Survey of tree species regeneration in canopy gaps forests in north of Iran.
Biodiversity has been regarded as a significant index in natural science and there has been significant attention to any factor decreasing biodiversity. Many scholars refer to biodiversity as the important index of the sustainable development. Preservation of biodiversity along with searching for the most suitable site and harvesting rule should be considered as the most important goal in forest planning . In forest management a gap is a physical space created by falling of one or more trees [4,3].  have studied the effect of creating gaps on natural regeneration and results showed that regeneration is dispersed and mostly belong to beech (Fagus orientalis) and Ash- tree (Fraxinus) and also there appears to be no clear difference between gaps and canopied areas.  studied the effect of the harvesting on the forest structure .Through their comparison between unlogged, 6-month and 18-year post-harvest forest stands they noticed that there was little difference in tree species composition and diversity between treatments, stem densities of both saplings and trees in unlogged forest were significantly higher than those in forest sampled 18 years after logging. Their evidence suggests that inadequate recruitment of Entandrophragma cylindricum and E. utile, the principal timber species, to justify continued timber extraction.
 conducted a study on the gap characteristics and their regeneration in old conifer forests in Japan. There was a 7% gap area with mean square of 43 [m.sup.2]. Gaps smaller than 40[m.sup.2] were more than the gaps more than 200[m.sup.2]. They concluded that shade-tolerant species such as Abies will regenerate before the gap formation, but the light-demanding species such as picea and Betula alba regenerate after the gap formation. Generally specific species, show a prominent preference regarding the gap size.  studied the utilized gaps and concluded that some species are more abundant by gap expasion and most of the gaps are occupied with a few number of pioneer species. In another study showed that with increase in altitude from sea level species richness decrease while species diversity and evenness continue to rise so that the maximum species diversity is observed at the altitude range of 100-700 meter above sea level and the least diversity of species is observed above 700 meter altitude . Because of high ecologic potential of Forests in Iran, it seems that there is a high regeneration and plan diversity in this .Such important goal motivated the researcher to conduct a field study in this area.
Material and Methods
The site of this study was under the coverage of The Forestry Plan "Narmash" which was started in total coverage of 1181 hectares since 1991 by The Natural Resource Administration of Roodsar, headquartered in north of Iran. About 1016 hectares of this plan which is divided into 27 parcels, is under harvest but 165 hectares of it is managed conservatory because of its high slope and rocky nature. The forests in this plan are located at the altitude of 120 - 950 m, between 50[degrees] 17'10" and 50[degrees],14',40" east longitude and 37[degrees] 30'20" and36[degrees]58' north latitude belonged to the middle sector of the forests area.Generally these forests are of Carpinus betulus species mixed with species such as Parrotia persica , Alnus subcordata ,Fagus orientalis ,Acer insigne, Acer cappadocicum , Diospyros lotus and Pterocarya fraxionifolia . Parcel No 122 (52 hectares) in eastern general orientation and parcel No 124 (48 hectares) in north eastern orientation which , harvested in 2001-2002 were selected for this study . Their lowest, highest and mean altitude were 550 m, 950m and 700 m respectively (Narmash Forestry) plan. Their mean annual evaporation rate was 844.9 mm, with the partial moisture of 91.05% and annual participation of 1257.5 mm mostly in autumn. The mean annual temperature in this site is 15.4 [degrees]c with minimum and maximum temperature of -7 [degrees]c and 37.5[degrees]c. In this study thirty five gaps in parcels 122 and 124 were defined and then classified in three small, medium and big size groups. Five gaps were randomly selected from each groups, providing 15 gaps totally as the sample of the study . For studying the vegetation coverage and tree species regeneration micro plats of (2x2 [m.sup.2]) were assigned in 1 meter distance of each other systematically (Fig. 1).  and concurrently, all gaps area were calculated based on the following equation .
[FIGURE 1 OMITTED]
Data Analysis was performed through analysis variance method (in a completely random Block plan) by SPSS soft ware and Tukey and ANOVA Tests were performed for comparing the means. Different biodiversity indexes were calculated and analyzed by DIVERSE soft wares and Figures were drown by Excel.
