How to balance forestry and biodiversity conservation – A view across Europe

590 Bad Windsheim – Maintaining diversity in dominated coppice forests S. Finnberg1,2, H. Bußler3 C 32 ¹ Forest manager, Bad Windsheim, Germany 2 Forschungsstation Fabrikschleichach, Universität Würzburg, Germany 3 Arbeitsgemeinschaft bayerischer Entomologen, Germany

The town of Bad Windsheim owns 1480 ha of for- berg in northwestern Bavaria. Approximately est in the Windsheim Bay, located between the 490 ha are dominated by conifers (mainly Norway southern Steigerwald and northern Frankenhöhe spruce (Picea abies) and Scots pine (Pinus sylvestris) region along the Aisch River. The region belongs to and 990 ha are dominated by broadleaves (oak the Keuper uplands (mid-Triassic period) of Franco- (Quercus spp.) being the dominant species with nia between Rothenburg ob der Tauber and Nürn- 553 ha, followed by (Fagus sylvatica) with

Germany

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< Fig. C 32.1. Reactivated coppice with standards in the Bad Windsheim forests. The canopy closure has been reduced to 30 % (Photo: Heinz Bußler).

591 Timber/Biomass

Groundwater Non-timber products

Statement Climate Erosion “We bring light back into the forest.”

Landscape Protection

Recreation Biodiversity

Table B 32.1. General information on the Bad Windsheim forests.

Total forest area 1480 ha; high forest 1034 ha // cws 369 ha Main management types Coppice with standards (cws) Total volume High forest: 221 000 m³ // cws 40 933 m³ Annual growth High forest: 7.0 m³/ha // cws: 2.0 m³/ha Cutting rate High forest: 5.8 m³/ha; 6000 m³ // cws: 12.3 ha per year 980 m³ Deadwood ca. 15 m³/ha Ownership Community forest Climate 9.2 °C mean annual temperature, 595 mm mean annual precipitation Geology Mostly Keuper – gypsum and dolomite marls, clay- and sandstones that were deposited during the Middle and Late Triassic epochs (about 220 million years ago) Soils Small-scale mosaic of sandy, marly or clayey soils, mostly nutrient rich Protected area Natura2000 area Special Areas of Conservation (SAC) 750 ha Special Protection Areas (SPA) 294 ha

98 ha). All forests designated as Natura 2000 areas accumulation of large dimensioned crown dead- are recent or former coppice with standards for- wood that was left to decay. Several scientific pro- ests. After a break of about 60 years, coppicing was jects are accompanying and monitoring the effect reintroduced on an area of 100 ha in one forest dis- of on tree mortality and coppicing capacity trict in 2010 . The stands of this district have gained of the after strong openings and active dead- a reputation of national importance for its rare wood accumulation. and Coleoptera fauna. However, it has to be mentioned that many insect species that are abundant in these stands are considered as forest Reactivating a medieval form of forest ‘pests’ elsewhere and are important factors con- management for biodiversity tributing to oak dieback. These include the two-spotted oak borer (Agrilus biguttatus) (fig. The forests of Bad Windsheim, and especially the C 32.2), the oak processionary (Thaumeto- coppice with standards stands, have gained a repu- poea processionea), and the gypsy moth (Lymantria tation as having a flora and fauna of national dispar) (Petercord 2015, 2018). Initially concerns importance (Bußler 2016). Among the 560 saprox- were raised that reactivation of coppicing would ylic beetles that are known in the region, 180 spe- create microclimates that are favourable to such cies are threatened and on the red list, six species insects through the opening of the canopy and the are from the list of ‘Urwald’ relict species. Around

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Fig. C 32.2. The two-spotted oak borer (Agrilus biguttatus) is the most abundant buprestid beetle in the coppice with standards forests (Photo: Heinz Bußler).

800 day-flying butterfly species (macrolepidoptera) broadleaved high forests, and in another 50 ha have been found in these stands, especially those coniferous species (mainly Norway spruce and Scots species depending on warm and light (inner) forest pine) were planted. Since this time, the coniferous edges with relatively high soil moisture, such as stands have been partially degraded by wind- Euphydryas maturna, Euplagia quadripunctaria, storms, drought, and bark beetle infestations; in and Eriogaster catax from Annex II, and Lopinga some cases the coniferous stands have completely achine from Annex IV of the Habitats Directive. vanished. Such conditions are usually found in floodplain for- With the aim of the conservation and mainte- ests or on seasonally wet sites. nance of rare and threatened species, the former Closely associated with, and benefitting from, practice of coppicing with the retention of old the cyclic gradations of Lymantria dispar and Thau- standards was reactivated in 2010 on about 100 ha metopoea processionea are the rare carabid bee- with the support of public funds from the Bavarian tles Calosoma inquisitor and C. sycophanta (fig. Government (Vertragsnaturschutzprogramm, VNP). C 32.4). Currently, there are 370 ha of forest stands man- Coppicing as a forest management practice has aged as coppice with standards. Usually the coppic- a tradition in Bad Windsheim of more than 1000 ing is done on areas of about 3 ha, by reducing the years. In the year 1414, the income of the town is canopy closure to 30 % (i.e. the retention of old documented as being exclusively from coppice for- oaks as standards). In the remaining high forests ests (Rabl 1982). Especially in the nineteenth cen- natural regeneration of oak and other light-de- tury fuel wood was the main product after oak manding species is promoted by creating small bark for tanning. The different forms of coppicing openings (minimum 0.3 ha) where all living trees were continuously practised until the mid-twenti- are removed to mimic gap dynamics of falling giant eth century. The last coppice cuts occurred in 1958, trees in primeval forests (Dolek et al. 2008). and after this about 150 ha were left to convert to

