Abstract
Swietenia macrophylla is an economically important tree species propagated by seeds that lose their viability in a short time, making seed germination a key stage for the species recruitment. The objective of this study was to determine the cardinal temperatures and thermal time for seed germination of S. macrophylla; and its potential distribution under different climate change scenarios. Seeds were placed in germination chambers at constant temperatures from 5 to 45 °C and their thermal responses modelled using a thermal time approach. In addition, the potential biogeographic distribution was projected according to the Community Climate System Model version 4 (CCSM4). Germination rate reached its maximum at 37.3 ± 1.3 °C (To); seed germination decreased to near zero at 52.7 ± 2.2 °C (ceiling temperature, Tc) and at 12.8 ± 2.4 °C (base temperature, Tb). The suboptimal thermal time needed for 50% germination was ca. 190 °Cd, which in the current scenario is accumulated in 20 days. The CCSM4 model estimates an increase of the potential distribution of the species of 12.3 to 18.3% compared to the current scenario. The temperature had an important effect on the physiological processes of the seeds. With the increase in temperature, the thermal needs for germination are completed in less time, so the species will not be affected in its distribution. Although the distribution of the species may not be affected, it is crucial to generate sustainable management strategies to ensure its long-term conservation.
Highlights
Swietenia macrophylla King (Meliaceae), commonly known as mahogany, is one of the most important timber resources in the Americas and the most valuable in Mexico [1,2]
At temperatures from 30 to 45 ± 2 ◦C, seeds of S. macrophylla began to germinate after 6 days, while at temperatures of 20 and 25 ± 2 ◦C this occurred after 18 days
Mexico represents the northern limit of the distribution of S. macrophylla in the American continent and the results presented in this study are based on the northernmost populations of the country, which is why they are considered representative of the germinative behavior of this species in Mexico, as well as the effect that climatic change can be predicted
Summary
Swietenia macrophylla King (Meliaceae), commonly known as mahogany, is one of the most important timber resources in the Americas and the most valuable in Mexico [1,2]. Chemical, mechanical, and anatomical properties of its wood contribute to its high economic value. It is in high demand for production of plywood and boards for the international markets in the United States, Japan, and Europe [3]. It is used for the construction of homes, boats, and fine cabinetmaking. According to Negreros-Castillo et al [8], S. macrophylla is considered a “financial keystone species” because its absence increases the probability that the forest will be converted to other lucrative land uses. It is highly important to generate information that helps understand the physiological processes involved in the seed germination as a criterion for the regeneration and conservation of the species
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