Tropical montane forests harbor high biodiversity and develop under heterogeneous topographic, climatic, and soil conditions. However, the influence of these environmental factors on their ecological dynamics remains poorly understood. This study was conducted to provide baseline information on the mechanisms underlying biodiversity in this complex mountain landscape. Specifically, we aimed to: (i) determine the floristic composition and forest structure of these ecosystems, and (ii) evaluate the effect of environmental gradients on species floristic composition and structural attributes in southern Ecuador. Across six localities, the tree community was sampled (composition, basal area, density, diameter, and maximum height) and edaphic, climatic, and topographic properties were characterized at the subplot level. Four discrete floristic groups and marked structural differences were identified among the evaluated forests. Environmental factors (mainly elevation and pH) explained a minor fraction of the floristic variation. In contrast, slope, elevation (associated with precipitation, temperature, and evapotranspiration gradients), and soil properties (depth, CEC, texture, and acidity) significantly modulated forest structure. We conclude that environmental factors determine density, biomass, and canopy height in these ecosystems. However, their weak influence on floristic composition suggests that community assembly is primarily mediated by biotic interactions or stochastic processes.
In this study parameters, correlations, and expected direct (DGg%) e indiretos (IGg%) genetic gains from mass selection and selection among progenies were estimated for growth, crown architecture, and reproductive traits in 105 open-pollinated Inga edulis progenies, 18 months old, established at three sites in the Peruvian Amazon, aiming at the simultaneous selection of multiple traits. Significant differences were detected among progenies for most traits within sites and joint sites. The estimation of narrow-sense heritabilities, mean-progeny heritability, and additive within progeny heritability showed that the traits are under genetic control and can be improved by mass selection or selection among progenies. The genotype-environment interaction was low for all traits, showing that selection can be carried out in only one of the site. The estimated genetic parameters were generally higher at site 1, indicating this site as more suitable for selection. The estimated genetic parameters were higher for diameter at breast height (D) in the joint site analysis, suggesting this trait as more suitable for direct selection. Genetic correlations were significantly greater than zero between D and the traits height, crown diameter, and fruit length, demonstrating that simultaneous genetic improvement of multiple traits is possible through direct selection for D. The greatest direct (DGg%) e indirect (IGg%) genetic gains were obtained through among and within progeny selection. The results show that crown architecture and reproductive traits can respond well to indirect selection based on direct selection for D.
Lianas, or woody climbers, are an important component of many tropical forests with fast growth responses to both natural environmental variations and human disturbances. Still, studies on their growth rate are rare to nonexistent. We sampled 22 specimens of Dalbergia frutescens, a liana that produces annual semi-porous growth rings in a secondary Atlantic Rainforest fragment in the megacity of S & atilde;o Paulo, Brazil. This forest fragment went through an intensive management of an exotic and invasive palm species, Archontophoenix cunninghamiana, that resulted in the removal of ca. 14 000 individuals in 2011 and 2012. We assessed the impacts of this management program on the growth of D. frutescens by measuring the tree-ring area in cross sections. Their ages ranged from 6 to 23 years old, and all samples had confluent rings. The occurrence of the confluent rings was not associated with any particular year, indicating that their formation is an intrinsic characteristic of this species. Despite the confluent rings, we successfully built a tree-ring basal area increment chronology spanning from 1995 to 2018. A piecewise regression indicated a growth release in 2014, right after the management of the palm trees. This study demonstrates the potential of tree-ring analysis in lianas as a valuable tool for detecting significant environmental changes and understanding the responses of lianas to natural and anthropogenic disturbances. These findings contribute to the broader understanding of tropical forest dynamics and the role of lianas in tracking ecological changes over time.
This study evaluated the efficacy of early selection in a secondgeneration Eucalyptus urophylla progeny trial by comparing three selection strategies: mass selection, combined selection (among and within families), and within-family selection. A randomized complete block design was used, comprising 23 progenies with 30 single-tree plot replicates. Diameter at breast height (DBH) and total height were measured annually from one to five years after planting. Early selection efficiency was tested for DBH at a selection intensity of 11.9% to compare the percentage of selected individuals across ages. The performance evaluated by the consistency of selected individuals across ages varied greatly. From the third year onward, the estimated proportion of consistently selected individuals reached 75%, indicating reliability of early selection for seed orchard establishment. Among the strategies, combined selection (among and within families) proved most effective at five years, yielding an estimated genetic gain of 6.3%.
Two new species of the Neotropical jumping plant-louse genus Mitrapsylla Crawford (Hemiptera: Psylloidea: Psyllidae: Ciriacreminae) are described from the highlands of the state of Minas Gerais in the Southeast Region of Brazil. Both species are associated with Chamaecrista (Fabaceae: Caesalpinioideae) and represent the first records of Psylloidea from this plant genus. Chamaecrista, especially its section Absus, has many species endemic to the Cerrado and Caatinga biomes in eastern Brazil. They are characterised by the presence of glandular trichomes that produce sticky secretion that hinders insect mobility and herbivory. Mitrapsylla burckhardtiella sp. nov. is unique within Mitrapsylla because of the long legs and rostrum in the adults and immatures, as well as the details of the tarsus, arolium and claws, the ventral position of the anus, the reduced sectasetae on the caudal plate and the presence of numerous long and thick capitate setae on dorsal sclerites and tubercles in the immatures. These character states are interpreted here as adaptations to living on young leaflets and stems of inflorescences of the densely hairy host plant Chamaecrista ursina, which may help to minimise contact with sticky exudates and camouflage the immatures on the surface of the host plant. In contrast, Mitrapsylla danieli sp. nov. associated with the sparsely haired Chamaecrista hedysaroides lacks these adaptations, and the morphology of adults and immatures is more similar to other Mitrapsylla spp. with non-sticky hosts. The phylogenetic relationships and systematic placement of the two new species within Mitrapsylla and other South American Ciriacreminae are also discussed on the basis of a phylogenetic analysis of the DNA sequences of the mitochondrial COI and cytb gene fragments, which we provide for the first time for four species of Mitrapsylla and two species of Queiroziella Burckhardt. As far as is known, M. burckhardtiella sp. nov. and M. danieli sp. nov. have a limited distribution in the highly diverse but threatened habitats of the Brazilian Cerrado and Campo Rupestre and may be of conservation importance, requiring further study.
