Sustainable management of non-timber forest products such as palm fruits is crucial for the long-term conservation of intact forest. A major limitation to expanding sustainable management of palms ...has been the need for precise information about the resources at scales of tens to hundreds of hectares, while typical ground-based surveys only sample small areas. In recent years, small unmanned aerial vehicles (UAVs) have become an important tool for mapping forest areas as they are cheap and easy to transport, and they provide high spatial resolution imagery of remote areas. We developed an object-based classification workflow for RGB UAV imagery which aims to identify and delineate palm tree crowns in the tropical rainforest by combining image processing and GIS functionalities using color and textural information in an integrative way to show one of the potential uses of UAVs in tropical forests. Ten permanent forest plots with 1170 reference palm trees were assessed from October to December 2017. The results indicate that palm tree crowns could be clearly identified and, in some cases, quantified following the workflow. The best results were obtained using the random forest classifier with an 85% overall accuracy and 0.82 kappa index.
The vast peat deposits in the Peruvian Amazon are crucial to the global climate. Palm swamp, the most extensive regional peatland ecosystem faces different threats, including deforestation and ...degradation due to felling of the dominant palm Mauritia flexuosa for fruit harvesting. While these activities convert this natural C sink into a source, the distribution of degradation and deforestation in this ecosystem and related C emissions remain unstudied. We used remote sensing data from Landsat, ALOS-PALSAR, and NASA's GEDI spaceborne LiDAR-derived products to map palm swamp degradation and deforestation within a 28 Mha area of the lowland Peruvian Amazon in 1990–2007 and 2007–2018. We combined this information with a regional peat map, C stock density data and peat emission factors to determine (1) peatland C stocks of peat-forming ecosystems (palm swamp, herbaceous swamp, pole forest), and (2) areas of palm swamp peatland degradation and deforestation and associated C emissions. In the 6.9 ± 0.1 Mha of predicted peat-forming ecosystems within the larger 28 Mha study area, 73% overlaid peat (5.1 ± 0.9 Mha) and stored 3.88 ± 0.12 Pg C. Degradation and deforestation in palm swamp peatlands totaled 535,423 ± 8,419 ha over 1990–2018, with a pronounced dominance for degradation (85%). The degradation rate increased 15% from 15,400 ha y−1 (1990–2007) to 17,650 ha y−1 (2007–2018) and the deforestation rate more than doubled from 1,900 ha y−1 to 4,200 ha y−1. Over 1990–2018, emissions from degradation amounted to 26.3 ± 3.5 Tg C and emissions from deforestation were 12.9 ± 0.5 Tg C. The 2007–2018 emission rate from both biomass and peat loss of 1.9 Tg C yr−1 is four times the average biomass loss rate due to gross deforestation in 2010–2019 reported for the hydromorphic Peruvian Amazon. The magnitude of emissions calls for the country to account for deforestation and degradation of peatlands in national reporting.
Display omitted
•The study area stores 3.88 ± 0.12 Pg C.•The degradation rate and deforestation rate of peatland palm swamps increased over the study period.•Over 1990–2018, emissions from degradation and deforestation amounted to 39.3 ± 3.5 Tg C.
Although tropical forests harbour most of the terrestrial carbon and biological diversity on Earth they continue to be deforested or degraded at high rates. In Amazonia, the largest tropical forest ...on Earth, a sixth of the remaining natural forests is formally dedicated to timber extraction through selective logging. Reconciling timber extraction with the provision of other ecosystem services (ES) remains a major challenge for forest managers and policy-makers. This study applies a spatial optimisation of logging in Amazonian production forests to analyse potential trade-offs between timber extraction and recovery, carbon storage, and biodiversity conservation. Current logging regulations with unique cutting cycles result in sub-optimal ES-use efficiency. Long-term timber provision would require the adoption of a land-sharing strategy that involves extensive low-intensity logging, although high transport and road-building costs might make this approach economically unattractive. By contrast, retention of carbon and biodiversity would be enhanced by a land-sparing strategy restricting high-intensive logging to designated areas such as the outer fringes of the region. Depending on management goals and societal demands, either choice will substantially influence the future of Amazonian forests. Overall, our results highlight the need for revaluation of current logging regulations and regional cooperation among Amazonian countries to enhance coherent and trans-boundary forest management.
