How do urban forests compare? Tree diversity in urban and periurban forests of the southeastern US

Es necesario comprender cómo las influencias antropogénicas afectan la diversidad forestal urbana y periurbana a escala regional. Este estudio tiene como objetivo comparar la composición de los árboles urbanos y periurbanos a lo largo de un gradiente geográfico, y probar hipótesis sobre la composición de especies y la homogeneidad ecológica. Combinamos datos de bosques urbanos (UF) de ocho ciudades del sureste de los EE. UU. Con datos de bosques periurbanos (PF) del programa de Análisis e Inventario Forestal del Servicio Forestal del USDA. Encontramos que la diversidad de árboles, así como los valores de riqueza de especies observados y estimados, fueron mayores en UF versus PF. El análisis de la estructura del tamaño de la comunidad también indicó una mayor proporción de árboles grandes y un mayor número de especies de árboles no nativas, invasoras y no clasificadas en la UF frente a la PF, independientemente de la ubicación. Tanto el tipo de bosque como la provincia ecológica tuvieron un efecto significativo en la composición de especies de la comunidad, ya que los bosques más cercanos en el espacio son más similares entre sí que los más distantes. Si bien el cambio y el manejo del uso de la tierra se han asociado con la homogeneización ecológica en paisajes dominados por humanos, descubrimos que la composición de las especies era más diferente a lo largo de las líneas latitudinales que entre los tipos de bosque, refutando esta hipótesis, al menos en términos de diversidad de árbolesThere is a need to understand how anthropogenic influences affect urban and periurban forest diversity at the regional scale. This study aims to compare urban and periurban tree composition along a geographic gradient, and test hypotheses about species composition and ecological homogeneity. We paired urban forest (UF) data from eight cities across the southeastern US with periurban forest (PF) data from the USDA Forest Service Forest Inventory and Analysis program. We found that tree diversity, as well as both observed and estimated species richness values were greater in UF versus PF. Community size structure analysis also indicated a greater proportion of large trees and greater numbers of non-native, invasive, and unclassified tree species in the UF versus the PF, regardless of location. Both forest type and ecological province had a significant effect on community species composition, with forests closer together in space being more similar to each other than those more distant. While land use change and management has been associated with ecological homogenization in human dominated landscapes, we found that species composition was more dissimilar along latitudinal lines than compared to between forest types, refuting this hypothesis, at least in terms of tree diversit

Nut production in Bertholletia excelsa across a logged forest mosaic: implications for multiple forest use

Although many examples of multiple-use forest management may be found in tropical smallholder systems, few studies provide empirical support for the integration of selective timber harvesting with non-timber forest product (NTFP) extraction. Brazil nut (Bertholletia excelsa, Lecythidaceae) is one of the world’s most economically-important NTFP species extracted almost entirely from natural forests across the Amazon Basin. An obligate out-crosser, Brazil nut flowers are pollinated by large-bodied bees, a process resulting in a hard round fruit that takes up to 14 months to mature. As many smallholders turn to the financial security provided by timber, Brazil nut fruits are increasingly being harvested in logged forests. We tested the influence of tree and stand-level covariates (distance to nearest cut stump and local logging intensity) on total nut production at the individual tree level in five recently logged Brazil nut concessions covering about 4000 ha of forest in Madre de Dios, Peru. Our field team accompanied Brazil nut harvesters during the traditional harvest period (January-April 2012 and January-April 2013) in order to collect data on fruit production. Three hundred and ninety-nine (approximately 80%) of the 499 trees included in this study were at least 100 m from the nearest cut stump, suggesting that concessionaires avoid logging near adult Brazil nut trees. Yet even for those trees on the edge of logging gaps, distance to nearest cut stump and local logging intensity did not have a statistically significant influence on Brazil nut production at the applied logging intensities (typically 1–2 timber trees removed per ha). In one concession where at least 4 trees ha-1 were removed, however, the logging intensity covariate resulted in a marginally significant (0.09) P value, highlighting a potential risk for a drop in nut production at higher intensities. While we do not suggest that logging activities should be completely avoided in Brazil nut rich forests, when a buffer zone cannot be observed, low logging intensities should be implemented. The sustainability of this integrated management system will ultimately depend on a complex series of socioeconomic and ecological interactions. Yet we submit that our study provides an important initial step in understanding the compatibility of timber harvesting with a high value NTFP, potentially allowing for diversification of forest use strategies in Amazonian Perù