593 How to balance forestry and biodiversity conservation – A view across Europe

Fig. C 32.3. A wide range of species from different groups are benefitting from the warm and light conditions in coppice with standards forests (e.g. Lopinga achine, , Rosa gallica, Saperda perforata, Potosia aeruginosa, Cerambyx scopolii) (Photos: Heinz Bußler, Sven Finnberg).

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Fig. C 32.4. Larvae of Calosoma sycophanta preying on a of Lymantria dispar (Photo: Sven Finnberg).

Seasonally wet coppice forests as a way that the harvest of timber mimicks the natural surrogate habitat for floodplain forests dynamics of a landscape that has been lost by the strong regulation of rivers. From geological maps it The biodiversity of the coppice with standards for- can be seen that on 83 km along the Aisch River ests in the Windsheim Bay is a result of different there are 4200 ha alluvial floodplain areas that factors. The site conditions are mainly determined were historically stocked with floodplain forests, by seasonally wet soils on gypsum marls as well as and swamp and mire forests. In this context, sea- clay and sandstones of the Early Keuper forma- sonally wet coppice with standards forests can tions. The area harbours mostly oak– for- serve as surrogate habitats for the foregone hard- ests of the Galio sylvatici-Carpinetum and Stellario wood floodplain forests; the lepidopteran and holosteae-Carpinetum associations. It has been coleopteran fauna from Windsheim Bay shows a largely disputed whether oak–hornbeam forests high degree of similarity with the lepidopteran and are anthropogenic forest ecosystems that would coleopteran fauna from the floodplain forests of not exist without human interference (Zollner the Rhine and the Danube. An important common 2018). However, we argue that the site conditions element with the floodplain forests is the presence in the Windsheim Bay are just perfect for such for- of aspen ( tremula), and especially old spec- ests to develop naturally. Another characteristic is imens, across the area. In high forests aspen is the hot and dry climate and the continuous habitat largely missing because of the past thinning prac- tradition with a great diversity of tree and shrub tices; sometimes only young specimens are retained species as well as a species-rich herb and grass layer along forest edges or roads (Dolek et al. 2008). where flowers are available throughout the com- Many lepidopteran and coleopteran species feed plete vegetation period. The coppicing practices on poplar species, and thus the presence of such create a mosaic of very open to closed stands in a trees is a key resource.

595 How to balance forestry and biodiversity conservation – A view across Europe

Crown deadwood and coppice stools: known from aspen and wild service tree (Sorbus key microhabitats torminalis), but already in 1889 Gayer mentioned that this also plays an important role for oaks and In general, coppice forests do not contain a lot of hornbeam (Carpinus betulus). lying deadwood owing to the intensity of the These stools provide a habitat complex consist- management practice. However, the lack of this ing of multiple structures such as living and dead type of deadwood is partially overcompensated by tissue, mycelium covered wood and small cavities. the high volumes of crown deadwood in living As an example, the stag beetle (Lucanus cervus) oaks: up to 20 m³/ha were measured on old trees occurs in stable and abundant local populations in in coppice with standards forests (Müller et al. Bad Windsheim, its larvae develop in the dead 2004). Another important microhabitat are the liv- roots of living coppice stools. Also, the smallest and ing coppice stools that can be up to 100 years old. rarest lucanid beetle of central Europe Aesalus scar- Interestingly, the coppice stools mostly do not abaeoides (fig. C 32.6) can be found in the coppice resprout from the stool itself (fig. C 32.5a), but with standard forests, one of only three known rather produce ‘suckers’ from the roots (fig. locations in Bavaria. C 32.5b), even when the stools were considered to While most xero-thermophilous species can be dead. The same phenomenon has been also use smaller structures to breed, some threat- observed on the stump of a 140-year-old standard ened species are more dependent on large veteran oak, felled in May 2016. The reproduction from trees with more complex habitat structures. Such the roots through polycormonal cloning is well trees are rare to absent owing to the past manage-

a b

Fig. C 32.5. (a) Classic oak coppice sprouting from sleeping buds directly from the stool. (b) Five-year-old ‘suckers’ from the root with faster height growth than the coppice shoots from the stool (Photo: Heinz Bußler).

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mostly dependant on cankers developing on large oaks, but can use oak stools as an alternative habi- tat. The caterpillar develops in the bark of the stools (Blum 1997).

Insect diversity – not a threat to oak vitality!

