Lado Monserrat, L.; Cristina Lull; Bautista Carrascosa, I.; Lidón A.; Herrera Fernandez, R. (2014). Soil moisture increment as a controlling variable of the Birch effect . Interactions with the pre-wetting soil moisture and litter addition. Plant and Soil. 379:21-34. doi:10.1007/s11104-014-2037-5. 1Soil moisture increment as a controlling variable of the "Birch effect". 21Results 22Overall, we found a relationship with the form: ΔR=a ΔSWC +b, where the slope (a) was 23 significant only when pre-wetting water potential was below a threshold value in the range of -24 * Corresponding author. luislado@hotmail.com ; Tel.: +34 963877346; fax: +34 963877139 2 100 to -1200 kPa. However, the threshold alone does not fully describe the role of preSWC in 1 slope variability. Substrate addition modified the ΔSWC sensitivity of Birch effect, enhancing it 2 in the clay loam and suppressing it in the sandy loam.3 Conclusions 4The intensity of the wetting is a dominant factor regulating Birch effect, and ΔSWC is useful for 5 its quantification.6 7

Lado Monserrat, L.; Lidón, A.; Bautista, I. (2015). Litterfall, litter decomposition and associated nutrient fluxes in Pinus halepensis: influence of tree removal intensity in a Mediterranean forest.

Our knowledge about the influence of silvicultural treatments on nutrient cycling processes in Mediterranean forests is still limited. Four levels of tree removal were compared in an Aleppo pine forest in eastern Spain to determine the effects on litterfall, litter decomposition and the associated nutrient fluxes after 12 years. Removal treatments included clearfelling, two shelterwood intensities (60 and 75 % of basal area removed) and untreated controls. Twelve years later, the basal area removed still explained 60 % of litterfall mass variance and 60 % of C, 52 % of N, 45 % of P, 17 % of K, 47 % of Ca and 60 % of Mg return variances. Litter decomposed somewhat more slowly in clearfellings compared to controls (p = 0.049), accumulated more Ca and released less K compared to the other three treatments. This was explained by contamination with mineral particles due to the poorly developed O horizon in clearfellings. We conclude that the management practices reduced the nutrient return via litterfall, but the nutrient release through decomposition seems poorly sensitive to canopy disturbance. In order to accurately quantify the harvesting impacts on nutrient cycling in this Mediterranean forest system, it is necessary to measure the litterfall of the understory layer.

In order to assess the sustainability of silvicultural treatments in semiarid forests, it is necessary to know how they affect the nutrient dynamics in the forest. The objective of this paper is to study the effects of silvicultural treatments on the net N mineralization and the available mineral N content in the soil after 13 years following forest clearings. The treatments were carried out following a randomized block design, with four treatments and two blocks. The distance between the two blocks was less than 3 km; they were located in Chelva (CH) and Tuéjar (TU) in Valencia, Spain. Within each block, four experimental clearing treatments were carried out in 1998: T0 control; and T60, T75 and T100 where 60%, 75% and 100 of basal area was eliminated, respectively. Nitrogen dynamics were measured using the resin tube technique, with disturbed samples due to the high stoniness of the plots. Thirteen years after the experimental clearings, T100, T75 and T60 treatments showed a twofold increase in the net mineralization and nitrification rates with respect to T0 in both blocks (TU and CH). Within the plots, the highest mineralization was found in sites with no plant cover followed by those covered by undergrowth. These results can be explained in terms of the different litterfall qualities, which in turn are the result of the proportion of material originating from Pinus halepensis Mill. vs. more decomposable undergrowth residues.