The peat‐forming wetland forests of Amazonia are characterized by high below‐carbon stocks and supply fruit, fibres and timber to local communities. Predicting the future of these ecosystem services ...requires understanding how hydrological conditions are related to tree species composition and the presence, or absence, of peat. Here, we use continuous measurements of water table depth over 2.5 years and manual measurements of pore‐water pH and electrical conductivity to understand the ecohydrological controls of these variables across the large peatland complex in northern Peruvian Amazonia. Measurements were taken in permanent forest plots in four palm swamps, four seasonally flooded forests and four peatland pole forests. All trees ≥10 cm diameter were also measured and identified in the plots to assess floristic composition. Peat occurs in eight of these twelve sites; three seasonally flooded forests and one palm swamp are not associated with peat. Variation in tree species composition among forest types was linked to high flood levels (maximum flooding height) and pH: seasonally flooded forests experience high flood levels (up to 3.66 m from the ground surface) and have high pH values (6–7), palm swamps have intermediate flood levels (up to 1.34 m) and peatland pole forests experience shallow flooding (up to 0.28 m) and have low pH (4). In contrast, the presence of peat was linked to variation in maximum water table depth (i.e. the depth to which the water table drops below the ground surface). Surface peat is found in all forest types where maximum water table depth does not fall >0.55 m below the ground surface at any time. Peat formation and variation in tree species composition therefore have different ecohydrological controls. Predicted increases in the frequency and strength of flooding events may alter patterns of tree species composition, whereas increases in drought severity and declines in minimum river levels may pose a greater risk to the belowground carbon stores of these peatland ecosystems.
Dominance of neotropical tree communities by a few species is widely documented, but dominant trees show a variety of distributional patterns still poorly understood. Here, we used 503 forest ...inventory plots (93,719 individuals ≥2.5 cm diameter, 2609 species) to explore the relationships between local abundance, regional frequency and spatial aggregation of dominant species in four main habitat types in western Amazonia. Although the abundance‐occupancy relationship is positive for the full dataset, we found that among dominant Amazonian tree species, there is a strong negative relationship between local abundance and regional frequency and/or spatial aggregation across habitat types. Our findings suggest an ecological trade‐off whereby dominant species can be locally abundant (local dominants) or regionally widespread (widespread dominants), but rarely both (oligarchs). Given the importance of dominant species as drivers of diversity and ecosystem functioning, unravelling different dominance patterns is a research priority to direct conservation efforts in Amazonian forests.
Dominance of neotropical tree communities by a few species is widely documented, but dominant trees show a variety of distributional patterns still poorly understood. Contrary to the widely supported positive abundance‐occupancy relationship in ecology, we found that among dominant Amazonian tree species, there is a strong negative relationship between local abundance and regional frequency and/or spatial aggregation across habitat types. Our findings suggest an ecological trade‐off whereby dominant species can be locally abundant (local dominants) or regionally widespread (widespread dominants), but rarely both (oligarchs).
Various historical processes have been put forth as drivers of patterns in the spatial distribution of Amazonian trees and their population genetic variation. We tested whether five widespread tree ...species show congruent phylogeographic breaks and similar patterns of demographic expansion, which could be related to proposed Pleistocene refugia or the presence of geological arches in western Amazonia. We sampled Otoba parvifolia/glycycarpa (Myristicaceae), Clarisia biflora, Poulsenia armata, Ficus insipida (all Moraceae), and Jacaratia digitata (Caricaceae) across the western Amazon Basin. Plastid DNA (trnH–psbA; 674 individuals from 34 populations) and nuclear ribosomal internal transcribed spacers (ITS; 214 individuals from 30 populations) were sequenced to assess genetic diversity, genetic differentiation, population genetic structure, and demographic patterns. Overall genetic diversity for both markers varied among species, with higher values in populations of shade‐tolerant species than in pioneer species. Spatial analysis of molecular variance (SAMOVA) identified three genetically differentiated groups for the plastid marker for each species, but the areas of genetic differentiation were not concordant among species. Fewer SAMOVA groups were found for ITS, with no detectable genetic differentiation among populations in pioneers. The lack of spatially congruent phylogeographic breaks across species suggests no common biogeographic history of these Amazonian tree species. The idiosyncratic phylogeographic patterns of species could be due instead to species‐specific responses to geological and climatic changes. Population genetic patterns were similar among species with similar biological features, indicating that the ecological characteristics of species impact large‐scale phylogeography.
Our study includes thorough and relatively uniform sampling of populations of five widespread western Amazonian tree species across a wide geographic area covering most of western Amazonia. As such, it is the first comparative phylogeographic study of the trees of western Amazonia, which houses the world's most species‐rich forests. By using plastid and nuclear markers sampled in 34 locations across Ecuador, Peru, and Bolivia, we studied the geographic patterns of genetic differentiation to test for shared impact of past climatic and geological events. We did not find spatially congruent phylogeographic breaks across species suggesting no common biogeographic history of these Amazonian tree species. The idiosyncratic phylogeographic patterns of species could be due instead to species‐specific responses to geological and climatic changes. Population genetic patterns were similar among species with similar biological features, indicating that the ecological characteristics of species impact large‐scale phylogeography.
