Plant Ecology and Evolution 150(3): 240-246, doi: 10.5091/plecevo.2017.1348
Persistent cotyledons and multiple-stem resprouting as strategies of oak seedlings for tolerating herbivory damage
expand article infoSandra M. Gelviz-Gelvez, Joel Flores, Ernesto Badano
‡ Instituto Potosino de Investigación Científica y Tecnológica, División de Ciencias Ambientales, Camino a la presa San José No. 2055, Colonia Lomas 4a. Sección, San Luis Potosí, S.L.P., C.P. 78216, Mexico
Open Access
Background and aims – Large cotyledonary reserves are plant adaptations to tolerate elevated herbivory during the recruitment phase. Oak seedlings have large cotyledons that promote epicotyl resprouting after it is browsed by herbivores. Several studies indicated that browsing can induce multiple stem resprouting, but these data are usually anecdotic. Thus, whether multiple stem resprouting is linked to cotyledonary reserves, or whether it improves seedling establishment, are questions that remain largely unexplored. This study tests the hypothesis that, after the primary stem has been clipped, those seedlings that retain their cotyledons resprout faster and display multiple-stem resprouting responses, also improving their survival and growth, as compared with seedlings without cotyledons.
Methods – We performed a greenhouse experiment in which seedlings of an endemic Mexican oak, Quercus xalapensis Humb. & Bonpl. (Fagaceae), were subjected to epicotyl clipping. A total of 200 clipped seedlings were used in this experiment and cotyledons were excised on half of the seedlings. Resprouting, survival and growth rates were monitored on both groups of plants, also counting the number of new stems they developed.
Results – Seedlings with and without cotyledons displayed different resprouting responses. Seedlings that retained cotyledons resprouted from the base of the plant, while seedlings with excised cotyledons resprouted from the fraction of the epicotyl that remained attached to the plant after clipping. Resprouting, survival and growth rates were higher in seedlings that retained the cotyledons. Only those seedlings that retained their cotyledons developed more than one new stem. Survival in these latter seedlings increased with the number of stems, while their growth rates showed the opposite pattern.
Conclusions – Our results indicate that large cotyledonary reserves and multiple stem resprouting may confer advantages to oak seedlings recruiting in habitats with elevated herbivory pressure.