Riparian Areas and Conservation of Herpetofauna in a Tropical Dry Forest in Western Mexico

Studies that assess the importance of riparian habitats in maintaining diversity of herpetofaunal assemblages in tropical dry forests are limited. We examined changes in abundance, diversity and composition of anuran, lizard and snake assemblages along stream edge–upslope gradients in conserved and disturbed areas of tropical dry forest on the Pacific coast of México. We sampled 659 plots in six watersheds over 2 yr. Two forest conditions (conserved and human disturbed, with three watersheds as replicates) were evaluated in the dry and rainy season. Within each watershed, plots were randomly located at three different distance categories from either stream edge: 0–10 m (near‐stream environment), 30–40 m (mid‐slope environment), and 50–60 m (upslope environment). Herpetofauna was surveyed by time‐constrained searches with a sampling effort of 1980 person‐hours. Eighteen anuran, 18 lizard and 23 snake species were recorded. Overall, abundance and diversity of lizards and snakes decreased from near‐stream to upslope areas in both forest conditions and seasons; while that of anurans followed this trend only for the conserved forest during the rainy season. Regardless of distance, abundance and diversity of anurans markedly decreased during the dry season, while that of snakes and lizards increased. Overall, our study shows that the importance of riparian areas for herpetofaunal conservation in dry tropical forests varies with forest condition and season.     

Distribution Patterns of Tropical Dry Forest Trees Along a Mesoscale Water Availability Gradient

Tropical dry forests (TDFs) host a large diversity of tree species but little is known of potential mechanisms that contribute to its maintenance. Given the paramount importance of water availability in such forests, tree species would be expected to show nonrandom patterns along water availability gradients, as well as differential individual species responses. In this work we explored whether that was true for 50 dominant tree species. Within a total area of 5.2 ha, divided into 26 transects each with ten 20 × 10 m plots, we registered presence–absence of these tree species with diameter at breast height ≥5 cm. We assessed the response of trees to four environmental variables differentially related to water availability in three steps: (1) identifying the shape of the response to individual environmental variables, (2) testing for artifacts in previous patterns due to spatial autocorrelation of presence–absence, and (3) identifying the environmental variable or combination of variables that best explained the pattern. We then classified the species with respect to their probability of occurrence along the gradient, and explored which components of the water cycle were likely to be driving the observed patterns. We found that 14 species were generalists, 16 drought tolerant, 9 intermediate, 3 water demanding and 8 showed mixed responses. Lateral flow and access to ground water most likely underlie such patterns. Our results confirm the key role played by water availability in tree species distribution. Water‐related niche differentiation seems to be crucial for maintaining the high diversity of this TDF. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .     

Landscape Genetics of Leaf-Toed Geckos in the Tropical Dry Forest of Northern Mexico

Habitat fragmentation due to both natural and anthropogenic forces continues to threaten the evolution and maintenance of biological diversity. This is of particular concern in tropical regions that are experiencing elevated rates of habitat loss. Although less well-studied than tropical rain forests, tropical dry forests (TDF) contain an enormous diversity of species and continue to be threatened by anthropogenic activities including grazing and agriculture. However, little is known about the processes that shape genetic connectivity in species inhabiting TDF ecosystems. We adopt a landscape genetic approach to understanding functional connectivity for leaf-toed geckos (Phyllodactylus tuberculosus) at multiple sites near the northernmost limit of this ecosystem at Alamos, Sonora, Mexico. Traditional analyses of population genetics are combined with multivariate GIS-based landscape analyses to test hypotheses on the potential drivers of spatial genetic variation. Moderate levels of within-population diversity and substantial levels of population differentiation are revealed by F _ST and D _est. Analyses using structure suggest the occurrence of from 2 to 9 genetic clusters depending on the model used. Landscape genetic analysis suggests that forest cover, stream connectivity, undisturbed habitat, slope, and minimum temperature of the coldest period explain more genetic variation than do simple Euclidean distances. Additional landscape genetic studies throughout TDF habitat are required to understand species-specific responses to landscape and climate change and to identify common drivers. We urge researchers interested in using multivariate distance methods to test for, and report, significant correlations among predictor matrices that can impact results, particularly when adopting least-cost path approaches. Further investigation into the use of information theoretic approaches for model selection is also warranted.     

