Browsing by Author "Karolewski, Piotr"

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    Needle nutrients in geographically diverse Pinus sylvestris L. populations
    (2002) Oleksyn, Jacek; Reich, Peter B; Zythowiak, Roma; Karolewski, Piotr; Tjoelker, Mark G
    Nutrient availability differs across climatic gradients, yet the role of genetic variation in potentially adaptive traits related to nutrient acquisition remains poorly understood. We examined needles of diverse Scots pine provenances grown under common-garden conditions throughout their entire life span. Based on similarities in nutrient concentration patterns, two groups of populations were identified. One comprised northern populations from 60° to 56° N, and another included populations from locations between 56° and 49° N. Northern populations sustained significantly higher concentrations of N, P, Ca, Mg, Na, Zn, Cu and Pb. Only K concentration was persistently lower in northern plants. We conclude that intraspecific genetic differences exist in foliage nutrient concentration among diverse populations. Since in northern conditions nutrient availability is often limited as a result of interactions between temperature, litter quality and its mineralization, a tendency toward higher foliage concentrations of macronutrients can be an adaptive feature enhancing plants metabolic activity in their native habitats.
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    Tree species effects on decomposition and forest floor dynamics in a common garden
    (Ecological Society of America, 2006) Hobbie, Sarah E; Reich, Peter B; Oleksyn, Jacek; Ogdahl, Megan; Zytkowiak, Roma; Hale, Cynthia; Karolewski, Piotr
    We studied the effects of tree species on leaf litter decomposition and forest floor dynamics in a common garden experiment of 14 tree species (Abies alba, Acer platanoides, Acer pseudoplatanus, Betula pendula, Carpinus betulus, Fagus sylvatica, Larix decidua, Picea abies, Pinus nigra, Pinus sylvestris, Pseudotsuga menziesii, Quercus robur, Quercus rubra, and Tilia cordata) in southwestern Poland. We used three simultaneous litter bag experiments to tease apart species effects on decomposition via leaf litter chemistry vs. effects on the decomposition environment. Decomposition rates of litter in its plot of origin were negatively correlated with litter lignin and positively correlated with mean annual soil temperature (MATsoil) across species. Likewise, decomposition of a common litter type across all plots was positively associated with MATsoil, and decomposition of litter from all plots in a common plot was negatively related to litter lignin but positively related to litter Ca. Taken together, these results indicate that tree species influenced microbial decomposition primarily via differences in litter lignin (and secondarily, via differences in litter Ca), with high-lignin (and low-Ca) species decomposing most slowly, and by affecting MATsoil, with warmer plots exhibiting more rapid decomposition. In addition to litter bag experiments, we examined forest floor dynamics in each plot by mass balance, since earthworms were a known component of these forest stands and their access to litter in litter bags was limited. Forest floor removal rates estimated from mass balance were positively related to leaf litter Ca (and unrelated to decay rates obtained using litter bags). Litter Ca, in turn, was positively related to the abundance of earthworms, particularly Lumbricus terrestris. Thus, while species influence microbially mediated decomposition primarily through differences in litter lignin, differences among species in litter Ca are most important in determining species effects on forest floor leaf litter dynamics among these 14 tree species, apparently because of the influence of litter Ca on earthworm activity. The overall influence of these tree species on leaf litter decomposition via effects on both microbial and faunal processing will only become clear when we can quantify the decay dynamics of litter that is translocated belowground by earthworms.