Results and Discussions
The results demonstrated that twelve tree species and 29 grass species were observed in these sites among which ,8 tree species were present in 100 - 200 [m.sup.2], 200 - 300 [m.sup.2] and 300-400 [m.sup.2] gaps. There were also 27 , 28 and 29 grass species in 100 - 200 [m.sup.2], 200 - 300 [m.sup.2] and 300-400[m.sup.2] gaps respectively among them , 6 tree species were in common between three gap levels . On the other hand, 22 grass species were in common in 100- 200 [m.sup.2], 200 - 300 [m.sup.2] and 300 - 400[m.sup.2] gaps. There was no shrub in the gaps. Also 300-400 squre meter gaps according to Shanno-wiener, Simpson, [N.sub.2] Hill's, [N.sub.1]Mc-Arthur indexes in sequence with the amounts 2.499, 0.807, 5.194 and 5.65 show the most tree diversity compared to other gaps(figures 2,3,4 and 5).
Also from the view point of evenness in tree layers the most amount is related to 300-400 square meters gaps (figure 6).
The tree species richness also in the gaps compared to other studied gaps with the amount of 8 has the most amount (figure 7).
Also 41 tree and grass species were observed among which, 34 tree and grass species were in 100 - 200 [m.sup.2] gaps, 35 tree and grass species were in 200 - 300 [m.sup.2] gaps and 37 tree and grass species were in 300 - 400 [m.sup.2] gaps (Figure 8).
Analysis has shown that there was no difference in regeneration among different gaps (Table1). Although there was some insignificant difference in field observation and number of generations in species such as Carpinus betulus, Gleditschia caspica, Pterocarya fraxinifolia. There was also higher number of plants in big gaps possible because of good seedling procedures and more suitable ecologic situations. Tree species were seen in all small and medium size gaps and also in big ones, until the center of the gap. Most of seedling Frequency was noticed in big gaps and the least one were seen in small gaps. There was negligible difference in the number of seedlings in small and medium sized gaps. There was more species in medium and big gaps than in small ones, although in big gaps, there were more seedlings. There was no significant difference in diversity of tree species in different gaps. But the diversity and number of tree species were different since tree harvesting and decrease of canopy density increased the light in the field resulting in the increase of the number of light demanding species in wider gaps.. Based on Tukey test, there was no significant difference (P=0.05). in tree layer among three gaps , although apparently there was some difference possibly because of the presence of animal in the area , wood burglary and unsuitable trees marking in the site of the study. Such evidence is just the opposite of the studies conducted by Haddadi moghaddam (2007) and shaghaghi (1996) in Gorgan province, both of them conducted their studies in the forests located in eastern region to Narmash forests. Light demanding species such as grass and Rosaceae were seen in all gaps. Referring to ANOVA analysis ,there was no significant difference of richness and evenness among gaps(Table2,3).
The more the gaps size and the area, the more the seedlings, although this increase is not in a specific scheme and there is little increase in number of gaps up to a mean level, decreasing sharply after that level. Seedlings Richness is less in small gaps and Richness is increased along with the increase in gap surface .But this increase continues up to 300 - 400 [m.sup.2] level, decreasing after that.This evidence is similar to the results of study that was conducted by  who proposed that the woody species are more in gaps lower than 4 acre. Yamamato on the other hand considers the 2 arc gaps field as the best site for the growth of Fagus crenata. Results also show that, the size of the gap provides no significant impact on species diversity in tree layer but increases the diversity in grass layer leading to a Major role in forest stability.
[1.] Barnes, B.V., D.R. Zak, S.R. Denton and S.H. Spur, 1997. Forest Ecology,. John Wiley & Sons Inc. USA, pp: 774.
[2.] Berg, E.C. and D.H. Van Lear, 2004. Yellow-poplar and oak seedling density responses to wind-generated gaps. Proceedings of the 12th biennial southern silvicultural research conference. Gen. Tech. Rep. SRS-71. Asheville, NC:U.S. Department of Agriculture, Forest Service, Southern Research Station, pp: 594.
[3.] Brokaw, N.V.L., 1996. Tree falls: frequency timing and consequences. Smithsonian Institute, Washington, D.C., pp: 101-108.
[4.] Watt, A.S., 1947. Pattern and process in the plant community. Journal. Ecology, pp: 1-22.
[5.] Deslow, J.S. and T. Spies, 1990. Canopy gaps in forest ecosystems: an introduction. Canadian. journal forest research, 20: 619.
[6.] Fallahchai, M.M., 2011. A biodiversity survey in deciduous broad- leaf forests north of Iran. International journal of Academic research, 3(2) : 1126-1130.
[7.] Haddadi Moghaddam, H., 2007. Biodiversity, MS.c thesis, Guilan University, Iran, pp: 105.
[8.] Hall, J.S., 2003. The effects of selective logging of forest structure and tree species composition in a Centeral African forests. Forest Ecology and Management.
