Simulating the germination response to diurnally alternating temperatures under climate change scenarios: comparative studies on Carex diandra seeds

Background and Aims Environmental temperature regulates plant regeneration by seed in several superimposed ways, and this complex regulation will be disrupted by climate change. The role of diurnally alternating temperatures (ΔT) in terminating dormancy will be a major player in this disruption, as its effects on seed germination are immediate. Methods We modelled the effect of ΔT on seed germination comparing two populations of the wetland sedge Carex diandra. We fitted a cardinal-temperature model to germination results in a thermal gradient plate, and used the model to simulate changes in germination under two representative concentration pathways scenarios (RCP2.6 and RCP8.5). Key Results Increasing ΔT decreased the base temperature for germination and the thermal time required for germination. RCP2.6 projected moderate increases in average temperatures and ΔT, whereas RCP8.5 projected higher warming and ΔT. The higher ΔT effect together with the warmer temperatures increased seed germination in both scenarios. By considering the effects of ΔT, the model projects considerable increases in germination. Conclusions Carex diandra germination will be very responsive to potential changes in ΔT as a consequence of climate change. This research highlights the role of ΔT in seed responses to climate change. Comprehensive cardinal-temperature models, encompassing the different effects of temperature on seed germination, are needed to understand how climate change will affect plant regeneration

Vegetation groups and habitats of neutro-basophilous fens in the Cantabro- Pyrenaean mountains

Los tremedales neutro-basófilos figuran entre los humedales con mayor riqueza de especies y más amenazados de Europa. Debido a su variabilidad ecológica y florística, la vegetación de estos hábitats puede estar sujeta a clasificaciones discordantes. En este trabajo utilizamos una base de datos de tremedales pirenaico-cantábricos para analizar los principales grupos de vegetación de estos medios y su relación con los tipos de hábitat europeos y la clasificación fitosociológica. Seleccionamos 295 muestras de acuerdo a la presencia de plantas higrófilas y calcícolas en el área de estudio (Carex lepidocarpa, C. davalliana, C. frigida y Eriophorum latifolium) y una estratificación espacial. Realizamos una clasificación utilizando datos sobre plantas vasculares y el sistema TWINSPAN modificado con una selección óptima de grupos. Analizamos los grupos de vegetación a partir de su distribución geográfica, variabilidad en altitud y pendiente, así como la similitud en la composición de especies mediante análisis de gradiente (DCA). Identificamos así cinco grupos relacionados con (i) tremedales de fuentes carbonatadas pirenaicas; (ii) fuentes carbonatadas cantábricas con el endemismo Centaurium somedanum; (iii) pastizales húmedos carbonatados pirenaico-cantábricos; (iv) tremedales carbonatados pirenaico-cantábricos; y (v) tremedales neutro-basófilos pirenaicos.Neutro-basophilous fens are among the most species-rich and threatened wetlands in Europe. Because of their ecological and floristic variability, vegetation of these habitats may be subject to classification inconsistencies. Here we use a vegetation database of Cantabro-Pyrenean fens to analyze the main vegetation groups related to these fens and their relationship with the European habitat types and phytosociological classification. We selected 295 vegetation relevés from the study area according to the presence of four calcicole specialists (Carex lepidocarpa, C. davalliana, C. frigida and Eriophorum latifolium) and geographical stratification. We classified the relevés using cover data of vascular plants, modified TWINSPAN analysis and classification crispness. We analyzed the vegetation groups according to their geographical distribution, variation in altitude and slope, and similarity of species composition using gradient analysis (DCA). We finally established five major vegetation groups: (i) Pyrenean calcareous spring fens related to high mountain streamsides, including Caricion davallianae communities with Carex frigida and relict plant communities of the Caricion maritimae alliance; (ii) Cantabrian calcareous springs with the endemic Centaurium somedanum and few fen species, which should be better assigned to tufa-forming springs; (iii) Pyreneo-Cantabrian calcareous fen grasslands, which could be included in alkaline fens or Molinietalia wet grasslands; (iv) Pyreneo-Cantabrian calcareous fens, possibly related to limestone bedrocks of Cantabrian Range and Western Pyrenees; and (v) Pyrenean neutro-basophilous fens, which seem to be part of extremely rich fens distributed on non-limestone substrates of Central and Eastern Pyrenees

