Response of Orthoptera Communities to Succession in Alluvial Pine Woodlands
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See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/271921446 Response of Orthoptera communities to succession in alluvial pine woodlands Article in Journal of Insect Conservation · April 2014 DOI: 10.1007/s10841-014-9632-x CITATIONS READS 2 53 4 authors, including: Felix Helbing Franz Löffler Universität Osnabrück Universität Osnabrück 6 PUBLICATIONS 12 CITATIONS 7 PUBLICATIONS 9 CITATIONS SEE PROFILE SEE PROFILE Thomas Fartmann University Osnabrück, Osnabrück, Germany 96 PUBLICATIONS 896 CITATIONS SEE PROFILE All content following this page was uploaded by Thomas Fartmann on 23 January 2016. The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. J Insect Conserv (2014) 18:215–224 DOI 10.1007/s10841-014-9632-x ORIGINAL PAPER Response of Orthoptera communities to succession in alluvial pine woodlands Felix Helbing • Tim Peter Blaeser • Franz Lo¨ffler • Thomas Fartmann Received: 19 July 2013 / Accepted: 2 April 2014 / Published online: 10 April 2014 Ó Springer International Publishing Switzerland 2014 Abstract During the past 150 years forest management mid-successional stages are the most important ones. Con- has dramatically altered in Central European woodlands, servation management for Orthoptera in this woodland type with severe consequences for biodiversity. Light forests that should aim at the reintroduction of cattle grazing and the fulfilled variable human demands were replaced by dark high restoration of the natural discharge and bedload-transport forests that function solely as wood plantations. In the Alps, regimes of the alpine rivers. by contrast, open woodlands are still present because the traditional land use as wood pasture has remained and Keywords Biodiversity conservation Á Disturbance physiographical conditions favour natural dynamics. The ecology Á Forest management Á Floodplain Á Grasshopper Á aim of our study was to investigate the effects of succession Vegetation structure on the Orthoptera communities of alluvial pine woodlands in the northern Alps. Orthoptera showed a clear response to succession, with each successional stage harbouring a unique Introduction assemblage. The influence of succession on species richness and abundance were identical: The values were highest in the In the past, European woodlands were used intensively by intermediate and lowest in the late seral stage. The diversity humans (Bergmeier et al. 2010; Ellenberg and Leuschner and abundance peak in the mid-successional stage probably 2010). They served as a source of litter, firewood and timber reflects a trade-off between favourable ambient temperatures and were grazed by livestock. As a consequence they had a for optimal development and sufficient food, oviposition light and heterogeneous structure containing a high level of sites and shelter against predators. Food shortage and easy biodiversity (Peterken 1996;Vera2000). During the past access for predators seemed to be limiting factors in the early 150 years the total area of woodlands increased continuously successional stage. In contrast, in the late successional stage in Central Europe; currently 30 % of the land surface is cov- adverse microclimatic conditions probably limit Orthoptera ered by woods (Steinecke and Venzke 2003). Nevertheless, occurrence. Although all three successional stages of the species richness is declining (Benes et al. 2006; Vodka et al. pine woodlands are relevant for conservation, the early and 2009). This species loss is mainly driven by changes in forest management (Peterken 1996; Simberloff 1999). With the introduction of modern forestry, traditionally used light for- F. Helbing Á T. P. Blaeser Á F. Lo¨ffler Á T. Fartmann (&) ests like coppiced woodlands or wood pastures were Department of Community Ecology, Institute of Landscape increasingly replaced by dark high forests, which solely Ecology, University of Mu¨nster, Heisenbergstr. 2, function as plantations to provide wood (Benes et al. 2006). 48149 Mu¨nster, Germany e-mail: [email protected] In the European Alps, by contrast, the wood pasture tra- dition is still in place (Sachteleben 1995; Mayer and Hu- Present Address: ovinen 2007; Gimmi et al. 2008; Garbarino et al. 2011) and T. Fartmann physiographical conditions favour natural dynamics (Ho¨lzel Division of Ecology, Department of Biology/Chemistry, University of Osnabru¨ck, Barbarastraße 11, 1996; Lederbogen et al. 2004). Landslides, avalanches and 49069 Osnabru¨ck, Germany bedload transport in the floodplains slow succession down 123 216 J Insect Conserv (2014) 18:215–224 and, hence, enhance the continuity of light woodlands. At the confluence of the ‘‘Rißbach’’ tributary at an altitude of northern edge of the Alps on dry, calcareous soils most of 780–860 m a.s.l (47°310N/11°180E; area: 860 ha). The these open woodlands are pine forests (Calamagrostio- bottom of the valley consists of lime gravel (Karl et al. Pinetum) (Ho¨lzel 1996). In the past, these pine woodlands 1977). Due to its location