2024-03-28T12:22:16Zhttps://www.tdx.cat/oai/requestoai:www.tdx.cat:10803/4026222023-06-09T10:55:26Zcom_10803_1col_10803_398033
nam a 5i 4500
Efecte del clima sobre les plantes
Vegetación y clima
Vegetation and climate
Ecologia forestal
Ecología forestal
Forest ecology
Dendrocronologia
Dendrocronología
Dendrochronology
Tree-ring networks at multiple geographical scales: patterns of coordinated ecological responses to global warming = Xarxes d'anells de creixement en arbres a escales geogràfiques múltiples: patrons de respostes ecològiques coordinades en front a l'escalfament global
[Barcelona] :
Universitat de Barcelona,
2017
Accés lliure
http://hdl.handle.net/10803/402622
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AAMMDDs2017 sp ||||fsm||||0|| 0 eng|c
Shestakova, Tatiana A.,
autor
1 recurs en línia (305 pàgines)
Tesi
Doctorat
Universitat de Barcelona. Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals
2016
Universitat de Barcelona. Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals
Tesis i dissertacions electròniques
Gutiérrez Merino, Emilia,
supervisor acadèmic
Voltas Velasco, Jordi,
supervisor acadèmic
TDX
Forest biomes are major reserves for terrestrial carbon and thus small shifts in the carbon balance of forests could have a large impact on the global carbon cycle. In spite of unambiguous evidence pointing to climate warming as modern factor increasing the risk of regional forest vulnerability, many uncertainties still remain preventing accurate predictions of forest productivity under future climate change. Improving our understanding of the diversity in tree performance at varying spatiotemporal scales must provide insights on the environmental responses of forests and their function as carbon holders in the coming years. To this end, we proposed a new conceptual framework to investigate tree-ring records by grouping chronologies into potentially homogeneous subsets based on mixed modeling principles, as illustrated for a Quercus spp. dataset from the northeastern Iberian Peninsula. Accordingly, we assessed spatiotemporal patterns of signal strength of tree-ring assemblages across environmental gradients and at multiple geographical scales. We used long-term tree ring-width (TRW) records to assess changes in the temporal coherence of radial growth in multispecies dendrochronological networks. In combination with stable isotope records (carbon isotope discrimination, Δ13C; oxygen isotope composition, δ18O) we characterized the physiological drivers of tree productivity under varying environmental conditions. Finally, we investigated shifts in climate sensitivity of tree growth and performance in response to warming-induced heat and drought effects. We found significant spatial autocorrelations for TRW, Δ13C and δ18O spreading over sites separated up to 1,000 km in Eurasia. However, growth synchrony was not uniform continent-wide, increasing along a latitudinal gradient and, thus, reflecting the extent of environmental coherence in the dominant climatic drivers of regional tree growth (i.e., rainfall patterns at mid latitudes vs. temperature patterns at high latitudes). Also, there were geographically-structured relationships between ring-width and either Δ13C (decreasing northwards and upwards) and δ18O (increasing northwards). These results pointed to limited CO2 diffusion impairing carbon uptake as main mechanism controlling the temporal coherence of forest growth signals at latitudes below 50°N in Europe and altitudes below ~1,600 m a.s.l. in Western Mediterranean. Notably, our results showed an increasing influence of climate on the spatial variability of tree growth over the twentieth century, ultimately leading to enhanced temporal coherence in ring-width records (spatial synchrony) along the local–continental continuum in most European
forests (except Fennoscandia) and also in central Siberia. Growth-climate analyses highlighted coherent shifts in vegetative activity towards more favorable periods depending on site location through an advanced onset of growth in the early season and temperature effects in summer (e.g., strengthening of drought-induced growth limitations in Mediterranean forests and relaxation of cold constraints in boreal forests). Increase in growth synchrony together with a tighter relationship between ring-width and Δ13C over the twentieth century suggested increasing drought effects on growth patterns in southern and central European forests and also in mountain Mediterranean forests. Particularly, our results indicated that warming-induced drought stress is spreading upwards in Mediterranean forests and northwards in temperate forests, overriding taxonomic imprints and local drivers of tree growth. However, uppermost and northernmost forests exhibited a diverging reaction to warming, which highlights the complexities of changing climate effects on peripheral forest populations, hence requiring further examination. Collectively, we demonstrated that broad-scale climatic variation influence ecophysiological traits in both conifers and hardwoods in ways that have previously gone unrecognized, which may help to understand the ecological implications of ecosystem functioning and make better predictions on future forest responses to the ongoing global warming. The evidence for substantial altitudinal and latitudinal variation in tree growth dependencies on leaf-level physiology could be valuable to forecast the extent by which future forests may progressively shift from temperature- to moisture-sensitive growth.
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