Can seed production and restricted dispersal limit recruitment in Pinus pinaster Aiton from the Spanish Northern Plateau?

Abstract

Natural regeneration faces increasing difficulties in dry forests from the Mediterranean basin, including for normally well-regenerating species such as maritime pine (Pinus pinaster Aiton). In this paper, we studied female fertility, seed dispersal and spread rates in P. pinaster from the Spanish Northern Plateau, where natural regeneration failure is a main concern for forest managers. For this purpose we periodically collected data from seed traps and trees located at two core locations across several years. We found sig-nificant variation in interannual cone production, with the best seed trees being the same across years. In addition, we found highly skewed distributions of female reproductive effort and large fertility differ-ences across stands located few kilometres away. Annual seed dispersal kernels fitted lognormal or 2Dt models depending on the stand analysed, with median dispersal distances between 14 and 25 m. Kernels fitted for maximum dispersal periods showed an outstanding intraseasonal variation of median dispersal distances, from 10 to 54 m, in association to variable patterns of rainfall and maximum wind speed.The amount of seed produced appeared to be enough to guarantee the natural regeneration of the stands during the typical 20-year regeneration period. Colonisation simulations concluded that Med-iterranean maritime pine has a notable dispersion capacity, which is strongly influenced by levels of fecundity and, especially, by the number and frequency of long-distance dispersal events. The latter play a key role in tree dispersion processes through enlarging the occupied area and fostering the invasion of abandoned crop land.Mating system Seed rain Dispersal kernel Dispersion Sortie-ND Mediterranean region

Natural regeneration in Iberian pines: A review of dynamic processes and proposals for management

“…In our specific study area only 20% of the seeds were released under the crown, while in a distance of three crown radii the number of dispersed seeds is similar to that beneath the crown (Calama et al, 2015b), resulting in a close to uniform distribution of the seed rain on the soil surface. For P. pinaster median dispersal distances in the territory varied between 14.1 to 24.5 m, with maximum distances over 54 m (Juez et al, 2014). Dispersal events are concentrated in only one period, from June to August, with maximum dispersal events associated with violent summer storms.…”

“…However, recent studies have given exact figures by counting cones on standing trees and collecting seed from traps (Ruano et al, 2015), resulting on average values around 7-24 seeds/m 2 , though showing large spatial and temporal availability (3.6 fold magnitude between years). Juez et al (2014) found that just a small fraction of mother trees are responsible for a high proportion of seed production. Ruano et al (2015) identified a climatic control over masting habit in the species, with the precipitation during the period of secondary growth of the cones positively affecting cone production.…”

Factors affecting cone production in Pinus pinaster Ait.: lack of growth-reproduction trade-offs but significant effects of climate and tree and stand characteristics

“…Establishing this link is especially important in the case of tradeoffs between reproduction and growth due to the high ecological and economic importance of these biological processes. The high intraspecific variability of cone production previously reported for P. pinaster (Tapias et al, 2004;Juez et al, 2014), along with the wide fluctuation in annual weather conditions that it typically endures, highlight the potential of this species as a case study for elucidating tradeoffs in resource allocation that may have ecological and economic importance. Moreover, a strong correlation has been recently reported in this species between environmental variables and minimum tree size required for production of female reproductive structure, probably reflecting environment-dependent costs of cone production (Santos-del-Blanco et al, 2012).…”

Assessing early fitness consequences of exotic gene flow in the wild: a field study with Iberian pine relicts

“…In the Iberian Peninsula, seed dispersal spans from May to October for P. pinaster (Juez et al. ) and from January to March for P. sylvestris (Castro et al. ).…”