# Pedunculate and Sessile Mixed Oak Forest Regeneration Process in Lithuania

^{1}

^{2}

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Materials and Methods

#### 2.1. Stand Description

#### 2.2. Data Analysis

^{2}plots were placed in areas where both species are recovering and determined species of each oak (1 plot: 54°14′02.91″ north latitude, 23°45′21.44″ east longitude, 2 plot: 54°14′12.66″ north latitude, 23°45′31.32″ east longitude, 3 plot: 54°14′22.41″ north latitude, 23°44′17″ east longitude, 4 plot: 54°14′41.91″ north latitude, 23°44′54.80″ east longitude).

_{p,g}) is calculated according to the quantity observed in undergrowth plot (N

_{p,g}) evaluating the plot area.

_{p,g}) of different height groups used for the calculation of undergrowth species’ peculiarities was investigated by the formula:

_{p,g}) may vary during its formation process with the changing of undergrowth amount (N

_{p,g}) and occupied area (B

_{p,g}).

_{1}, m

_{2}is characterized by the characteristic of growth rate, p—type index, t—the period of formation, and X—independent variable.

## 3. Results and Discussion

#### 3.1. Spreading of Oak Undergrowth

#### 3.2. External Factors Influencing the Growth of Undergrowth

#### 3.3. Mathematical Modelling of Oak Undergrowth

_{p,g}) are summarizes in the mathematical modelling data set. The total results of undergrowth quantity included 4 × 4 size distribution, where interdependence of elements can be evaluated with ${X}^{2}$ criterion [30]. Such volume statistics, with 6 degrees of freedom at the 0.05 significance level, were ${X}_{0.05}^{2}\left(6\right)=12.5$. The quantity of all total undergrowth oak species and age groups was interdependent because statistic ${X}^{2}=26.6$ is greater than critical. The total undergrowth quantity was an expression of the extensive system properties that can be characteristic only of the study system.

_{p,t}) in Equation (7) and analysed variables chosen should be compatible with the characteristics of the test process, and the validity of the obtained dependencies can be solved only on the basis of Fisher criterion (F) and coefficient of determination (R

_{2}) values [30]. Therefore, regression analysis was performed on pedunculate and sessile oak species and their hybrids and on the whole oak undergrowth depending on the period and the formation of all possible interactions between variables (Table 5). In the regression analysis, for the purpose of better images, non-absolute values of the density of the oak densities of Ap presented in Table 5 were used, and their relative values at the time of observation (t = 0) were captured in terms of values.

^{2}= 0.996):

_{kr}) undergrowth of hybrids (Table 5, line 13). Similar interdependences were determined for undergrowth of pedunculate oak (lines 2 and 3).

_{kr}), although the data determination coefficient was high in all studied oak trees:

_{1}by relative approach. The largest average density increase rate was for the undergrowth of pedunculate oak and smallest for sessile oak. The total oak undergrowth density increase rate was higher than the values obtained by individual components (Equation (8)). That strengthening of oak undergrowth density increase rate as one formation property was significant, indicating the effect of the biological system.

## 4. Conclusions

_{1}(P) = 0,377, m

_{1}(H) = 0.285, m

_{1}(S) = 0.238, m

_{1}(V) = 0.402), which will in the future change the species composition of stands. Sessile oaks positively influence the development of undergrowth, because a whole undergrowth has formed at a higher rate than the individual components of the undergrowth. Quantitative percentage distribution indicators of oak undergrowth by age groups have similar trends to those obtained by other authors, exploring common oak undergrowth structure of different types of oak and showing that the 5-year period investigating the formation of groups is the right height. We found an increased number of hybrid oaks in the undergrowth. The admixture of sessile oaks in the oak stand had a positive impact on the development of undergrowth.

