Silva Fennica 44(4) research notes SILVA FENNICA www.metla.fi/silvafennica · ISSN 0037-5330 The Finnish Society of Forest Science · The Finnish Forest Research Institute Forest Habitat Loss and Fragmentation in Central Poland during the Last 100 Years Tomasz D. Mazgajski, Michał Żmihorski and Katarzyna Abramowicz Mazgajski, T.D., Żmihorski, M. & Abramowicz, K. 2010. Forest habitat loss and fragmentation in Central Poland during the last 100 years. Silva Fennica 44(4): 715–723. The process of habitat fragmentation consists of two components – habitat loss and fragmenta- tion per se. Both are thought to be among the most important threats to biodiversity. However, the biological consequences of this process such as species occurrence, abundance, or genetic structure of population are driven by current, as well as previous, landscape configurations. Therefore, historical analyses of habitat distribution are of great importance in explaining the current species distribution. In our analysis, we describe the forest fragmentation process for an area of 178 km2 in the northern part of Mazowsze region of central Poland. Topographical maps from the years 1890, 1957 and 1989 were used. Over the 100-year period, forest cover- age in this area changed from 17% to 5.6%, the number of patches increased from 19 to 42, while the area of the forest interior decreased from 1933 ha to 371 ha. The two components of fragmentation were clearly separated in time. Habitat loss occurred mainly during the first period (1890–1957) and fragmentation per se in the second (1957–1989). Moreover, we recorded that only 47.7% of all the currently (in 1989) afforested areas constitute sites where forests previously occurred (in 1890 and 1957). For forest dwelling organisms characterized by low dispersal abilities, the effective forest coverage seems to be a half of the real forest area in the studied landscape. New afforestations should be planned especially to increase those patches which contain ancient forest, where various plants and animals sensitive to fragmentation may have survived. Keywords fragmentation, landscape history, forest continuity, deforestation, ancient forest, afforestation Addresses Mazgajski and Żmihorski, Polish Academy of Sciences, Museum & Institute of Zool- ogy, Wilcza 64, PL 00-679 Warsaw, Poland; Abramowicz, Department of Ecology, University of Warsaw, Banacha 2, PL 02-097 Warsaw, Poland E-mail [email protected] Received 3 September 2009 Revised 9 March 2010 Accepted 8 October 2010 Available at http://www.metla.fi/silvafennica/full/sf44/sf444715.pdf 715 Silva Fennica 44(4), 2010 research notes 1 Introduction a consequence, the present distribution of some species in the landscape can be better explained Habitat fragmentation is one of the most impor- by the historical distribution of the habitat than tant transformations of the environment signifi- by the current landscape configuration (Jonsell cantly affecting abundance and distribution of and Nordlander 2002, Schrott et al. 2005, Helm species in the modern landscape (Saunders et al. et al. 2006). Because of this, knowledge about the 1991, Fahrig 2003, Ewers and Didham 2006). In historical landscape is necessary to better under- general, this process leads to a decreased amount stand forest distribution in the modern landscape of suitable habitat, increased isolation between and to explain the occurrence of forest dwelling patches and, as a consequence, the occurrence of organisms (Marcucci 2000, Gu et al. 2002, Cas- edge-related effects. However, a detailed analysis tellon and Sieving 2006, Johansson et al. 2008). of this process suggests that we should describe it This topic is especially important in light of recent as a combination of two components – habitat loss programs aimed at increasing forest coverage in and fragmentation per se (e.g. Fahrig 2003). The many European countries. reactions of forest dwelling organisms may differ In analysis of long term landscape changes, simple in situations where a huge intact forest is partially differences in forest cover (or more general the cut, compared to where the overall habitat area share of a particular habitat) and especially changes is unchanged, but the total number of patches in patch characteristics should be described. For increases. However, both components are most many forest dwelling organisms the effect of land- often treated jointly in analyses of deforestation scape characteristics like patch size, shape and and not described in detail. isolation, presence of corridors etc. on probability Habitat fragmentation (in the broad sense) and of their occurrence, extinction and recolonization its ecological consequences are relatively well is well known (e.g. Hinsley et al. 1995, Bellamy known in the case of forest ecosystems that have et al. 1996b). Therefore knowledge of the patch been converted into arable land over several centu- pattern arrangement in the environment as well ries throughout Europe. Forest fragmentation sig- as species requirements, allows predicting species nificantly