Structure, Spatio-Temporal Dynamics and Disturbance Regime of the Mixed Beech–Silver Fir–Norway Spruce Old-Growth Forest Of

Plant Biosystems, 2015 Vol. 149, No. 6, 966–975, http://dx.doi.org/10.1080/11263504.2014.945978 ORIGINAL ARTICLE Structure, spatio-temporal dynamics and disturbance regime of the mixed beech–silver fir–Norway spruce old-growth forest of Biogradska Gora (Montenegro) R. MOTTA1, M. GARBARINO2, R. BERRETTI1, I. BJELANOVIC3, E. BORGOGNO MONDINO1,M.Cˇ UROVIC´ 4, S. KEREN5, F. MELONI1, & A. NOSENZO1 1Department of Agriculture, Forestry and Food Sciences, University of Turin, Via Leonardo da Vinci 44, Grugliasco, Italy; 2Department D3A, Universita` Politecnica delle Marche, Via delle Brecce Bianche, I-60131 Ancona, Italy; 3Faculty of Forestry, University of Belgrade, Kneza Viseslava 1, Belgrade, Serbia; 4Biotechnical Faculty, University of Montenegro, Mihaila Lalica 1, Podgorica, Montenegro and 5Faculty of Forestry, University of Banja Luka, Vojvode Step Stepanovica 75 a, Banja Luka, Bosnia and Herzegovina Abstract The structure and the spatio-temporal dynamics of the mixed beech–silver fir–Norway spruce old-growth forest of Biogradska Gora (Montenegro) have been analysed at different spatial scales: at the landscape scale, using a high-resolution SPOT5 satellite image and at the stand level with an intensive field survey. This remote-sensing approach has been used to obtain a land cover map in order to define the main vegetation types and to detect the large canopy gaps (.150 m2). The structural characteristics have been delineated in a 50-ha study area in which a regular 120-m grid was superimposed over a 1:10,000 raster map and 30 sampling points have been obtained. The forest is characterized by a high volume of living trees (1029.6 m3 ha21) and coarse woody debris (420.4 m3 ha21) and by small-scale disturbances (individual trees to small groups) with a low incidence of intermediate disturbances (18 forest canopy gaps . 150 m2 over 1230 ha). The two approaches have proved useful to delineate the spatio-temporal dynamics. The Biogradska Gora forest dynamics are dominated by very small- scale processes, which are partially autogenic and partially caused by allogenic factors. The influence of large-scale or intermediate disturbances has shown to be negligible. Keywords: Old-growth forest, satellite images, forest structure, gaps, disturbances, coarse-woody debris Downloaded by [RMIT University] at 01:21 02 March 2016 Introduction human impact and major natural disturbances and show three main structural characteristics: old and The structural analyses of forest ecosystems have large trees, abundant coarse woody debris in shown that the temporal and spatial interplay different decay stages and a multilayered vertical between individual tree mortality and larger disturb- structure (Franklin 1993; Foster et al. 1996; Motta ances at varying scales, from small gaps to land- 2002; Franklin & Van Pelt 2004). scapes, creates a multitude of developmental Characterizing the old-growth stage and the pathways (Runkle 1982; Oliver & Larson 1996). complete forest development cycle is particularly The type and number of developmental stages may difficult in regions, like central-southern Europe, in depend on different spatial scales, forest species and which the anthropogenic effects have been of long the disturbance regime (Franklin et al. 2002; Kra´l duration and have interacted with natural factors so et al. 2010; Alessandrini et al. 2011) before the stage much that the effects of natural disturbance and known as “old-growth stage” is reached (Franklin & human activities are now almost impossible to Spies 1991). There are many definitions of this stage distinguish (Garbarino et al. 2009; Motta et al. but most researchers agree that old-growth stands 2010; Barbati et al. 2012). In this region, human develop after long periods without any relevant land-use has been the most important driving force Correspondence: R. Motta, Department of Agriculture, Forestry and Food Sciences, University of Turin, Via Leonardo da Vinci 44, Grugliasco, Italy. Tel: þ 390116705538. Fax: þ390116705556. Email: [email protected] q 2014 Societa` Botanica Italiana 2 Biogradska Gora old-growth forest 967 behind the shaping of the landscape and the structure proclaimed a National park. In the core area of the of the forest stands (Farrell et al. 2000; Garbarino park, that is the valleys of the Biogradska and et al. 2013). The forests have been intensively Jezersˇtica rivers surrounding Biogradsko Lake, there managed or cleared, and even in the most remote are several different forest types, but the most places there are signs of past grazing, litter collecting important is the mixed beech (Fagus sylvatica L.) and charcoal production (Gimmi et al. 2008; Diaci and silver fir (Abies alba Mill.) type, with sparse et al. 2010). Norway spruce (Picea abies (L.) Karst.) (Cˇ urovic´ The human impact has not been uniform over et al. 2011a, 2011b; Andjelic´ et al. 2012). The other the entire region and substantial tracts of virtually relevant