Effects of Vegetation Thinning on Above- and Belowground Carbon in a Seasonally Dry Tropical Forest in Mexico

Mature tropical forests are disappearing and secondary forests are becoming more abundant, thus there is an increasing need to understand the ecology and management of secondary forests. In the Yucatan Peninsula, Mexico, seasonally dry tropical forests are subject to frequent fire, and early-successional stands are extremely dense. We applied vegetation thinning (removal of all stems < 2 cm in diameter) to hasten secondary succession and open the understory to reduce the fire ladder in an 11-yr-old stand. We quantified the effect of vegetation thinning on above- and belowground carbon over 5 yr. Aboveground carbon included all standing vegetation and belowground carbon included fine roots and organic carbon in the Oi, Oe, and Oa soil horizons. Trees with diameter of 2–10 cm and > 10 cm had higher carbon accumulation rates in thinned plots than in control plots. Carbon stored in the Oi-horizon and the Oe > 2 mm fraction remained significantly higher in thinned plots even 5 yr after treatment. Carbon in fine roots was significantly higher in thinned plots, and radiocarbon (¹⁴C) data suggest that fine roots in thinned plots were recently produced in comparison with fine roots in control plots. We did not find significant differences in total ecosystem carbon after 5 yr (126 ± 6 and 136 ± 8 Mg C/ha, respectively). These results suggest rapid carbon recovery and support the hypothesis that young tropical forests thinned to hasten succession and reduce the fire hazard may have only a short-term negative impact on carbon accumulation in vegetation and soils.     

Patterns and Correlates of Tropical Dry Forest Structure and Composition in a Highly Replicated Chronosequence in Yucatan,Mexico

Research on tropical dry forest (TDF) succession i0s needed for effective conservation and management of this threatened and understudied ecosystem. We used a highly replicated chronosequence within a 37,242‐ha TDF landscape to investigate successional patterns by plant size class and to evaluate the influence of stand age, topographic position, soil properties and spatial autocorrelation on forest structure and composition. We used a SPOT5 satellite image to obtain a land‐cover thematic map, and sampled woody vegetation (adults: >5 cm diam; saplings: 1–5 cm) and soil properties in 168 plots distributed among four vegetation classes: VC1 (3–8‐yr‐old forest), VC2 (9–15‐yr‐old forest), VC3 (>15‐yr‐old forest on flat areas), VC4 (>15‐yr‐old forest on hills). Stem density decreased with stand age and was lowest in VC3, while height, basal area and species density increased with age and were higher in older than in younger forests. Topographic position also influenced forest structure and composition. Basal area and height were largely determined by stand age, whereas stem and species density, and composition were influenced mostly by soil variables associated with fertility, and by spatial autocorrelation. Adults and saplings showed contrasting patterns and correlates of community structure, but similar patterns and correlates of composition, possibly due to the prevalence of coppicing. Our results show that our sampling approach can overcome several limitations of chronosequence studies, and provide insights in the patterns and drivers of succession, as well as guidelines for forest management and conservation. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .     

