عنوان مقاله [English]
Canopy gaps are amongst the most important small-scale phenomena in many temperate, old growth forests, and play a fundamental role in composition and structure of stands. Their occurrence in Hyrcanian forests is associated with numerous effects, including the establishment of species regeneration and increasing forest biodiversity. Due to the importance of in-depth information on canopy gaps, a number of their characteristics were studied in an intact mixed broad-leaved stand in Shast-Kalateh experimental forest Golestan province. We investigated 82 canopy gaps (with a size larger than 40m2) in the compartments 3, 4, 5 and 7 of the forest. For each canopy gap, two parameters of length (L, as the longest distance within the gap) and the width (W, as the largest distance perpendicular to the length) were measured. In addition, data on natural regeneration was sampled within all gaps by species-specific measurement of individuals with DBH 2, with average and median gap size of 470 and 278.6 m2, respectively. The most frequent canopy gaps were those < 400 m2 (71.95%). We observed only few gaps >1000 m2. Most gaps were formed by tree mortality, where hornbeam trees were responsible for 51.45% of gaps. In this study, the increase of gap size to 400 m2 led to increasing the regeneration of tree species. In contrast, the regeneration of main species decreased when gap area increased by more than 500 m2. Hornbeams were the most frequent regenerations in canopy gaps. Finally, the results showed that canopy gaps are crucial factors for regeneration and restoration of forest trees. Therefore, this study calls for increased attention to the different aspects of canopy gaps in order to achieve sustainable management objectives in forestry plans.
- Amanzadeh, B., Amani, M., Amin, M. and Salehi, M., 2004. Investigation on regeneration of natural gaps in the Asalem Forests. Pajouhesh and Sazandegi, 71: 19-25 (In Persian).
- Amanzadeh, B., Pourmajidian, M.R., Shagheb-Talebi, Kh. and Hojati, S.M., 2015. Impact of canopy gap size on plant species diversity and composition in mixed stands (Case study: Reserve area, district No. 3 Asalem forests). Forest and Wood Products (Iranian Journal of Natural Resources), 68(2): 287-301 (In Persian).
- Amiri, M., Rahmani, R. and Sagheb-Talebi, Kh., 2015. Canopy gaps characteristics and structural dynamics in a natural unmanaged oriental beech (Fagus orientalis Lipsky) stand in the north of Iran. Caspian Journal of Environmental Sciences, 13(3): 259-274.
- Anonymous, 2008. Forestry plan. Department of Natural Resources and Watershed Management of Golestan Province, Gorgan, 284p (In Persian).
- Amoli Kondori, A.R., Marvi Mohajer, M.R., Zobeiri, M. and Etemad, V., 2012. Natural regeneration of tree species in relation to gaps characteristics in natural beech stand (Fagus orientalis Lipsky), north of Iran. Iranian Journal of Forest and Poplar Research, 20(1): 152-164 (In Persian).
- Attiwill, P.M., 1994. The disturbance of forest ecosystems: The ecological basis for conservative management. Forest Ecology and Management, 63: 247-300.
- Bottero, A., Garbarino, M., Dukic, V., Govedar, Z., Lingua, E., Nagel, TA. and Motta, R., 2011. Gap-phase dynamics in the old-growth forest of Lom, Bosnia and Herzegovina. Silva Fennica, 45: 875-887.
- Brokaw, N.V.L., 1985. Gap-phase regeneration in a tropical forest. Ecology, 66: 682-687.
- Dehdashtifar, M., Jalali, S.Gh.A., Esmailzadeh, O. and. Kahyani, S., 2014. Influence of canopy gaps size and dead trees on natural regeneration in the Experimental Forest Station of Tarbiat Modares University. Journal of Wood and Forest Science and Technology, 21(2): 149-168 (In Persian).
- Delfan-Abazari, B., Sagheb-Talebi, Kh. and Namiranian, M., 2004. Regeneration gaps and quantitative characteristics of seedlings in different development stages of undisturbed beech stand (Kelardasht, northern Iran). Iranian Journal Forest and Poplar Research, 12(2): 302-306 (In Persian).
- Garbarino, M., Mondino, E.B., Lingua, E., Nagel, T.A., Dukic, V., Govedar, Z. and Motta, R., 2012. Gap disturbances and regeneration patterns in a Bosnian old-growth forest: A multispectral remote sensing and ground-based approach. Annual Forest Sciences, 69: 617-625
- Kenderes, K., Mihok, B. and Standovár, T., 2008. Thirty years of gap dynamics in a central European beech forest reserve. Forestry, 81: 111-123.
- Kucbel, S., Jaloviar, P., Saniga, M., Vencurik, J. and Klimas, V., 2010. Canopy gaps in an old-growth fir-beech forest remnant of western Carpathians. European Journal of Forest Research, 129: 249-259.
