Abstract Poplar trees (Populus species and their hybrids) are commonly cultivated on agricultural land for their high biomass production during the first rotation. However, stand development during the long-term second rotation is less understood. This study evaluated the effects of a single thinning at age 7 on growth dynamics at both stand and dominant trees levels in a second rotation poplar plantation (clone OP42) in southern Sweden. Four treatments were applied: unthinned (6000 stems ha⁻1), light thinning (3000 stems ha⁻1), medium thinning (1100 stems ha⁻1), and heavy thinning (550 stems ha⁻1). Tree mortality, height, diameter, and stem volume/biomass were monitored over 11 years post-thinning. By age 18, the above ground volume/biomass at the stand level was primarily concentrated in trees with diameters greater than 21 cm. The standing volume/biomass of individual dominant tree ranged from 0.80 m3 (268 kg dry matter, DM) to 0.87 m3 (292 kg DM) in the medium and heavy thinnings, and from 0.64 m3 (214 kg DM) to 0.67 m3 (224 kg DM) in the unthinned and lightly thinned plots. The total stand-level volume/biomass production in unthinned and lightly thinned plots was maximized by an 18-year rotation, with the mean annual increment (MAI) culminating at 33 m3 ha−1 yr−1 (11 Mg DM ha−1 yr−1). In the medium thinning, MAI reached 38 m3 ha⁻1 yr⁻1 (12.7 Mg DM ha⁻1 yr⁻1) at age 18 and continued to increase thereafter, a trend also observed in the heavy thinning. For dominant trees, culmination of MAI had not yet occurred under any treatment.

Abstract Many tree species show pronounced masting patterns, i.e. high inter-annual variability in seed production, which is strongly synchronised across large areas. Yet, when observing fructification intensity at the individual level, substantial intra-annual variability between trees becomes apparent. The drivers of this variability have so far been only investigated in studies of few species, individuals and/or over short time periods. In this study, we thus analysed potential predictors of individual fructification intensity for eight tree species common in central Europe (Fagus sylvatica, Quercus petraea/robur, Acer pseudoplatanus, Fraxinus excelsior, Picea abies, Abies alba, Pinus sylvestris, Pseudotsuga menziesii) across 15 years (2006–2020) and the area of Southern Germany. We utilised a comprehensive forest monitoring dataset, for which fructification intensity and crown condition are assessed visually each year for thousands of trees at fixed positions. Employing generalised additive models, fructification at the tree level was modelled best when considering predictors related to weather as well as tree age, crown condition and social position. The probability of (strong) fructification was higher in dominant trees, and did also increase as trees became older until a certain species-specific age had been reached, with the effect ultimately turning negative in very old trees. High crown defoliation had a negative effect on the probability of (strong) fructification in almost all species. Yet, in some species (e.g. Fagus sylvatica), weak crown defoliation had a positive effect on fructification intensity, potentially indicating different life strategies between species.

Abstract The immense biodiversity of the Mediterranean forest, the Iberian dehesa, is being damaged by different invasive or native animal species. This fact is currently associated to climate change and/or human activity, as it also happens in other areas of the planet. This study highlights this key issue based on the protected Cerambyx cerdo and the invasive Cerambyx wellensii, both feeding on the live wood of Quercus spp. trees which populate the dehesa. The possible biological damage which these insects are creating is not presented as evident, but the worrying effects faced by this protected ecosystem are pointed out. This study focuses on the demand for genetic data analysis from Cerambycids inhabiting the dehesa and it also aims to reveal the relationship between both native and invasive Cerambyx species by using a small-scale survey. The existing genetic diversity, Adult’s Sex-ratio (ASR), Sexual size dimorphism (SSD) and Spatial Analysis of Molecular Variance (SAMOVA), suggested the competition and/or hybridisation of these two species until the depletion to possible extinction of the authentic Cerambyx cerdo (the biological jewel of this forest). Accordingly, C. cerdo has begun to conform a “Cerambyx spp. complex” at the expense of the demographic expansion of Cerambyx welensii coupled with the progressive reduction of its own lineages.

Abstract Given the lack of studies focusing on the economic aspects of pine forests with resin production objectives, this study has analysed the economically optimal rotation age and profitability of two forest plantations that are commonly used for resin production in their respective countries: Slash pine in Brazil and Maritime pine in Spain. The scope of the two case studies encompassed resin, timber production and carbon sequestration, assuming that the latter could be traded in voluntary markets. An initial conservative assumption was made that resin can be picked only three years before final felling. The main objective was to demonstrate whether the economically optimal rotation varies with the introduction of resin and carbon, and whether the profitability of resin is comparable to that of timber. Additionally, an alternative scenario was considered wherein resin tapping was allowed for a prolonged period. The results have demonstrated that the integration of provisioning (resin and wood) with regulating (carbon) ecosystem services significantly increases profitability compared to the option of timber production alone, while the optimal rotation age is modified to a much lesser extent. It is also concluded that, at least in some situations, resin production should not be considered a secondary or complementary product to timber production. Furthermore, it is imperative to emphasize the need for appropriate silvicultural models to manage these three products jointly.