Cyanobacterial Microbiotic Crusts in Eroded Soils of a Tropical Dry Forest in the Baja California Peninsula,Mexico

This study deals with the cyanobacterial composition, and the nitrogen fixation of four members, of cryptobiotic crusts collected from eroded soils in a transitional area between arid and tropical climatic environments. Identification was based on microscopic analyses. Morphotypes were identified directly from reactivated natural crusts and from cultured strains. The identified morphotypes were Scytonema cf. ocellatum, Scytonema sp., Microcoleus cf. paludosus, M. cf. sociatus, Calothrix cf. elenkinii, C. cf. marchica, Nostoc cf. microscopicum, and Phormidium sp. Results show that the cyanobacterial composition of the microbiotic crusts studied is different from those in warmer and cooler deserts, particularly the absence of Microcoleus cf. vaginatus and Nostoc cf. commune in our samples. Such differences could be caused by the transitional character of the area. The results of the acetylene reduction assay show that the capacity of nitrogen fixation of some morphotypes is limited to the heterocyst-forming morphotypes.     

Controls of Soil Spatial Variability in a Dry Tropical Forest

We examined the roles of lithology, topography, vegetation and fire in generating local-scale (<1 km²) soil spatial variability in a seasonally dry tropical forest (SDTF) in southern India. For this, we mapped soil (available nutrients, Al, total C, pH, moisture and texture in the top 10cm), rock outcrops, topography, all native woody plants ≥1 cm diameter at breast height (DBH), and spatial variation in fire frequency (times burnt during the 17 years preceding soil sampling) in a permanent 50-ha plot. Unlike classic catenas, lower elevation soils had lesser moisture, plant-available Ca, Cu, Mn, Mg, Zn, B, clay and total C. The distribution of plant-available Ca, Cu, Mn and Mg appeared to largely be determined by the whole-rock chemical composition differences between amphibolites and hornblende-biotite gneisses. Amphibolites were associated with summit positions, while gneisses dominated lower elevations, an observation that concurs with other studies in the region which suggest that hillslope-scale topography has been shaped by differential weathering of lithologies. Neither NO₃⁻-N nor NH₄⁺-N was explained by the basal area of trees belonging to Fabaceae, a family associated with N-fixing species, and no long-term effects of fire on soil parameters were detected. Local-scale lithological variation is an important first-order control over soil variability at the hillslope scale in this SDTF, by both direct influence on nutrient stocks and indirect influence via control of local relief.     

Soil Effects on Forest Structure and Diversity in a Moist and a Dry Tropical Forest

Soil characteristics are important drivers of variation in wet tropical forest structure and diversity, but few studies have evaluated these relationships in drier forest types. Using tree and soil data from 48 and 32 1 ha plots, respectively, in a Bolivian moist and dry forest, we asked how soil conditions affect forest structure and diversity within each of the two forest types. After correcting for spatial effects, soil‐vegetation relationships differed between the dry and the moist forest, being strongest in the dry forest. Furthermore, we hypothesized that soil nutrients would play a more important role in the moist forest than in the dry forest because vegetation in the moist forest is less constrained by water availability and thus can show its full potential response to soil fertility. However, contrary to our expectations, we found that soil fertility explained a larger number of forest variables in the dry forest (50 percent) than in the moist forest (17 percent). Shannon diversity declined with soil fertility at both sites, probably because the most dominant, shade‐tolerant species strongly increased in abundance as soil fertility increased.     

Understanding the Interaction of Rural People with Ecosystems: A Case Study in a Tropical Dry Forest of Mexico

The aim of this study was to help understand the interaction of rural people with tropical dry forests. It was based on social research conducted in the Chamela-Cuixmala region, on the Pacific coast of Mexico. The analytical tools used in the study included stakeholder identification, environmental history and social perceptions. The two main social groups in the study were ejidatarios, who own most of the territory, and avecindados, who possess no land but have high population numbers. Through an interpretative methodological approach we documented the vision and meaning that rural people give to their natural and social worlds. The agricultural development model promoted by the Mexican government for decades was identified as the main driver of ecosystem transformation. Rural people, who arrived recently in the region, were proud of the pasture-lands that were transformed from tropical forests. Conservation policies implemented during the last two decades were viewed as impositions although people recognized the value of services provided by ecosystems. This case study has helped to unravel the main dimensions of the human system and how it relates to structures of signification. The social panorama unveiled can be used as an initial basis to promote further research on the social-ecological system of the Chamela-Cuixmala region and to develop future participatory management schemes.     

