Eurasian Journal of Forest Science

Number 1, 2016

1-16
LONG-TERM POLLEN MONITORING EXPERIMENTS FOR THE PERIOD 1994-2008 IN THE RILA MOUNTAINS, BULGARIA

Authors: Spassimir Tonkov1*, Elissaveta Bozilova1, Dolja Pavlova1, Ivan Raev2

Abstract

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The annual pollen influx in the altitudinal zone 1800-2050 m a.s.l. produced by plant communities in the coniferous and subalpine vegetation belts of the northwestern Rila Mts. was analyzed for the period 1994-2008. The results from the five pollen traps placed on south and north slopes of a ridge revealed the dominance of Pinus diploxylon-type (Pinus mugo, Pinus sylvestris) and relatively constant presence of Picea abies and Pinus peuce pollen, with the exception in years of abundant flowering (1997, 1999, 2003 and partly 2005). The species Fagus sylvatica which grows at lower altitudes showed very good capabilities of pollen dispersal upslope. The trapping results indicated a cyclicity in the flowering of beech, with maximal pollen influx values in years 1994, 1999, 2005 and 2007, most probably dependent on the local climatic conditions. Pollen of deciduous trees such as Quercus, Carpinus betulus, Corylus, Alnus, Betula, although in less quantities, was also recorded in the traps. The herb component constituted only a small part of the total annual pollen influx. The results from long-term pollen trapping experiments could be applied to monitor the future trends in forest development in relation to climate change and local disturbances.

17-30
LITTER PRODUCTION, DECOMPOSITION AND NUTRIENT RELEASE OF WOODY TREE SPECIES IN DHANAULTI REGION OF TEMPERATE FOREST IN GARHWAL HIMALAYA

Authors: Sushil Saha, G.S.Rajwar and Munesh Kumar* and Kalidas Upadhaya

Abstract

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The study has been carried out in Dhanaulity region of temperate forest of Garhwal Himalaya to understand litter production, their decomposition and concentration of nutrients release by leaf litter at different altitudes. The results indicate that the litter production with altitude in each season reduced in order of Lower>middle>upper altitudes, while in each altitudes the seasonal litter production reduced in order of summer>rainy>winter. The value of decomposition constant (k) was reduced as 0.511, 0.438 and 0.256 at lower, upper, middle altitude respectively. The concentration of nutrients seasonally (irrespective altitude), potassium reduced from summer (0.92%), rainy (0.90%) and winter (0.84%) however, phosphorus shown reverse trend with potassium as summer (0.104%), rainy (0.108%) and winter (0.203%) whereas nitrogen was highest in rainy (1.13%) followed by winter (1.11%) and summer (1.01%). The nutrient concentration with altitude (irrespective season), potassium increased with increasing altitudes, whereas, phosphorus and nitrogen have not shown any trend with altitude.

31-39
Bioclimatic factors affecting the distribution of Quercus robur L. (pedunculate oak) subspecies in Turkey

Authors: Osman Yalçın YILMAZ 1, Hatice YILMAZ

Abstract

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Number of views: 422

Understanding the distribution of individual species and the factors affecting their distribution is a key issue in biogeography, ecology and conservation. This study was carried out to determine bioclimatic factors affecting the two pedunculate oak subspecies (Quercus robur L. subsp. robur and Q. robur subsp. pedunculiflora (K.Koch) Menitsky ) of Turkey and their tolerances to these factors. Mean Temperature of Coldest Quarter (Bio 11), Temperature of Coldest Month (Bio 6), Temperature Annual Range (Bio 7), Temperature Seasonality (Bio), Precipitation Seasonality (Bio 15), Isothermality (Bio 3), Annual Mean Temperature (Bio1) are highly correlated bioclimatic variables that effect the distribution of pedunculate oak subspecies. Multinominal logistic regression result showed that the Bio4 is the only factor explain most of the distribution of subspecies robur and subspecies pedunculiflora. The results also indicate that subspecies pedunculiflora shows a greater tolerance for extreme variation such as more drought summer and colder winters extreme variations during hot summers whereas subspecies robur is more sensitive to these climate variables

40-47
SOME ORTHOTROPIC MECHANICAL PROPERTIES OF SESSILE OAK (QUERCUS PETREA) AS INFLUENCED BY MOISTURE CONTENT

Authors: Ergün GÜNTEKİN1 *, Tuğba YILMAZ AYDIN1, Peter NIEMZ2

Abstract

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Number of views: 390

In this study, the influence of moisture content on some orthotropic mechanical properties of sessile oak which is one of the most important wood species grown in Turkey and common in the furniture industry have been investigated. The properties studied include Young’s modulus, Poisson’s ratios and compression strength of oak wood in three anatomical directions. These properties are important input parameters for three dimensional modeling of mechanical behavior in advanced computer programs such as finite elements. The samples which were approximately 20 x 20 x 60 mm in dimensions were conditioned at 20 °C and 50, 65, 85, 95 % relative humidity conditions for 6-8 weeks and subjected to compression tests in order to determine elastic and strength properties. Results indicate that properties investigated significantly differ among all anatomical directions. Young’s modulus ranged from 10305 to 6984 N/mm2 in L direction, from 2032 to 1132 N/mm2 in R direction and from 1208 to 715 in T direction. Compression strength varied between 48.5 and 25.5 N/mm2 in L direction, 16.45 and 9.60 MPa in R direction, and 10.2 and 7.1 in T direction. Poisson’s ratios are found to be in between 0.061 and 0.7. Results indicated that all properties of the samples tested were strongly affected by moisture content.