Climate of Chamela, Jalisco, and trends in the south coastal region of Mexico

Abstract

SummaryThe warm, seasonally dry climate of Mexico's south coast is represented by data from the biological station at Chamela, Jatisco, and is compared with 26 other localities. The mean annual temperature was 24.9 °C; monthly mean maximums were equitable (29.1 ° to 32.0 ° ) but minimums showed significant seasonal changes (14.8 ° to 22.9°). Local winds were strongest in the late dry season. Most cyclonic features moved parallel to the coast. Hurricanes made landfall much more frequently along some parts of the coast than others. The average annual precipitation was 748 ram, with a coefficient of variation of 16% for eight years. Rainfall was measurable on an average of 53 days per year, but the seven heaviest rains contributed over 50%of the total; 80% of the total fell between 2 July and 4 November. Occasionally, there was substantial rain in December or January. For unsheltered lowland localities, rainfall increased with elevation, as did length of the wet season. Longer-term records (40 and more years) from four localities showed significant oscillations in precipitation that were correlated between sites. ZusammenfassungDas Klima von Chamela (Jalisco) und Trends an der siidlichen Kiistenregion Mexikos Das warme, jahreszeitlich trockene Klima der mexikanischen Kiiste wird anhand der Daten der biologischen Station Chamela (Jalisco) untersucht und mit 26 anderen Stationen verglichen. Das Jahresrnittel der Temperatur betrug 24,9 °C, die mittleren Monatsmaxima schwankten geringftigig zwischen 29,1 und 32,0 °C, die mittleren Monatsminima dagegen stark zwischen 14,8 und 22,9 °C. Die lokalen Windsysteme entwickelten sich am besten am Ende der Trockenzeit. Die meisten Zyklonen zogen entlang der Ktiste, tropische Wirbelsttirme drangen bevorzugt an bestimmten Kiistenstreifen ins Landesinnere vor. Die Jahressumme des Niederschlags betrug 748 mm, mit einer 16%-Schwankung in acht Jahren. Met~barer Niederschlag fiel an 53 Tagen im Jahr, mehr als 50% des Gesamtniederschlags stammte jedoch yon den 7 st~irksten Ereignissen. 80% der Jahressumme 298 S.H. Bullock wurden zwischen 2. Juli und 4. November gemessen. Gelegentlich trat starker Niederschlag im Dezember oder Januar auf. Ftir nicht abgeschirmte Gebiete erh6hte sich der Gesamtniederschlag und die Dauer der Regenzeit mit der Seeh6he. Liingere Zeitreihen (mindestens 40 JaNe) in vier Regionen zeigten bedeutende Schwankungen des Niederschlags, wobei die Stationen miteinander korreliert waren.

Abiotic factors influencing tropical dry forests regeneration

“…In some TDF in Mexico, there may be years with eight consecutive months of drought (Bullock, 1986). This seasonal nature of rainfalls is correlated with the deciduous character of TDF and clearly plays a major role in structuring patterns of metabolic activity and growth in this biome.…”

“…The climatic seasonality TDF are formed by a large group of plant communities habiting warm climates (Aw), with a high climatic seasonality (Bullock, 1986;Murphy and Lugo, 1986), in which the beginning of the rain period can be predictable but the amount and periodicity of rains are very variable and unpredictable. In some TDF in Mexico, there may be years with eight consecutive months of drought (Bullock, 1986).…”

“…(Murphy and Lugo, 1986;Terborgh, 1992, Swaine et al 1990. Drastic changes in TDF may occur regarding the availability of resources generated by causes other than the formation of gaps, for example, their marked seasonal rainfall pattern (Bullock, 1986). Also, in the rain season, there might be a rainless period (nearly a month) which leads to the loss of leaves in some trees, and consequently to changes in the availability of light in the understorey vegetation (Huante and Rincón, 1998a, b).…”

Aspects of the population biology of the gregarious tree Cordia elaeagnoides in Mexican tropical deciduous forest

“…With few decades of data, multi-year fluctuations in rainfall were shown in the region of distribution of C. elaeagnoides (Bullock 1986). Patches of mass mortality of trees were observed following the extremely dry years of 1985 and 1986 (with 64% and 77% of normal rainfall).…”

“…Annual precipitation averaged 707 mm (1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991), with about 80% falling between mid-June and September (Bullock 1986). At Chamela, C. elaeagnoides flowers abundantly in October, which is usually after the end of the wet season, and the fruits ripen at least a month later.…”