Monitoring two REINFFORCE network arboreta adaptation to climate change and abiotic factors

Mestrado - Mediterranean Forestry and Natural Resources Management - Instituto Superior de Agronomia

Many forest ecosystems studies have correlated recent climate trends with changes in phenology, and indicated that climate warming appears to lengthen the growing season and increase tree growth rates. In addition, changes in climate variables may have direct influence on insect pests and pathogens affecting both their survival and development. Also, climate change is expected to increase the frequency of extreme weather events. Depending on the timing of spring warmth, early and accelerated leaf development has the potential to increase the frequency and magnitude of leaf damage from freezing events. Forest ecosystems, store approximately 1200 gigatonnes of carbon. This is considerably more carbon than is present in the atmosphere (IPCC, 2007). Recently, the mutual interaction between forests and climate change has become one of the most important issues for research to address this concern, REINFFORCE program has established a network arboreta with the main objective of improving our general understanding of 35 species’ capacity to cope with future climate changes by planting the same genetic material under 38 different climates from the south of Portugal to the south of Scotland (from latitude 37° to 58°). In this regard, the aim of this study is to characterize in two REINFORCE arboreta (Lisbon and Sintra) the survival, growth, leaf phenology and tolerance to pests and cold, for 5 selected species (Quercus robur L., Q. rubra L., Q. shumardii Buckley., Betula pendula Roth. and Acer pseudoplatanus L.), relating their behavior with the origin of the propagating material. This, would allow to have information on the behavior of these species under the present climate conditions in the two studied arboreta, and if different provenances of the same species respond differently to the current conditions in the arboreta, or not. This type of study further provides information about the suitable species to be used in afforestation programs, where present study can be considered a preliminary work easing the way for further research regarding forests and afforestation. Our study involved measurements of each of the following parameters: plant growth, morphological parameters, phenology and insects damage (which was carried out according to protocols defined under REINFFORCE project), and spring frost tolerance. This last parameter was estimated by measuring conductivity of leaf discs electrolyte leakage after applying controlled freezing treatment using a cryostat (Aralab, Lisbon, Portugal) for five different temperatures (–3, –5, –6.6, –9, and –10.5 C°). In a comprehensive overview to the results, we have found an apparent relation between frost and the time of bud bursting and the sensitivity to insect respectively. Betula pendula was the earliest species to bud burst in both sites, being thus the highest exposed to spring frost. It was also the least species to be affected by insect damage which, in turn, indicates that the earlier bud bursting for B. pendula, may have caused a noticeable gap between the bud bursting (where the leaves are the most sensible to insect attack) and between the development of the insects that attack the leaves. On the laboratory no significant difference were found among species on frost tolerance.