Data from: Is active management the key to the conservation of saproxylic biodiversity? Pollarding promotes the formation of tree hollows

Trees with hollows are key features sustaining biodiversity in wooded landscapes. They host rich assemblages of often highly specialised organisms. Hollow trees, however, have become rare and localised in Europe. Many of the associated biota is thus declining or endangered. The challenge of its conservation, therefore, is to safeguard the presence of hollow trees in sufficient numbers. Populations of numerous species associated with tree hollows and dead wood are often found in habitats that were formed by formerly common traditional silvicultural practices such as coppicing, pollarding or pasture. Although it has been occasionally mentioned that such practices increase the formation of hollows and the availability of often sun-exposed dead wood, their effect has never been quantified. Our study examined the hollow incidence in pollard and non-pollard (unmanaged) willows and the effect of pollarding on incremental growth rate by tree ring analysis. The probability of hollow occurrence was substantially higher in pollard than in non-pollard trees. Young pollards, especially, form hollows much more often than non-pollards; for instance, in trees of 50 cm DBH, the probability of hollow ocurrence was ~0.75 in pollards, but only ~0.3 in non-pollards. No difference in growth rate was found. Pollarding thus leads to the rapid formation of tree hollows, a habitat usually associated with old trees. It is therefore potentially a very important tool in the restoration of saproxylic habitats and conservation of hollow-dependent fauna. If applied along e.g. roads and watercourses, pollarding could also be used to increase landscape connectivity for saproxylic organisms. In reserves where pollarding was formerly practiced, its restoration would be necessary to prevent loss of saproxylic biodiversity. Our results point to the importance of active management measures for maintaining availability, and spatial and temporal continuity of deadwood microhabitats

Co-occurrence of three Aristolochia-feeding Papilionids (Archon apollinus, Zerynthia polyxena and Zerynthia cerisy) in Greek Thrace

Slancarova, Jana, Vrba, Pavel, Platek, Michal, Zapletal, Michal, Spitzer, Lukas, Konvicka, Martin (2015): Co-occurrence of three Aristolochia-feeding Papilionids (Archon apollinus, Zerynthia polyxena and Zerynthia cerisy) in Greek Thrace. Journal of Natural History 49 (29): 1825-1848, DOI: 10.1080/00222933.2015.100628

Is active management the key to the conservation of saproxylic biodiversity? Pollarding promotes the formation of tree hollows.

Trees with hollows are key features sustaining biodiversity in wooded landscapes. They host rich assemblages of often highly specialised organisms. Hollow trees, however, have become rare and localised in Europe. Many of the associated biota is thus declining or endangered. The challenge of its conservation, therefore, is to safeguard the presence of hollow trees in sufficient numbers. Populations of numerous species associated with tree hollows and dead wood are often found in habitats that were formed by formerly common traditional silvicultural practices such as coppicing, pollarding or pasture. Although it has been occasionally mentioned that such practices increase the formation of hollows and the availability of often sun-exposed dead wood, their effect has never been quantified. Our study examined the hollow incidence in pollard and non-pollard (unmanaged) willows and the effect of pollarding on incremental growth rate by tree ring analysis. The probability of hollow occurrence was substantially higher in pollard than in non-pollard trees. Young pollards, especially, form hollows much more often than non-pollards; for instance, in trees of 50 cm DBH, the probability of hollow ocurrence was ∼0.75 in pollards, but only ∼0.3 in non-pollards. No difference in growth rate was found. Pollarding thus leads to the rapid formation of tree hollows, a habitat usually associated with old trees. It is therefore potentially a very important tool in the restoration of saproxylic habitats and conservation of hollow-dependent fauna. If applied along e.g. roads and watercourses, pollarding could also be used to increase landscape connectivity for saproxylic organisms. In reserves where pollarding was formerly practiced, its restoration would be necessary to prevent loss of saproxylic biodiversity. Our results point to the importance of active management measures for maintaining availability, and spatial and temporal continuity of deadwood microhabitats

Figure 4 in Co-occurrence of three Aristolochia-feeding Papilionids (Archon apollinus, Zerynthia polyxena and Zerynthia cerisy) in Greek Thrace

