Cambial Activity and Phenology in Three Understory Species along an Altitude Gradient in Mexico

Teresa Terrazas,Lauro López-Mata,Mayte S Jiménez-Noriega

doi:10.3390/f12040506

Teresa Terrazas, Lauro López-Mata + Show 1 more

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https://doi.org/10.3390/f12040506

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Abstract

The aims of this study were to evaluate the cambial activity and phenology of three species with different life forms (Alchemilla procumbens, Acaena elongata and Ribes ciliatum) along an altitudinal gradient and to establish which environmental variables (light, soil humidity and temperature) had the greatest influence on cambial activity and phenological stages. Over two years, data on phenology, growth and cambium were gathered every four weeks in three to six sites per species in Sierra Nevada, Mexico. The results showed that Ribes is the only species that terminates cambial activity with leaves senescence and is influenced by the minimum soil temperature. The light environment influenced the vegetative stages in Alchemilla (cryptophyte), while in Acaena (hemicryptophyte), the mean soil temperature explained the findings related to leaf area during the dry season and growth along the gradient. In the three species, the reproductive phase dominated for a longer period at higher elevations, especially in Alchemilla. Only Ribes, the phanerophyte, showed a similar cambial activity to other trees and shrubs. Although cambium reactivates during the dry season, no xylogenesis occurs. The three species varied during the time in which vascular cambium was active, and this was dependent on the altitude. Specifically, the variation was more rhythmic in Ribes and switched on and off in Alchemilla. It is likely that, depending on the life form, vascular cambium may be more or less susceptible to one or more climate factors.

Highlights

It is well known that, in temperate regions, the activation of the vascular cambium of tree species is closely related to the development of leaves due to increases in the environmental temperature [1,2]
The phenological changes associated with climatic factors and seasonal periods occur simultaneously with radial growth, a product of cambial activity, suggesting that phenological events may promote the onset of cell division in the vascular cambium (VC) [6,9]
Cambial activity and the presence of leaves during the dry season were strongly correlated to the minimum soil temperature in Ribes, which at the highest site was below 3 ◦C, with a humidity greater than 90% when fruiting is present

Summary

Introduction

It is well known that, in temperate regions, the activation of the vascular cambium of tree species is closely related to the development of leaves due to increases in the environmental temperature [1,2]. The phenological changes associated with climatic factors and seasonal periods occur simultaneously with radial growth, a product of cambial activity, suggesting that phenological events may promote the onset of cell division in the vascular cambium (VC) [6,9]. This correlation has been recorded in both temperate [10,11,12] and tropical [3,4,13] tree species. High temperatures promote the onset of cambial activity [14] and phenophases [15], while periods of higher levels of precipitation and light hours induce increased cell division in the VC [16]

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