To understand these fluxes, we quantified the annual N2O emissions from three tropical mountain rainforests (primary mountain rainforest, PMR; secondary mountain rainforest, SMR; and Podocaipus imbricatus plantation,
PIP) in the Jian-fengling National Natural Reserve on Hainan Island, China. The average of N2O emissions in this area was 2.52 +/- 033 kg N-N2O ha(-1) yr(-1) (3.52 kg N-N2O ha(-1) yr(-1) in the wet season and 1.62 kg N-N2O ha(-1) yr(-1) in the dry season) during our study period, with highly seasonal variations. The mean N2O emission rates were significantly higher during the wet season (68% of the total average) than the dry season (32% of the total average) (P smaller than 0.05). PIP had the highest N2O emission rate at 3.49 +/- 0.61 kg N-N2O ha(-1) yr(-1) (4.74 kg N-N2O ha(-1) yr(-1) in the wet season and 232 kg N-N2O ha(-1) yr(-1) in the dry season), followed by SMR MDV3100 at 3.03 +/- 0.64 kg N-N2O ha(-1) yr(-1) (4.16 kg N-N2O ha(-1) yr(-1) in the Nutlin 3 wet season and 1.97 kg N-N2O ha(-1) yr(-1) in the dry season), and then PMR at 1.53 +/- 0.49 kg N-N2O ha(-1) yr(-1) (2.21 kg N-N2O ha(-1) yr(-1) in the wet season and 0.94 kg N-N2O ha(-1) yr(-1)
in the dry season). We observed a significant Gaussian relationship between the N2O fluxes and soil temperature for SMR and PIP but no significant relationship in PMR. There was a significant exponential relationship between the N2O fluxes and water filled pore space (WFPS) in SMR and PIP but not in PMR. (C) 2014 Elsevier Ltd. All rights reserved.”
“Understanding how genetic diversity is structured on oceanic island taxa requires the integration of physical, biological and anthropomorphic factors. Founder effects coupled with limited dispersal over sea barriers typically result in low levels of genetic variation in island populations. In widespread species, restriction in gene flow across large areas leads to patterns of isolation by distance (IBD),
find more but recent population-based studies indicate that genetic structure on islands can be complex even at local scales. Here, we investigated the patterns of genetic variation in a widespread island palm (Phoenix canariensis) displaying reproductive syndromes associated with extensive dispersal (wind pollination and zoochory). Genetic variation was assessed at eight nuclear microsatellite loci in 330 individuals of 15 Canarian populations. Our results showed that levels of within-population genetic diversity in P. canariensis depend on the island considered, with a strong decreasing pattern from the easternmost and oldest island to the westernmost and youngest islands. A Mantel test supported a stepping-stone model of differentiation across the archipelago that fits the sequence of island emergence, and results from ABC and clustering analyses also corresponded with this progression rule.