Kolsum Shabaninejad (1), Hassan Pourbabaei (1)*, Ali Salehi (1),
and Sayyed Paiman Misaghi (2)

1. Department of Forestry, Faculty of Natural Resources, University of Guilan, Sowmehsara,
P.O. Box 1144, Guilan, Iran. E-mails: kshabaninejad@yahoo.com;
h_pourbabaei@guilan.ac.ir*; asalehi@guilan.ac.ir
2. Department of Natural Resources, Mazandaran Province, Iran.
E-mail: payman.misaghi@gmail.com

Biodiversity of ecosystems is determined to a considerable extent by the diversity of herbaceous species. The aim of this study was to examine and compare diversity of herbaceous species in the forest, ecotone, and pasture located in upland areas in Shirud, Mazandaran Province, Iran. In each area, eight 100 m² circular sampling plots were established along a transect using random-systematic method, and coverage of herbaceous species was recorded in each plot. There were significant differences in diversity, evenness and richness among the forest, ecotone and pasture areas. The results of ANOVA and Duncan's tests indicated that the forest and pasture sites had higher diversity compared to ecotone. Jaccard and Sorensen's similarity coefficients also confirmed the better growing conditions for herbaceous species in the forest and pasture sites in comparison to the ecotone. This paper presents evidence that species diversity is closely linked to grazing intensity.

Maria Broshtilova* and Kostadin Broshtilov

Oak Forest Experimental Station, 8008 Burgas, Bulgaria. E-mails: mbroshtilova@abv.bg*; kbroshtilov@abv.bg

The rainfall amount and its chemical composition were studied in the period 2009–2013 in the Pismenovo arboretum, situated close to Black Sea coast (Tsarevo State Forest Service). The objective of the proposed work comprises conducting of prolonged studies on N, P₂O_5, K₂O, Ca and Mg content and the highlighting of the particularities in the seasonal dynamics of the above mentioned elements in the leaves of some tree species. The purpose of this work comprises a conducting of longer comparative research on the dynamics of the chemical composition of atmospheric precipitations under the canopy of different forest-tree plantations. The results showed that Black pine (Pinus nigra Arn.) crowns capture 29.2 % of the total rainfall amount at open field. The same percentage in Atlas cedar (Cedrus atlantica Manetti) was 34.4 %, in Common oak (Quercus robur L.) - 6.5 %, in Black locust (Robinia pseudoacacia L.) - 23.3 % and the throughfall in the 75-year-old coppice oak forest was 15.8 %. A difference in the chemical composition of throughfall has been determined, depending on age and species (coniferous or deciduous). The pH value of the throughfall and that of rain water at open field had acid to slightly acid reaction, and the acidity increased during the winter. The lowest values of pH were measured in the water passed through Black pine crowns, and the highest ones - in the water passed through the crown of Black locust. Most nitrate ions were registered in the throughfall fluxes of Black pine. Most ammonium ions were detected in the throughfall fluxes of the 75-year old coppice oak forest, and chloride ions - in the throughfall of Atlas cedar. The content of calcium and magnesium in the throughfall also increases in comparison to that one measured in open field fluxes. The highest content of these two elements was recorded in the throughfall of Black locust.

Maria Broshtilova* and Kostadin Broshtilov

Oak Forest Experimental Station, 8008 Burgas, Bulgaria.
E-mails: mbroshtilova@abv.bg*; kbroshtilov@abv.bg