Storage and Flux of Nutrients in a Dry Tropical Forest in India

Storage and flux of N, P, Ca, K and Na were studied in a drytropical forest The nutrient concentrations in different growthforms were in the order herb > shrub > tree, whereas thestanding state of nutrients followed the order tree > shrub> herb The total storage (kg ha^–1) in vegetation amountedto 567 N, 37 P, 278 Ca, 256 K and 46 Na The share of above-groundparts in vegetation storage was 82 % for N, 83 % for P, 76 %for Ca, 85 % for K and 79 % for Na From 56 to 71 % of foliarN, P and K was withdrawn during senescence Nutrient input (kgha^–1 year^–1) from the vegetation (above-ground +below-ground) to forest floor amounted to 115 N, 8 P, 62 Ca,38 K and 10 Na compared to total net annual uptake (kg ha^–1)of 143 N, 10 P, 78 Ca, 52 K and 12 Na, indicating marginal accumulationin the system Fine roots were as important a pathway of nutrientreturn as leaf litter Turnover rate and turnover time for differentnutrients on the forest floor ranged, respectively, between72 and 83 % and 12 and 1 39 years Dry tropical forest, nutnent concentration, standing state, uptake, internal cycling, turnover     

Dry Season Den Use by Pygmy Spotted Skunk (Spilogale pygmaea) in a Tropical Deciduous Forest of Mexico

Dry season den use by the pygmy spotted skunk Spilogale pygmaea , an endemic and threatened species of western Mexico, was evaluated at the micro and macrohabitat level, in the tropical deciduous forest of Chamela, Jalisco, Mexico. During the dry seasons of 1997, 1998, and 2000, 79 skunk den sites (29 for females and 50 males) were located using Radiotelemetry. Dens were underground excavations with one to five access points, located mostly on open ground or under live or dead trees. Skunks exhibited a continued reuse of dens but evidence of simultaneous occupation by two or more skunks was not found. Microhabitat den-site analysis showed that skunks showed flexibility and individual variation in usage of the microhabitat surrounding den sites inside the forest. Macrohabitat den-site analysis showed that skunks were not selecting either tropical deciduous or tropical semideciduous forest; however, no dens were located outside the forest in transformed habitats, strengthening the hypothesis of the association of this species with the tropical deciduous forests on the Pacific coast of Mexico. The current deforestation rates of the tropical deciduous forest in the coast of Jalisco could be reducing the potential den sites for pygmy spotted skunks and exposing them to adverse environmental conditions and predation.     

Phenology of Plumeria alba and its Herbivores in a Tropical Dry Forest

Understanding phenology in plant populations requires distinction between proximate mechanisms and ultimate (evolutionary) causation. Leaf production and abscission, flower production, and herbivory were monitored for 2 yr in a population of the stem succulent tree, Plumeria alba L. in the Guánica State Forest in southwest Puerto Rico. Dependence of phenological events on abiotic (rainfall and day length) and biotic factors (herbivore abundance/damage) was quantified to discern potential relationships. Leaf flush and flowering were not associated with periods of highest rainfall as might be expected in a dry tropical forest. Rather, these events were highly correlated with day length. We observed that most leaf flush began in March and April, which was several months before the wettest period of the year (August to November). This result is consistent with other studies that show that leaf flush in Plumeria is under photoperiodic control and that the plants initiate growth and reproduction when cloudiness is low and seasonal light availability is greatest. Herbivore damage by caterpillars of the sphinx moth Pseudosphinx tetrio is restricted primarily to the wettest season, consistent with the hypothesis that early leaf flush and reproduction has been selected to avoid herbivory. It is not clear whether photoperiodic control of leaf flush and reproduction serves to maximize seasonal light availability, minimize the impact of herbivores, or both. However, it is clear that peak rainfall is not likely to have been the sole selective factor determining leaf flush and flowering in P. alba .     

