The diversity and floristic composition of a primeval forest was studied, located in the district of Yambrasbamba–Bongará–Amazonas, delimiting a 1 ha area, and at an altitude of 1890 m.a.s.l. All individuals with diameter at breast height (DBH) ≥ 10 cm were inventoried. The plant diversity in the area was measured and a description of its composition and floristic structure was made. The following were recorded: a total of 640 trees distributed in 39 families, 60 genera and 152 species. The value of the Simpson’s index (D) was 0.974 and that of the Shannon–Wiener index was 4.264, indicating that the species had a high abundance of individuals. In turn, Fisher’s alpha value (α) was 23.744, indicating a regular diversity in montane forests in relation to different altitudinal gradients. The families with the highest number of individuals were Melastomataceae, Rubiaceae, Euphorbiaceae, Phyllanthaceae, and Lauraceae. The most abundant species were Alchornea acutifolia Müll.Arg. with 47 individuals (7.34%), Chimarrhis glabriflora Ducke with 39 individuals (6.09%), Hieronyma alchorneoides Allemão with 39 individuals (6.09%), and Cyathea lasiosora (Kuhn) Domin with 33 individuals (5.16%). A comparative analysis was carried out of plots of montane and premontane forests, and the studied plot presented had the third-highest register of families and genera, behind the plots studied in the provinces of Oxapampa and Chanchamayo.

The genus Cinchona L. has important medicinal, cultural, and economic value and is the emblematic tree of Peru. The genus is mainly found in the cloud forests of the Andes. However, the expansion of agriculture and livestock farming in the department of Amazonas is degrading these ecosystems and has reduced the size of the genus’s populations. In this work, we model the potential distribution under current conditions of three Cinchona species (C. capuli L. Anderson, C. macrocalyx Pav. Ex DC., and C. pubescens Vahl.) to identify areas with a high likelihood of species presence and their key conservation and reforestation zones. We fitted a maximum entropy (MaxEnt) model using nineteen bioclimatic variables, three topographic variables, nine edaphic variables, and solar radiation. Under current conditions, the potential distribution of C. capuli covers 17.22% (7243.98 km²); C. macrocalyx, 29.11% (12,238.91 km²); and C. pubescens, 22.94% (9647.63 km²) of the study area, which was mostly located in central and southern Amazonas. Only 24.29% (25.51% of C. capuli, 21.02% of C. macrocalyx, and 26.35% of C. pubescens) of the potential distributions are within protected areas, while 10,987.22 km² of the surface area of the department of Amazonas is degraded, of which 29.80% covers the area of probable occurrence of C. capuli, 38.72% of C. macrocalyx, and 34.82% of C. pubescens. Consequently, it is necessary to promote additional conservation strategies for Cinchona, including the establishment of new protected areas and the recovery of degraded habitats, in order to protect this species.

In this study, we present the species of the genus Gynoxys recorded in the department of Amazonas, Peru. From March 2021 to October 2023, a review of exsiccata preserved in national herbaria, virtual databases of international herbaria, and field collections in different localities was carried out. We report 22 species of Gynoxys in Amazonas, of which two are new records for Peru and six are first reports for Amazonas. The genus is mainly distributed in the southern part of the department, inhabiting mainly moorlands and high altimontane forests of the Yungas, mostly located above 2900 meters above sea level (m a.s.l). En este estudio presentamos las especies del género Gynoxys registrados en el departamento de Amazonas, Perú. Desde marzo del 2021 hasta octubre del 2023 se realizó un trabajo de revisión de exsicatas conservados en herbarios nacionales, base de datos virtuales de herbarios internacionales y colectas de campo en diferentes localidades. Se reporta 22 especies de Gynoxys en Amazonas, de los cuales dos son registros nuevos para Perú y seis son primeros reportes para Amazonas. El género muestra una distribución principalmente en la zona sur del departamento, habitando principalmente en páramos y bosques altimontanos de las Yungas, situados mayormente por sobre los 2900 m s.n.m.

Forests at the altitudinal limits between seasonally dry tropical forests (SDTF) and montane forests in northeastern Peru are key for biodiversity and ecological connectivity. Sixteen 0.1-ha plots were surveyed along a 1900–2700 m a.s.l. gradient, recording 133 species, 76 genera, and 47 families, reflecting high floristic heterogeneity. Diversity indices showed a unimodal pattern, peaking in the transition zone between 2300 and 2500 m (Hill_q1 = 22.36; Hill_q2 = 15.92; estimated richness = 49 species). Diversity decreased at lower SDTF elevations (1900–2100 m) and higher montane sites (>2500 m), likely due to thermal and water limitations. Species dominance shifted along the gradient: Vachellia aroma and Inga adenophylla dominated SDTF, whereas Aiouea montana , Clethra revoluta , and Ilex scopulorum characterized montane forests. Beta diversity revealed pronounced species replacement and highlighted plot S08 as an ecotone with species from both ecosystems. Diameter-class distributions followed an inverted “J” pattern, indicating active regeneration in both ecosystems, with higher recruitment in SDTF. Altitude drives species replacement and shapes a unimodal diversity pattern. We recommend restoring dominant SDTF species, such as Vachellia aroma and Inga adenophylla , in degraded lower-elevation areas, and conserving ecotonal belts as altitudinal corridors to enhance biodiversity and climate resilience areas, and conserving ecotonal belts as 32 altitudinal corridors to enhance biodiversity and climate resilience.

In this research, species distribution prediction models (i.e., MaxEnt) were applied to analyze the suitability of the ecological environment among the clades of the genus Gynoxys in Peru. Bioclimatic, edaphic, and topographic variables were integrated to predict the areas with the most significant potential for optimal development of this genus. These data were combined to generate potential distribution maps, taking into account the most relevant variables for each clade. The validation of the MaxEnt model showed an outstanding performance, reaching AUC indices above 0.9, reflecting the high accuracy of the predictions. The results reveal that the key variables influencing the selection of the clade occurrence areas are: mintempwarmest (47.70% contribution) in the Discoide clade, topowet (33.20%) in the Gynoxys clade, and monthcountbytemp10 (33.30%) in the Praegynoxys clade. The potential distribution areas of these clades were 132,594 km² for Discoide, 168,574 km² for Gynoxys, and 37,392 km² for Praegynoxys. The areas with the highest probability of presence of the genus were found in the Andean regions of northern and central Peru. However, a significant proportion of these areas were threatened by habitat fragmentation and land degradation. In terms of conservation, it was found that 32.05, 35.46, and 61.02% of the potential distribution areas of the discoid, Gynoxys, and Praegynoxys clades, respectively, are conserved, which could be a relevant factor for the preservation of this genus. These findings underscore the relevance of safeguarding key areas for conserving Gynoxys and montane ecosystems in Peru, emphasizing the need for protection strategies that guarantee the long-term sustainability of these species and their associated habitats.