pools, we calculated that NH 4 + provided more than 80% of the mineral N uptake in Ericaceae and about 60% in grasses. Together, such ionic and temporal complementarity would reduce competition between species and could be a major mechanism promoting species diversity.