The qualitative characteristics of naturally-developed deciduous forest stands in abandoned agricultural lands | Dabiski ieaugušo lapu koku audžu kvalitatīvie rādītāji neizmantotās lauksaimniecības zemēs
2009
Daugaviete, M., Latvian State Forest Research Inst. Silava, Salaspils (Latvia)
Forest resource monitoring data shows that, in the period since 1991, the area of naturally-afforested abandoned agricultural lands has reached 353 000 hectares. The quality of these naturally-developed forest stands varies, and therefore one of the main tasks of the study is to carry out an analysis of these stands and develop recommendations for their management. The study shows that the quality of naturally-developed broadleaved stands largely depends on (1) the distance of seed stand; (2) the composition and age of seed stand; (3) how much the area adjacent to the stand is covered in grass; (4) the location of the area adjacent to the stand in relation to the azimuth. The research data show that the age of trees changes along with the increase of distance from the source of seeds (on average from 2 to 15 years), and consequently their average diameter and height changes as well. While in direct proximity of the source of seeds the average diameter of grey alder reaches 5.3 cm and the height reaches 7.4 m, which corresponds to an age of 10-15 years, around a distance of 70-80 m the average diameter of grey alder reaches only 1.1 cm, height - 2 m, which corresponds to an age of 2-3 years. The timber volume of a dominant crop of deciduous forest stands at an age of 6-10 in such naturally-developed stands in agricultural lands reaches 24-35 m**3haE-1, but the timber volume of level II - on average 3-15**3haE-1. The results of the study allow concluding that these low-value stands not developed in time, having appeared by way of natural afforestation, may be used as biomass-producing areas for renewable wood resources. It is practically impossible to turn these low-value forest stands that have already reached the age of 10-15 years into productive forest stands due to the very large variety of species, uneven density and, therefore, uneven wood yield.
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