Species Structure, Dry Matter Dynamics and Carbon Flux of a Dry Tropical Forest in India

Species composition, plant biomass and net primary productivitywere studied on three sites of a dry tropical forest The forestwas characterized by small structure with 38–10.4 m2 ha^–1tree and 3 1–7 8 m² ha^–1 shrub basal cover Speciesdiversity was highest for the mid-slope site while the concentrationof dominance was greatest for the hill-top stand The beta diversitywas 3 1 Total standing crop of vegetation averaged 66 98 t ha^–1with 46 70 t ha^–1 in the tree layer, 13.97 t ha^–1in the shrub layer, 0.35 t ha^–1 in the herb layer, 2 83t ha^–1 in the litter layer and 3 13 t ha^–1 in fineroots Of the total annual litterfall (4 88–6.71 t ha^–1),69% was accounted for by leaves and 31% by non-leaf matter Netprimary production (NPP) ranged between 11 3 and 19 2 t ha^–1year^–1, to which the contributions of trees, shrubs andherbs averaged 72, 22 and 6%, respectively Contribution of rootsto NPP was substantial and ranged from 2 9 to 5 3 t ha^–1year^–1 A total of 83% of vegetation carbon was storedin the above-ground plant parts while the above-ground NPP wasresponsible for 72% of the total carbon input into the systemThe contribution of foliage, herbaceous vegetation and fineroots to carbon turnover was disproportionately larger comparedto their share in the total standing crop Carbon budgeting indicatedthat the forest was an accumulating system, over at least theshort term Dry tropical forest, biomass, litterfall, net primary production, carbon budget, carbon flux     

Diversity and Coexistence of Ectoparasites in Small Rodents in a Tropical Dry Forest

To understand the mechanisms driving species diversity is central to community ecology. Here, we explored if habitat partitioning is associated with a species‐rich ectoparasite community in small rodents from a tropical dry forest in western Mexico. We trapped 199 mice in three 0.5 ha‐plots from eight small rodent species for every two months, from July 2011 to April 2012, and collected their ectoparasites. We identified 17 species of mites, two sucking lice species, two phoretic species, and one commensal species. The most abundant ectoparasite species was Steptolaelaps liomydis, representing 42 percent of all ectoparasites collected; seven ectoparasite species had < 10 individuals. Eighteen ectoparasite species (of 22 species) were collected from the most abundant rodent Liomys pictus. C‐score and the number of checkerboard species pairs were significantly higher against a random expectation. Ectoparasite species in L. pictus mice showed host microhabitat partitioning; Fahrenholzia ehrlichi and Fahrenholzia texana were found only in the anterior dorsal area, Ornithonysus sp. occurred along the dorsal part, Ixodes species were restricted to the ears, and Steptolaelaps liomydis was found throughout the body. We also identified ectoparasite communities with distinct species composition in two rodent species that use contrasting macrohabitats (L. pictus, strictly terrestrial; Peromyscus perfulvus, mostly arboreal). The remaining and low abundant rodent species showed a species‐poor ectoparasite community composition. We conclude that habitat partitioning at both macro and microhabitat scales appeared to characterize the species‐rich ectoparasite community. Conversely, most rodent host species with low abundances showed a species‐poor ectoparasite community.     

The Impact of Cyclone Fanele on a Tropical Dry Forest in Madagascar

Cyclones, which change tree communities and alter forest structure, are thought to have had a significant selective pressure on the flora and fauna of Madagascar. Very little information, however, is available on the actual impact of cyclones on Malagasy ecosystems. On 21 January 2009, Cyclone Fanele made landfall on the western coast of Madagascar with sustained winds of 185 km/h. We examined the immediate effects of the cyclone on tropical dry forest structure in the Kirindy Mitea National Park. In July and August 2009, we measured the height, diameter at breast height (dbh), and damage for 1361 trees in nine 25 × 25 m plots. We found that: (1) over 95 percent of trees experienced some sort of damage, including 8.8 percent mortality; (2) understory and emergent trees experienced significantly higher mortality than canopy trees; and (3) stem density was reduced 9.2±4.5 percent and biomass was reduced 13.4±8.1 percent after the cyclone. Dbh was the best predictor of trunk damage and mortality. This extensive alteration of forest structure will have a substantial short‐ and long‐term impact on the biotic communities of western Madagascar.     

