Tree growth phenology changes within the change of climate and it’s influence on stem growth — thoughts and questions
First, let’s say that studying trees is very much needed in this, anthropocentric world. Trees provide valuable resource (wood) which is, in different forms, used on daily basis. Naturally, the best quality wood comes from forests. So, in order to have the best wood we need healthy forest. Also, from the ecological point of view, forests are very useful terrestrial ecosystems. According to Dow et al. (2022), net forest CO2 sink of approximately 1.6 Gt carbon per year offsets approximately 20% of anthropogenic emissions, dramatically slowing the pace of atmospheric CO2 accumulation and climate change. But, as forest ecosystems are struggling to adapt to manmade climate change their carbon sink role remains uncertain (Etzold et al., 2021). Number of papers are being published every year aimed at the impact of climate change on forest ecosystems.
The effect of global warming on tree growth phenology is one of the topics not yet fully explored. It is known that trees annual biological cycle is synchronized with local climate conditions (temperature, solar radiation, precipitation). Various studies on intra-annual tree growth of temperate forests have shown that rapid climate changes occurring during one tree life period cause the tree to start its annual recurring phenomena (e.g. bud burst, stem growth…) earlier (Kramer 1996).
Changes in the phenology of trees such as advancement of leaf unfolding and flowering of 2–3 days per decade on average during the last 50 years, have been attributed to the temperature increase that many regions have experienced in the last decades because of global warming (Morin et al., 2010). Also, changes such as, increased soil waterlogging in spring, and especially severe drought stress in summer could lead to growth depressions, range shifts of species, drought damages and potential dieback events in forest ecosystems (Scharnweber et al., 2020).
But how does this reflect on the length and ending of intra-annual growth period? Does this mean that the growth period in the future could be longer, resulting in higher Net Primary Production or could it cause disturbances in growth? Are these processes different among different species? Also, what is the relation between leaf phenology and stem growth? And, in the end, what is the effect of competition on growth phenology? Do dominant and suppressed trees react differently to climate change in the sense of earlier start of growing season? These are the questions I will be trying to answer in the next couple of years during my research.
