Gap-phase dynamics in the old-growth forest of Lom, Bosnia and Herzegovina

Abstract

We investigated forest canopy gaps in the mixed beech (Fagus sylvatica L.), silver fir (Abies alba Miller), and Norway spruce (Picea abies (L.) Karst.) old-growth forest of Lom in the Dinaric Mountains of Bosnia and Herzegovina. Gap size, age, gap fraction, gapmaker characteristics and the structure and composition of gapfillers were documented to investigate gap dynamics. The percentages of forest area in canopy and expanded gaps were 19% and 41%, respectively. The median canopy gap size was 77 m 2 , and ranged from 11 to 708 m 2. Although there were many single tree-fall gaps, the majority had multiple gapmakers that were often in different stages of decay, suggesting gap expansion is important at the study site. Of the gapmakers recorded, 14% were uprooted stems, 60% snapped stems, and 26% were standing dead trees. Dendroecological analysis suggests that gap formation varied in time. The density of gapfillers was not correlated to gap size, and the species composition of gapfillers varied between seedling, sapling, and tree life stages. The results suggest that gaps are mainly formed by endogenous senescence of single canopy trees. Exogenous disturbance agents, most likely related to wind and snow, act mainly as secondary agents in breaking weakened trees and in expanding previously established gaps. Although the findings are partially consistent with other studies of gap disturbance processes in similar old-growth forests in central Europe, the observed gap dynamic places the Lom core area at the end of a gradient that ranges from forests controlled by very small-scale processes to those where large, stand replacing disturbances predominate.

Gap disturbances and regeneration patterns in a Bosnian old-growth forest: a multispectral remote sensing and ground-based approach

“…Gap size had little influence on regeneration density in Lom, which was also found in a companion 263 study (Bottero et al 2011). This finding is confirmed by other studies in southeastern European …”

Long-term transformation of submontane spruce-beech forests in the Jizerské hory Mts.: dynamics of natural regeneration

“…(Čermák & Grundmann 2006) and from Slovakia (Konôpka & Pajtík 2015). A high pressure on fir and factually the disposal of its natural regeneration by game browsing were described by Bottero et al (2011) in Bosna and Herzegovina, by Jaworski et al (2002) in the Western Carpathians or by Klopcic et al (2010) in Slovenia; the latter authors reported about unfenced firbeech stands, where great damage to fir recruits or even the total disposal of fir regeneration by browsing was observed. In relation to the high game pressure Vrška et al (2001) concluded that selected forest stands should be fenced to provide natural spontaneous development of the regeneration of spruce-fir-beech forests.…”

Comparative Structural Dynamics of the Janj Mixed Old-Growth Mountain Forest in Bosnia and Herzegovina: Are Conifers in a Long-Term Decline?

“…Documented climatic events, likely coupled with anthropogenic disturbances, are indicated in this study by the following: (1) beech dominance among small trees in all inventories and its increase overall dbh classes in recent inventories; (2) the future decrease of the beech middle-story modelled with transition probabilities; (3) the IQ shape of dbh frequency distribution in the 1950s for conifers in all old-growth forests and (4) changes in dbh frequency distributions. Other recent studies have also suggested these events, e.g., the disturbance study in Motta et al [47] and gap age analysis in Bottero et al [48].…”

“…These forests therefore represent an excellent resource for the study of interactions of climatic fluctuations and indirect anthropogenic disturbances, both of which are well documented in the literature [33,[37][38][39][40][41]. The Janj old-growth forest has received less scientific attention [42,43] than the forests of Perucica (e.g., [5,19,[44][45][46]) and Lom [32,47,48]. The aims of this study were (1) to describe the structural changes over a 60-year period in the Janj old-growth forest and (2) to compare and contrast the changes with those in the Lom and Perucica (Bosnia and Herzegovina) old-growth forests and other similar old-growth forests in Europe.…”