Long-Term Forest Dynamics of Oromediterranean Fir Forests in Greece

Robert Brandes,Anastasia Christopoulou

doi:10.15177/seefor.20-02

Robert Brandes, Anastasia Christopoulou

Open Access

https://doi.org/10.15177/seefor.20-02

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Abstract

The present study illustrates the situation of the genus Abies in the Mediterranean and in Greece, focusing in detail on the oromediterranean forest of the southern Peloponnese, at Mt. Taygetos. The existing pattern of forest dynamics (mosaic cycle) and also the timberline dynamics are presented and explained. Since fir forests are highly susceptible to drought-related impacts (fire and fir dieback: insect outbreaks/ forest pathogens), the analysis of the present situation is put into perspective by looking at the role of direct human influence and the climatic fluctuations of the past, taking into consideration dendrochronological findings and archival climate records. In view of climate warming the question is whether in recent decades the fingerprints of climate change can already be observed in the Greek fir forests. The study concludes that drought periods and climatic extremes have been an essential part of Greek climate for many centuries, causing high natural forest vulnerability. Therefore, fir dieback and fires are not a new phenomenon either – but in recent decades the accumulation of fuel, caused by land abandonment, has increased the danger of large wildfires. Nevertheless, the Greek mountain forests are highly endangered by increases in aridity and/or more frequent climate extremes (heat waves), together with increased risk of wildfires. Recommendations for an active forest management (counteracting expected adverse effects of climate change, by focusing on the establishment of an Abies cephalonica Loudon /Pinus nigra J. F. Arnold mosaic cycle) and further scientific research are provided.

Highlights

The consequences of global warming on forest ecosystems and vegetation dynamics are an important ecological issue (Peters 1990, Lindner et al 2010) that should be considered under adaptive forest management (Lindner et al 2014, Yousefpour et al 2017)
The droughtrelated process framework of fir dieback presents a threat to the existence of fir forests in Greece
The regressive timberline dynamics are an indication that in recent decades drought has caused the decay of older firs and prevented regeneration on dry, rocky sites

Summary

Introduction

All Mediterranean Abies species grow in relatively moist and cool mountain areas, where they withdrew after the last ice age, forced by the increasingly dry and warm Mediterranean climate. The disjunction of their habitats caused the formation of various endemic species. Growing at its ecological boundary makes the genus sensitive in regard to climate-ecological fluctuations or even profound climatic changes For this reason Brandes and Ise (2007) identified the Abies forests as highly suitable study objects, in order to detect fingerprints of climate change (Walther 2001) in the vegetation of the Mediterranean. Global warming is most likely to exacerbate tree stress near the margins of the geographical or altitudinal species ranges, i.e. observations should be concentrated at ecological boundaries of zonal tree species (Delcourt and Delcourt 1992, Paine and Baker 1993)

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Conclusion