IMASL   20939
INSTITUTO DE MATEMATICA APLICADA DE SAN LUIS "PROF. EZIO MARCHI"
Unidad Ejecutora - UE
artículos
Título:
A global meta-analysis of soil exchangeable cations, pH, carbon, and nitrogen with afforestation
Autor/es:
ST BERTHRONG; EG JOBBÁGY; RB JACKSON
Revista:
ECOLOGICAL APPLICATIONS
Editorial:
Ecological Society of America
Referencias:
Lugar: Washington DC; Año: 2009
ISSN:
1051-0761
Resumen:
The conversion of
non-forested lands to forest plantations, or afforestation, can sequester
atmospheric carbon dioxide, but the rapid growth and harvesting of biomass may
deplete nutrients and degrade soils if managed improperly. The goal of this
study was to evaluate how afforestation affects mineral soil quality, including
pH, sodium, exchangeable cations, organic carbon, and nitrogen, and to examine
the magnitude of these changes regionally where afforestation rates are high.
We also examined potential mechanisms to reduce the impacts of afforestation on
soils and to maintain long-term productivity. Across diverse plantation types
(153 sites) to a depth of 30cm of mineral soil, we observed significant
decreases in nutrient cations (Ca, K, Mg), increases in sodium (Na), or both
with afforestation. Across the dataset, afforestation reduced soil
concentrations of the macronutrient Ca by 29% on average (p<0.05).
Afforestation by Pinus alone
decreased soil K by 23% (p<0.05). Overall, plantations of all genera also
led to an average 71% increase of soil Na (p<0.05). Average pH decreased 0.3
units (p<0.05) with afforestation. Afforestation caused a 6.7% and 15%
(p<0.05) decrease in soil C and N content respectively, though the effect
was driven principally by Pinus
plantations (15% and 20% decrease, p<0.05). Carbon to nitrogen ratios in
soils under plantations were 5.7-11.6% higher. In several regions with high
rates of afforestation, cumulative losses of N, Ca, and Mg are likely in the
range of tens of millions of metric tons. The decreases indicate that trees
take up considerable amounts of nutrients from soils; harvesting this biomass
repeatedly could impair long-term soil fertility and productivity in some
locations. Based on this study and a review of other literature, we suggest
that proper site preparation and sustainable harvest practices, such as
avoiding the removal or burning of harvest residue, could minimize the impact
of afforestation on soils. These sustainable practices would in turn slow soil
compaction, erosion, and organic matter loss, maintaining soil fertility to the
greatest extent possible