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1.
Interactions among nitrogen fixation and soil phosphorus acquisition strategies in lowland tropical rain forests 总被引:1,自引:0,他引:1
Megan K. Nasto Silvia Alvarez‐Clare Ylva Lekberg Benjamin W. Sullivan Alan R. Townsend Cory C. Cleveland 《Ecology letters》2014,17(10):1282-1289
Paradoxically, symbiotic dinitrogen (N2) fixers are abundant in nitrogen (N)‐rich, phosphorus (P)‐poor lowland tropical rain forests. One hypothesis to explain this pattern states that N2 fixers have an advantage in acquiring soil P by producing more N‐rich enzymes (phosphatases) that mineralise organic P than non‐N2 fixers. We assessed soil and root phosphatase activity between fixers and non‐fixers in two lowland tropical rain forest sites, but also addressed the hypothesis that arbuscular mycorrhizal (AM) colonisation (another P acquisition strategy) is greater on fixers than non‐fixers. Root phosphatase activity and AM colonisation were higher for fixers than non‐fixers, and strong correlations between AM colonisation and N2 fixation at both sites suggest that the N–P interactions mediated by fixers may generally apply across tropical forests. We suggest that phosphatase enzymes and AM fungi enhance the capacity of N2 fixers to acquire soil P, thus contributing to their high abundance in tropical forests. 相似文献
2.
Phosphatase activity and nitrogen fixation reflect species differences,not nutrient trading or nutrient balance,across tropical rainforest trees 下载免费PDF全文
Sarah A. Batterman Jefferson S. Hall Benjamin L. Turner Lars O. Hedin J. Kimiko LaHaela Walter Pete Sheldon Michiel van Breugel 《Ecology letters》2018,21(10):1486-1495
A fundamental biogeochemical paradox is that nitrogen‐rich tropical forests contain abundant nitrogen‐fixing trees, which support a globally significant tropical carbon sink. One explanation for this pattern holds that nitrogen‐fixing trees can overcome phosphorus limitation in tropical forests by synthesizing phosphatase enzymes to acquire soil organic phosphorus, but empirical evidence remains scarce. We evaluated whether nitrogen fixation and phosphatase activity are linked across 97 trees from seven species, and tested two hypotheses for explaining investment in nutrient strategies: trading nitrogen‐for‐phosphorus or balancing nutrient demand. Both strategies varied across species but were not explained by nitrogen‐for‐phosphorus trading or nutrient balance. This indicates that (1) studies of these nutrient strategies require broad sampling within and across species, (2) factors other than nutrient trading must be invoked to resolve the paradox of tropical nitrogen fixation, and (3) nitrogen‐fixing trees cannot provide a positive nitrogen‐phosphorus‐carbon feedback to alleviate nutrient limitation of the tropical carbon sink. 相似文献
3.
David Püschel Martina Janoušková Martina Hujslová Renata Slavíková Hana Gryndlerová Jan Jansa 《Ecology and evolution》2016,6(13):4332-4346
Considered to play an important role in plant mineral nutrition, arbuscular mycorrhizal (AM) symbiosis is a common relationship between the roots of a great majority of plant species and glomeromycotan fungi. Its effects on the plant host are highly context dependent, with the greatest benefits often observed in phosphorus (P)‐limited environments. Mycorrhizal contribution to plant nitrogen (N) nutrition is probably less important under most conditions. Moreover, inasmuch as both plant and fungi require substantial quantities of N for their growth, competition for N could potentially reduce net mycorrhizal benefits to the plant under conditions of limited N supply. Further compounded by increased belowground carbon (C) drain, the mycorrhizal costs could outweigh the benefits under severe N limitation. Using a field AM fungal community or a laboratory culture of Rhizophagus irregularis as mycorrhizal inoculants, we tested the contribution of mycorrhizal symbiosis to the growth, C allocation, and mineral nutrition of Andropogon gerardii growing in a nutrient‐poor substrate under variable N and P supplies. The plants unambiguously competed with the fungi for N when its supply was low, resulting in no or negative mycorrhizal growth and N‐uptake responses under such conditions. The field AM fungal communities manifested their potential to improve plant P nutrition only upon N fertilization, whereas the R. irregularis slightly yet significantly increased P uptake of its plant host (but not the host's growth) even without N supply. Coincident with increasing levels of root colonization by the AM fungal structures, both inoculants invariably increased nutritional and growth benefits to the host with increasing N supply. This, in turn, resulted in relieving plant P deficiency, which was persistent in non‐mycorrhizal plants across the entire range of nutrient supplies. 相似文献
4.
A meta-analysis of mycorrhizal responses to nitrogen, phosphorus, and atmospheric CO2 in field studies 总被引:5,自引:5,他引:0
Kathleen K. Treseder 《The New phytologist》2004,164(2):347-355