La Montaña region, in southern Mexico, is characterized as a highly human-modified landscape with a rough topography, extreme poverty and structural violence. In this region, Xuajin Me'Phaa, an Indigenous non-governmental organization conformed by ca. 300 peasants, implements productive restoration projects and trades organic hibiscus (Hibiscus sabdariffa L.) as its main monetary income. Nonetheless currently, organic hibiscus yield is low compared to the potential yields in the region. Thus, it is necessary to explore alternative sustainable land management systems which enable farmers to increase hibiscus crop productivity, while halting land degradation. This study assessed the impact of six different agroecological fertilization protocols (AFPs) on hibiscus productivity planted in an alley cropping system with Calliandra houstoniana trees. The AFPs were based on the combination of three local plant amendments: C. houstoniana mulch, Mucuna pruiriens var. utilis green manure and hibiscus stover, and a commercial bio-fertilizer (Azospirillum + Rhizophagus). Simultaneously, the performance of C. houstoniana trees was assessed. The AFPs were applied in the alley cropping system and evaluated from 2016 to 2018. After 3 years, in the AFPs which included C. houstoniana mulch, hibiscus yielded significantly more (419 ± 27 kg dry calyxes ha−1 in average) than AFPs which did not include this species (264 ± 15 kg ha−1). The 18-month-old C. houstoniana trees yielded 0.6 t ha−1 of dry biomass and 1.12 t ha−1 of wooden stakes, a relatively low production. In conclusion, our results show that alley cropping with a denser arrangement of C. houstoniana trees in combination with mulching of this tree species, and use of mucuna green manure represent a promising agroforestry system for organic hibiscus production.

In the semi-deciduous forests of Santa Rosa National Park in the Pacific coastal lowlands of northwestern Costa Rica, the large and fast-growing tree Spondias mombin(Anacardiaceae) experiences greater than 95% post-dispersal seed predation by a bruchid beetle (Amblycerus spondiae) on its nuts that have been dispersed to any part of pristine or secondary successional forest. Nuts dispersed (by white-tailed deer) to abandoned pastures immediately adjacent to the forest suffer less than 20% post-dispersal seed predation but seedlings are killed by frequent grass fires. S. mombin displays significant recruitment of saplings and young trees only on forest edges free of fire for long intervals. The very high percent seed predation in the forest and the failure of many nuts to ever be dispersed away from the parent tree is attributed directly and indirectly to the absence of a herbivorous (frugivorous) megafauna that would have been part of the habitat of S. mombin through most of its evolutionary history. These large animals would have consumed large numbers of S. mombin fruits and thereby dispersed the nuts in such a manner as to have both led to more escape from bruchids and an overall reduction in the bruchid population density. By their defecation patterns, these mammals would also have defecated more nuts in sites of high quality for S. mombin sapling survival than is the case at present. In contemporary habitats, S. mombin is culturally deprived in that it can no longer interact with the habitats, animals and densities of animals whose selective pressures were a major force in the evolution of the tree's traits.

Phytomass was determined for a tropical deciduous forest in Chamela, Jalisco, México. The mean canopy height was 6.9 m, and the total basal area was 25.6 m2 ha−1 (dbh > 3.0 cm). The estimated phytomass for this forest (85 Mg ha−1) is among the highest values for tropical dry forests with similar seasonal climates. A stepwise multiple regression analysis showed that phytomass can be predicted firstly by basal area (R2 = 0.88), then by wood specific gravity (R2 = 0.91), and finally by the inclusion of tree height in the regression (R2 = 0.92). Each new independent variable explained significant variance in the phytomass estimation.

The canopy dynamics and light climates within a 20 by 60 m quadrat were studied in a disturbed moist deciduous forest near Bombay, India. A map was drawn of individual trees within the quadrat, the taxa were identified, and their phenology was followed from November 1984 to July 1985. The quadrat contained 14 species, the most common being Tectona grandis, Terminalia tomentosa, Butea monosperma, Mitragyne parviflora and Albizia procera. Some individuals were in leaf at all times, more so at the moister east end of the quadrat. In November at the end of the rainy season, light measurements documented percentages of total daily photosynthetic photon fluence (PPF) at 10.0% of full sunlight; 44% of this flux was due to sun-flecks whose duration was approximately 17% of the daytime hours. Values for six sites were similar to mid-day measurements along a 40 m transect, and consistent with the 94% canopy cover of the sites, photographed with a fish-eye lens. The March dry season measurements revealed a more intense radiation environment (54% of solar PPF), and 59% of the photosynthetic photon flux density at mid-day along the transect. Canopy openings were increased to a mean of 59.4%. Light in the understorey in November was spectrally altered, with typical R:FR ratios of 0.30, compared to March values identical to those of sunlight, at 1.10.