Colonization Strategies of Two Liana Species in a Tropical Dry Forest Canopy

Lianas impose intense resource competition for light in the upper forest canopy by displaying dense foliage on top of tree crowns. Using repeated access with a construction crane, we studied the patterns of canopy colonization of the lianas Combretum fruticosum and Bonamia trichantha in a Neotropical dry forest in Panama. Combretum fruticosum flushed leaves just before the rainy season, and its standing leaf area quickly reached a peak in the early rainy season (May–June). In contrast, B. trichantha built up foliage area continuously throughout the rainy season and reached a peak in the late rainy season (November). Both species displayed the majority of leaves in full sun on the canopy surface, but C. fruticosum displayed a greater proportion of leaves (26%) in more shaded microsites than B. trichantha (12%). Self-shading within patches of liana leaves within the uppermost 40–50 cm of the canopy reduced light levels measured with photodiodes placed directly on leaves to 4–9 percent of light levels received by sun leaves. Many leaves of C. fruticosum acclimated to shade within a month following the strongly synchronized leaf flushing and persisted in deep shade. In contrast, B. trichantha produced short-lived leaves opportunistically in the sunniest locations. Species differences in degree of shade acclimation were also evident in terms of structural (leaf mass per area, and leaf toughness) and physiological characters (nitrogen content, leaf life span, and light compensation point). Contrasting leaf phenologies reflect differences in light exploitation and canopy colonization strategies of these two liana species.     

Disturbance and Seasonal Dynamics of Mycorrhizae in a Tropical Deciduous Forest in Mexico1

Mycorrhizal fungi were sampled in a deciduous tropical forest on the Pacific coast of Mexico during different seasons and in natural treefall gaps and pastures. All 12 plant species sampled in the forest were arbuscular mycorrhizal. The percent root infection and spore production were closely related to the phenology of the plants. Most tree species and all herbaceous species had the highest infection in the summer rainy season, but two species, Opuntia excelsa and Jacquinia pungens, had highest infection in the dry season. Unusually high rainfall during the dry season was associated with increased infection but not increased spore production. Spore density was low for all species at all sample times, except at the beginning of the July 1993 rainy season in, when we observed up to 28 spores/g soil. The percent cover of shrubs or herbs did not increase in gaps after two years, and we observed no colonizing seedlings. No plant species with cover higher than 2.7 percent occurred exclusively in gaps or forest. The percent mycorrhizal infection did not differ significantly between gaps and forest. Spore counts were as high in the gaps as in the forest in two of the three gaps but lower in the third gap. The lack of significant response of plants in these gaps after two years differed from the rapid response in tropical rainforests. It is likely related to the small size of the gaps and to light infiltration to the forest floor. Pastures were dominated by two species of exotic grasses and one species of mycorrhizal fungus, whereas forests had 15 fungal species. The slow regrowth of vegetation in gaps was not limited by mycorrhizal fungi, since they were still abundant after the treefalls, but recovery in pastures could be affected by low fungal diversity and dominance of grasses.     

