Jump A.S., Hunt J.M., Peñuelas J. (2007) Climate relationships of growth and establishment across the altitudinal range of Fagus sylvatica in the Montseny Mountains, northeast Spain. Ecoscience. 14: 507-518.EnllaçDoi: 10.2980/1195-6860(2007)14[507:CROGAE]2.0.CO;2
A rise in elevation of the temperate biome has been reported in the mountains of northeast Spain. We aimed to determine the principal climatic factors limiting growth and establishment of the dominant temperate tree, Fagus sylvatica, across its altitudinal range and how its climate-response has varied over time. We determined the climate-response of the growth of adult trees and the establishment of juveniles using dendroecological methods at 3 sites along an elevational gradient spanning this species' full altitudinal distribution of approximately 1000-1650 in above sea level. We found strong altitudinal variation in growth and establishment responses to climate. The most common growth response was to high spring and summer temperature (April-July), which promoted growth and establishment at the upper treeline but had the opposite effect at low altitudes. Precipitation was strongly limiting for adult growth at the lower limit of F. sylvatica and declined in importance with increasing altitude. Sensitivity of growth to summer temperature increased over the second half of the 20th century. Future increases in summer temperature are likely to have negative consequences for growth and establishment at this species' low altitude, low latitude range-edge, particularly if temperature increase is not matched by increasing precipitation.
Jump A.S., Peñuelas J. (2007) Extensive spatial genetic structure revealed by AFLP but not SSR molecular markers in the wind-pollinated tree, Fagus sylvatica. Molecular Ecology. 16: 925-936.EnllaçDoi: 10.1111/j.1365-294X.2006.03203.x
Studies of fine-scale spatial genetic structure (SGS) in wind-pollinated trees have shown that SGS is generally weak and extends over relatively short distances (less than 30-40 m) from individual trees. However, recent simulations have shown that detection of SGS is heavily dependent on both the choice of molecular markers and the strategy used to sample the studied population. Published studies may not always have used sufficient markers and/or individuals for the accurate estimation of SGS. To assess the extent of SGS within a population of the wind-pollinated tree Fagus sylvatica, we genotyped 200 trees at six microsatellite or simple sequence repeat (SSR) loci and 250 amplified fragment length polymorphisms (AFLP) and conducted spatial analyses of pairwise kinship coefficients. We re-sampled our data set over individuals and over loci to determine the effect of reducing the sample size and number of loci used for SGS estimation. We found that SGS estimated from AFLP markers extended nearly four times further than has been estimated before using other molecular markers in this species, indicating a persistent effect of restricted gene flow at small spatial scales. However, our SSR-based estimate was in agreement with other published studies. Spatial genetic structure in F. sylvatica and similar wind-pollinated trees may therefore be substantially larger than has been estimated previously. Although 100-150 AFLP loci and 150-200 individuals appear sufficient for adequately estimating SGS in our analysis, 150-200 individuals and six SSR loci may still be too few to provide a good estimation of SGS in this species. Journal compilation © 2006 Blackwell Publishing Ltd.
Peñuelas J., Ogaya R., Boada M., Jump A.S. (2007) Migration, invasion and decline: Changes in recruitment and forest structure in a warming-linked shift of European beech forest in Catalonia (NE Spain). Ecography. 30: 829-837.EnllaçDoi: 10.1111/j.2007.0906-7590.05247.x
Altitudinal upward shifts of species' ranges have occurred across a wide range of taxonomic groups and geographical locations during the twentieth century in response to current climate warming. However, actual data of plant species' altitudinal shifts are still scarce and not always clear. Here we provide a more detailed investigation of a previously reported European beech Fagus sylvatica forest altitudinal shift in the Montseny Mountains (Catalonia, NE Spain) now based on field photographic survey and on the population age structure and the recruitment patterns in the high Fagus limit (HFL), the central forest area (CFA) and the low Fagus limit (LFL). Monitoring of the lowest altitudinal range shows that beech forest is being progressively replaced by Mediterranean holm oak forest. Holm oaks are characterized by recruitment rates more than three times higher than those of beech in the LFL in the last decades. The percentage of young individuals in the LFL is only half that in the HFL and CFA. In the highest altitudinal range, present day and early 20th century photographs show that the HFL has gained density and has shifted altitudinally upwards, advancing with establishment of new, vigorous outpost trees (13 individuals per each 100 m of tree-line). They are mostly (89%) younger than 35 yr old and mostly (97%) located up to 70 m (with a few up to 105 m) ground surface distance above the current tree line (36-51 m altitude) at the highest altitudes (1600-1700 m). The beech forest upward shift is a likely consequence of warming, but land-use practice changes (cessation of burning by shepherds) have made it possible. These changes in vegetation distribution and population structure constitute a new indication of the complex global change effects on life in mountain ecosystems. © 2007 The Authors.
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