Conditions Determining Natural Regeneration After Wildfires in the Pinus Halepensis (Miller, 1768) Forests of Kassandra Peninsula (North Greece)
Total Page：16
File Type：pdf, Size：1020Kb
Pores;~;ology Management EISEVIER Forest Ecology and Management 92 (1997) 199-208 Conditions determining natural regeneration after wildfires in the Pinus halepensis (Miller, 1768) forests of Kassandra Peninsula (North Greece) Thekla Tsitsoni Unirersiq of Thessaloniki, Deportment of Forestry and Natural Emironment, Laboratoq of Siiciculture. 54006 Thessaloniki, Greece Accepted 2 August 1996 Abstract Post-fire natural regenerationin Aleppo pine (Pinus halepensis)forests of KassandraPeninsula (North Greece) was studied.The KassandraPeninsula is characterizedby a Mediterranean-typeclimate with a mild sub-humidwinter and a long xerothermicperiod. Samplingwas done on 74 plots in four different areasof the peninsula.The total meanregeneration indiceswere satisfactoryin maturestands and varied between0.60 and 14.26;they had their lowest valuesat the upper positionand increaseddescending the hillside, showingstatistically significant differences. The slopewas also found to be an importantfactor determiningnatural regeneration, which wasbest in areaswith a slopeof O-50%. A recurrenceof fire in one of the areasstudied, 4 yearsafter the first fire, proved to be destructivefor the naturalregeneration. Keywords: Natural regeneration: Wildfires; Aleppo pine forests; Mediterranean ecosystems 1. Introduction mechanisms evolved by these species, they have been called ‘fire-tolerant’ (Le Houerou, 1974; Dafis, Greece is a Mediterranean country in which the 1986). Especially the species Pinus halepensis and problem of fire is great, due to the climatic condi- Pinus brutia maintain the germination capacity of tions prevailing in summer (high temperatures and their seedslong after fire (Dafis, 1986, 1987), a fact drought). This problem is major in the zone of the known in the ancient times as recorded by evergreen broadleaves where mostly pyrophilic Theophrastus according to Thanos et al. (1989). A species of the genera Pinus, Quercus, Erica and similar natural regeneration behaviour after fire has Cisrus appear. These speciesare known to be highly been observed in other species such as Pinus flammable and big areas are burnt every year. The banksiana by Roe et al. (1971) and Beaufait et al. wildfires are, however, an integral part of the (1975). Mediterranean-type environment, and this is justified In the present research,the natural regeneration of by the high post-fire regeneration capacity of the the Aleppo pine, after wildfire, is studied. It is a burnt Mediterranean ecosystems(Naveh, 1974; Tra- dominant forest speciesin the Mediterranean ecosys- baud et al., 1985; Thanos et al., 1989; Thanos and tems and spreadsfrom sealevel up to 600-800 m in Marcou, 1991). Due to the numerous adaptation the Quercetalia ilicis vegetation zone and especially 0378-I 127/97/$17.00 Copyright 0 1997 Elsevier Science B.V. All rights reserved. PII SO378-1127(96)03909-6 200 T Tsitsorti / Forest ihhg~ rind Manugrmrr~t 92 f 19971 199-208 in the Adrachno-Quercetum ilicis plant formation species is in danger due to the frequent fires occur- where it has its optima1 growth. In Greece it is found ring during summer. in Peloponnesos, Epirus, Sterea Hellada, Euboea, The purpose of this research was: (1) to study the Chalkidiki, Pelio, Ionean and Aegean islands. From possibilities for natural regeneration of the Aleppo a silvicultural-biological point of view. Aleppo pine pine after fire. (2) to determine conditions favorable is a photophilic. dry-warm, frugal species preferring for natural regeneration after fire. and (31 to draw) alkaline and neutral soils (Nahal. 1962; Quezel, conclusions on forestry practice. 1986). Wildfires make the Aleppo pine more com- petitive against the rich shrubby vegetation of the exceptionally flammable species composing its un- 2. Study area derstorey in relation to which it is less competitive under normal conditions (Dafis. 