forest species that are present are sycamore untouched forests survived until the second part of maple (Acer pseudoplatanus L. and Acer platanoides the 19th century (Peterken 1996). In that period, L.), mountain ash (Fraxinus excelsior L.), rowan improvements in transportation and harvesting (Sorbus aucuparia L.) and wych elm (Ulmus montana technology as well as the increasing demand for With.). wood and fuel from industry have drastically reduced The main purpose of this study was to analyse the extent of the last remains of virgin forests. In the structure and dynamics of the beech, silver fir and same time, forest administrations started to establish Norway spruce mixed Biogradska Gora old-growth forest reserves as hunting reserves or to preserve forest using both remote sensing and intensive some parts of virgin forests (Diaci 1999). Most of ground control in order to (1) describe its main these reserves were of relatively small, sometimes just structural characteristics, (2) reconstruct the spatio- a few hectares, while moderately sized and large temporal disturbance dynamics and (3) compare the reserves, from hundreds to several thousands of structure and dynamics of this forest with other hectares, were extremely rare (Schuck & Hyto¨nen central-southern European mixed old-growth 2000). Natural disturbances may operate at very forests. different scales and the disturbance size could often be larger than the size of a small forest reserve. In order to accommodate these processes, each forest Material and methods reserve should be tailored to minimum size Study site thresholds in order to allow all the disturbances the subsequent dynamic stages to develop. In small This research was conducted in the Biogradska Gora forest reserves, effects can influence several factors National park in the north-western part of the and processes, such as the forest microclimate, tree Bjelasica mountain range in the Dinaric Alps mortality, animal habitat use and the invasion of alien (Montenegro). This forest is the largest of a network species (Gascon et al. 2000; Laurance et al. 2002). of remaining virgin forest of the same forest type that As a consequence, most of the small reserves in can be found in the Balkans peninsula from Slovenia central-southern Europe are not potentially able to to Montenegro (Maunaga 2001; Anic´ & Mikac 2008; capture the whole natural temporal and spatial Nagel & Svoboda 2008; Diaci et al. 2010; Motta variability (Cissel et al. 1999; Landres et al. 1999; et al. 2011). Fraver et al. 2009) and large, well-preserved forests The lowest part of the park is in the Tara valley Downloaded by [RMIT University] at 01:21 02 March 2016 are extremely important, from the scientific point of (about 830 a.s.l.) while the highest part is the Crna view, because of their potential role in the Glava peak (2139 m a.s.l.). The park covers an area reconstruction of both the disturbance regime and of 5650 ha (Figure 1). Different forest categories the development stages of the forest with special exist within the park but the most important are (a) reference to the old-growth stage (Marchetti et al. pure beech and (b) mixed beech, silver fir and 2010; Ziaco et al. 2012; Burrascano et al. 2013). Norway spruce. The annual average precipitation at One of the largest long-term preserved forests in Biogradsko lake (1093 m a.s.l.) is 1962 mm, with a central-southern Europe is in the “Biogradska Gora” maximum in November and a minimum in July. National park (Montenegro). The history of The mean annual temperature is around 58C. The measures adopted to protect this forest dates back bedrock is mainly made up of eruptive rocks to 1885 when, after the liberation of Kolasˇin from the (Cˇ urovic´ 2011). Two forest types were identified in Turks in 1878, the local people offered the the mixed silver fir, beech and spruce forest on the Biogradska Gora forests to the duke (later the king basis of phytosociological releve´s: Abieti-Fagetum of Montenegro) Nikola Petrovic´ (Bilovitz et al. dinaricum Treg. 1957 and Piceeto-Abieti-Fagetum 2009). At that time, most of the Bjelasica mountains s. lat. Treg. 1957, the main difference between these forests were virgin or near-virgin forests that had being the occurrence of Norway spruce. According to never been significantly influenced by human activity the profiles and the physical and chemical character- (Peterken 1996). At the beginning, the forest was istics of soils, they can be classified as brown acid – used as a royal hunting reserve, and in 1952, it was dystric cambisol (Cˇ urovic´ 2011). 968 R. Motta et al. 3 Figure 1. Location of the Biogradska Gora National park. Remote sensing about 9 m. Both the panchromatic and the multi- spectral bands were orthoprojected and an RMSE for Owing to the absence of forest maps, a satellite image the GCPs of 1.54 m was obtained. As the ground was used to analyse the vegetational cover and survey was mainly planned and performed to obtain identify the best site for the intensive study area.

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