key: cord-023036-rnt6ivcy
authors: Turc̄ek, F. J.
title: THE BIRD SUCCESSION IN THE CONIFER PLANTATIONS ON MAT‐GRASS LAND IN SLOVAKIA (CSR).
date: 2008-04-03
journal: Ibis (Lond 1859)
DOI: 10.1111/j.1474-919x.1957.tb03050.x
sha: 
doc_id: 23036
cord_uid: rnt6ivcy

1. The species‐composition, number of individuals and biomass per one‐hectare are given. The three groups of areas studied were: (1) bare pastures, with an intermediate number of bird species, few individuals and high biomass of mainly carnivorous and insectivorous birds; (2) conifer plantations 1 to 5 years old, with the smallest number of bird species and the smallest biomass, but an intermediate number of individuals; (3) plantations six to twenty years old, with the highest number of both species and individuals of birds, but only intermediate biomass. 2. The change from pasture to forest occurs about six to ten years after planting. The last forest birds come in about 20 years after planting. 3. Birds have an important role in establishing the shrub layer and mixing some tree‐species into the plantation, by dissemination. 4. Throughout the entire successional series the bird population seems to have a kernel of species, while other species come or go and/or change in density with the stages.

The area studied consists of several hundred hectares around BanskP Stiavnica in Central Slovakia, between about 300 and 900m. a d . A detailed description of the plant communities concerned, both treeless and afforested, was given by Korenek (1956). In the present study the area is divided into three groups, namely, (1) unafforested pastures, (2) plantations one to five years old, (3) plantations six to twenty years old. This division, especially between groups (2) and (3) is artificial, but in the development of the bird community a marked change can be observed about the fifth or sixth year after planting.

The bird (and also mammal) population has been studied since 1946 but mainly qualitatively and not regularly (TurEek 1954 (TurEek , 1955 . Quantitative studies were carried out in the years 1954, 1955 and 1956 from March to October over a total of 28 days. In group (1) areas birds have been counted on 14 nearly square 10-hectare sample plots and on line transects A total of 45 birds species has been found.

(1) Pasture (2) Plantations 1 to 5 years RESULTS.

The bird species found, their density and biomass per hectare in each group of areas are given in Table 1 . The birds are expressed as mean number per hectare and their masses calculated according to the weight-data used in earlier work (Turtiek 1956). The nesting species in each area are marked n, the dominant species by an asterisk. The succession of the bird community in respect of species is shown in Table 2 . While group (2) has no species peculiar to it, group (1) has nine such species and group (3) has 16. Table 3 gives the distribution of species according to their utilization of the respective areas. This division is similar to one given by Kendeigh (1941).

In Table 4 it is of particular interest that the mean weight of the birds found in each group (obtained by dividing the total biomass of the respective group by the total number of individuals of the same group) diminishes with the age of the plantation. In the plantations studied, mainly of Norway spruce and Scots pine mixed with some European larch and a few deciduous trees, we were able to study the development of the bird community from bare pasture up to a forest of about 20 years of age. Although some German ecologists (cf. Tischler 1955) are of opinion that such a study of succession is not dynamic, this comparison of areas at different stages of development is the only possible way; for-as Yapp (1955) states-it would be indeed impossible for one man to follow through the complete succession in a single wood. The first group, bare pastures, is characterized by the dominance of the mat-grass, with here and there crippled spruce and juniper or hawthorn. Only small patches-usually the moist ones-are utilized as meadows for hay, the others being intensively grazed and in most parts burned off in early spring. The solitary trees and shrubs are suitable for the nesting, singing or shelter of some birds while the rocks and groups of stones are suitable for others. The ground breeders are not abundant, for the grass is short and overgrazed, the surface constantly disturbed and burned. The rock breeders and the birds nesting among stones are more protected and more abundant. Small rodents are abundant, firstly the Ground Squirrel Citellus citellus, with an average summer population of about 15 individuals (over 4 kg. biomass) per hectare (Turkk 1955), secondly the Field Vole Microtus arvalis. This abundance is responsible for the high density of raptorial birds, but it is only temporary, as the squirrels are below ground October-March and the voles below the snow in winter. A second seasonal food-supply consists of Saltatoria from about mid-July to October, and a minor one of spiders March to May. Owing to these nutritional circumstances most of the bird species are carnivorous and omnivorous, while the herbivorous species are almost absent or forage outside the pastures. Thus, the Goldfinch Carduelis carduelis forages there for thistle seeds in late summer, while the Linnet C. cannabina forages in relatively distant fields. While most of the mamma1 species are herbivorous there, most of the bird species are carnivorous and insectivorous, owing to the abundance of herbivoroug 1957 591 mammals and insects, respectively. As shown in Table 3 , most of the bird species utilize the bare pastures for foraging only, as e.g. the thrushes, Starling Sturnus vulgaris, crows and Magpie Pica pica as well as birds of prey.

The density of the bird population is low and similar to those given in the literature from other countries (Lack 1951 , Kendeigh 1941 ), but the biomass is relatively high, owing to the presence of large species, e.g. raptors and crows. I n this group no occasional species are mentioned, such as the Turtle Dove Streptopelk turtur collecting grit there, or the Nutcracker Nucifraga caryocatuctes visiting groups of hazel shrubs for nuts in late summer and autumn. Similarly, the participation of the owls could not be numerically evaluated.

The second group is characterized by a dense cover of grasses and other ground vegetation after the elimination of grazing, burning, disturbance and hay utilization. The young conifers are from 0.3 to about 1 m. high, but their crowns do not form any layer. The species of birds are fewer, none are specific to this group, and most are shared with group (1). There are only two new species, the whitethroats Sylvia communis and S. curruca.

