Nutrient cycling in deciduous forest ecosystems of the Sierra de Gata mountains: aboveground litter production and potential nutrient return

Abstract

-The potential nutrient return in a chestnut coppice (Castanea sativa Miller) over a period of 3 years (1991)(1992)(1993)(1994) has been established and compared with the returns found in four deciduous oak (Quercus pyrenaica Wild.) forests (1990)(1991)(1992)(1993) located in the Sierra de Gata mountains (central Spanish system). A convergence of abscission phenology patterns was observed among the different ecosystems studied, together with a delay in leaf fall at the warmest plot. This similarity is logical since the plots harbour the same deciduous species which are, however, subjected to climatological variations. The chestnut coppice was found to be more productive than the oak forests, the amounts of leaves, branches, flowers and total litterfall being significantly greater. Statistical analysis showed a highly significant correlation between the chestnut coppice and the oak forest aboveground production, ranging between 0.82 and 0.96 for the leaves and between 0.72 and 0.89 for the total litter. In general, the leaf organs of the chestnut trees showed a higher concentration of bioelements than the oaks, with N and Ca predominant in the buds, Ca and Zn in the branches, K in the fruits, and above all Fe and Cu in the other plant remains. In all the forests studied, the potential nutrient supply fluctuated over the years and depended strongly on phenological factors; above all it was found to be governed by the leaves, which contributed most to the return of mineral nutrients to the soil. The most marked potential nutrient return through the oak aerial organs occurred on the plot with the lowest rainfall, particularly with respect to P and Ca. Considering all the forest plots, the general sequence of the amount of bioelements returning with the litterfall to the soil was as follows:with the exception of one oak plot (

Evolution of forest soil properties after liming with a by-product derived from a sugar beet mill

“…This forest has a limited aboveground production (2.6 ± 0. 16 [8]. The site is considered a marginal area due to the low economic production and is basically appropriate for purposes of conservation of natural species.…”

“…Studies regarding better knowledge of these forest ecosystems have been previously performed (e.g., [1,8,9,10]), mainly focused on biogeochemical cycles of nutrients. Gallardo et al [8] observed different values of Open Access *Correspondence: juanf.gallardo@csic.esproduction of these deciduous oak forests according to different areas; these differences seemed to be inversely related to the amount of annual rainfall, which caused differences in soil acidity.…”

“…Gallardo et al [8] observed different values of Open Access *Correspondence: juanf.gallardo@csic.esproduction of these deciduous oak forests according to different areas; these differences seemed to be inversely related to the amount of annual rainfall, which caused differences in soil acidity. It is well known that when the soil pH is lower than 4.0, Mn 2+ and Al 3+ cations exist in soluble forms [11], increasing their plant availability and causing toxicity, inhibiting forest growth [12].…”

Nutrient efficiency and resorption in Quercus pyrenaica oak coppices under different rainfall regimes of the Sierra de Gata mountains (central western Spain)

“…Furthermore, Cole and Rapp [10] and Gallardo et al [20] have shown that N-, P-and Ca-return to the soil is mostly achieved through litterfall, while K-return is mainly due to canopy leaching; Mg is intermediate between these two possibilities and varies according to the ecosystem studied. Consequently, it is difficult to compare the results on NUE from different studies because the data are obtained from different calculations, depending on previous definitions of NUE and the ecosystems.…”

“…When requirements are greater than uptake, the plant must meet the rest of its needs for nutrients by retranslocating them from old organs to new ones. Following this line of thought, Carceller et al [8] calculated bioelement resorption as the difference between the leaf mineral mass at the end of August minus the potential return of nutrients to the soil through the leaf litter [20].…”