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

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.

Microclimatic Alteration after Logging Affects the Growth of the Endangered Lichen Lobaria pulmonaria

“…Meristematic fragments grew on average more than non-meristematic ones, regardless of aspect. Similarly, our previous study highlighted that north-exposed meristematic fragments measured after one year had higher growth rates (0.16–0.18 cm 2 ) than non-meristematic ones (0.02–0.06 cm 2 ), irrespective of forest management (i.e., comparing logged versus unlogged stands) [ 20 ]. On the other hand, the results also point out the capacity of both meristematic and non-meristematic tissues to regenerate and grow, even after severe damage, as previously observed for other lichen species [ 42 ].…”

“…Nevertheless, like many other organisms, L. pulmonaria possesses different mechanisms for acclimation, which, within a certain range, allows it to withstand changes in microclimatic conditions after forest logging. As an example, the species is able to adapt to high light stress through the melanisation of the thallus [ 33 ], as already observed as a response to logging, or in transplant experiments [ 20 , 21 , 34 ]. Lobaria pulmonaria synthesizes melanins when exposed to high solar radiation; this melanisation requires sufficient hydration of the thallus to occur and may effectively reduce high light stress by increasing energy dissipation and reducing photosynthetic activity [ 33 ].…”

“…In a previous study [ 20 ], comparing young and adult L. pulmonaria thalli exposed for one year in logged and unlogged stands (on the northern side of Turkey oaks), a lower growth of L. pulmonaria was observed on isolated trees in the logged stand, especially in the case of adult thalli. Similarly, native thalli on isolated trees appeared thinner and showed lower photosynthetic performance and water holding capacity when compared with healthy samples from unlogged forests or retained forest patches [ 21 ], with consequent implications for their growth and the possibility of providing ecosystem services.…”

Bark Water Storage Plays Key Role for Growth of Mediterranean Epiphytic Lichens

“…As demonstrated by our temporal simulation, this approach, generally valid, is even more critical in a Mediterranean environment where the prolonged summer water deficit makes the bark a fundamental reservoir for the survival of poikilohydric species. The quantification of the water requirements of epiphytic communities and of the water potentially available in the forest environment will allow to detail targeted forestry interventions compatible with the maintenance of the communities within their physiological optimum (Bianchi et al, 2020).…”

Wanted: virtual or live! How lichens are becoming part of mass internet culture

“…As conservationists stress, people care and value what they are familiar with (Jepson and Barua 2015). Among lichens, a good example is Lobaria pulmonaria: a relatively rare lichen mainly threatened by habitat destruction (Bianchi et al 2020). In 2017, a local environmental association in the Murlo Municipality (Siena, Italy; Comitato Amici del Crevole, 2017) added the presence of a rich community of L. pulmonaria to the list of ecological features requiring protection in a forested area.…”