Foliar nutrient status and nutritional relationships of young Pinus radiata D. Don plantations in northwest Spain

Abstract

Fifty-four plots of young Pinus radiata D. Don plantations on abandoned agricultural land in Galicia (northwest Spain) were selected for nutritional diagnosis. Nutritional status was assessed by foliar analysis using the critical levels method. The relationships between foliar nutrient concentrations and the plantation's growth and survival and the topsoil physical and chemical properties were also analyzed. The most common deficiencies among plots were P and Mg. Foliar N concentrations were relatively high and generally they were above the critical level. Foliar N:P, N:K and N:Mg ratios were significantly unbalanced in 31, 44 and 17 out of 54 studied plots. Foliar P levels were significantly higher on sites with previous herbaceous land use and on soils with a finer texture, whereas foliar Mg levels were higher at low altitudes. Foliar nutrient levels were not significantly correlated with their respective soil levels except in the case of K. Foliar Ca and Mg concentrations correlated positively with topsoil pH. Growth correlated positively with foliar K and Mg concentrations and negatively with foliar N:P, N:K and N:Mg ratios. Percentage of dead and poor state plants were negatively correlated with foliar P, K and Ca levels and positively correlated with foliar N:P and N:Mg ratios. These results suggested that nitrogen may be in excess and may condition the uptake of other nutrients. Foliar N level was considered as an unfavorable parameter whereas foliar P, K, Ca and Mg concentrations were considered as favorable parameters for P. radiata establishment in Galicia.

Relationship among soil parameters, tree nutrition and site index of Pinus radiata D. Don in Asturias, NW Spain

“…The least fertile soils with low levels of available P generally had a shallow soil depth. Similar deficiencies, particularly in P and extractable bases have been observed in acid forest soils under radiata pine plantations in Spain (Romanyà and Vallejo, 1996;Zas, 2003;Zas and Serrada, 2003). Romanyà and Vallejo (2004) showed that Atlantic radiata pine plantations grow in soils rich in organic matter and N and in shallow soils with low pH, low available P and general low fertility.…”

“…Asturian forest soils are characterized by moderate or shallow depth, high organic matter content in the upper horizon, and high or moderate acidity (pH around 4), except in eastern Asturias, where most of the rocks are basic (Guitian et al, 1985). The Spanish radiata pine plantations are not fertilized resulting in widespread nutritional deficiencies (Romanyà and Vallejo, 1996;Zas and Serrada, 2003). The soils were classified as Ustorthent, Ustochrept and Dystrochrept (Soil Survey Staff, 1999) developed on whitish quartzite (9 stands), black slate (8), feldspar sandstone (15), and conglomerate (6) (IGME, 2001).…”

“…In Galicia nutrient deficiencies have been diagnosed in young plantations (Zas, 2003;Zas and Serrada, 2003), and the impact of soil preparation techniques have been related to the fertility and the nutritional status of repopulated stands (Merino and Edeso, 1999). In each of these studies, physical and chemical characteristics of the soil were considered to be the most important factors determining the productivity of the species.…”

“…Studies show that foliar analysis is a very useful tool for relating soil characteristics to the nutrient status of the trees (Brañas et al, 2000;Zas, 2003;Zas and Serrada, 2003). The interest with these types of studies lies in differentiating between variables that determine site productivity.…”

“…Some studies in NW Spain have shown important nutritional problems in mature stands of radiata pine on typically acid forest soils. Phosphorus (P) deficiencies were the most frequent (Brañas et al, 2000;Romanyà and Vallejo, 2000;Sánchez et al, 2002;Zas and Serrada, 2003), while nitrogen (N) is rarely deficient and it sometimes occurred in excess in stands with a balanced nutrition (Palacios et al, 1995;Zas and Serrada, 2003). The amounts of P are usually decisive in determining the variation in productivity of radiata pine in highly geochemically altered acidic leached soils (McLaughlin, 1996).…”