Tez özetleri Astronomi ve Uzay Bilimleri Anabilim Dalı

Community: Abies bornmülleriana-Fagus orientalis

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  Typical subcommunity: Abies bornmülleriana-Fagus orientalis
  
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  Subcommunity: Fagus orientalis-Abies bornmuelleriana-Pinus sylvestris
  
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  Subcommunity: Actaea spicata-Abies bornmülleriana-Fagus orientalis
  

Altitude, metamorphic bedrock and land exposure were found as statistically the most important variables. On the other hand, the amount of variability explained by loamy-lime bedrock increases when marginal effects of the environmental variables are considered. The amount of variability explained by altitude, which is 31 % , increases to 44 % with the conditional effect of land exposure. In addition it was found that total variability explained by all bedrock types is 39 %.

Mean Ellenberg indicator values precisely reflect site conditions. For instance, Physospermum cornubiense-Pinus sylvestris, which occurs on sunny exposures of Ayıkaya Hill, has low moisture and temperature indicator values with a high light indicator values. On northern exposures, Vaccinium arctostaphylos-Fagus orientalis and Abies bornmülleriana-Fagus orientalis communities have a high mean moisture indicator values and their mean temperature values decrease with increasing altitude. For this reason, ecological species groups of soil nutrient content, soil reaction, light, moisture, temperature and continentality were determined from the indicator values of species in ordination analysis.

High soil pH, which determines the occurence of many nutrients like total calcium concentration, indicates productivity. Therefore a positive correlation is seen among soil reaction, soil nutrient content and moisture indicator values in the vegetation analysis. This is reflected in higher stand top height in the comunities with high pH indicator values. In contrast, although Physospermum cornubiense-Pinus sylvestris community which occurs on sunny exposures of Ayıkaya Hill has a high pH value, has a low moisture and nutrient indicator value due to direct radiation. However, this community shows a good development because of its wide ecological amplitude.

The highest species numbers are found in Physospermum cornubiense-Pinus sylvestris and Erica arborea-Quercus petraea communities. Soil nutrient content and stand cover has a possitive influence on the species diversity of communities. In closed stand high soil nutrient causes an increase in species number. On the other hand, on sunny exposures productivity is low but species number is high due to stand canopy is less closed. However, when stand cover percentages were compared, species numbers decrease in stands with 100% and 50% cover percentages but diversity of species increases in stands with 80-90 cover percentages.

Forest communities which are distributed close to forest limit in the region have stand structure in the form of tree collectives. Tree collectives are stabil stand structure characteristics of high mountain forests. Unappropriate silvicultural applications caused windthrow and stem breaking in the region.

In the context of the study, vegetation researches which were carried out in similar ecosystems were stored in the TURBOVEG program and a regional vegetation database were formed. Similar vegetation types with Ayıkaya region were found with the classification of regional vegetation data. General vegetation characteristics of Ayıkaya region, which is in the euxine part of Euro-Siberian phytogeographic region, have high similarities with Zonguldak-Çitdere and Karabük-Büyükdüz regions but low similarities with Düzce-Elmacık mountain and southern part of Ilgaz mountain which are in the sub-euxine part of the region. In addition, beech and oak forest types on northern part of Ilgaz mountain are close to those of Ayıkaya region.

Two grassland communities were determined from the classification glassland sample plots:

Class: Astragalo-Brometea

Alliance: Hyperico-Verbascion

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  Alchemilla pseudocartalinica-Astrantia maxima community
  
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  Teucrium chamaedrys-Bromus riparius community
  

Ayıkaya alpine grassland vegetation has the widest natural distribution on the Ayıkaya Hill (1970 m) except from forest openings in the region. The southern part of the hill has steep slopes (60-100% inclination) and is dominated by xerophyte species. This community was determined as Teucrium chamaedrys-Bromus riparius. On northern slopes where mesophilic and forest transitional species occur determined as Alchemilla pseudocartalinica-Astrantia maxima.

The Teucrium chamaedrys-Bromus riparius community has the highest species number. The Alchemilla pseudocartalinica-Astrantia maxima community has relatively low species number due to grazing effect. However, the species that occur in this community, i.e. Cynosurus cristatus, Cirsium vulgare, Urtica dioica, Dactylis glomerata, Rumex crispus etc., are the indicators of grazing.