The study took place in the period 2008-2012 in Pismenovo arboretum, situated in the peripheral sub-region of Strandzha Mountain (South-Eastern Bulgaria). Nitrogen and macroelement contents were examined in the leaves of 21-25-year-old specimen belonging to the following species: Pinus nigra Arn. ssp. austriaca Hoss, Pinus nigra Arn. ssp. laricio Poiret, Cedrus deodara Loud., C. atlantica Manetti, C. libani A. Rich., Cupressus sempervirens L., Quercus petraea (Matt.) Liebl. (3 provenances), Q. robur L. (4 provenances), Q. pubescens Willd., Q. rubra L., Q. suber L., Q. harwissiana Stev., Q. frainetto Ten., Fagus sylvatica L., F. orientalis Lipsky and Tilia tomentosa Moench. Nitrogen content in the leaves of most deciduous species was the highest in May, maintaining comparatively high values in June and gradually lowering in the next months until the end of growing period. P₂O₅ content had its maximum value in the summer months, keeping relatively high values until the end of the growing period. K concentration in the leaves of most species was highest in August. Ca and Mg content gradually increased from the beginning to end of the growing period. N, P and K content in the coniferous species was significantly lower as compared to the one in the leaves of the deciduous species, which makes the latter ones more tolerant to soil fertility. Of conifers, the lowest concentration of these substances was recorded in the needles of the Atlas cedar. In deciduous species the highest content was measured in Tilia tomentosa and Quercus hartwissiana and the lowest one - in the leaves of the Cork oak. There were also differences among the provenances within a species. In Cedar needles, Ca and Mg concentration is 2 times higher, compared to that one in the needles of Black pine and Pinus nigra Arn. spp. laricio. It is obviously a characteristic biological particularity. The differences should be considered when modelling nutrient circulation in forest stands and when evaluating the longterm sustainability of forest management.

Ibrahim Molla and Emiliya Velizarova*

Department of Forest Ecology, Forest Research Institute – Bulgarian Academy of Sciences,
132 St. Kliment Ohridski Blvd., 1756 Sofia, Bulgaria. E-mails: mollata@abv.bg, velizars@abv.bg*

Acid-base properties in cinnamonic forest soils (Chromic Luvisols) and forest litter under
different fire-affected stands of tree species have been studied. The samples were taken
immediately after fire, 1 month, 3 months and 1 year after it from affected and from unaffected
(control) areas. The depth at which soil sampling was performed was from 0 cm to 5 cm and
from 5 cm to 20 cm. Soil and litter acidity (pH) was measured potentiometrically in an aqueous
extract. The most pronounced changes in pH values in comparison with the control variants was
established in soil samples, taken from influenced by a surface fire broadleaf stand of Quercus
pubescens Willd. The pH changes in the samples from forest litter were more pronounced than
the changes registered in soil samples. A trend of a soil acidity increase was established till one
year after fire influence for Austrian pine plantations and oak stands.

Rumen Petrin

Forest Research Institute – Sofia, Bulgarian Academy of Sciences, 132 St. Kliment
Ohridski Blvd., Sofia 1756, Bulgaria. E-mail: lesni4eja2014@gmail.com

The present study has been carried out to reveal the structure according to height of relatively even-aged - mature and middle-aged Scots pine dendrocoenoses in Rila and the Rhodopes Mountains and Sakar Mountain. A total of 111 sample plots have been established, 68 of these being in mature, natural Scots pine forests and 43 in young and middle-aged ones. Study has been aimed at analysing the structure according to height of natural Scots pine dendrocoenoses with a view to model their volume and their assortment structure. The height curves for both age groups of stands have been investigated. Yurdan Douhovnikov's method of natural indicators (MNIs) has been applied. Three groups of curves have been found out according to their levels of declivity, namely: slightly inclined curves, characteristic of the stands of zero natural indicator (ZNI) SHo > 1.1, semi-steep curves with 0.86 ≤ SHo ≤ 1.09, and steep curves with SHo ≤ 0.85. The distribution according to types of declivity has been investigated in two scenarios - separately and as a whole. This investigation has resulted in finding distributions of close values in both scenarios for the particular age groups, especially the general distribution. That gives reasons for investigating the stands as a whole in terms of their height structure through the method of natural indicators regardless of age. It was found that the average relative curves of the heights (or average curves of normal numbers) surveyed dendrocoenoses of Scots pine and United average curve of the relative heights of Turin are too close on his course. Since an average curve of Turin has been established for all species, this proximity proves the possibility of establishing common average diluted curves of the heights of Scots pine along with other tree species.