Cordia elaeagnoides is locally important within a large area of southern México as a highly gregarious canopy tree of dry forest and as a timber species. Its recruitment is problematic so studies of its reproduction and population dynamics were undertaken. The distylous flowers are apparently self-compatible, and pollination and seed dispersal are by wind. Pre-dispersal mortality is largely from embryo abortion, and post-dispersal predation is mostly by generalist rodents. Some seeds may survive in enforced dormancy for two or more years. Recruitment was apparently absent for more than a decade, but had previously occurred within established stands, where size classes were interspersed at random. Population size structure suggests that recruitment over the last century occurred in several pulses. Growth rates determined from ring counts and remeasurement of marked trees support a size-age relationship. The youngest reproductive trees are estimated to be about 18 years old, and about 5% of the present population is over 95 years old.

Continuous litterfall measurements were made from 1977 to 1982, at two sites with contrasting topography in a mature tropical deciduous forest in Chamela, Jalisco, on the Pacific Coast of Mexico (19° 30′ N, 105° 03′ W). The climate is strongly seasonal with the annual rainfall (x = 748 mm) concentrated in six months (June to November) and a mean annual temperature of 24.9°C. Results of the five-year study show that at the Valley Site (slope <5°) the mean annual litterfall was 6.58 ±0.15 (SE) Mg ha−1 y−1 composed of 73.3% leaves, 17.1% woody material, 5.6% reproductive remains and 4.0% finely fragmented debris. At the Hill Site (slope 20°–40°) mean annual litterfall was 3.95 ± 0.16 Mg ha−1 y−1, consisting of 68.8% leaves, 17.0% woody material, 9.4% reproductive remains and 4.7% fragmented debris. At the Valley Site the year-to-year variation in total litterfall was not significant. In contrast, at the Hill Site it fluctuated markedly from year to year. Litter production exhibited a pronounced seasonally: at the Hill Site total litterfall peaked near the onset of the dry season; at the Valley Site it occurred two months later, apparently as a result of differences in soil moisture availability between the study sites.

We studied the relationships between soil nutrient availability and microbial biomass and activity of two contrasting soil conditions in a tropical deciduous forest in western Mexico. Hilltops have higher pH, water, dissolved organic C, and ammonium concentrations than hillslopes. Our main hypothesis was that soil microbial biomass, microbial activity and bacterium species richness would be higher in soils with high availability of nutrients. Fifteen soil cores, 0–5 cm depth, were taken in the dry, early rainy and rainy season, from each of the ten replicate plots in hilltop and hillslope positions located on three contiguous small watersheds. We measured moisture, C, N and P availability, potential C mineralization, net nitrification, microbial biomass and culturable heterotrophic and nitrifying bacteria in composite samples from each plot. Microbial biomass, species richness of culturable heterotrophic bacteria and C mineralization were significantly higher on hilltops than on hillslopes. Net nitrification was, in contrast, significantly higher on hillslopes than on hilltops and counts of culturable nitrifying bacteria were also significantly higher in the rainy-season samples. Hilltops and hillslopes had low similarity in composition of culturable heterotrophic bacterial species, particularly during the rainy season. The results suggested that C and N availability and seasonal changes in soil moisture are important controlling factors for some soil culturable-bacterial species, which may affect both C mineralization and nitrification in these tropical deciduous forest soils.

The effect of an open landfill and the seasonality of a tropical deciduous forest in Jalisco, Mexico, was tested on the home range and group size of coyotes Canis latrans under the Resource Dispersion Hypothesis (RDH), which proposes that in social carnivores dispersion of patches of limited resources determines home-range size, whereas independently, abundance of resources affects group size. The predictions in this study were that coyotes using the landfill, where food is available all year due to the continuous arrival of food wastes that are concentrated in a single patch, would have smaller, seasonally constant home ranges than coyotes living outside, where food is distributed in several patches. In this area, coyotes would increase their home ranges during the dry season due to seasonal changes in resource availability. Also, a larger coyote group size should exist in the landfill, where food abundance is greater. Home-range size and group size of coyotes living in and outside the landfill were estimated by radio-tracking. Home ranges of coyotes in the landfill varied from 0.9 to 9.5 km2, whereas home-range sizes of coyotes outside the landfill varied from 10.9 to 43.7 km2. Seasonality had no effect on the home-range sizes. We identified a group of four adult coyotes in the landfill and no group formation in coyotes outside. These results support the predictions about home-range and group size of coyotes in relation to landfill presence, and indicate that under the circumstances of our study, coyotes follow the postulates proposed by the RDH.