Scaling of stem and crown in eight Cecropia (Cecropiaceae) species of Brazil

The scaling of stem and crown was studied in eight Cecropia species in Amazonian and southeastern forests of Brazil. The Amazonian species, C. concolor; C. palmata, C. purpurascens, C. sciadophylla, and C. ulei were studied in Manaus, Amazonas, Brazil. The southeastern species, C. glaziovii, C. hololeuca, and C. pachystachya were studied in Linhares, Espirito Santo, Brazil. Measures of diameter, height, number of branches, number of leaves, and total leaf area were log transformed and regressed on height. Three models of mechanical designs of trees, elastic, constant stress, and geometric similarity, were tested for Cecropia. None of the models can totally describe Cecropia, but geometric similarity was a close approximation. Most of the species did not vary in diameter-height relationships between unbranched and branched individuals. Safety factors diminished with height in most species studied. The crown-height relationships were similar for all species. Numbers of branches and leaves showed some variation among species and are related to height of first branching. Total leaf area had a constant allometric relationship among species, although regression intercepts differed according to species leaf areas. The scaling relationships of stem and crown in Cecropia varied with adult size of the studied species.88593994

Architectural patterns of eight Cecropia (Cecropiaceae) species of Brazil

Architectural patterns of eight Cecropia species were studied in Amazonian and Southeastern Brazil. Height, diameter, height of first branching, number of branches and leaves, leaf area, internode length and branching ratio were measured for undamaged trees. The Amazonian species C. concolor; C. palmata, C. purpurascens, C. ulei and C. sciadophylla were studied in Manaus. Cecropia galziovii, C. hololeuca and C. pachyshachya were studied in Linhares, Espirito Santo. All except C. hololeuca and C. sciadophylla are myrmecophytes. In both areas, size and architectural characters are displayed as a gradient from open habitats to forest. Cecropia hololeuca and C. sciadophylla are common in forests and had similar architectures, with low branching ratios, and a height of first branch of around 9 m, about 3 m higher than the other species. The branching pattern of both species and the maximum height recorded (approximate to 20-25 m respectively) allow them to remain in the canopy longer than the other Cecropia species. Cecropia concolor and C. pachystachya measure up to 13 m in height and are typical of open habitats. The remaining species occupy forest margins and are intermediates between these two extremes.196321522

Shade trees and tree pruning alter throughfall and microclimate in cocoa (Theobroma cacao L.) production systems

Shade trees in agroforestry systems protect the understory cocoa from climate extremes. Shade tree pruning manages microclimatic conditions in favor of cocoa production while tree diversity is maintained. Adaptation of pruning has to consider seasonal changes in temperature and precipitation to protect the understory cocoa. Context Structural characteristics of tree stands such as species diversity, tree density, and stratification can affect throughfall and microclimate. Pruning changes the canopy and may therefore modulate internal conditions. Aims The aim of this study is to assess the environmental growing conditions of cocoa trees. Methods We monitored canopy openness and the impact of stand structure on throughfall and microclimate in three cocoa production systems (monoculture, agroforestry, and successional agroforestry) and a natural regrowth in a long-term trial in Bolivia from 2013 to 2015. We further focused on the effect of annual shade tree and cocoa pruning on these variables to evaluate the potential impact of this activity. Results Agroforestry systems buffered extreme climate events like temperature fluctuations compared to monocultures but reduced light and throughfall drastically. Spatial variability of throughfall and transmitted light were low under a high and closed shade tree canopy. Shade tree pruning resulted in higher canopy openness, light transmittance, and throughfall, while the buffer function of the agroforestry systems concerning temperature and humidity fluctuations was reduced. Conclusion Differences between cocoa production systems regarding throughfall and microclimate were overlain by pruning activities. Cocoa agroforestry systems are temporal dynamic systems. Pruning timing and intensity is pivotal for balancing light and water availability under seasonally varying environmental conditions to conserve micro-environments for cocoa production with less exposure to unfavorable climate