The raptor population falls rapidly, apparently owing to the decrease, almost the absence, of the Ground Squirrel and to the favourable cover for other small mammals, voles in particular. But the absence of grazing, hay utilization and disturbance is favourable to ground-nesting birds. The most abundant bird is the Linnet, nesting in young spruces and juniper-shrubs; none was found in pines. In general, group (2) areas are transitional so far as the birds are concerned, with nine of group (1) species lost and only two species gained. In all, the number of birds per unit area is higher than in group (l), though their biomass is lower.

In group (3) there is a canopy of trees about 1.5 to 7 m. high, that may or may not touch. Grass disappears except on open patches, the ground is covered with fallen needles and seedlings of shrubs or trees, mainly broadleaved, begin to appear owing to dissemination by animals, mainly birds. Sixteen new species of forest-birds come in. The change from group (2), which is ecologically a shrubby pasture, into forest both physiognomically and ecologically, occurs in about six to ten years after planting. The forest species of birds, such as tits, Cuckoo, Turtle Dove (nesting) now appear; but it is only after ten years, when the first cones are formed, that the first seedeating species, such as the Great Spotted Woodpecker Dendrocopus major (and the squirrel Sciurus m~uis) colonize. The last newcomers-after about 15 to 20 years-are the Hazel Grouse Tetrastes bonasia (seeking cover) and Chaffinch Fringilla coehbs (for nesting). Since for tits there is no suitable nesting site, only the Coal Tit Parus ater is present, nesting in the ground. I n this late group of birds belongs also the Greenfinch Chloris chloris, which prefers, too, spruce. As the grass disappears from the floor, the roosting and burying birds, namely the thrushes and the Jay Garrutusglandmius, have IBIS 99 an important role at this time. Blackbirds Twdus merukz, in particular, regularly roost at this group of plantations during the non-breeding season and in their faeces they disseminate many plants, such as Taxus, Sambunrs, Rosa, Cratuegus, Jutriperus, Rubrrs, Ribes, Pnmus. On the other hand, Jays bury there many acorns of oaks (mainly Qwrcus sesdzk) and beech-nuts in September and October. On three sample plots, each 100m. square, I found in autumn 1956 from 51 to 83 seedlings and saplings of 13 treespecies, carried there by birds. Thus, the forming of a shrub layer or stratum is in this'case the almost exclusive r6le of birds, so that they are of great importance in seral stages. Group (3) is the highest in number of bird species and individuals, but the biomass of birds is slightly lower than in the first group. The distribution of bird species according to their ecological requirements (Table 3) is more regular, without the extremes of group Here again, (cf. TurEek 1956) . the species dominant numerically are not those dominant in biomass and each group is dominated to some degree by bird species common to all three groups, i.e. by the species ecologically the most valent.

As the bird population has not been distinguished according to the kind of plantation, for example pine and spruce, or mixed plantations, a direct comparison with Lack's (1951) data is hardly possible, The population in the Slovakian areas is, however, in both density and number of species higher than those given by Lack. Apart from any differences in method and calculation of results, the reason for this may be that the areas studied are no more than 1 to 5 km. from forests, so that birds can easily colonize from there.

For the same reason the surrounding areas will influence the populationsuccession of birds (and other animals, as well as plants) during the seral stages. The most striking difference between the English and Slovakian plantations is the absence of the Willow Warbler PhyZloscopus irochiZus from the plantations described here. This may be due to geographical and ecological causes. In the area studied (and southwards to the Danube) the Willow Warbler is abundant only during the migrations (less in autumn than spring), and mainly in localities with flowering willows and poplars. As a nesting species it is absent in the south and in the area studied it is confined to moist young forest stands, mainly mixed, its density rising with the altitude, up to about 1300m. a.s.1. (the limit of beech and most deciduous trees). Now, the areas in our three groups are extremely dry, the plantations up to about ten years after planting having a heavy grass floor, and are not dense enough to be favourable for this warbler. Probably still other factora are responsible. It might be concluded that the WilIow Warbler is in this case compensated for by the two whitethroats, as is the Nightingale Lust3m.a megmhynchar in the heavily inundated parts of bottomland woods around the (1) and (2).

The dominance of species in the three groups is of interest.

Danube by the Garden Warbler Sylvia borin and to some degree by the Dunnwk.

In the present succession of the bird community it is evident that the entire series has a kernel of species, that persists through all the sera stages, while the remaining species change in abundance or come or go with the stages.

1. The s ecies-composition, number of individuals and biomass per one-hectare are given. h e three groups of areas studied were : (1) bare pastures, with an intumediate number of bird species, few individuals and high biomass of mainly carnivorous and insectivorous birds; (2) conifer plantations 1 to 5 years old, with the smallest number of bird species and the smallest biomass, but an intermediate number of individuals; (3) plantations six to twenty years old, with the highest number of both species and individuals of birds, but only intermediate biomass.

The change from pasture to forest occurs about six to ten years after planting. The last forest birds come in about 20 years after planting.

3. Birds have an important role in establishing the shrub layer and mixing some t r e

tions by birds

Synokologie der Landtiere

Birds and mammals of the mat-grass community in the vicinity of Banskh &avnica

On the distribution of the Ground Squirrel

On the bird population of the spruce-forest community in Slovakia

The succession of birds in developing Qumcctum petracac

Zur Frage der Borstengrasweidenaufforstung in der Slowakei. Further changes in bird life caused by afforestation

species into the plantation, by dissemination.

Throughout the entire successional series the bird population seems to have a kernel of species, while other species come or go and/or change in density with the stages.