Decomposition and element concentrations of silver birch leaf litter as affected by boron status of litter and soil

Abstract

Inadequate boron (B) nutrition can affect the structural integrity and chemical composition of plant tissues. The changes in mass and element concentrations were studied using silver birch (Betula pendula Roth) leaf litter from seedlings grown with or without added B (B litter + or B litter −). The litter was produced in a growth room, and it was incubated in either B fertilised or control forest plots (B soil + or B soil −) between the moss and humus layers in two Norway spruce stands for 13 months. Additionally, the field decomposition experiment included longterm N and P application treatments (N soil and P soil ). B litter + somewhat reduced the remaining litter mass. In contrast, B soil + increased it, possibly because of lower soil pH. The +N soil treatment reduced the remaining mass. B litter + increased the remaining P, S, Cu, Cd, Ni and Zn but reduced Pb. Remaining B was high in the B litter -which also accumulated B from soil. B soil increased remaining Ca, Cd, Mg, Na, Pb, and slightly reduced N (in N fertilised plots). These changes in decomposition and element release have a potential to affect nutrient, carbon, and heavymetal cycles in areas where B deficiencies are common, and where B fertilisation is practised.

Decomposition and element concentrations of Norway spruce needle litter with differing B, N, or P status

“…This result does not support the original hypothesis that B would increase the initial litter decomposition rate through litter quality. The result also contrasts with the results of our previous study on silver birch litter, as birch litter decayed initially slightly faster if the B nutrition during growth was adequate, but long-term B treatment in soil slowed down the litter decay (Lehto et al 2009). Norway spruce litter is much more resistant to decomposition than silver birch litter.…”

“…Using a histological method, Dell and Malajczuk (1994) found increased lignification in eucalypts after B fertilisation in very low-B conditions, but B fertilisation did not affect lignification in Pinus radiata in another study (Turvey et al 1992). In our earlier study, silver birch leaf litter had slightly higher lignin concentration if grown with adequate B (Lehto et al 2009). We have not found earlier reports on a decreasing effect of P on lignin, particularly in interaction with B.…”

“…In our earlier study, adequate boron (B) nutrition during growth increased slightly the initial mass loss of birch leaf litter in the first year, in comparison to litter grown with low B (Lehto et al 2009). This may be due to a difference in the chemical composition and structural organisation of the cell wall, as B is known to be associated with the pectic compounds in cell walls due to its role in the formation of the primary cell wall (Matoh et al 1997).…”

“…This increased initial decomposition rate has often been found (Berg et al 1987), and it was found also Table 2. Each point is mean of 2 plots (two experimental sites) in a silver birch litter decomposition study in these same sites (Lehto et al 2009). The result on no-effect of P fertiliser on mass loss agrees with earlier results (Smolander et al 1994), although there are not many published studies on the role of P on decomposition.…”

“…This may be due to a difference in the chemical composition and structural organisation of the cell wall, as B is known to be associated with the pectic compounds in cell walls due to its role in the formation of the primary cell wall (Matoh et al 1997). The litter of birch plants with adequate B retained larger amounts of nutrients and metals, which could be related to a higher degree of structural organisation (Lehto et al 2009). …”