- Mataji, A., Babaie-Kafaki, S. and Kiadaliri, H., 2008. Spatial pattern of regeneration gaps in managed and unmanaged stands in natural beech (Fagus orientalis) forests. Iranian Journal of Forest and Poplar Research, 16(1): 149-157 (In Persian).
- McCarthy, J., 2001. Gap dynamics of forest trees: A review with particular attention to boreal forests. Environmental Reviews, 9: 1-59.
- Mohammadi, L., Marvie-Mohadjer, M.R., Etemad, V. and Sefidi, K., 2014. Quantitative characteristics of regeneration in natural and tree fall canopy gaps in the mixed beech stands, northern Iran (Case study: Namkhaneh district, Kheyrud forest). Iranian Journal of Forest, 6(4): 457-570 (In Persian).
- Mihok, B., Galhidy, L., Kelemen, K. and Standovar, T., 2005. Study of gap-phase regeneration in a managed beech forest: Relations between tree regeneration and light, substrate features and cover of ground vegetation. Acta Silvatica and Lignaria Hungarica, 1: 25-38.
- Mousavi-Mirkolaei, S.R., Sagheb-Talebi, Kh., Tabari, M. and Pourmajidian, M.R., 2003. Determine the gap size to improve the regeneration of beech. Iranian Journal of Natural Resources, 58(1): 39-46 (In Persian).
- Mountford, E.P., Saville, P.S. and Bebber, D.P., 2006. Patterns of regeneration and ground vegetation associated with canopy gaps in a managed beech wood in southern England. Forestry, 79: 389-408.
- Muscolo, A., Bagnato, S., Sidari, M. and Mercurio, R., 2014. A review of the roles of forest canopy gaps. Journal of Forestry Research, 25(4): 725-736.
- Nagel, T.A., Svoboda, M., Ruugani, T. and Diaci, J., 2010. Gap regeneration and replacement patterns in an old-growth Fagus–Abies forest of Bosnia–Herzegovina. Plant Ecology, 208: 307-318.
- Orman, O. and Dobrowolska, D., 2017. Gap dynamics in the western Carpathian mixed beech old-growth forests affected by spruce bark beetle outbreak. European Journal Forest Research, 136(3): 1-11.
- Parhizkar, P., Sagheb-Talebi, K., Mataji, N. and Namiranian, M., 2011. Influence of gap size and development stages on the silvicultural characteristics of oriental beech (Fagus orientalis Lipsky) regeneration. Caspian Journal of Environmental Sciences, 9(1): 55-65.
- Petritan, AM., Nuske, RS., Petritan, IC. and Tudose, NC., 2013. Gap disturbance patterns in an old-growth sessile oak (Quercus petraea L.) - European beech (Fagus sylvatica L.) forest remnant in the Carpathian mountains, Romania. Forest Ecology and Management, 308: 67-75
- Pickett, S.T.A. and White, P.S., 1985. The Ecology of Natural Disturbance and Patch Dynamics. Academic Press, Orlando, United States, 472p.
- Runkle, J.R., 1982. Patterns of disturbance in some old-growth mesic forests of Eastern North-America. Ecology, 63: 1533-1546.
- Sagheb-Talebi, Kh. and Schütz, J.Ph., 2002. The structure of natural oriental beech (Fagus orientalis) forests in the Caspian region of Iran and the potential for the application of the group selection system. Forestry, 75(4): 465-472.
- Sagheb-Talebi, Kh, Delfan-Abazari, B. and Namiranian, M., 2005. Regeneration process in natural uneven-aged Caspian beech forests. Swiss Forest Journal, 156(12): 477-480.
- Sefidi, K. and Marvi-Mohajer, M.R., 2010. Characteristics of coarse woody debris in successional stages of natural beech (Fagus orientalis Lipsky) forests of northern Iran. Journal of Forest Sciences, 56(1): 7-17.
- Sefidi, K., Marvi Mohajer, M.R., Mosandel, R. and Copenheaver, C.A., 2011. Canopy gaps and regeneration in old-growth Oriental beech (Fagus orientalis Lipsky) stands, northern Iran. Forest Ecology and Management, 262: 1094-1099.
- Yamamoto, S.I., 2000. Forest gap dynamics and tree regeneration. Journal of Forest Research, 5: 223-229.
- Yamamoto, S.I., Nishimura, N., Torimaru, T., Manabe, T., Itaya, A. and Becek, K., 2011. A comparison of different survey methods for assessing gap parameters in old-growth forests. Forest Ecology and Management, 262: 886-893.
- Zeibig, A., Diaci, J. and Wagner, S., 2005. Gap disturbance patterns of a Fagus sylvatica virgin forest remnant in the mountain vegetation belt of Slovenia. Forest Snow and Landscape Research, 79: 69-80.