Frugivory and Seed Dispersal by Brown Lemurs in a Malagasy Tropical Dry Forest

In the Ankarafantsika tropical dry forest (northwestern Madagascar), the common brown lemur (Eulemur fulvus fulvus) is the largest frugivore and probably the sole disperser of large‐seeded plants (seed diameter > 10 mm). To investigate seed dispersal by this primate, I recorded the feeding activities of a troop; also conducted fecal analyses, germination trials on defecated seeds, and a vegetation survey over 1 yr (beginning Dec 2006). Brown lemurs mostly consumed fruit (68%). The fruit of Vitex beraviensis was the most exploited resource (21% of total feeding time). Among dung samples, 1126 contained intact seeds of 70 plant species, with a median of six seeds and two species per sample. These data indicate that the brown lemur population dispersed approximately 9854 seeds/km²/d. Although the number of annually defecated seeds was overwhelmingly the largest in Grewia triflora, many of the small seeds were often clumped in dung piles. In contrast, large seeds of V. beraviensis occurred in the largest number of dung samples. The rate and time of seed germination in V. beraviensis were improved by passage through brown lemur guts. Therefore, V. beraviensis may readily establish seedlings in sites of brown lemur fecal deposition. Vitex beraviensis and brown lemurs are probably involved in a strong mutualism. Twenty‐three large‐seeded plants were probably dependent on brown lemurs for seed dispersal and some of these species were common trees in the forest. Maintenance of these key plant–animal interactions will probably contribute to the conservation of species diversity and intact regeneration of the Ankarafantsika forest.     

Carrying Capacity and Potential Production of Ungulates for Human Use in a Mexican Tropical Dry Forest

Data are provided on the carrying capacity and potential production for sustainable human use of white-tailed deer ( Odocoileus virginianus ) and collared peccary ( Pecari tajacu ) in a protected tropical dry forest at Chamela on the Pacific coast of Mexico. In this paper, the carrying capacity was defined as the equilibrium density plus the number of animals removed by predators. The equilibrium point was estimated from the density dependent relationship between the finite population growth rate and the current density according to a logistic model. Annual density was estimated using the line transect method. Carrying capacity estimates were 16.5 to 17.2 deer/km² and 9.3–9.5 peccaries/km², representing a combined biomass of 841–874 kg/km². A potential production for human use of 2.1 deer/km² and 4.4 peccaries/km² was estimated employing the model of Robinson and Redford (1991) . The data suggest that, in the protected tropical dry forest of Chamela, the density and biomass of wild ungulates can maintain a similar or greater density and biomass than other Neotropical forests. To obtain an accurate estimation of the maximum sustainable yield ( MSY ), it is necessary to consider predation. From a management point of view, it is important to consider that carrying capacity varies as a function of the rainfall pattern.     

Seasonal Patterns of Flowering and Fruiting in a Dry Tropical Forest in Jamaica1

Tropical dry forests occupy more area and are more endangered than rainforests, yet their regeneration ecology has received less study and is consequently poorly understood. We recorded the flowering and fruiting phenology of a tropical dry forest in Jamaica over a period of 26 mo within ten 15 × 15‐m plots. Community‐wide recruitment reached a maximum in the wet season, whereas no recruitment occurred during the dry season. We observed a unimodal peak in rainfall and fruit production, and the periodicity and intensity of seed production were significantly correlated with rainfall seasonality (the optimal time for germination). Flowering at the community and system levels lagged behind a significant increase and subsequent decrease in rainfall by 7 and 3 mo, respectively, indicating that the dominant factor controlling flowering periodicity is the passage of the major (4‐mo long) rainy season and changes in soil moisture conditions. Fruiting lagged behind flowering by 2 mo and a significant increase in fruiting occurred 2 mo prior to a significant increase in rainfall. At the population level, a correspondence analysis identified a major dichotomy in the patterns of flowering and fruiting between species and indicated two broad species groups based on their time of peak fruiting and the number of times they were in fruit. These were either individuals which were usually in peak fruit 1–2 mo prior to the start of the major rainy season or those that were in fruit more or less continuously throughout the year with no peak fruiting time. This study supports the view that seasonal variation in rainfall and hence soil water availability constitutes both the proximate and the ultimate cause of flowering periodicity in tropical dry forests.