Research Article ii FF o o r r e e s s t t doi: 10.3832/ifor2347-010 Biogeosciences and Forestry vol. 11, pp. 72-78 Analysis of growth of recruits of natural regeneration of Sorbus torminalis (L.) Crantz - a rare European forest tree species Leszek Bednorz, We compared growth and survival of wild service tree (Sorbus torminalis [L.] Renata Nowinska Crantz) recruits of different origin (generative: seedlings; vegetative: root suckers) established in a fenced plot at the Forest District of Krzyz (north- western Poland). Total height, annual growth of the dominant shoot, stem diameter at root collar, number of first-order branches, and mortality were measured every year over the period 2011-2015 (5 years). In 2011, a total of 382 multi-age recruits originated both from seeds (212) and root suckers (170) were recorded. Five-year mortality was higher in the generative progeny (12.3% - only youngest seedlings) as compared with vegetative recruits (2.9%). The growth rate of individuals markedly increased with height as absolute val- ues, but slightly decreased in terms of relative growth. Statistical analysis revealed that the effect of the recruit origin on growth was noticeably weaker than that of age, defined in terms of development (height) classes. The origin of recruits had a major effect on the annual growth of the dominant shoots and a minor (though significant) effect on stem diameter and the number of first-order branches. Overall, the analysis of growth rate showed that genera- tive recruits grow faster than the vegetative ones. Our results highlight the importance of stimulating the generative regeneration and protecting seed- lings as a conservation strategy for Sorbus torminalis. Keywords: Sorbus torminalis, Regeneration, Growth, Mortality, Seedlings, Root Suckers Introduction Pyttel et al. 2013). It reproduces both by (Koop 1987). Furthermore, in case of Sor- The wild service tree Sorbus torminalis seeds and root suckers, the latter espe- bus torminalis, root suckering may some- (L.) Crantz is a typical rare forest species cially at the distribution border in north- times be the only possible way to repro- with a scattered distribution (Rasmussen & eastern Europe (Hoebee et al. 2006, Ras- duce and survive. Kollmann 2004). It is distributed across mussen & Kollmann 2007, Rasmussen & The wild service tree is often considered a western, central and southern Europe, but Kollmann 2008, Rich et al. 2010, Jankow- light-demanding/semi-shade species, often also occurs in south-western Asia and ska-Wroblewska et al. 2016). However, out-competed by other hardwood species north-western Africa. The species is a mi- abundant regeneration by root suckers has (Hochbichler 2003, Demesure-Musch & Od- nor component of various oak and some- also been observed in the centre of the dou-Muratorio 2004, Bednorz 2007, 2009 times beech or pine-dominated forests, species distribution, in Switzerland (Rotach Paganova 2007). On the other hand, some where it is usually found at low density 2000) and in Germany (Ewald et al. 1994, observations and studies show that the (<30 trees ha-1 – Demesure-Musch & Od- Schüte 2001, Pyttel et al. 2013). The recruits species is shade tolerant and can persist dou-Muratorio 2004) and only exception- are often browsed by deer, so their protec- for many years under the canopy of other ally occurs in considerable densities (Müller tion by fencing is recommended (Nicolescu deciduous trees (Pyttel et al. 2013). et al. 2000, Hochbichler 2003, Pyttel et al. et al. 2009, Bednorz et al. 2012). Vegetative In Poland, Sorbus torminalis occurs rarely 2013). reproduction could be particularly impor- in deciduous and mixed forests in its west- The wild service tree forms fleshy, brown tant under circumstances where natural ern and southern part and the species has fruits, dispersed by birds and small mam- growth of forest trees is difficult, e.g., near been protected by law since 1946. Re- mals (Oddou-Muratorio et al. 2004, Ras- the distribution limit of the species, in dy- cently, active protection measures have mussen & Kollmann 2004, Rich et al. 2010, namic habitats or under heavy shade been implemented in Polish state forests to preserve this species. Initiation of natu- ral regeneration and protection of recruits Department of Botany, Poznan University of Life Sciences, Wojska Polskiego 71C, 60-625 against browsing damage are among the Poznan (Poland) basic tools of active protection of natural populations of the wild service tree (Bed- @ Leszek Bednorz ([email protected]) norz 2007, 2009, Bednorz et al. 2012). Although knowledge of the development Received: Jan 04, 2017 - Accepted: Oct 25, 2017 of natural regeneration is essential for properly planning conservation activities, Citation: Bednorz L, Nowinska R (2018). Analysis of growth of recruits of natural there are no studies comparing the growth regeneration