Although Agrilus biguttatus is the most common beetle found in the stools there is no relation between the presence of the species and the mor- tality of single stools. The highest average number Fig. C 32.6. Aesalus scarabaeoides (Photo: Heinz Bußler). of A. biguttatus individuals per stool was even observed in ‘extraordinarily vital’ shoots (Finnberg and Bußler 2019). ment practices and could only be found in adjacent The presence of the two relatively large cer- pasture forests with longer habitat tradition. ambycid beetles, Rhagium sycophanta and Cer- Among the most common species found in the ambyx scopolii, in the coppice stools depends very coppice stools is vespiformis, a moth much on the availability of large stools but has no of the family (fig. C 32.7). This species is influence on their mortality. It is remarkable that

Fig. C 32.7. Colourful and common, but largely unknown: Synanthedon vespiformis (Photo: Heinz Bußler).

597 How to balance forestry and biodiversity conservation – A view across Europe

Fig. C 32.8. In 2016, gauze cages were used to protect oak stools from insect colonisation one year after the cut to investigate the effect of insects on oak mortality (Photo: Heinz Bußler). both species can be found already only one year Conclusion after the cut, since the time required for matura- tion of these beetles is usually known to be at least Despite the presence of almost all forest pest spe- two to three years (Bense 1995). The shortened cies that are known to contribute to the phenome- development time may be a consequence of global non of oak decline, there has been no increase in warming; the average annual temperature in this tree mortality in the coppice with standards forests area is over 10 °C nowadays, and the extended in Bad Windsheim. However, the very open stands warm period enables a shorter development cycle and the additional enrichment with oak deadwood for these beetles. has often created negative reactions from visitors. A very different species assemblage from the Often they regard this management practice as too coppice stools can be found on lying deadwood radical. Very often the prevailing opinion is that that has accumulated as a more recent measure to the only way to maintain or increase biodiversity enrich the traditional coppicing practices: only 25 % levels is to set forest aside from management. Here of the species found on large logs and strong dead we argue that the practice of coppicing with branches are also found on the oak stools. The most retained standards is necessary to preserve species dominant species are usually the bark beetles Scoly- that lack their original natural habitat such as tus intricatus and Xyleborinus saxeseni. Interest- floodplain forests, but also to preserve the richness ingly Agrilus biguttatus is rarely found on the lying of trees and shrubs. Additionally, to setting aside deadwood. The reason for that may be that the forests from management we urgently need a dis- breeding places in the bark are often already occu- cussion about dynamics in forest ecosystems! pied by larvae of e.g. Plagionotus arcuatus, P. detri- tus (fig. C 32.9), Xylotrechus antilope, and Cerambyx scopolii.

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Fig. C 32.9 Adult Plagionotus detritus on an oak log. The larvae of this species often compete for breeding sites with the two-spotted oak borer (Agrilus biguttatus), a pest of oak (Photo: Heinz Bußler).

tem Wald in Westmittelfranken am Beispiel des Kehren- References berges. Mitteilungen aus der Staatsforstverwaltung Bense, U., 1995: Longhorn beetles. Markgraf Verlag, Bayerns 42: 52–58. Bayerisches Staatsministerium für Weikersheim. 471 p. Ernährung, Landwirtschaft und Forsten, München. Blum, E., 1997: Synanthedon vespiformis. In: Ebert, G. (ed) Zollner, A., 2018: Gemeinsam für die Eichen-Lebensraum- Die Schmetterlinge Baden-Württembergs, Bd. 5 Nacht- typen. LWF aktuell 4: 22–23. falter III. 133–136. Bußler, H., 2016: Eichenwälder und Biodiversität in der Windsheimer Bucht. AFZ-DerWald 20: 33–34. Dolek, M.; Bußler, H.; Schmidl, J.; Geyer, A.; Bolz, R.; Liegl, A., 2008: Vergleich der Biodiversität verschiedener Eich- enwälder anhand xylobionter Käfer, Nachtfalter und Ameisen. In: Bayerisches Landesamt für Umwelt (ed) Ökologische Bedeutung und Schutz von Mittelwäldern in Bayern, UmweltSpezial. 7–37. Finnberg, S.; Bußler, H., 2019: Insektenvielfalt im Mittel- wald. AFZ-DerWald 20: 22–25. Gayer, K., 1889: Waldbau. Verlag Paul Parey, Berlin, 619 p. Gößwein, S.; Lemmer, H.; Petercord, P. 2017: Prachtkäfer profitieren vom Trockensommer 2015. LWFaktuell 112, 1: 14–17. Müller, J.; Bußler, H.; Simon, U.; Hacker, H., 2004: Eichen- furnier Trotz Widderbock. AFZ-DerWald 16: 879–882. Petercord, R. 2015: Rolle der Eichenfraßgesellschaft beim Eichensterben. AFZ-DerWald 8: 17–19. Petercord, R., 2018: Waldschutzkunde Eiche. LWF aktuell 4: 9–11. Rabl, A., 1982: Beitrag zur forstgeschichtlichen Entwick- lung am Kehrenberg. In: Künneth, W. (ed). Das Ökosys-

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