Soil thermal buffer and regeneration niche may favour calcareous fen resilience to climate change

This is a pre-copyedited, author-produced PDF of an article accepted for publication in Folia Geobotanica following peer review. The version of record (Fernández-Pascual, E., Jiménez-Alfaro, B., Hájek, M., Díaz, T. E., & Pritchard, H. W. (2015). Soil thermal buffer and regeneration niche may favour calcareous fen resilience to climate change. Folia Geobotanica 50, 293-301) is available online at: http://dx.doi.org/10.1007/s12224-015-9223-y.Calcareous fens are azonal habitats permanently saturated by groundwater. This is expected to have a buffer effect on soil temperature, alleviating climate changes and allowing plant communities to occupy diverse climatic regions. We analysed the extent of such buffering and its relation with a relevant plant trait, the seed germination niche breadth, along altitudinal gradients in fens of the Cantabrian Mountains (Spain) and the Western Carpathians (Slovakia). In each fen we recorded soil temperature for several years and compared it with WorldClim predictions for air temperature. We also collected seeds from five Cyperaceae fen specialists to evaluate the influence of soil temperature on germination. Although soil temperatures and WorldClim were strongly correlated, their absolute values differed substantially, showing a narrower thermal amplitude and warmer minimum winter temperature in the soil. The greatest differences in soil temperature and germination niche breadth were those between mountain regions. Narrower germination niches correlated with the colder Slovakian winter. Our results suggest that the soil thermal buffer allows species to prevent frost temperatures in winter, but also high summer temperatures in warm regions, explaining their wide distribution ranges. The warm regeneration niche does not match the cooler soils, but shows variability and potential for adaptation. While this findings support resilience to climate warming, changes in precipitation rather than temperature seem to be the main threat for fen persistence.The Masaryk University of Brno provided institutional support. E.F.P. was supported by the Government of Asturias (Grant BP09-107, Programa de Ayudas Predoctorales ‘Severo Ochoa’, Plan de Ciencia, Tecnología e Innovación del Principado de Asturias) and the FP7-Marie-Curie-COFUND programme of the European Commission (Grant ‘Clarín’ ACA14-19); B.J.A. by the project ‘Employment of Best Young Scientists for International Cooperation Empowerment’ (CZ.1.07/2.3.00/30.0037) co-financed by the European Social Fund and the state budget of the Czech Republic; M.H. by the Academy of Sciences of the Czech Republic (RVO 67985939)

Germination ecology of the perennial Centaurium somedanum, a specialist species of mountain springs

To improve understanding of how a rare endemic species of Centaurium adapts to a specialized ecological niche, we studied the germination ecology of the mountain spring specialist, C. somedanum, a perennial species restricted to an unusual habitat for this genus. We conducted laboratory experiments with fresh seeds collected from two populations for three consecutive years, to investigate: (1) the effect of temperature and light ongermination; (2) the existence of seed dormancy; and (3) inter-population and inter-annual variation in germinability. Germination occurred only in the light and at relatively low temperatures (15?228C) with no differences between constant and alternating regimes, and a significant decrease at high temperatures (258C and 308C). We found non-deep simple morphophysiological dormancy and variation in seed germinability depending on the year of seed collection. C. somedanum diverged from the common germination characteristics of the genus in: (1) its germination at lower temperatures, which contrasts with what is generally expected in wetland species but could be adaptive in the spring habitat; and (2) its morphophysiological dormancy, which we report here for the first time in the genus and which could be an adaptation to its mountain habitat