## Author Contributions

## Acknowledgments

## Conflicts of Interest

## References

- Götmark, F.; Kiffer, C. Regeneration of oaks (Quercus robur/Q. petraea) and three other tree species during long-term succession after catastrophic disturbance (windthrow). Plant Ecol.
**2014**, 215, 1067–1080. [Google Scholar] [CrossRef] - Navarro, L.M.; Pereira, H.M. Rewilding abandoned landscapes in Europe. In Rewilding European Landscapes; Pereira, H., Navarro, L., Eds.; Springer: New York, NY, USA, 2015; pp. 3–23. [Google Scholar]
- Arroyo-Rodríguezm, V.; Melo, F.P.; Martínez-Ramos, M.; Bongers, F.; Chazdon, R.L.; Meave, J.A.; Tabarelli, M. Multiple successional pathways in human-modified tropical landscapes: New insights from forest succession, forest fragmentation and landscape ecology research. Biol. Rev.
**2017**, 92, 326–340. [Google Scholar] [CrossRef] [PubMed] - Vizoso-Arribe, O.; Díaz-Maroto, I.; Vila-Lameiro, P.; Díaz-Maroto, M. Influence of the canopy in the natural regeneration of Quercus robur in NW Spain. Biologia
**2014**, 69, 1678–1684. [Google Scholar] [CrossRef] - Goebel, P.C.; Hix, D.M. Development of mixed-oak forests in southeastern Ohio: A comparison of second-growth and old-growth forests. For. Ecol. Manag.
**1996**, 84, 1–21. [Google Scholar] [CrossRef] - Karazija, S.; Jurelionis, J.; Vaičiūnas, V. Lietuvos ąžuolynai: Išsaugojimo ir atkūrimo problemos [Lithuanian oak forests: Problems of preservation and restoration]. In Savaiminis ąžuolynų atžėlimas [Self-Contained Regeneration of Oak Trees]; Karazija, S., Ed.; Lututė: Kaunas, Lithuania, 1997; pp. 135–141, (Lithuanian with English summary). [Google Scholar]
- Kullberg, Y.; Bergström, R. Winter browsing by large herbivores on planted deciduous seedlings in southern Sweden. Sweden Scand. J. For. Res.
**2001**, 16, 371–378. [Google Scholar] [CrossRef] - Helay, W. Influence of deer on the structure and composition of oak forests in central Massachusetts. In The Science of Overabundance; Mc Shea, W.J., Underwood, H.B., Rappole, J.H., Eds.; Smithsonian Institution Press: Washington, DC, USA, 1997; pp. 249–265. [Google Scholar]
- Lorimer, C.G.; Chapman, J.W.; Lambert, W.D. Tall understory vegetation as a factor in the poor development of oak seedlings beneath mature stands. J. Ecol.
**1994**, 82, 227–237. [Google Scholar] [CrossRef] - Brudvig, L.A.; Asbjornsen, H. Dynamics and determinants of Quercus alba seedling success following savanna encroachment and restoration. For. Ecol. Manag.
**2009**, 257, 876–884. [Google Scholar] [CrossRef] - Götmark, F. Careful partial harvesting in conservation stands and retention of large oaks favour oak regeneration. Biol. Conserv.
**2007**, 140, 349–358. [Google Scholar] [CrossRef] - Kleinschmit, J. Intraspecific variation of growth and adaptive traits in European oak species. Ann. Sci. For. Suppl.
**1993**, 50, 166–185. [Google Scholar] [CrossRef] - Bacilieri, R.; Ducousso, A.; Kremer, A. Genetic, morphological and phenological differentiation between Quercus petraea (Matt.) Liebl. and Quercus robur L. in a mixed stand of northwest of France. Silvae Gen.
**1995**, 44, 1–10. [Google Scholar] - Jensen, J.S. Provenance variation in phenotypic traits in Quercus robur and Quercus petraea in Danish provenance trials. Scand. J. For. Res.