Patterns of gall‐inducing insect diversity tend to be influenced by both habitat‐related and plant‐related characteristics. We investigated the distribution patterns of galling insects in four ...vegetation types (terra firme forest, white‐sand dry forest, white‐sand wet forest and palm swamp forest) of the Peruvian Amazon to test if the insect gall diversity (1) differs among different types of vegetation and (2) depends on host plant richness. In total, we found 11,579 galls belonging to 249 insect gall morphotypes, distributed across 30 botanical families and 75 plant species. Among host plant families, Fabaceae showed the greatest richness of insect gall morphotypes. We found that galling species richness was lower in palm swamp forest than in white‐sand forests, which can be explained by the lower richness of plants in this type of vegetation. However, we found no evidence of greater richness in xeric habitats (e.g., white‐sand dry forest) than in more mesic vegetation (terra firme forest), contradicting the hypothesis of hygrothermal stress. We also found that plant species richness was positively influenced with the richness and abundance of galling species, regardless of vegetation type. Galling insect species composition differed significantly between vegetation types, similarly to the floristic composition. Our findings show that the diversity of galling insects in the tropical rainforests of Peruvian Amazon are mainly influenced by host plant composition and host plant richness.
in Spanish is available with online material.
Los patrones de diversidad de insectos inductores de agallas tienden a estar influenciados tanto por características relacionadas con el hábitat y las plantas. Investigamos los patrones de distribución de insectos inductores de agallas en cuatro tipos de vegetación (bosque de tierra firme, bosque seco de arena blanca, bosque húmedo de arena blanca y bosque de pantano de palmas) de la Amazonía peruana para evaluar si la diversidad de insectos inductores de agallas (1) difiere entre diferentes tipos de vegetación y (2) depende de la riqueza de las plantas hospederas. En total, encontramos 11,579 agallas pertenecientes a 249 morfotipos de insectos inductores de agallas, distribuidos en 30 familias botánicas y 75 especies de plantas. Entre las familias de plantas hospederas, Fabaceae mostró la mayor riqueza de morfotipos de insectos inductores de agallas. Encontramos que la riqueza de especies inductoras de agallas era menor en el bosque de pantano de palmas que en los bosques de arena blanca, lo cual puede explicarse por la menor riqueza de plantas en este tipo de vegetación. Sin embargo, no encontramos evidencia de una mayor riqueza en hábitats xéricos (por ejemplo, bosque seco de arena blanca) que en vegetación más mesica (bosque de tierra firme), contradiciendo la hipótesis del estrés higrotermal. También encontramos que la riqueza de especies de plantas fue positivamente influenciada por la riqueza y abundancia de especies inductoras de agallas, independientemente del tipo de vegetación. La composición de especies de insectos inductores de agallas difería significativamente entre los tipos de vegetación, de manera similar a la composición florística. Nuestros hallazgos muestran que la diversidad de insectos inductores de agallas en los bosques tropicales de la Amazonía peruana está principalmente influenciada por la composición y la riqueza de las plantas hospederas.
We found that galling species richness was lower in palm swamp forests than in white‐sand forests, which can be explained by the lower richness of plants in this type of vegetation. However, we found no evidence of greater richness in xeric habitats (e.g., white‐sand dry forest) than in more mesic vegetation (terra firme forest), contradicting the hypothesis of hygrothermal stress. Moreover, plant species richness was positively influenced by the richness and abundance of galling species. Galling insect species composition differed significantly between vegetation types, similar to the floristic composition.
When 2 Mha of Amazonian forests are disturbed by selective logging each year, more than 90 Tg of carbon (C) is emitted to the atmosphere. Emissions are then counterbalanced by forest regrowth. With ...an original modelling approach, calibrated on a network of 133 permanent forest plots (175 ha total) across Amazonia, we link regional differences in climate, soil and initial biomass with survivors' and recruits' C fluxes to provide Amazon-wide predictions of post-logging C recovery. We show that net aboveground C recovery over 10 years is higher in the Guiana Shield and in the west (21 ±3 Mg C ha-1) than in the south (12 ±3 Mg C ha-1) where environmental stress is high (low rainfall, high seasonality). We highlight the key role of survivors in the forest regrowth and elaborate a comprehensive map of post-disturbance C recovery potential in Amazonia.
PDF
