Allometric relationships of frequently used shade tree species in cacao agroforestry systems in Sulawesi, Indonesia

Abstract

Shade trees play an important role within agroforestry systems by influencing radiation and wind regimes as well as nutrient and hydrological cycling. However, there is a lack of quantitative assessments of their functions. One of the reasons is the rare information on structural characteristics of shade tree species. Therefore, the aim of this study is to provide basic information on the structure of frequently used shade tree species for the implementation of models simulating the ecosystem processes in agroforestry systems. The investigation of the shade trees was conducted at two cacao agroforestry sites on Sulawesi, Indonesia. The measurements of the main structural parameters: diameter at breast height, tree height, trunk height, crown length and crown radius were carried out for the shade tree species Aleurites moluccana, Cocos nucifera and Gliricidia sepium. For data collection, the National Forest Inventory Field Manual Template by FAO (2004) was applied. Based on this information allometric functions were derived for the correspondent shade tree species. The best significant relationships were obtained for the heightcrown length relationship of the dicotyledonous tree species' A. moluccana and G. sepium with a coefficient of determination r 2 = 0.925 and r 2 = 0.738, respectively, and the height-crown length relationship of the monocotyledonous palm C. nucifera with r 2 = 0.663. The transferability tests 'analysis of covariance' and 'homogeneity of slopes' have shown that the obtained allometric functions are also applicable to other cacao agroforestry systems of the region.

The spatial distribution and height of associated crops influence cocoa tree productivity in complex agroforestry systems

“…The tallest trees are much more competitive for light than species below (Coomes and Allen 2007). Indeed, the taller the trees, the larger the crown area (Tiralla et al 2013), and the larger the crown area, the more shade is provided below (Asante et al 2021). The intensity of the effect of the trait on the functioning of the system is hypothesized to depend on the spatial arrangement of the individuals, i.e., on the distance between them (Damour et al 2018;de Bello et al 2010).…”

Allometric relationships between stem diameter, height and crown area of associated trees of cocoa agroforests of Ghana

“…Thirdly, the fact that DBH was a better predictor of CA compared to H may be attributable to the fact that growth in tree height terminates when maximum height is attained while growth in diameter is indeterminate 11 , 19 , 21 . Since tree height terminates asymptotically at a point, it ceases to grow together with CA, possibly reducing its ability to predict CA, while DBH continues to grow together with CA, increasing its ability to predict CA.…”

“…3 – 6 ] are generally applied in agroforestry ecosystems [e.g., Refs. 7 – 11 ]. While generic equations provide a convenient approach for estimating tree attributes across a broad range of species, recent advances in ecological science emphasize the significance of species-specific equations.…”

“…Refs. 1 , 11 ]. Furthermore, it is laborious, expensive and difficult to measure tree crowns and heights in both cocoa agroforestry and forest ecosystems.…”

Adaptation and Participatory Evaluation of Shrub Forage Legumes in Highlands of Sud-Kivu, Democratic Republic of the Congo (DRC)

“…Yet multipurpose forage production is a major component in animal livestock systems to enhance animal production, to control erosions and protect the environment. Shade trees play an important role within the agroforestry systems by influencing radiation and wind regimes as well as nutrient and hydrological cycling [4]. This study aimed to use for adaptation, combined with farmers' participatory evaluation the improved shrub forage legumes previously tested by the International Center for Tropical Agriculture (CIAT) Colombia in tropical Central Asia and Latin America whose ecological conditions are similar to those in DRC.…”