Vitality and Growth of the Threatened Lichen Lobaria pulmonaria (L.) Hoffm. in Response to Logging and Implications for Its Conservation in Mediterranean Oak Forests

Elisabetta Bianchi,Renato Benesperi,Luca Di Nuzzo,Sonia Ravera,Chiara Vallese,Juri Nascimbene,Giorgio Brunialti,Luisa Frati,Zuzana Fačkovcová,Paolo Giordani,Luca Paoli

doi:10.3390/f11090995

Abstract

Forest logging can be detrimental for non-vascular epiphytes, determining the loss of key components for ecosystem functioning. Legal logging in a Mediterranean mixed oak forest (Tuscany, Central Italy) in 2016 heavily impacted sensitive non-vascular epiphytes, including a large population of the threatened forest lichen Lobaria pulmonaria (L.) Hoffm. This event offered the background for this experiment, where the potential effects of logging in oak forests are simulated by means of L. pulmonaria micro-transplants (thallus fragments <1 cm). Our working hypothesis is that forest logging could negatively influence the growth of the thalli exposed in logged stands compared to those exposed in unlogged stands. One hundred meristematic lobes and 100 non-meristematic fragments are exposed for one year on 20 Turkey oak trees (Quercus cerris), half in a logged and half in an unlogged stand. Chlorophyll (Chl) a fluorescence emission and total chlorophyll content are used as a proxy for the overall vitality of the transplants, while their growth is considered an indicator of long-term effects. Generally, vitality and growth of the transplants in the logged stand are lower than in the unlogged stand. Both vitality and growth vary between the meristematic and non-meristematic fragments, the former performing much better. Hence, irrespective of forest management, meristematic fragments show higher growth rates (0.16–0.18 cm2 year−1) than non-meristematic ones (0.02–0.06 cm2 year−1). Considering that a conservation-oriented management for this species should be tailored at the habitat-level and, especially, at the tree-level, our results suggest that for appropriate conservation strategies, it is necessary to consider the life cycle of the lichen, since the probability of survival of the species may vary, with meristematic fragments having more chance to survive after logging.

Highlights

Biodiversity is increasingly threatened by several anthropogenic factors [1,2,3,4,5]
L. pulmonaria populations in relation to forest management often depends on the regenerative capacity of the thalli, we focus our attention on the behavior of thalli with meristematic and non-meristematic properties
Concerning non-meristematic fragments, the difference between FV /FM values in the logged and unlogged stands was not significant (p > 0.05). Both types of fragments in the unlogged stand were characterized by significantly higher (p < 0.05) chlorophyll contents compared with those in the logged stand

Summary

Introduction

Biodiversity is increasingly threatened by several anthropogenic factors [1,2,3,4,5]. Five main pressures have been recently pinpointed [6], including the overexploitation of species; the introduction of invasive alien species; pollution from industrial, mining and agricultural activities; changes in land use; climate change. Due to these pressures, some models predict that up to 50% of the species are expected to become extinct in the 50 years [7,8,9]. Non-vascular epiphytes fulfill various ecological functions in forests They contribute to water and nutrient cycling by intercepting and retaining nutrients from atmospheric humidity, with some adding nitrogen by nitrogen fixation [16,17,18]. They provide resources and microhabitats for bark-dwelling invertebrates, birds, and mammals [19,20]

Results

Discussion

Conclusion