**2008**, 23, 179–188. [Google Scholar] [CrossRef] - Curtu, A.L.; Gailing, O.; Leinemann, L.; Finkeldey, R. Genetic variation and differentiation within a natural community of five oak species (Quercus ssp.). Plant Biol.
**2007**, 9, 116–126. [Google Scholar] [CrossRef] [PubMed] - Jensen, J.S.; Hansen, J.K. Geographical variation in phenology of Quercus petraea (Matt.) Liebl. and Quercus robur L. oak grown in a greenhouse. Scand. J. For. Res.
**2008**, 23, 179–188. [Google Scholar] [CrossRef] - Abadie, P.; Roussel, G.; Dencusse, B.; Bonnet, C.; Bertocchi, E.; Louvet, J.M.; Kremer, A.; Garnier-Géré, P. Strength, diversity and plasticity of postmating reproductive barriers between two hybridizing oak species (Quercus robur L. and Quercus petraea (Matt) Liebl.). J. Evol. Biol.
**2012**, 25, 157–173. [Google Scholar] [CrossRef] [PubMed] - Eriksson, G. Quercus petraea and Quercus robur: Recent Genetic Research; The Silva Slovenica Publishing Centre, Slovenian Forestry Institute: Ljubljana, Slovenia, 2015; p. 104. ISBN 978-961-6993-01-2. [Google Scholar]
- Rupšys, S. Matematinis modeliavimas (miškotvarkoje ir ekologijoje) [Mathematical Modeling (in Forest Management and Ecology)]; LŽŪU LC: Akademija, Lithuania, 2007. [Google Scholar]
- Tuminauskas, S. Bekotis ąžuolas pietų Lietuvoje [Sessile oak in Lithuania]. Mūsų Girios
**1957**, 5, 11–13. (In Lithuanian) [Google Scholar] - Patalauskaitė, D. On the quercetalia robori-petraeae in Lithuania. Botanica Lithuanica
**2008**, 14, 113–119. [Google Scholar] - Vaičys, M. Miško augaviečių tipai [Types of Forest Sites]; Vaičys, M., Ed.; Lututė: Kaunas, Lithuania, 2006; ISBN 9955-692-41-3. [Google Scholar]
- [WRB] World Reference Base for Soil Resources 2014. International Soil Classification System for Naming Soils and Creating Legends for Soil Maps; World Soil Resources Reports, FAO: Rome, Italy, 2014. [Google Scholar]
- Patalauskaitė, D. Communities of Quercus petraea in Lithuania. Acta Biol. Univ. Daugavp.
**2007**, 7, 159–164. [Google Scholar] - Navasaitis, M.; Ozolinčius, R.; Smaliukas, D.; Balevičienė, J. Lietuvos dendroflora [Dendroflora in Lithuania]; Lututė: Kaunas, Lithuania, 2003. (In Lithuanian) [Google Scholar]
- Baliuckas, V. Paprastojo (Quercus robur) ir bekočio ąžuolo (Q. petraea) rūšių introgresija Trako miške (Introgression of pedunculate (Quercus robur) and sessile (Q. petraea) oak species in Trakas Forest). Bot. Lith.
**2000**, 6, 375–387. [Google Scholar] - Carlise, A.; Brown, A.F. The assessment of the taxonomic status of mixed oaks (Quercus ssp.) populations. Watsonia
**1965**, 6, 120–127. [Google Scholar] - Kremer, A.; Dupouey, J.L.; Deans, J.D.; Cotrell, J.; Csaikl, U.; Finkeldey, R.; Espinel, S.; Jensen, J.; Kleinschmit, J.; Van Dam, B.; et al. Leaf morphological differentiation between Quercus robur and Quercus petraea is stable across western European mixed oak stands. Ann. For. Sci.
**2002**, 59, 777–787. [Google Scholar] [CrossRef] - Borazan, A.; Babaç, M.T. Morphometric leaf variation in oaks (Quercus) of Bolu Turkey. Ann. Bot. Fenn.
**2003**, 40, 233–242. [Google Scholar] - Čekanavičius, V.; Murauskas, G. Statistika ir jos taikymai [Statistics and Its Applications]; TEV: Vilnius, Lithuania, 2001. (In Lithuanian) [Google Scholar]
- [LR AM] LR AM Miškų departamentas. Miško atkūrimas ir veisimas (Teisės aktų rinkinys) [Reforestation and Breeding (Legislative Package)]; UAB Lodvila: Vilnius, Lithuania, 2011. (In Lithuanian) [Google Scholar]