of Sorbus torminalis (L.) Crantz - a rare European forest tree species. iForest and survival of Sorbus torminalis recruits 11: 72-78. – doi: 10.3832/ifor2347-010 [online 2018-01-25] originated from seeds and root suckers in natural populations. Several studies investi- Communicated by: Emanuele Lingua gated the growth and survival rate of wild service tree seedlings cultivated in nurs- © SISEF http://www.sisef.it/iforest/ 72 iForest 11: 72-78 Bednorz L & Nowinska R - iForest 11: 72-78 y o ′ r eries or progeny-provenance plots (Espah- found in forest compartment 295 (52 57 Moreover, the architecture of suckers did t o s bodi et al. 2008, Sulkowska & Wojda 2015), 36.9″ N, 15 58′ 38.3″ E; elevation 64 m not suggest any former intensive grazing. e r but no data are available so far on the a.s.l.), Three plots with abundant offspring o spontaneous regeneration of such species were fenced to protect the recruits against Data analysis F in the forest, with the exception of Schüte browsing by deer. Moreover, hornbeam In order to analyse the effects of origin d n (2001) who investigated the growth and seedlings overgrowing Sorbus torminalis and age on the mortality and growth of a shade tolerance of root suckers in a natural recruits were removed once a year by the Sorbus torminalis recruits, the individuals s e population in Germany. local forest service. were separated into two categories: gener- c n In this study, we analysed the survival and ative progenies (seedlings) and vegetative e i growth of Sorbus torminalis recruits (both Data collection progenies (suckers) and into four age-de- c s root suckers and originated from seeds) in Data was collected within the largest plot velopment classes based on their total o the Forest District of Krzyz (north-western (0.41 ha), which was chosen for the de- height: (CI) up to 15 cm; (CII): 16-49 cm; e g Poland). Fenced plots were established in tailed study for two reasons: (i) because of (CIII): 50-79 cm; (CIV): over 79 cm. The ori- o i the forest to investigate offspring under the large number of recruits originated gin of recruits was determined on the basis B conditions of releasing from browsing and both from seeds and root suckers; (ii) be- of morphological features, mode of distri- – limitation of competition from hornbeam cause the light regime (semi-shade) was bution and supported by a genetic analysis t s seedlings. We addressed the following approximately the same for all recruits performed on the sample of 66 individuals e r questions: (1) does the survival rate of S. over the plot. All the individuals of S. tormi- (Burczyk J & Jankowska-Wroblewska S - o F torminalis recruits depend on their age (ex- nalis within the plot were mapped using an unpublished data). i pressed as age-related development electronic tachymeter GTS-229® (Topcon To analyse how the population of recruits classes of offspring) and origin (seedlings Ltd., Singapore). Each recruit was provided changed over time, the mortality of vege- and root suckers)? (2) To what extent the with label and sequential number. Three tative and generative progenies over the growth rate of S. torminalis recruits does adult trees of the species growing within five years was determined, together with depend on their age and origin? the fenced plot were also mapped. The the distribution of specimens in the differ- plot was monitored each autumn since ent age-development classes in 2011 and Materials and methods 2011. During the five subsequent years 2015. (2011-2015), each of the recruits were mea- All analyses that concerned plant growth Study area sured for the following characters: total were based on the age-development classi- The wild service tree occurs in only one height, annual growth of the dominant fication carried out in 2011. First, multivari- site at the Forest District of Krzyz, namely shoot, stem diameter at root collar and the ate and variate analyses of variance (MA- in the moraine upland of the Drawa Valley, total number of first order branches. An- NOVA and ANOVA, respectively) were per- within the area of the Debina Forestry. The nual growth was defined as the length be- formed to compare the size of progenies study area is a deciduous mesic forest habi- tween the scars left on the stem by the last of different age-development classes in the tat on cambisoils, represented by a low- winter buds and the stem top. As we were first and last years of observations. Next, density seed stand of pedunculate oak not able to clearly pinpoint the age of re- hierachical multiple regression was used to with scant admixture of hornbeam and cruits, we used age-development classes estimate differences in growth rate among beech. This forest is not under legal protec- expressed in terms of offspring height (see progenies of different age and origin. The tion. The average annual precipitation in “Data analysis”).