For five years (from 2009 to 2014 and from 2010 to 2016), the phenological response and the litter production in forests with Rhizophora mangle have been evaluated before the interstitial water chemistry change along the coast of Campeche, Mexico ( Fig. 1). To date, conditions of severe drought have been recorded in 2009 through the Standardized Precipitation Index of -1.5 and for 2015, with -1.16. Therefore, a deficit in rainfall of 22.1% between 2009 and 2016 has been defined throughout the state of Campeche. With decreases of 9.5% to the south of the state (in the Terminos Lagoon) and to the north of 64.4% (in the Petenes Biosphere Reserve).
The main results, established significant differences per year, with respect to the precipitation seasons of the year (p < 0.001), and between years and seasons of the year (p < 0.001). In addition to registering an interaction in the salinity (p < 0.05), the redox potential (p < 0.001), and the precipitation (p < 0.001) de la laguna de Términos, the river Champotón, and the Reserve of the Biosphere the Petenes (Fig.2).
Fig. 1. Map of the seven study forests of mangroves that border the coast of Campeche, México: (a) Laguna de Términos, (b) River Champotón, y (c) Reserve of the Biosphere the Petenes.
Also, significant differences have been established between the years, this refers to the production of leaves and propagules (p < 0.001), and between the seasons, with the production of leaves, flowers and propagules (p < 0.001).
Finally, the determining factor in the production of flowers during the periods of rain and low water during the study period was salinity. For the production of propagules was the redox potential and salinity in the forests of R. mangle in the state of Campeche. The results of this study suggest a low phenotypic plasticity in R. mangle.
Fig. 2. Reproductive phenology based on litter in seven mangrove forests along the coast of Campeche, Mexico from 2009 to 2010 and from 2014 to 2016. The southern region includes Laguna de Términos, and the northern region includes Champotón River and the Reserva de Los Petenes Biosphere.
The success in the permanence and persistence of many plant species is their adaptive capacity to the modifications of their habitat. In this section we present the results of a study in which the adaptation of the Avicennia germinans forests to these environmental modifications was analyzed. The study sites were: Atasta, Sabancuy and Xibujá in the region of the lagoon of Terms where there are important forests of Avicennia (Fig. 3).
Fig.3. Sampling stations in laguna de Términos, Campeche.
It was proved that A. germinans forests have the ability to adapt to the different environmental conditions of interstitial water and methane concentration, through changes in their morphology and physiology of the root system (pneumatophores).
The adaptive plasticity of A. germinans gives it advantages in heterogeneous environments, expressing in probably three different phenotypes in front of three environmental scenarios, by altering the density and height of its pneumophores, which surely leads to a physiological and morphological of the plant in response to the variation of the physicochemical conditions of interstitial water.
Given the degree of deterioration that currently affect mangrove ecosystems, it is considered that this study provides information that may be useful in the development of models to predict the responses of species to climatic variability and environmental conditions of sites. of restoration.
Fig. 4. Pneumatophores in a mangrove forest, with dominance Avicennia germinans, east (Xibujá) of the Flora and Fauna Protection Area Laguna de Términos (apfflt), Campeche.
Fig. 5. Capture of methane emission with static cylindrical polypropylene chambers and with a metal valve, in a forest of Avicennia germinans located east (Xibujá) of apfflt.