**Figure 1.**Trakas Forest in Alytus district, Veisiejai Forest Enterprise, Seirijai Forest District in Lithuania (54°14′11″ N, 23°45′30″ E, 190 m a.s.l.): (

**a**) circles—locations of the sampling sites of the undergrowth; squares—the location of sampling sites of the first storey of the stand in Trakas Forest; numbers and lines indicate forest blocks; (

**b**) rectangular area shows the location of Trakas Forest in Lithuania and smaller black circles indicate the nearest natural sessile oak stands in Poland.

**Figure 2.**Oak undergrowth distribution by height groups and species. Brightest colour indicates an area where there is no oak undergrowth. Different colours indicate differing numbers of oaks in the plots. The plot area is 78.5 m

^{2}. The largest number of oak undergrowth in the group up to 0.5 m height was: for Q. robur, 26; hybrids, 15; Q. petraea, 17. Respectively, in the group with height 0.5–1.5 m: 13, 13, 3; in the group of 1.5–3.0 m height: 10, 2, 0; and in the group with height over 3.0 m: 10, 3, 4.

**Figure 3.**The first stand storey (larger circles) and undergrowth (smaller circles) distribution by species in four study plots of 0.5 ha each. The letters of legend indicate: P—pedunculate oak, H—hybrid oak, S—sessile oak.

**Figure 4.**Abundance of oak undergrowth (P—pedunculate oak, H—hybrid oak, S—sessile oak) in different forest sites: Ne—eutrophic soils of normal moisture, Nm—mesoeutrophic soils of normal moisture, Se—eutrophic soils of normal moisture on slopes (>15°), Sm—mesoeutrophic soils of normal moisture on slopes (>15°), Tm—mesoeutrophic gleyic soils of temporary overmoisture, Pm—mesoeutrophic gley soils of permanent overmoisture.

**Figure 5.**The abundance of oak undergrowth depending on the first storey prevailing species: P—pedunculate oak, H—hybrid oak, S—sessile oak. In the x array: O—oak sp., Sp—Norway spruce, T—the total oak undergrowth, Pi—silver pine, A—black alder, L—small-lived lime, B—common birch, Ho—common hornbeam.

**Figure 6.**The vector distribution between two axes (RDA): pedunculate oak (

**top**), sessile oak (

**lower**) and their hybrid (

**middle**) in four undergrowth (Ug) height classes (y) and their dependence from site density (D) and covering of underbrush (UbC) and herbaceous plant (HC) (x).

**Figure 7.**The dependence of the relative density (A

_{V}/A

_{V}

_{,0}) on the total oak undergrowth in the formation period: 1—data of observations, 2—Gomperz curve, 3—exponent curve.

**Figure 8.**Relative amount of exponential dependence on the age of the pedunculate oak undergrowth compared with other authors’ observation data in different oak stands: 1—exponential curve to Δt = 3 year, 2—exponential curve to Δt = 5 year, 3—an exponential curve to Δt = 7 years. Points—data of observations [6].

Oaks (p) | Undergrowth Height Group (g) | Average Density (A_{p}) | The Maximum Density (${\mathit{A}}_{\mathit{p}}^{\mathbf{max}})$ | |||
---|---|---|---|---|---|---|

1 | 2 | 3 | 4 | |||

Sessile oak | 621 | 212 | 0 | 191 | 418 | 2930 |

Hybrid ^{1} oak | 479 | 363 | 140 | 193 | 436 | 3822 |

Pedunculate oak | 867 | 539 | 449 | 335 | 1047 | 4586 |

Total species | 895 | 621 | 401 | 328 | 1106 | 8408 |

^{1}In all the tables, data shown of first and other generations interspecific hybrids between pedunculate and sessile oaks.

**Table 2.**The total amount (N

_{p,t}) of oak trees in the undergrowth in plots dependent on the formation period (t) in years (Equation (3)).

Oaks (p) | Period of Undergrowth Formation | Relative Amount of Undergrowth | ||||
---|---|---|---|---|---|---|

t = −3 | t = −2 | t = −1 | t = 0 | N_{p}_{,0}/N_{p}_{,−3} | % | |

Sessile oak | 15 | 15 | 20 | 59 | 3.9 | 0.048 |

Hybrid oak | 59 | 70 | 144 | 253 | 4.3 | 0.21 |

Pedunculate oak | 176 | 250 | 449 | 912 | 52 | 0.74 |

Total undergrowth | 250 | 335 | 613 | 1224 | 4.9 | 100 |

**Table 3.**Dependence of occupied number of plots (B

_{p,t}) of oak trees in the undergrowth by the formation period (t) in years (Equation (5)).

Oaks (p) | Period of Undergrowth Formation (t) | Relative Amount of Plot Numbers B_{p,}_{0}/B_{p,}_{−3} | |||
---|---|---|---|---|---|

t = −3 | t = −2 | t = −1 | t = 0 | ||

Sessile oak | 10 | 10 | 13 | 18 | 1.8 |

Hybrid oak | 39 | 49 | 67 | 74 | 1.9 |

Pedunculate oak | 67 | 73 | 92 | 111 | 1.7 |

Total | 97 | 106 | 125 | 141 | 1.5 |

**Table 4.**Oak trees in the undergrowth density change (A

_{p,t}) dependent on the formation period, units/ha (Equation (6)).

