Shifts in Forest Species Composition and Abundance under Climate Change Scenarios in Southern Carpathian Romanian Temperate Forests

Abstract

The structure and functioning of temperate forests are shifting due to changes in climate. Foreseeing the trajectory of such changes is critical to implementing adequate management practices and defining long-term strategies. This study investigated future shifts in temperate forest species composition and abundance expected to occur due to climate change. It also identified the ecological mechanisms underpinning such changes. Using an altitudinal gradient in the Romanian Carpathian temperate forests encompassing several vegetation types, we explored forest change using the Landis-II landscape model coupled with the PnET ecophysiological process model. We specifically assessed the change in biomass, forest production, species composition and natural disturbance impacts under three climate change scenarios, namely, RCP 2.6, 4.5 and 8.5. The results show that, over the short term (15 years), biomass across all forest types in the altitudinal gradient will increase, and species composition will remain unaltered. In contrast, over the medium and long terms (after 2040), changes in species composition will accelerate, with some species spreading (e.g., Abies alba Mill.) and others declining (e.g., Fagus sylvatica L.), particularly under the most extreme climate change scenario. Some forest types (e.g., Picea abies (L.) karst forests) in the Southern Carpathians will notably increase their standing biomass due to climate change, compared to other types, such as Quercus forests. Our findings suggest that climate change will alter the forest composition and species abundance, with some forests being particularly vulnerable to climate change, e.g., F. sylvatica forests. As far as productivity and forest composition changes are concerned, management practices should accommodate the new conditions in order to mitigate climate change impacts.

Last millennium climate variability in the Romanian Carpathians: a synthesis

“…Shifts to another ecosystem's climate have been observed in many forest species' climate envelopes (Mihai et al, 2022). Moreover, the warming trend has caused some plant species to expand their range while others have contracted (García-Duro et al, 2021). Simulations indicate that changes in species composition can be followed by a notable decrease in aboveground live carbon storage (Kruhlov et al, 2018).…”

Carpathian Forests: Past and Recent Developments

“…Higher temperatures are expected to increase the risks of pest outbreaks and wildfires, and temporal and spatial changes in precipitation patterns may affect the hydrology of forest areas [25]. These complex and interrelated changes will affect forests [32][33][34][35] and require adaptations in forest management [36,37].…”

More losses than gains? Distribution models predict species-specific shifts in climatic suitability for European beech forest herbs under climate change

“…Owing to the mesophilous nature of beech forests avoiding too dry and too wet sites (Leuschner and Ellenberg, 2017) and relatively high requirements of the understory herbs for soil moisture and air humidity (Leuschner and Lendzion, 2009), this forest type might be negatively impacted by changing macroclimate. In the study coming from Romanian Carpathians (García-Duro et al, 2021), forests dominated by Fagus sylvatica were most vulnerable to climate change, with drought periods associated with large mortality events. Moreover, beech regeneration showed a reduction of its distribution in the dry-warm range (Axer et al, 2021).…”