1986, 1987; Wag- The research was conducted at the state and com- ner, 1970). munity forests of Kassandra Peninsula. which is the The Aleppo pine forests in Kassandra Peninsula first of the three peninsulas of Chalkidiki from the were selected for two reasons: (1) because this species west to the east; it occupies an area of about 35000 reaches its optima1 growth in this area (Dafis, 19691, ha (Fig. I). and (2) because the existence and conservation of The climate of the area belongs to the Mediteran- this species is very important for the already high nean type (Balafoutis, 1977) and, according to the touristic development of the area. However, the bioclimatic diagram of Emberger ( 1959). to the sub- Fig. 1. Vegetation map in Kassandra Peninsula. I. cultivated lands; 2. forests of Pinus brutia and Pinus hulepensis: 3, forests of Pinus halepensis; 4, scrub of macquis (Quercion ilicis): 5, villages. T. Tsitsoni/ Forest Ecology and Management 92 (1997) 199-208 201 humid Mediterranean zone (Mavrommatis, 1980); 5-8%, while in other unburnt sites of Kassandra this is also confirmed by the vegetation spectrum of Peninsula it ranges from 2% to 4%. The total nitro- the area (Tsitsoni and Karagiannakidou, 1992). The gen of the local soils ranged from 0.02% to 0.3% dry period has an average duration of 4.5 months, (Tsitsoni, 1991). from the middle of April to the end of September, The vegetation of the area consists of the charac- and the mean annual rainfall is 559.1 mm according teristic Mediterannean floristic components, the to the data from the meteorogical station of Kassan- Allepo pine dominating. The species prevailing in dria 1975-1990 (Tsitsoni, 1991). shrubby vegetation include Pistacia lent&w, Smi- The soils occupied by the Aleppo pine in Kassan- lax aspera, Phillyrea media, Quercus cocci’era, As- dra are loamy-clayey with a high content of loam, paragus acutifolius, Lonicera implexa, Cistus in- except for a few areas such as Polychrono (one of canus, Myrtus communis, Arbutus unedo, Arbutus the four studied areas) where there was a relatively adrachne, Erica arborea and Erica manipul$ora; high content of sand. A characteristic feature of these those prevailing in herbaceous vegetation include soils is the high pH ranging from 7.0 to 8.4. The Rubia peregrina, Brachypodium retusum, Brachy- contents of organic matter in the burnt area is about podium pinnatum, Carduus pycnocephalus. Carex Table 1 Characteristics of natural regeneration in various sites of Aleppo pine forest at Nea Skioni, burnt on July 1977 (measurements were taken during July-September 1985) Location on hillside No. RJ(m-‘J Height (cm) Age (years) Exposure Slope (%o) Mean RJ cm-‘) l-30 31-60 > 60 (/pper Prof. Hlias 2.8 0.4 0.3 2.1 7 E 25 Livadakia 2.7 - - 2.7 5 W 35 Frama 2.4 - 0.3 2.1 8 SE 50 2.85 Nekrotafeio 3.5 2.9 0.6 7 S 40 Trambala 0.6 0.2 0.2 0.2 2-5 SE 75 Anemi (a) 1.3 - - 1.3 7-8 W 75 0.83 Anemi (b) 0.6 - - 0.6 7-8 S 75 Total mean RI 1.99 Middle Prof. Hlias 8 6.2 0.6 - 5.6 7 E 25 Livadakia 9 8.3 1.3 0.6 6.4 7 W 35 Frama 10 2.8 - 2.8 5-8 SE 50 5.58 Nekrotafeio 11 5.0 5.0 8 S 40 Trambala 12 0.7 0.7 5 SE 80 Anemi (a) 13 0.7 0.7 8 W 80 0.63 Anemi (b) 14 0.5 - - 0.5 7 S 80 Total mean RI 3.45 Lmt Prof. Hlias 15 8.4 1.0 5.6 1.8 7 E 25 Livadakia 16 5.6 0.2 0.3 5.1 7 W 35 Frama 17 17.0 - 17.0 8 SE 50 9.0 Nekrotafeio 18 5.0 - - 5.0 8 S 40 Trambala 19 0.3 - - 0.3 5 SE 80 Anemi (a) 20 1.4 - - 1.4 8 W 75 1.2 Anemi (b) 21 1.9 - - 1.9 7-8 S 75 Total mean RI 5.1 RI, regeneration index. 202 T. Tsitsoni / Forest Eco1og.v and Management 92 C 19971 19%2OK Table 2 In the above areas, 74 sample plots were taken on Analysis of variance of the relationship between regeneration different slopes and at three positions on the hillside index and the parameters of position and the slope (Nea Skioni) (upper, middle, low). The sample plots were squares Source d.f. Mean square F P of 10 m X 10 m. Each sample plot was divided into Main effect 7 27.073 283.00 0.000 100 squares of 1 m’ and we randomly took ten Position 2 23.899 249.8 1 0.000 squares, counting the number, age and height of Slope 5 28.343 296.27 0.000 Position X Slope 8 15.131 158.16 0.000 seedlings in them. In each square the seedlings were Explained IS 20.704 2 16.41 0.000 classified into three classes according to their height: Residual 5 0.096 in the first. the seedlings measuring l--30 cm were Total 20 15.552 classil-ied, in the second those measuring 3 I-60 cm and in the third class those higher than 60 cm. As regeneration index we defined the number of flacca, Asparagus monspesulanum, Brachypodium seedlings per square metre. For each position on the syluaticum and Tummus communis (Lavrediades, hillside, the total mean regeneration index was calcu- 1961; Tutin et al., 1964-1980; Tsitsoni. 1991). lated in all areas. In all positions on the hillside. the mean regeneration index was calculated separately for slopes of O-50% and slopes greater than 50%. 3. Methods The relationship between the regeration index, on the one hand, and the parameters of position on the The research on natural regeneration after fire was hillside and the slope, on the other, were tested by carried out from July to September of 1985, in four analysis of variance (two-way ANOVA).