Tree Growth in Relation to Climate Change: Understanding the Impact on Species Worldwide

Climate change is one of the most important environmental issues of our time, which has profound effects on ecosystems all over the world [1]. Given its vital role in forest dynamics and carbon sequestration, the effect of climate change on tree growth has drawn the most attention of all its effects [2]. Understanding the various aspects linked to climate change and their impact on tree growth is crucial for forecasting future forest composition and dynamic and efficiently managing forest resources, explaining its significant and increasing interest not only at the species scale but also for biodiversity and ecosystem services [3,4].

Climate is known to influence tree growth since it controls photosynthesis, cell division, and tree metabolism [5,6]. Notwithstanding, climate acts at different spatial and temporal scales [2,7,8], adding to the soil condition and microfauna dynamic [9,10]. Climate variables, including temperature, precipitation, and moisture availability, all affect tree growth [11]. These variables can alter over time as a result of climate change and are not constant in different locations [2]. As a result, different tree species are responding differently throughout the world in terms of growth [2,12,13]. Thus, the structure and function of forests may be significantly impacted by this difference in growth patterns [12,14,15].

Tree growth response is also species-specific, linked to growth habit [2] and autecology [14,16,17]. In addition, this response depends on the stand structure and composition [18,19,20]. Nevertheless, there is a general decline trend for trees facing drought conditions [21,22] or in more heat-limiting (high latitude and altitude, or in cold-air pooling) environments coupled with cloudiness [23] or snowpack [24]. Thus, these factors weaken the tree and cause mortality [25,26,27]. Tree growth is a key for competitive advantage and thus is considered as a proxy for predicting future species and vegetation migration [28].

Tree growth tends to decrease as we move towards higher latitudes, attributed to colder temperatures, shorter growing seasons, and reduced light availability in these regions [29]. As we ascend in elevation, tree growth typically slows down due to lower temperatures and reduced nutrient availability in the soil [6,29]. However, tree species adapted to high-altitude environments may exhibit unique growth patterns and adaptability to changing climate conditions [30,31,32]. In addition, drought events are becoming increasingly common under climate change scenarios [33]. Drought limits the availability of water, leading to physiological stress and decreased tree growth [34,35,36]. In extreme cases, prolonged drought can even lead to tree mortality [37,38,39].

Research on how climate change can affect tree growth in Europe, Asia, and America has revealed that significant timber species could lose adequate habitat in the next decades and suffer from a combination of rising trends and decreased precipitation throughout the growing season [40,41]. Some species, on the other hand, might actually widen their range and even exhibit better growth rates in some areas of their current range [42,43]. They might also demonstrate promise for commercial species when they become established in new areas. Furthermore, the intricate relationships between tree growth and temperature, water, and nutrients increase the complexity of tree growth [2,44]. Forest management might be adjusted to the new growing conditions that are gradually but surely emerging by utilizing mixed forests’ potential resilience to changes in growth conditions [45]. In order to further our understanding of how climate change may affect tree growth, this Special Issue was initiated.

The impact of climate change on tree growth has implications at multiple scales—local, regional, and large-scale. At the local and regional level, changes in tree growth can affect the distribution and composition of tree species [46]. Some species may become more dominant, while others may decline, potentially leading to shifts in entire ecosystems and disrupting species interactions [47]. At a larger scale, climate change can influence the location of ecotones—transitional areas between different ecosystems. As tree species respond differently to changing climate conditions, ecotones can shift, potentially affecting species migration patterns and altering biodiversity patterns [48,49].

While climate change poses significant challenges to tree growth, some species are showing remarkable resilience and adaptability [50,51,52]. Tree species with broader ecological niches and genetic diversity are often better equipped to cope with changing conditions [53]. Understanding the adaptive capacity of different species and promoting diverse forests can enhance the overall resilience of forests to climate change [54]. All these explain the complexity of tree growth associated with climate change-induced and the contradictory findings from different studies [55,56,57].

As the climate continues to change, it is essential to monitor and understand the impact on tree growth worldwide [58,59]. By studying the relationships between climate variables and growth patterns, we can better predict future forest dynamics and develop sustainable management strategies. It is crucial for policymakers, scientists, and land managers to collaborate and implement adaptive measures to preserve the resilience and functionality of forests in the face of climate change.

Numerous studies were mostly conducted in more limiting environments, i.e., higher latitudes [60,61,62] or elevations [63,64,65] and with more common and widespread species, such as black spruce, trembling aspen in North America [66,67,68], Norway spruce, Scots pine, and common beech in Europe [69,70], and larches in Siberian Asia [71,72]. Although these previous studies are very relevant to assess how trees respond to climate change, knowledge gaps remain because there is uncertainty about the response of less common species to climate change-induced events in other parts of the world, such as in the southern hemisphere [73]. In addition, the question still arises about how trees react to climate change in physiological and phenological terms [74].

All in all, this Special Issue offers readers a variety of research investigating the relationships between climate change and tree growth in various biomes (boreal, temperate, cool subalpine), on various continents (North and South America, Europe, and Asia), at various scales (from local populations to latitudinal and altitudinal gradient studies), and with various species (evergreen and deciduous conifer and broadleaf). As much as the editors enjoyed putting this Special Issue together, we hope readers will too. As well, this Special Issue gives a good insight that deals with the above-mentioned aspects and to increase our knowledge and to have ample information on how tree species responded to climate change. Likewise, it will promote discussion, exchange, and debate between scientists and also make forest decision-makers aware for future management.