Species area-relationships and frequency ? Floristical data analysis of 44 isolated woods in northwestern Germany

Abstract

44 isolated ancient woods (9,3-8579 ha) in southeastern Lower Saxony (northwestern Germany), where the Tertiary hilly country meets the Pleistocene plain, were investigated. Complete lists of 273 vascular plant species showing a more or less strong preference for woodlands were made for each wood including all the species of the groups Querco-Fagetea, Trifolio-Geranietea, Galio-Calystegietalia (selection of species) and Epilobietea. The majority of character species of woods show either a low or a high frequency, whereas fewer ones have medium frequencies. Most of the rarer species have their main occurrence in the larger woods. The number of species of all of the four groups increases with area of the wood and the correlation between the number of species and the log of area is related by a highly significant linear regression. Comparison of a single wood with two smaller woods of the same total area reveals that the two smaller woods on average have the greater number of wood species. Considering this and the fact that the rarer species have their main occurrence in the larger woods, when discussing questions of nature conservation a simple comparison of number of species and area is problematical.

The Effects of Urbanization and Human Disturbance Upon Plant Community Structure and Bird Species Richness, Diversity, and Abundance in a Natural Forested Area (Forest Park) in Portland, Oregon

“…Increased habitat fragmentation causes the abundance and diversity of native species to decrease as forested areas decrease in size (Askins and Philbrick 1987;Blair 1996;Laster 1988, 1989;Friesen et al 1995;Gavareski 1976;Harris 1984;Lynch and Whigham 1984;Mcintyre 1995;McLellan et al 1986;Robinson et al 1995;Rosenberg and 6 Raphael1986;Solinska-G6rnicka and Symonides 1990;Terborgh 1989;Weaver and Kellman 1981;Wiens 1994;Wilcove 1985;Zacharias and Brandes 1990;Zipperer 1993).…”

“…In part, this is believed to be because the matrix separating the "islands" is, unlike water, capable of supporting terrestrial life. Most researchers have found greater diversity in larger forests (Askins 1994(Askins , 1995Blake 1983;Blake and Karr 1987;DeGraaf 1991DeGraaf , 1995Donovan et al 1995b;Gavareski 1976;Hoover et aL 1995;Lent and Capen 1995;Lynch and \Vhigham 1984;Mcintyre 1995;McLellan et al 1986;Robinson et al 1995;Rosenberg and Raphael 1986;Temple 1986;Verner 1986;Wiens 1994;Wilcove 1985), although neither area (size) nor distance from the nearest large forest ("the mainland") have been shown adequately to predict the number of species a forest of a given size can support (Blake 1983;Blake and Karr 1987;Blondel 1985;Laster 1988, 1989;Gavareski 1979;Haila 1986;Levenson 1981;Lovejoy and Oren 1981;McLellan et al 1986;Rowntree 1986;Tramer and Subrweir 1975;Weaver and Kellman 1981;Whitcomb et al 1981;Zacharias and Brandes 1990). There does, however, seem to be a minimum critical size that a forest remnant must be in order to support a near normal avian biodiversity (Blake 1983;Dzwonko and Laster 1989;Gotfryd and Hansell 1986;Johnson et al 1981;…”

“…As urbanization increases, frequently accompanied by increased fragmentation of the existing forest, the number of native species decreases, whereas the number of exotic species increases (Bagnall 1979;Becher and Brandes 1985;Greller et al 1990;Johnson et al 1981;Kowarik 1990;Levenson 1981;Moran 1984;Seidling 1990;Sukopp 1990;Yost et al 1991;Zacharias and Brandes 1990;Zipperer et al 1990). …”

Deciduous and semi-deciduous oak forests (Quercus robur, Q. petraea and Q. pyrenaica) floristic composition in the Northwest Iberian Peninsula

“…Conversely, the lowest species richness occurs in stands of Quercus spp., highly altered by wood extraction (Guitián Rivera 1995). An aspect of interest, well-known the floristic diversity, is to determine the area to conserve and the species number (Zacharias & Brandes 1990). In this sense, the effect of silviculture is critical because thirty years without forest management are sufficient to change the forest floristic composition (Aude & Lawesson 1998).…”

“…Similarities occur in geophytes and hydrophytes, with values that are close to those presented by Silva-Pando (1994), and lower than reported by Buide et al (1998) for Galician flora and by Amigo et al (2001). Therophytes are scarce because most relevés were conducted in stands located in the zones with Oceanic climate (Zacharias & Brandes 1990). With regard to the separate analyses of the three oak forests (Fig.…”