at the northern edge of the Alps, benefited from grazing at the expense of mixed forests. the study area is characterized by a wet (annual precipi- Today, however, they are threatened by succession. tation 1,300–1,600 mm) and cool mountain climate Depending on the intensity of grazing and natural dynamics (annual temperature 6.7 °C) (Kru¨n/Vorderriß and Mitten- the pine forests usually form mosaics of different succes- wald meteorological stations, respectively; DWD 1952, sional stages, from very light stands without a real tree layer 2013). up to woodlands with a relatively dense canopy. Although the Isar Valley is one of the last remaining The high value of the pine woodlands on dry, calcareous near-natural floodplains in the Alps, it has been altered by soils in the northern Alps for plant conservation is well- the diversion of water for hydroelectricity (Homes et al. known and studied in detail (Ho¨lzel 1996; Schmitt et al. 1999). Since 1923 the complete discharge of the river Isar, 2010). In contrast, studies concerning the relevance of this except at peak flows, has been diverted to lake ‘‘Wal- woodland type for animal conservation are largely missing chensee’’ for hydroelectric power generation (Hering et al. (Ho¨lzel 1996). This also applies to Orthoptera, although 2004). As a consequence the riverbed is dry most times of Schlumprecht and Waeber (2003) point out the high rele- the year. However, the speed of succession was low due to vance of these pine woodlands for this insect group. the lack of water in the well-drained floodplain soils. Orthoptera are considered sensitive indicators of environ- Hence, areas with open gravel bars and open vegetation mental changes (Bazelet and Samways 2011;Schirmeletal. were still widespread. In 1990 a residual flow of the Isar 2011;Fartmannetal.2012) since habitat selection depends water (3 m3/s in winter, 4.8 m3/s in summer) was estab- on a complex combination of different and often interrelated lished favouring late-successional plant communities due environmental factors (see review in Ingrisch and Ko¨hler to better water and nutrient supplies (Schauer 1998). Today 1998). The main drivers are vegetation structure (Gardiner the floodplain is characterized by a mosaic of open gravel et al. 2002; Poniatowski and Fartmann 2008) and microcli- bars and gravel bars with pioneer vegetation dominated by mate (Willott and Hassall 1998; Gardiner and Dover 2008; Calamagrostis pseudophragmites (Calamagrostietum Weiss et al. 2012). Predation and food supply are partly pseudophragmites) and willow shrubberies (Salicetum interrelated with the aforementioned environmental factors eleagno-purpureae) (Schauer 1998). Pine forests (Ca- and may also be important, particularly in habitats with sparse lamagrostio-Pinetum) dominate in those parts of the vegetation (Belovsky and Slade 1993;Wu¨nsch et al. 2012). floodplain currently rarely flooded or no longer flooded The aim of this study was to analyse the Orthoptera (Ho¨lzel 1996). Only the pine woodlands in the outermost communities along a successional gradient in alluvial pine southwest of the study area are currently grazed by cattle woodlands, which with respect to its area is the most (Kraus pers. comm.) important type of dry pine woodlands in the Bavarian Alps The study area is part of a Natura 2000 site (‘‘Karwendel (Ho¨lzel 1996). Fieldwork was done in the Upper Isar mit Isar’’) and one of the largest German nature reserves Valley (southern Bavaria, Germany), one of the last rem- (‘‘Karwendel und Karwendelvorgebirge’’) (BfN 2013). nants of the old braided river systems of the Alps and the Moreover, it belongs to one of the 30 national biodiversity part of the river Isar that is most like a natural floodplain hotspots (Ackermann et al. 2012). (Reich 1991; Hering et al. 2004). In particular we addres- sed the following research questions: Sampling design 1. Do Orthoptera species richness and abundance differ The pine woodlands of the study area were divided between successional stages? according to Sa¨nger (1977) into sections with homogenous 2. Do all and threatened species show different patterns? vegetation structure. To avoid edge effects (Bieringer and 3. How should pine woodlands be managed to promote Zulka 2003; Schirmel et al. 2010) only those sections with Orthoptera? a size of at least 500 m2 were chosen as plots (Poniatowski and Fartmann 2008; Fartmann et al. 2012). This was the Materials and methods case for 50 sites that represented all successional stages of the pine woodlands across the study area. Study area Orthoptera sampling took place once per plot in August 2010. Densities were recorded with a box quadrat, which is The study was conducted in the Upper Isar Valley in among the best sampling methods to ascertain Orthoptera southern Bavaria (Germany) between ‘‘Wallgau’’ and the abundance (Gardiner and Hill 2006). The box quadrat had 123 J Insect Conserv (2014) 18:215–224 217 Table 1 Overview of sampled environmental parameters and their statistical analysis Sampled parameter Factor levels Statistics Mean (±SE) Min.–Max.