vehkaoja_nummi_beaves__Anuran_conservation_HerPetozoA.qxd 28.07.2015 15:07 Seite 1 HerPetozoA 28 (1/2): 75 - 87 75 Wien, 30. Juli 2015 beaver facilitation in the conservation of boreal anuran communities (Anura: bufonidae, ranidae) Die Förderung des bibers und die erhaltung der borealen Anurengemeinschaften (Anura: bufonidae, ranidae) miA veHkAoJA & P etri nummi kurzFASSunG Artensterben und Habitatverlust verlaufen in europa und weltweit rasant. Amphibien und Feuchtlebens - räume sind ganz wesentlich davon betroffen. letztere warden in der borealen zone häufig durch die Dammbau- tätigkeit des bibers ( Castor sp.) bereitgestellt. Die Autoren untersuchten die Anurenfauna in zehn derartigen biber-Gewässern, zehn nicht vom biber bewohnten und acht temporären Wasserkörpern in Finland. Alle drei in der region heimischen Anurenarten (erdkröte, moor- und Grasfrosch) besiedelten die biber-Gewässer, wobei der moorfrosch in nicht vom biber bewohnten und temporären Gewässern des Gebietes nicht gefunden wurde. moorfrösche profitierten offensichtlich vom teichbaua und dem Fällen von bäumen durch den biber und die damit verbundene Schaffung einer vielzahl von seichten Gewässerabschnitten mit breiten emersen vegetationsgürteln. Die ergebnisse zeigen, daß biber qualitative hochwertige Anurenhabitate schaffen und das vorkommen des moorfrosches begünstigen.. es wird angeregt, biber als ingenieure bei der Wiederherstellung von Ökosystemen einzusetzen, um die ziele des Amphibienschutzes zu unterstützen. AbStrACt A rapid loss of species and habitats is occurring globally. Amphibians and wetlands are important compo - nents of this overall decline. Wetlands in the boreal region are frequently constructed by damming activities of an ecosystem engineer, the beaver ( Castor sp.). the authors investigated the anuran fauna in ten such ‘beaver ponds’, ten ‘non-beaver ponds’ and eight temporary ponds in Finland. All three anuran species present in the region occu - pied the beaver ponds, including a species absent (the moor Frog Rana arvalis nilSSon , 1842 ) in natural waters (non-beaver ponds and temporary ponds). moor Frogs obviously benefitted from pond construction and removal of trees by beavers leading to a plenitude of shallow water and a wide belt of emergent vegetation. the results show that beavers offer high-quality habitats for anurans and facilitate the occurrence of moor Frogs. it is sug - gested that these ecosystem engineers could be used in ecosystem restoration. the beaver clearly represents a species that promotes amphibian conservation. key WorDS Amphibia: Anura: bufonidae, ranidae; Rana arvalis , Rana temporaria , Bufo bufo , beaver, Castor , beaver pond, ecosystem engineer, draining, boreal amphibian community facilitation, ecology, conservation, Finland introDuCtion Species and habitat loss at a global % of europe’s amphibians are threatened scale is occurring at an increasing rate. Am - reflects this trend ( temPle & C ox 2009). phibians and wetlands compose a consider - Pond, wetland protection and restoration are able proportion of this overall loss, even in the principle methods for conserving pond- areas not under immediate human influence breeding am phibians ( StevenS et al. 2007). (PetrAnkA et al. 2004; GibbonS et al. 2006; boreal ecosystems are under consider - SAyim et al. 2009; DoDD 2010). Since the able stress. the boreal climate is severe and 1900s, approximately half of the world’s often unpredictable ( HAnSki et al. 1998), wetlands were destroyed ( bArber 1993), which creates additional challenges for wet - and during this time, at a regional scale, up land conservation. Furthermore, nearly 14 to two-thirds of european wetlands became million hectares of wetlands have been lost ( AmezAGA et al. 2002). the fact that 23 drained for forestry in northern europe vehkaoja_nummi_beaves__Anuran_conservation_HerPetozoA.qxd 28.07.2015 15:07 Seite 2 76 m. v eHkAoJA & P. n ummi (PAAvilAinen & P äivänen 1995, SuiSlePP long hydroperiod compared to temporary et al. 2011). most of these wetlands are in the ponds. beaver ponds may harbor a relative - boreal zone. more than 5.5 million hectares ly rich fish population, but large amount of of wetlands and forests have been drained in woody debris and aquatic vegetation protect Finland alone ( PeltomAA 2007). Ditches both the larvae and adult frogs from preda - drain excess surface water which affects the tors. in addition they provide suitable at - natural quality and processes of aquatic tachment places for spawn ( PoreJ & ecosystems, resulting in reduced wetland HetHerinGton 2005). the tadpole diet diversity ( SuiSlePP et al. 2011). Wetland loss varies widely in the relative amounts of pro - reduces amphibian productivity and abun - teins, carbohydrates and lipids. this diet dance via the