Snow damages on trees of an uneven age in mixed broadleaf forests:effects of topographical conditions and tree characteristics     

Farzam Tavankar  Angela Lo Monaco  Mehrdad Nikooy  Rachele Venanzi  Amireslam Bonyad  Rodolfo Picchio 《林业研究》2019,(4):1383-1394

Snow damage on natural stands is an important problem concerning mountainous forest management.In the present research,the frequency and intensity of heavy snow damage on natural stands and the relationship of damages with characteristics of trees,stand and topography were studied in mountainous forests of northern Iran.A systematic sampling design was applied to the study area(140 ha),with 122 circular plots.The grid dimension was100 m and each plot area was 1000 m^2.The four types of snow damage to trees include:crown damage(8.6%),stem breakage(5.4%),uprooting(3.2%),and bending(1.4%).The frequency of crown damage grew with an increase inthe diameter at breast height(DBH),while the frequency of stem breakage,uprooting and bending decreased with an increase the DBH.The frequency of crown damage,stem breakage,and total damages was related to tree species(p<0.01).Not all tree species were equally susceptible to snow damage.The amount of damage grew with increasing elevation and slope angle and decreased with increasing soil depth.Young trees(DBH<25 cm)were more susceptible to snow damage than other trees.Snow damage decreased by as the trees in the stand became more mixed in age.The susceptibility of trees to snow damage increased by height and slenderness coefficient.With adequate silvicultural operation,snow damage can be reduced to a minimum level in these natural forests.  相似文献   

Mycorrhiza inoculation effects on seedling establishment,survival and morphological properties of Ziziphora clinopodioides Lam.     

Reyhaneh Azimi  Mohammad Farzam  Mohammad Pessarakli  Mohammad Kia Kianian 《Journal of plant nutrition》2013,36(20):2692-2704

In this paper, the establishment and growth of medicinal species Ziziphora clinopodioides Lam. were studied through inoculation with two mycorrhizal fungi species, Glomus mosseae and Glomus intraradices, in arid/semi-arid Bahar-Kish rangelands, Iran in 2012 and 2013. The root colonization percentage of Ziziphora, as well as their establishment and growth were enhanced in 2013 using G. mosseae. In this year, less rainfall and higher temperature decreased the survival, growth and morphological traits of the studied plants. Growth and establishment of the inoculated plants using G. intraradices improved in 2013, while inoculation with G. mosseae showed more beneficial effects in 2012. In both years, the strain, the growth and establishment percentage of seedlings in inoculated treatments with mycorrhizal species were significantly improved. According to the results, G. intraradices mycorrhizal fungi is recommended as a biological fertilizer in increasing the forage production and the initial establishment of Ziziphora in arid and semi-arid rangelands.  相似文献   

Long-term assessment of soil physicochemical properties and seedlings establishment after skidding operations in mountainous mixed hardwoods     

Tavankar  Farzam  Nikooy  Mehrdad  Ezzati  Sättar  Jourgholami  Meghdad  Latterini  Francesco  Venanzi  Rachele  Picchio  Rodolfo 《European Journal of Forest Research》2022,141(4):571-585

One of the basic requirements for sustainable forest management in mixed broadleaved stands is to provide suitable conditions for natural regeneration of trees. These conditions include, but are not limited to, the frequency, quality and the composition of seedling species. Compacted soil layers caused by forest machinery traffic are the most common problem affecting seedling establishment and growth after skidding operations. In this study, we evaluated the frequency, quality, diversity of seedling species and physicochemical properties of soil on 10-, 20- and 30-year-old abandoned skid trails. Further comparison to the values of the mentioned above parameters in control areas allowed for the evaluation in terms of natural recovery processes, under varying traffic intensity and the longitudinal slope of the skid trails in a mixed broadleaved forest. Results showed that there is a significant positive trend of recovery for soil physicochemical properties and ecological characteristics (density and quality) of seedling growing on the skid trails. The time required to recover soil properties and ecological attributes of seedlings increased with increasing traffic intensity and slope of the skid trail. Our results showed that it takes 20 and 30 years to fully recover the chemical and physical properties of the soil, respectively. On the 30-year-old skid trails, density and species diversity indices were fully recovered, but the quality of the seedlings was not restored to the control conditions. The results suggest the importance of a proper planning of the skid trail network, avoiding in particular skid trails with a slope gradient higher than 20%.

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Healing ability and diameter growth of lime-trees (<Emphasis Type="Italic">Tilia begonifolia</Emphasis> Stev.) following logging wounds     

Farzam Tavankar  Angela Lo Monaco  Rodolfo Picchio  Rachele Venanzi  Mehrdad Nikooy 《European Journal of Forest Research》2018,137(1):45-55

Lime-trees (Tilia begonifolia Stev.) have countless ecological and economical values in the northern forests of Iran. Bole wounds on residual trees are commonly caused by logging. The healing ability of bole wounds and the effect of bole wounds on diameter growth in lime-trees were assessed in a natural mixed uneven-age stand. The susceptibility to decay in relation to the wound severity was also evaluated. Condition and location of lime-trees before and after selective logging were determined through systematic plot sampling. The position of each lime-tree was identified on a topographical map using the global positioning system. After 10 years from wound occurrence, tree and wound characteristics were also re-measured. Overall, 68 stems (9.7 stem ha^?1) of lime-trees were found in the sampled area, 25 stems (36.8%) were damaged in the form of bole wound, and 43 stems (63.2%) were undamaged. Statistical differences between wounded or non-wounded lime-trees in terms of diameter and height were not found. Most of the wounds occurred at the height of < 1 m; the average wound size was 370.5 cm². Wound severity was related to wound size and wound position. Wound width healing rate was 6.2 mm year^?1. The wound shape was found to be a healing factor as the healing rate by width was higher than that by length. Healed wounds were only 12, 60% of bole wounds resulted in decay. Diameter growth of wounded trees was 43.5% lower than undamaged trees. The average annual diameter growth decreased by increasing wound severity. The results indicated the lime-tree is a very sensitive species to damage caused by logging (bole wound). Single-tree selection cutting needs more careful logging operations to reduce damage on residual lime-trees in order to safeguard this species, valuable in ecologic and economic terms.  相似文献