Oaks (p) | Period of Undergrowth Formation (t) in Years | |||
---|---|---|---|---|

t = −3 | t = −2 | t = −1 | t = 0 | |

Sessile oak | 191 | 191 | 196 | 418 |

Hybrid oak | 193 | 182 | 274 | 436 |

Pedunculate oak | 335 | 436 | 622 | 1047 |

Total | 328 | 403 | 625 | 1106 |

**Table 5.**The relative density of the development of oak trees in the undergrowth, with group regression analysis (Equation (7)).

No. | Function of Undergrowth Status | Critical Value of Criterion F | Indexes | ||||
---|---|---|---|---|---|---|---|

Criterion F | Determination Coefficient (R^{2}) | Constant (C) | Coefficient | Coefficient m1 | |||

Quercus robur | |||||||

1 | A_{P}/A_{P,}_{0}= f (t) | 18.5 | 84.7 | 0.977 | 0.934 | 0.377 | |

2 | A_{P}/A_{P,}_{0}= f (t, A_{H}/A_{H,}_{0}) | 200 | 487 | 0.999 | 0.525 | 0.636 | 0.258 |

3 | A_{P}/A_{P,}_{0}= f (t, A_{S}/A_{S,}_{0}) | 200 | 290 | 0.998 | 0.49 | 0.432 | 0.306 |

Quercus petraea | |||||||

5 | A_{S}/A_{S,}_{0}= f (t) | 18.5 | 3.4 | 0.626 | 0.799 | 0.238 | |

6 | A_{S}/A_{S,}_{0}= f (t, A_{H}/A_{H,}_{0}) | 200 | 5.8 | 0.920 | 0.153 | 1.828 | −0.107 |

7 | A_{S}/A_{S,}_{0}= f (t, A_{P}/A_{P,}_{0}) | 200 | 38.9 | 0.988 | 0.077 | 2.549 | −0.328 |

Hybrid oak | |||||||

8 | A_{H}/A_{H}_{,0}= f (t) | 18.5 | 10.6 | 0.841 | 0.896 | 0.285 | |

9 | A_{H}/A_{H,}_{0}= f (t, A_{P}/A_{P,}_{0}) | 200 | 11 | 0.957 | 0.228 | 1.500 | −0.046 |

10 | A_{H}/A_{H,}_{0}= f (t, A_{S}/A_{S,}_{0}) | 200 | 6.4 | 0.927 | 0.494 | 0.708 | 0.169 |

Total | |||||||

11 | A_{V}/A_{V,}_{0}= f (t) | 18.5 | 49.3 | 0.961 | 0.917 | 0.409 | |

12 | A_{V}/A_{V,}_{0}= f (t, A_{P}/A_{P,}_{0}) | 200 | 120 | 0.996 | 0.336 | 1.098 | 0.165 |

13 | A_{V}/A_{V,}_{0}= f (t, A_{H}/A_{H,}_{0}) | 200 | 8891 | 0.999 | 0.398 | 0.922 | 0.235 |

14 | A_{V}/A_{V,}_{0}= f (t, A_{S}/A_{S,}_{0}) | 200 | 50.3 | 0.990 | 0.577 | 2.549 | −0.328 |

**Table 6.**Group regression analysis of the dependence of the formation period of the total amount (N

_{p,t}) of oak trees undergrowth.

Function of Undergrowth Condition | Critical Value of Criterion F | Indexes | |||
---|---|---|---|---|---|

Oaks | Criterion F | Determination Coefficient (R^{2}) | Constant (C) | Coefficient (m_{1}) | |

Sessile oak | 18.5 | 94 | 0.979 | 0.920 | 0.552 |

Hybrid oak | 18.5 | 41 | 0.953 | 0.939 | 0.509 |

Pedunculate oak | 18.5 | 6 | 0.760 | 0.744 | 0.440 |

Total | 18.5 | 68 | 0.972 | 0.915 | 0.537 |

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**MDPI and ACS Style**

Jurkšienė, G.; Baliuckas, V. Pedunculate and Sessile Mixed Oak Forest Regeneration Process in Lithuania. *Forests* **2018**, *9*, 459.
https://doi.org/10.3390/f9080459

**AMA Style**

Jurkšienė G, Baliuckas V. Pedunculate and Sessile Mixed Oak Forest Regeneration Process in Lithuania. *Forests*. 2018; 9(8):459.
https://doi.org/10.3390/f9080459

**Chicago/Turabian Style**

Jurkšienė, Girmantė, and Virgilijus Baliuckas. 2018. "Pedunculate and Sessile Mixed Oak Forest Regeneration Process in Lithuania" *Forests* 9, no. 8: 459.
https://doi.org/10.3390/f9080459