Fine-root turnover rates of European forests revisited: An analysis of data from sequential coring and ingrowth cores

Brunner I., Bakker M.R., Björk R.G., Hirano Y., Lukac M., Aranda X., Børja I., Eldhuset T.D., Helmisaari H.S., Jourdan C., Konôpka B., López B.C., Miguel Pérez C., Persson H., Ostonen I. (2013) Fine-root turnover rates of European forests revisited: An analysis of data from sequential coring and ingrowth cores. Plant and Soil. 362: 357-372.
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Doi: 10.1007/s11104-012-1313-5

Resum:

Background and Aims: Forest trees directly contribute to carbon cycling in forest soils through the turnover of their fine roots. In this study we aimed to calculate root turnover rates of common European forest tree species and to compare them with most frequently published values. Methods: We compiled available European data and applied various turnover rate calculation methods to the resulting database. We used Decision Matrix and Maximum-Minimum formula as suggested in the literature. Results: Mean turnover rates obtained by the combination of sequential coring and Decision Matrix were 0. 86 yr-1 for Fagus sylvatica and 0. 88 yr-1 for Picea abies when maximum biomass data were used for the calculation, and 1. 11 yr-1 for both species when mean biomass data were used. Using mean biomass rather than maximum resulted in about 30 % higher values of root turnover. Using the Decision Matrix to calculate turnover rate doubled the rates when compared to the Maximum-Minimum formula. The Decision Matrix, however, makes use of more input information than the Maximum-Minimum formula. Conclusions: We propose that calculations using the Decision Matrix with mean biomass give the most reliable estimates of root turnover rates in European forests and should preferentially be used in models and C reporting. © 2012 The Author(s).

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Influence of tree size, reduced competition, and climate on the growth response of Pinus nigra Arn. salzmannii after fire

Valor T., Pique M., Lopez B.C., Gonzalez-Olabarria J.R. (2013) Influence of tree size, reduced competition, and climate on the growth response of Pinus nigra Arn. salzmannii after fire. Annals of Forest Science. 70: 503-513.
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Doi: 10.1007/s13595-013-0284-x

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Context: After wildfire, surviving trees are of major ecological importance as they can help in the post-fire regeneration process. Although these trees may be damaged, they may also benefit from reduced fuel hazard and competition. However, little is known about the long-term growth response of surviving trees. Aims: This study aims to explain short- to long-term variations in the postfire growth of surviving black pines in an area burnt in 1994, focusing on levels of fire severity and tree sizes. Methods: Relative basal area increments were used to detect time-course variations in postfire radial tree growth depending on fire severity. Linear mixed-effects models were used to describe the factors affecting postfire ring growth. Results: In the short term, fire caused stronger reduction in growth in small trees with increasing bole char height. However, as time since fire increased, a positive effect of fire on growth due to reduced competition counteracted the short-term fire impacts. Indeed, small surviving trees demonstrated a surge in growth 15 years after the fire. Conclusion: It was concluded that reduced competition might offset the short-term negative effects of fire in surviving black pines. © 2013 INRA and Springer-Verlag France.

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