Figure 4. Results of model for eggs and larval records. (A) Interaction plot showing average egg batch sizes for individual butterfly species on individual species of Aristolochia plants; (B) box-plots (medians and quartiles) showing the amount of canopy closure (variable Trees10: see Material and methods) above Aristolochia plants bearing eggs of the respective butterflies; (C) numbers of larvae of the three studied butterfly species recorded during searches for larvae, note the unbalanced scale on the x-axis; (D) interaction plot showing average number of larvae of the three studied butterfly species in individual instars. For panels (A, C, D) dotted line, Archon apollinus; dashed line, Zerynthia cerisy; full line, Zerynthia polyxena.Published as part of Slancarova, Jana, Vrba, Pavel, Platek, Michal, Zapletal, Michal, Spitzer, Lukas & Konvicka, Martin, 2015, Co-occurrence of three Aristolochia-feeding Papilionids (Archon apollinus, Zerynthia polyxena and Zerynthia cerisy) in Greek Thrace, pp. 1825-1848 in Journal of Natural History 49 (29) on page 1840, DOI: 10.1080/00222933.2015.1006281, http://zenodo.org/record/399967

Figure 3 in Co-occurrence of three Aristolochia-feeding Papilionids (Archon apollinus, Zerynthia polyxena and Zerynthia cerisy) in Greek Thrace

Figure 3. Estimates of the adult daily population sizes based on mark–recapture data: year 2010, when only data for Archon apollinus (most of flight period) and Zerynthia cerisy (late tail of flight period) allowed the estimation; year 2011, A. apollinus, Z. cerisy, Zerynthia polyxena. The error lines present standard errors of estimates, see Table 3 for model parameters.Published as part of <i>Slancarova, Jana, Vrba, Pavel, Platek, Michal, Zapletal, Michal, Spitzer, Lukas & Konvicka, Martin, 2015, Co-occurrence of three Aristolochia-feeding Papilionids (Archon apollinus, Zerynthia polyxena and Zerynthia cerisy) in Greek Thrace, pp. 1825-1848 in Journal of Natural History 49 (29)</i> on page 1835, DOI: 10.1080/00222933.2015.1006281, <a href="http://zenodo.org/record/3999678">http://zenodo.org/record/3999678</a&gt

Figure 1 in Co-occurrence of three Aristolochia-feeding Papilionids (Archon apollinus, Zerynthia polyxena and Zerynthia cerisy) in Greek Thrace

Figure 1. Position of the study area in northeastern Greece (dark dot on the map) and mutual positions of the three study subsites, with the mosaics of individual biotopes. The longest single moves of three study species: Aa, Archon apollinus; Zc, Zerynthia cerisy; Zp, Zerynthia polyxena.Published as part of <i>Slancarova, Jana, Vrba, Pavel, Platek, Michal, Zapletal, Michal, Spitzer, Lukas & Konvicka, Martin, 2015, Co-occurrence of three Aristolochia-feeding Papilionids (Archon apollinus, Zerynthia polyxena and Zerynthia cerisy) in Greek Thrace, pp. 1825-1848 in Journal of Natural History 49 (29)</i> on page 1828, DOI: 10.1080/00222933.2015.1006281, <a href="http://zenodo.org/record/3999678">http://zenodo.org/record/3999678</a&gt

Radial growth of willows.

<p>Mean radial growth of pollards (solid line; n = 8) and unmanaged willows (dashed line; n = 10) at the Pastvisko site, Czech Republic. Although pollard willows show increased growth rates after the pollarding event of 2003 (vertical dashed line), the pattern was not significant in our study.</p

Results of hollow presence analysis.

<p>Pollarding and DBH affect hollow occurrence in willows. Output of generalized linear regression models with binomial distribution (coefficient estimates are on <i>logit</i> scale), <i>lnDBH</i>  =  ln-transformed DBH, factor variable <i>management</i> is represented by its levels, 'pollard' and 'unmanaged'. Coefficients are displayed for (A) full model with interaction between variables (<i>lnDBH</i>: χ² = 172.71, d.f. = 1, P<0.001; <i>management</i>: χ² = 145.34, d.f. = 1, P<0.001; <i>lnDBH:management</i>: χ² = 4.21, d.f. = 1, P = 0.04) and for (B) restricted model without interaction. For both models n = 1126.</p

Sebek_et_al_Pollarding

Comparison of hollow formation between pollard and unmanaged trees. The worksheet "Hollow incidence" gives information on presence/absence (1/0)of hollows (cavities) in trees. The worksheet "Incremental growth" contains measurements of tree rings from 8 pollard and 10 unmanaged trees. See the article for more information on study design

Forms of pollard and unmanaged trees.

<p>A pollard (A) and an unmanaged tree (B), shown with their most common type of tree hollows (grey colored): hollows formed in the upper parts of the trunk as a result of bared heartwood after pruning are common in pollards, whereas hollows formed after a branch fall are the most common hollow type in unmanaged trees.</p