The rise and fall of arbuscular mycorrhizal fungal diversity during ecosystem retrogression.
Ecosystem retrogression following long-term pedogenesis is attributed to phosphorus (P) limitation of primary productivity. Arbuscular mycorrhizal fungi (AMF) enhance P acquisition for most terrestrial plants, but it has been suggested that this strategy becomes less effective in strongly weathered soils with extremely low P availability. Using next generation sequencing of the large subunit ribosomal RNA gene in roots and soil, we compared the composition and diversity of AMF communities in three contrasting stages of a retrogressive >2-million-year dune chronosequence in a global biodiversity hotspot. This chronosequence shows a ~60-fold decline in total soil P concentration, with the oldest stage representing some of the most severely P-impoverished soils found in any terrestrial ecosystem. The richness of AMF operational taxonomic units was low on young (1000's of years), moderately P-rich soils, greatest on relatively old (~120 000 years) low-P soils, and low again on the oldest (>2 000 000 years) soils that were lowest in P availability. A similar decline in AMF phylogenetic diversity on the oldest soils occurred, despite invariant host plant diversity and only small declines in host cover along the chronosequence. Differences in AMF community composition were greatest between the youngest and the two oldest soils, and this was best explained by differences in soil P concentrations. Our results point to a threshold in soil P availability during ecosystem regression below which AMF diversity declines, suggesting environmental filtering of AMF insufficiently adapted to extremely low P availability.
Institute of Botany, Academy of Sciences of the Czech Republic, Zámek 1, Průhonice, CZ-252 43, Czech Republic.
Manuela
M
Krüger
School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia.|Grupo de Estudios Ambientales, IMASL-CONICET & Universidad Nacional de San Luis, Av. Ejercito de los Andes 950 (5700), San Luis, Argentina.
François P
FP
Teste
School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia.|Institut de recherche en biologie végétale, Département de sciences biologiques, Université de Montréal, 4101 Sherbrooke Est, Montréal, QC, H1X 2B2, Canada.
Etienne
E
Laliberté
School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia.
Hans
H
Lambers
Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancon, Republic of Panama.
Megan
M
Coghlan
School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA, 6009, Australia.|Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancon, Republic of Panama.
Graham
G
Zemunik
Trace and Environmental DNA Laboratory, Department of Environment and Agriculture, Curtin University, Kent Street, Perth, WA, 6845, Australia.
Michael
M
Bunce
D001315:Australia; D044822:Biodiversity; D004271:DNA, Fungal / Q000235:genetics; D017753:Ecosystem; D059014:High-Throughput Nucleotide Sequencing; D038821:Mycorrhizae / Q000145:classification* / Q000235:genetics; D010758:Phosphorus / Q000737:chemistry; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology; D017422:Sequence Analysis, DNA; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology
D004271:DNA, Fungal; D012987:Soil; D010758:Phosphorus
Glomeromycota; community ecology; dune chronosequence; ecosystem development; nutrient limitation; phosphorus