Quercus rugosa seedling dynamics in relation to its re‐introduction in a disturbed Mexican landscape

Abstract

In order to define the 'regeneration niche' and then promote the re-introduction of Quercus rugosa into a disturbed area we studied seed predation, germination, seedling survival and growth of this species at three different sites: the forest interior, the forest border and a disturbed site, along a disturbance gradient. Acorn removal on the ground was high at the sites, with higher removal rates from 25-seed clusters than from 5-and 1-seed clusters. More seeds were removed at the forest border than at the other two sites, although in all cases some seeds remained in the soil for periods long enough for them to germinate and produce seedlings. Seed germination and seedling establishment were more successful and similar in the forest interior and the forest border, and much less successful at the disturbed site, due to acorn desiccation. Seedling survival was strongly affected by site, with the highest survival at the forest border and the lowest survival at the disturbed site after a year.The subsequent dry season, which was particularly harsh, caused a drop in survival both at the forest border and the disturbed site. In the former, a closer analysis revealed that partially shaded microsites enhanced survival, while in the latter overall survival was very low, with approximately 5 % of the seedlings surviving, compared to 50 % final survival at the other sites. There was a positive correlation between seed size and seedling survival at the forest border. The three size variables measured (seedling height, basal diameter and crown area) did not increase noticeably during the 20-month study period at the forest interior, while growth still occurred at the forest border and the disturbed site. However, during the two dry seasons there were large drops in mean seedling height and crown area at the disturbed site, due to more frequent dieback, causing large variation in seedling size.These results show that extensive re-introduction of this species to the disturbed area will probably fail under present conditions, and that careful selection or duplication of microsites that mimic the partial shade of the forest border is a sound method for improving oak establishment at this site.

Edge effects in a tropical montane forest mosaic: experimental tests of post‐dispersal acorn removal

“…Other studies have found no difference in seed removal between the edge and forest interior (Notman et al 1996;Wong et al 1998). Bonfil and Soberon (1999) found that acorn removal of Quercus rugosa in a dry oak forest in Mexico was higher in the forest border compared with the forest interior and a disturbed shrubland, however they did not test replicated and adjacent habitats. The distance at which the seeds were placed from the edge varied greatly between studies.…”

Restoration of a degraded oak forest in Mexico City by introducing tree native species

“…It is likely that the increases observed in basal area were mainly due to the number of new sprouts, whereas decreases could be related to volume loss associated with water deficit (Cabrera-García et al 1998). Seedlings of other oak species like Q. rugosa, Q. glaucoides M. Martens & Galeotti and Q. candicans Née also experienced biomass losses when planted in the forest or in a degraded grassland (Cabrera-García et al 1998, Bonfil & Soberón 1999, Rubio-Licona 2009, Gómez-Cirilo 2010, due to either the death of the main stem that was broken before, or to the dry conditions in the sites where they were planted.…”

“…In order to contribute to connect these areas, improve the environmental conditions of Barranca de Tarango and preserve the original vegetation, we committed ourselves in assisting in the recovery of this forest by employing one of the most widely used ecological restoration practices consisting on planting tree native species (Harrington 1999, SER 2002) in a forest edge and an open area. It is known that forest edges are suitable places for the restoration of disturbed ecosystems (Bonfil & Soberón 1999, Asbjornsen et al 2004, López-Barrera & Newton 2005, López-Barrera et al 2006, Bueno & Llambí 2015, but, is the open area equally appropriate for restoration as is the forest edge? To answer this question, we established experimental plots in a forest edge and an open area adjacent to it in order to introduce three native species.…”

Effect of hydropriming and acclimation treatments on Quercus rugosa acorns and seedlings

“…It has also been reported that, in a shade house, Q. rugosa acorns receiving daily watering remain viable on the soil for only 35 days (Robledo 1997). Nevertheless, in disturbed sites, 46% of acorns germinate if protected from dehydration inside cages and covered by litter (Bonfil and Soberón 1999). The change in the WC db of the acorns exposed to dehydration or hydropriming treatments was calculated from the relationship between fresh and dry mass because fresh mass masked the acorn WC, as occurs in other species Sánchez-Coronado et al 2007).…”

“…The transition between seed to seedling life stages is very difficult for white oaks in disturbed environments. They exhibit high mortality due to seeds and seedlings dehydration, which occurs easily in some of the harsh environments where Q. rugosa occurs, such as lava fields (Bonfil and Soberón 1999). Thus, we focus on pre-germination treatments as a way to improve the germination, establishment and growth of Q. rugosa seedlings.…”