Palaeomagnetic dating of two recent lava flows from Ceboruco volcano, western Mexico

Two lava flows from the Ceboruco volcano in west-central Mexico were sampled for palaeomagnetic dating. The younger one was emitted in 1870 and used to validate the method, while the older one known as Ceboruco flow is of unknown age but probably younger than ∼1005 AD and older than 1528 AD. Each flow was sampled in at least four sites, in order to unravel between site variations. For the 1870 flow, between site differences were notable and additionally post-cooling block movements were important; therefore, two sites had to be rejected. Three sites from the vent area and one at the tip of the 1870 flow provided well-constrained directions. This is also true for Ceboruco lava flow, and overall mean directions and palaeointensities were then used for palaeomagnetic dating applying the Matlab tool archaeo_dating and the global palaeosecular variation model SHA.DIF.14k. For the 1870 lava flow, the dating resulted in an age ranging between 1755 and 1871 AD (95 per cent probability level), which includes the real emplacement age. In addition, the Ceboruco lava flow was dated between 1000 and 1134 AD, which is close to the large plinian Jala eruption producing the crater of Ceboruco volcano around 1005 AD. This age is older than previously assumed and suggests an emplacement only shortly after the Jala eruption. As this lava flow is considered to be the youngest one of seven post-Jala lava flows, the age also defines a period of inactivity of Ceboruco volcano of about 730–860 yr before the historic 1870 eruption. Future volcanic hazard analysis will have to take into account this result. Our work also shows that multiple sampling of single lava flows is important to obtain a reliable mean direction. Sampling sites have to be carefully selected so that they represent un-tilted parts of the flows. We interpret this to be the case for the Ceboruco lava flow, while three of the six sites of the 1870 lava flow may have been partly or completely affected by movements after thermoremanent magnetization acquisition. Unfortunately, no better sites were found for this flow.Ing. J. Escalante supported studies with the MicroMag AGFM and the Curie balance, and E. Nava warranted the functionality of the laboratory computers and the network. This work was supported by UNAM project IN 112712 (HB and FJPC) and Conacyt grant no. 180032 (HB and ANM). FJPC has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie SklodowskaCurie grant agreement no. 659901.Peer reviewe

Aboveground-trait variations in 11 (sub)alpine plants along a 1000-m elevation gradient in tropical Mexico

International audienceWith the aim to explore how plants acclimate to elevation changes in the understudied (sub)alpine tropics we tested two hypotheses along a 1000-m elevation gradient in Mexico: (H1) due to a severe increase in abiotic constraints at higher elevations, the functional traits of the plant species will converge toward more resource conservation, and (H2) the specific growth forms and biogeographic origins present in the (sub)alpine tropics may influence the interspecific trait variation along the gradient. We measured five aboveground functional traits: specific leaf area (SLA), leaf dry-matter content (LDMC), leaf thickness, leaf area and plant height, of 11 species representing four growth forms: rosette, tussock grass, shrub and tree the soil microclimate. Microclimatic data revealed a steep decrease in soil water content at higher elevations. Across all species and all individuals, SLA, plant height and leaf area decreased with elevation, whereas LDMC and leaf thickness increased, all of which revealing adjustments towards resource conservation in line with H1. Consistently with H2, the functional traits of the growth forms that were characteristic of tropical alpine regions (tussock grasses and erect shrubs) were less sensitive to changes in elevation compared to more generalist growth forms such as forbs. In addition, within the growth form “rosette” the functional traits of species of tropical biogeographic origin changed with elevation, whereas those of Holarctic origin did not. Our data indicate a convergence of plant traits toward improved resource conservation at higher elevations, which may be influenced partially by the growth form and the biogeographical origin of plant species

Shifts in soil and plant functional diversity along an altitudinal gradient in the French Alps

International audienceAltitude integrates changes in environmental conditions that determine shifts in vegetation, including temperature, precipitation, radiation and edaphogenetic processes. In turn, vegetation alters soil biophysical properties through litter input, root growth, microbial and macrofaunal interactions. The belowground traits of plant communities modify soil processes in different ways, but it is not known how root traits influence soil biota at the community level. We collected data to investigate how elevation affects belowground community traits and soil microbial and faunal communities. This dataset comprises data from a temperate climate in France and a twin study was performed in a tropical zone in Mexico.Data description: The paper describes soil physical and chemical properties, climatic variables, plant community composition and species abundance, plant community traits, soil microbial functional diversity and macrofaunal abundance and diversity. Data are provided for six elevations (1400 – 2400 m) ranging from montane forest to alpine prairie. We focused on soil biophysical properties beneath three dominant plant species that structure local vegetation. These data are useful for understanding how shifts in vegetation communities affect belowground processes, such as water infiltration, soil aggregation and carbon storage. Data will also help researchers understand how plant communitiesadjust to a changing climate/environmen

Drivers of soil biophysical processes along an elevational gradient at Pico de Orizaba volcano, Mexico

International audienceElevational gradients are characterized by major shifts in environmental conditions, reflected through changes in climatic and soil variables. These shifts strongly impact the composition, community structure and specific functional traits of vegetation. Vegetation, in turn, influences soil properties through litter input, root growth and the release of root exudates, thereby influencing soil microbial and faunal communities. Here, we report and briefly describe data of soil and underlying bedrock physical and chemical properties, climatic variables, plant community composition and species abundance, soil microbial diversity and macro and mesofaunal abundance and diversity. Data are provided for 6 elevations (3400–4600 m) ranging from pine forest to alpine prairie. We focused on soil biophysical properties beneath several keystone or community-structuring plant species with different growth forms: (1) tree (Pinus hartwegii Lindl.); shrub (Oxylobus arbutifolius (Kunth) A. Gray and Chionolaena lavandulifolia (Kunth ex Kunth) Benth. & Hook.f. ex B.D.Jacks.); and (3) herb (Lupinus montanus Kunth and Senecio roseus Sch.Bip.). These data are useful for understanding how shifts in abiotic conditions and vegetation communities along an elevational gradient affect soil ecosystem services such as water infiltration, soil aggregation and carbon (C) storage, and modify soil biodiversity. The collected data also provide useful information to understand how alpine vegetation, soil macro- and meso-fauna, and soil bacterial communities may shift under a climate change scenario