number and density of breeding mainly comprises vegetal detritus ( CAStA- sites by changing the natural hydrological neDA et al. 2006) such as filamentous green regime of an area ( SuiSlePP et al. 2011). algae and epiphytic diatoms ( kuPFerberG the use of ecosystem engineers in 1997), but some studies have indicated that ecosystem restoration has recently received all anuran larvae are carnivorous to some increasing attention ( byerS et al. 2006; degree ( SCHieSAri et al. 2009). the animal bArtel et al. 2010). beavers ( Castor sp .) component of the tadpole diet includes cili - act as ecosystem engineers in the northern ates, flagellates, amoebae ( bAFFiCo & Hemisphere ( JoneS et al. 1994; WriGHt et ubeDA 2006) and other zooplankton, which al. 2002), and both beaver species play a are very abundant in beaver ponds ( bleDzki similar ecological role along the waterways et al. 2011). beaver ponds also provide (DAnilov et al. 2011). they create and overwintering places for adult frogs both in maintain special habitats by constructing water and on land ( DAlbeCk et al. 2007). dams ( bAker & H ill 2003). Damming only a few studies examined beaver changes both abiotic and biotic conditions effects on drained landscapes, e.g., ule- via hydrological changes, which can affect a vičiuS et al. (2009) who found that, in lith - large number of other species. beaver mod - uania, beaver activity improved the ecolog - ifications create wetland patches varying in ical value of drainage canals. nonethe less, successional stage, thereby increasing struc - the influence of beavers on amphibians in tural heterogeneity at the landscape scale boreal forest landscapes remains poorly (nAimAn et al. 1988; SnoDGrASS 1997; studied, although wetlands in these land - CunninGHAm et al. 2006; HyvÖnen & scapes are often significantly affected by nummi 2008). riparian zones along water damming. Due to the eradication of the bodies are especially modified. tree felling beaver in the last centuries, the landscapes creates openings in the riparian forest, persisted in an unnatural state for a long resulting in open and sunny ponds ( PAStor time, especially in europe, where beaver- & n AimAn 1992; krylov et al. 2007). belts created wetlands are currently lacking. of emergent vegetation can be wide due to However, european beavers have recently flooding ( nummi 1992), and submerged and begun returning to their former range, often floating vegetation dominates in older aided by reintroductions ( SJÖberG & b All beaver ponds ( rAy et al. 2001; nummi & 2011; HAlley et al. 2012). the european kuuluvAinen 2013). Detritivorous inverte - beaver ( Castor fiber ) was reintroduced to brates, e.g., chironomids and Asellus are the Finland in 1935. Along with these reintro - most abundant benthic invertebrates in ductions, the American beaver ( Castor boreal beaver ponds ( mCDoWell & canadensis ) was brought to Finland in 1937. nAimAn 1986; n ummi 1989). it was the aim of this study to investi - beavers dams create warm, shallow gate the beaver effect on the Finnish anuran water, rich emergent vegetation and large community in a landscape where 100 % of amounts of woody debris, conditions that the forests are drained. there are only three are favored by many amphibian species dur - native anuran species in Finland: the ing breeding ( CunninGHAm et al. 2006; Common Frog Rana temporaria (l innAeuS , DAlbeCk et al. 2007; StevenS et al. 2007). 1758) , the moor Frog Rana arvalis nilS- beaver ponds are favorable for amphibian Son , 1842 and the Common toad Bufo bufo larval development because they have a (linnAeuS , 1758 ). vehkaoja_nummi_beaves__Anuran_conservation_HerPetozoA.qxd 28.07.2015 15:07 Seite 3 beaver facilitation of boreal frog communities 77 r e 0 n n n e ) e h 1 o o mAteriAlS AnD metHoDS i n l D n t t s ) ) ) l / l a a e i 8 9 4 g t . z C e e e . 8 8 9 4 7 1 m n g u a . - - - a ( w i l the study area (6,650 ha) was sit - e 7 7 8 8 2 8 e e a m . h . j . v C i t v s 3 7 6 e i s t x f uated in evo in southern Finland (61°10’n, i ( ( ( o e f u n a w d h o a e D t t r y 25°05’S), which belongs to the southern m g r s r f ü d r e f e o o s e d boreal vegetation zone ( AHti et al. 1968). s b u e s n m ä r a 9 9 d r e u H . e r 5 e the area consists of approximately 100 S w p 4 4 t e b u e a a n h w m G e lakes and ponds (average size circa 4.3 ha) m t w t i u s s n r n n . e i ö o - e interrelated with brooks. the altitudinal l i d n p t m e m e m y e a j s g u t topography of the area varies from 125 m to p 6 t n . r e ) ) r e o n o m ) ) 0 ü g i e 0 i r g ) n . 2 f 185 m a.s.l. the soil in evo is low in nutri - % i s e o . x a % 0 ( r d 8 k s . ( p a e v 6 c 1 1 9 e ö a 6 . s 7 s d 8 r ents. Forestry has molded the development - d h h m e n n r 8 0 1 - e 8 e W e 5 e p - a e h u 3 6 5 .