Stand age influence on litter mass ofPinus nigraplantations on dolomite hills in Hungary

Abstract

In Hungary, plantations of Pinus nigra Arn. (Austrian pine) involve large areas of dolomite rock grasslands and have caused the impoverishment or local extinction of the original flora. In addition to these conservation concerns, an important economic problem is the flammability of these forests. Fire risk depends on the amount of accumulated flammable organic components. Thus, the purpose of our research was to quantify the mass of litter accumulated in Austrian pine stands and to examine the correlation between litter mass, stand age, and slope aspect. Forty-eight sampling sites were selected with stand ages ranging from 21 to 108 years. Stands represented four age classes and three exposure types. At each sampling site, litter mass was determined in the following three fractions: needles, branches, and cones. The litter fractions showed their maximum quantities in age class 61–80 years (needles = 17 560 kg/ha, branches = 2764 kg/ha, and cones = 2960 kg/ha). For the needle litter, a significant increase with age was detected through the age classes of 21–40, 41–60, and 61–80 years, and then a significant decrease occurred in stands above 80 years. In the case of branch litter, the age-dependent increase was again significant to its maximum quantity, but the decrease in old stands proved to be insignificant. With cone litter, age dependence could not be detected. Exposure of the stands had no effect on the quantities of the three litter fractions. The amount of accumulated litter of Austrian pine stands many times exceed the litter quantity of the rock grasslands (the original vegetation prior to afforestation). Furthermore, it is two or three times higher than the amount of litter reported from native zonal forests of Hungary. Therefore, the Austrian pine stands are subjected to an increased risk of fire, especially in age class 61–80 years.

Soil seed bank of the invasive Robinia pseudoacacia in planted Pinus nigra stands

“…The black locust was naturalized in East Asia in the second half of the 19 th century; nowadays the invader regularly appears in indigenous Pinus thunbergii stands and broad-leaved forests, chiefly in the vicinity of severely disturbed urban regions (MAEKAWAand NAKAGOSHI 1997, LEE et al 2004, SONG et al 2005, TANIGUCHI et al 2007, MORIMOTO et al 2010. Frequent fire events prove that pine plantations in Hungary are highly susceptible to forest fires in view of their accumulated resinous needle litter (CSERESNYÉS and CSONTOS 2004;CSERESNYÉS et al 2006CSERESNYÉS et al , 2011. The heat effect is capable of breaking the physical dormancy of black locust seeds (MARJAI 1995, thus initiating a quick colonization by the invader in the burnt area (AULD andDENHAM 2006, JUNG et al 2009).…”

Modelling the growth of young individuals of Pinus nigra on thin carbonate soils under climate change in Hungary

“…Due to the permanency of the soil thickness in case of young individuals the soil thickness has no influence on the deviation of the individual trends (Cseresnyés et al 2006). According to the plantation of same aged individuals of the Site-1 and Site-2 we calculated the correlation between the proportion of the measured and the calculated (estimated) annual vertical growth values and the soil depth values.…”

“…Although pines have an important role in the conservation and the reestablishment of the thin soil layer in karren landscapes (Veress 2010) the extensive plantation of Pinus nigra caused the degradation of the dolomite grassland flora and fauna (Csontos et al 1996). In addition, P. nigra stands are subjected to an increased risk of fire, especially in age class 61-80 years in Hungary (Cseresnyés et al 2006). However, P. nigra is a drought tolerant tree; the development of the annual rings is noticeably affected by drought Tíscar 2010, Martín-Benito et al 2008).…”

Contrasting effects of land use legacies on grassland restoration in burnt pine plantations

“…With the presence of pines, the originally treeless communities experience major changes in environmental conditions such as altered radiation (Cseresnyés et al, 2006), nutrient cycling (Farley and Kelly, 2004) and hydrological regime (Holmes et al, 2000). Dickie et al (2014) observed major changes in soil attributes caused by Pinus contorta invasion into native grasslands in New Zealand.…”