Unit:
Τομέας Οικολογίας και ΤαξινομικήςLibrary of the School of Science
Author:
Χριστοπούλου Αναστασία
Dissertation committee:
Μ. Αριανούτσου- Φαραγγιτάκη, Καθηγήτρια Τμήματος Βιολογίας ΕΚΠΑ (Επιβλέπουσα) , Π. Δημητρακόπουλος, Αναπληρωτής Καθηγητής Παν. Αιγαίου ,Αθ. Καλλιμάνης Επίκουρος Καθηγητής Παν. Πατρών
Original Title:
Διερεύνηση της ιστορικής παρουσίας της φωτιάς και πρότυπα χωρικής μεταπυρικής αναγέννησης σε δασικά οικοσυστήματα Pinus nigra J. F. Arnold του όρους Ταϋγέτου
Translated title:
Dendrochronology-based fire history reconstruction and post-fire regeneration patterns of Pinus nigra J. F. Arnold in Mount Taygetos, Southern Greece
Summary:
The aim of this study was to investigate the historical presence of fire in
Pinus nigra J. F. Arnold (Black pine) forest ecosystems, as well as to document
the spatial patterns of its post-fire regeneration on Taygetos mountain range
of Southern Greece that was severely burned in 2007.
Dendrochronology has been used to investigate whether fire-regime attributes
can be reconstructed from fire-scarred trees and also to examine the
consistency of fire occurrence and spatial extent through time within the study
area. Partial cross-sections were sampled within the perimeters of the more
recent known large fires in the region, those of 2007 and 1998. The overall
mean fire interval between 1845 and 2007 was 4.9 yrs, while for the larger
fires this time window was 16.2 yrs. Even at the individual-sample scale, with
the sample mean fire interval equalling 29.5 years, the fire frequency still
falls within the range of the ‘‘predictable stand-thinning fire’’ regime. The
majority of fire scars recorded were dated to the warm and dry season of summer
to fall. During the last 165 years of fire reconstruction, neither fire
frequency nor percentage of trees scarred by fires varied significantly.
Nevertheless, the size of the area burned as well as the type of fire seem to
have changed, with the 2007 event being the most extended crown fire
encountered so far. Our study has provided additional evidence that Pinus nigra
is indeed a fire-resistant tree species provided that it is exposed to surface
fires, even if they are recurrently occurring. Shifts from this pattern may
lead to local extirpation of the species, as in the case of severe and extended
crown fires.
In order to investigate the post-fire regeneration patterns of black pine after
the 2007 high severity crown fire a network of 18 sites was selected.
Regeneration density was higher at the edges of patches that have remained
unburned within the periphery of fire (0.406 individuals / m2) as compared to
isolated burned areas (0.007 individuals/m2) although a significant between
sites heterogeneity was recorded. Boosted regression tress analysis was used to
explore the effects of environmental and microhabitat variables on black pine
post-fire regeneration. The number of fires a site has experienced had a
negative effect on regeneration density, while the presence of recovering ferns
had a positive effect. The most important variable related to the black pine
post-fire regeneration was distance from unburned patches. The result of the
current study substantiates the importance of maintaining fire- resistant
stands with large trees that are more likely to survive after a surface fire
and which can also serve as seed sources for the recolonization of the burned
area after severe crown fires.
Keywords:
Black pine, Fire regime, Dendrochronology, Post-fire regeneration, Dispersal patterns;
Number of references:
294