[9.] Hung, W., 2003. Species diversity forest structure and composition in Tanzanian tropical forest. Forest ecology and management, 173: 11-24.
[10.] James, R., 1997. Treefalls: Gap dynamics in the southern Appalachian. Ecology, 68(2): 417-424.
[11.] Park, A., 2005. Natural regeneration and environmental relationships of tree species in login gaps in a Bolivian tropical forest. Forest Ecology and management, 217: 147-157.
[12.] Renato, A. and Ferreira de Lima, 2005. Gap size measurement: The proposal of a new field method. Forest Ecology and Managemen, 214 : 413-419.
[13.] Runkel, J.R., 1985. comparison of methods for determining fraction of land area in treefall gaps. Forest science, 31: 15-19.
[14.] Shaghaghi, V., 1996. Survey of ten year application of selection method for beech species. MS.c thesis, Gorgan colege of Are : culture and natural science, pp: 140.
[15.] Yamamoto, S.I., 1989. Gap dynamics in climax Fagus crenata forests. Botany. Management. (Tukyo), 102: 93-114.
[16.] Yamamoto, S.I., 1995. Gap characteristics and gap regeneration in a sunalpine old-growth coniferous forests, central Japan. Ecology. Research. (Tukeyo), 10: 31-39.
(1) Mir Mozaffar Fallahchai, (2) Seyed Armin Hashemi and (3) Amir Bonyad
(1,2) Department of Forestry, Lahijan Branch, Islamic Azad University, Lahijan, Iran.
(3) Department of Forestry, Faculty of Natural Resources, Guilan University, Somae Sara, Guilan, Iran.
Mir Mozaffar Fallahchai, Seyed Armin Hashemi and Amir Bonyad: Survey of Tree Species Regeneration in Canopy Gaps Forests in North of Iran.
Mir Mozaffar Fallahchai, Department of Forestry, Lahijan Branch, Islamic Azad University, Lahijan, Iran.
Table 1: The means comparison variance analysis in different gaps. Source of Variation Sum of Squares Degree of freedom Between Groups 383558.902 2 Within Groups 194283337.60 42 Total 194666896.51 44 Source of Variation Mean of Squares F Sig. Between Groups 191779.451 .041 (ns) 0.959 Within Groups 4625793.75 Total n.s = non-significant. Table 2: The species evenness variance analysis in different gaps. Source of Sum of Degree of Mean of F Sig. variation squares freedom squares Between groups .009 2 .004 1.158 (n.s) 0.376 Within Groups .022 6 .004 Total .031 8 n.s = non-significant. Table 3: The species richness variance analysis in different gaps. Source of Sum of Degree of Mean of F Sig. variation squares freedom squares Between Groups 0.222 2 .111 .121 (n.s) 0.888 Within Groups 5.500 6 .917 Total 5.722 8 n.s =non-significant. Fig. 2: Mean and standard deviation of Shannon-winner diversity in different gaps. Gap Size 100-200 200-300 300-400 H' 2.439 2.294 2.499 S-D 0.0139 0.0149 0.0091 Note: Table made from bar graph. Fig. 3: Mean and standard deviation of Simpson diversity in different gaps. Gap Size 100-200 200-300 300-400 1-D 0.795 0.763 0.807 S-D 0.0025 0.003 0.0008 Note: Table made from bar graph. Fig. 4: Mean and standard deviation of N2 Hill diversity in different gaps. Gap Size 100-200 200-300 300-400 n2 4.878 4.224 5.194 S-D 0.0405 0.0391 0.0138 Note: Table made from bar graph. Fig. 5: Mean and standard deviation of N1 Mc-Arthur diversity in different gaps. Gap Size 100-200 200-300 300-400 n1 5.42 4.91 5.65 S-D 0.0431 0.0404 0.00808 Note: Table made from bar graph. Fig. 6: Mean and standard deviation of Evenness in different gaps. Gap Size 100-200 200-300 300-400 Eveness 0.38 0.225 0.446 S-D 0.0026 0.0017 0.00236 Note: Table made from bar graph. Fig. 7: Richness of Tree species in different gaps. Gap Size 100-200 200-300 300-400 Richness 7 7 8 Note: Table made from bar graph. Fig. 8: Richness Vegetation species. Gap Size 100-200 200-300 300-400 Richness 34 35 37 Note: Table made from bar graph.
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|Title Annotation:||Original Article|
|Author:||Fallahchai, Mir Mozaffar; Hashemi, Seyed Armin; Bonyad, Amir|
|Publication:||Advances in Environmental Biology|
|Date:||Sep 1, 2011|
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