affects several aspects of reproduction occurrence or distribution both for contemporary and demography of organisms; reduces disper- and historical landscapes (e.g. Bailey et al. 2002). sion, abundance and anticipated life expectancies For such analysis data should be gathered not only of subpopulations. It also renders habitat more for changes in overall forest cover, but detailed vulnerable to invasions of exotic and eurytopic descriptions of patch characteristics should be species (Redpath 1995, Fahrig 2002, Doherty and made. However, such data concerning Poland Grubb 2002, Levey et al. 2005, Mazgajski and are scarce, and papers published to date focused Rejt 2006, Bolger 2007). Therefore, knowledge mostly on changes in forest cover in particular about habitat fragmentation in space and time is administrative or geographical units (Maruszczak crucial for biodiversity conservation planning. 1950, Szymański 1993b, Degórska 1996). Reliable analysis of forest fragmentation and In this paper we used historical maps to describe its impact on organisms requires that historical the pattern of forest fragmentation in the northern changes in habitat configuration should be taken part of the Mazowsze region in Central Poland. into account (Dzwonko 2001, Gu et al. 2002, This part of Mazowsze has one of the smallest Uotila et al. 2002). The existing pattern of forest forest covers in Poland – ca 16.3% (value for the distribution in the current landscapes has been whole country is 29%). Therefore, we assumed shaped over hundreds of years (e.g. Kouki et al. that this area would be very useful for analysis of 2001). Forest fragmentation was driven mainly forest fragmentation history. The aim of our work by landscape transformations made by humans is to quantify and describe in detail the phenom- and depended on the development of civilization enon of deforestation in the region during the last in a given region. Therefore, the distribution of century in the context of its consequences for bio- forest patches in the modern landscape is a con- diversity conservation. We paid special attention sequence of recent as well as historical human to distinguishing between the two components of activity (Partel et al. 1999, Kouki et al. 2001). As the fragmentation process. 716 . Mazgajski, Zmihorski and Abramowicz Forest Habitat Loss and Fragmentation in Central Poland during the Last 100 Years 2 Material and Methods 1993a). The first map we used was from the “Karte des westlichen Russlands” series, and was 2.1 Study Area printed in 1915. However, the map is based on an older Russian map, and thus it is assumed that The analysis was conducted in the Ciechanów presents situation in 1890 (according to Maru- Upland (a part of North Mazowsze Lowland) szczak 1950 and Szymański 1993a). In the other in Central Poland. In this region farmland pre- two maps used, the revision dates are provided. dominates, and forest cover is very low. The mean The maps were scanned and rectified in Erdas annual temperature is +7 °C, annual precipitation Imagine 8.3 software, with a root mean square reaches 650 mm and the length of the growing (RMS) error of 0.4 pixel. For every forest patch season is 210 days (Matuszkiewicz 2001). Poor we computed: the area (ha), perimeter (m), area and semi-rich pine forests (Querco roboris Pin- of the ecotone zone (ha) which covers the forest etum and Serratulo Pinetum) and oak-hornbeam area up to 50 m from the edge, and forest interior associations (Tilio Carpinetum) dominate as zone (ha) i.e. the forest area situated more than potential vegetation in the study area (according 50 m away from the edge. It is a well know fact to Matuszkiewicz 2001 and references therein). that intensity of most of the biotic and abiotic In 32 studied forest patches in this area, 1659 factors like air temperature, light intensity, soil trees were measured (methods and details see moisture or increased impact of predators differs Żmihorski et al. 2010), among them birch (Betula between the ecotone zone and the forest interior, sp.) and pine (Pinus sylvestris) predominate (26 and various so called “edge effects” are observed. and 22% of measured trees, respectively), but A distance of fifty meters was chosen as an edge oak (Quercus sp., 13%), and alder (Alnus gluti- effect measurement because at further distances nosa, 13%) also constitute an important part. The the biotic and abiotic differences start to disappear study area represents a landscape typical for most (see review by Murcia 1995). We also assessed the Polish farmland predominated by arable fields number of forest interior patches for every forest and meadows, with small and mid-sized forest patch in the study area. Moreover, we computed patches and scattered built-up areas. The farmland three simple indices of the patch shape. These is quite possibly, typical of the farmland of other indices are: the proportion of the forest interior to central European countries, allowing us to refer the whole patch area, the proportion of the perim- our results to a broader scale.