Forest Biodiversity Assessment in Peruvian Andean Montane Cloud Forest

Cloud forests are unusual and fragile habitats, being one of the least studied and least understood ecosystems. The tropical Andean dominion is considered one of the most significant places in the world as rega rds biological diversity, with a very high level of endemism. The biodiversity was analysed in an isolated remnant area of a tropical montane cloud forest known as the ?Bosque de Neblina de Cuyas?, in the North of the Peruvian Andean range. Composition, structure and dead wood were measured or estimated. The values obtained were compared with other cloud forests. The study revealed a high level of forest biodiversity, although the level of biodiversity differs from one area to another: in the inner areas, where human pressure is almost inexistent, the biodiversity values increase. The high species richness and the low dominance among species bear testimony to this montane cloud forest as a real enclave of biodiversity

Assessing methods for comparing species diversity from disparate data sources : the case of urban and peri-urban forests

Multi-scale forest inventory and monitoring data are increasingly being used in studies assessing forest diversity, structure, disturbance, and carbon dynamics. Also, local-level urban forest inventories are providing plot data and protocols to study tree diversity and ecosystem services in urban forests worldwide. But, differences in the sampling methods underlying these disparate protocols and data sources is a non-trivial concern in formulating comparative analyses. We assess commonly used methods for comparing tree diversity in peri-urban and urban forests when available data have different sample sizes, plot sizes, and sampling intensities. We present methods for appropriately evaluating species richness, as well as methods for comparing species distributions via community data matrices. Using permanent plot data from the southeastern United States, we present a case study comparing urban and peri-urban forests along a north–south gradient, and assessing species richness and the ecological homogenization hypothesis. Our findings indicate that comparisons of tree species richness among communities, or forest types, are often inconclusive since commonly used sample sizes do not provide precise estimates of the number of species present. While the ecological homogenization hypotheses can be tested under conditions of unequal sampling effort, we suggest robust methods such as PERMANOVA and the Raup-Crick dissimilarity index. A framework for selecting appropriate methods is also discussed. As forests are increasingly being altered by anthropogenic drivers, future studies using disparate data sources must account for differences in measurements and sampling protocols in order to produce results that are both statistically defensible and useful for science-based management. © 2018 The Authors

Assessing methods for comparing species diversity from disparate data sources : the case of urban and peri-urban forests

Multi-scale forest inventory and monitoring data are increasingly being used in studies assessing forest diversity, structure, disturbance, and carbon dynamics. Also, local-level urban forest inventories are providing plot data and protocols to study tree diversity and ecosystem services in urban forests worldwide. But, differences in the sampling methods underlying these disparate protocols and data sources is a non-trivial concern in formulating comparative analyses. We assess commonly used methods for comparing tree diversity in peri-urban and urban forests when available data have different sample sizes, plot sizes, and sampling intensities. We present methods for appropriately evaluating species richness, as well as methods for comparing species distributions via community data matrices. Using permanent plot data from the southeastern United States, we present a case study comparing urban and peri-urban forests along a north–south gradient, and assessing species richness and the ecological homogenization hypothesis. Our findings indicate that comparisons of tree species richness among communities, or forest types, are often inconclusive since commonly used sample sizes do not provide precise estimates of the number of species present. While the ecological homogenization hypotheses can be tested under conditions of unequal sampling effort, we suggest robust methods such as PERMANOVA and the Raup-Crick dissimilarity index. A framework for selecting appropriate methods is also discussed. As forests are increasingly being altered by anthropogenic drivers, future studies using disparate data sources must account for differences in measurements and sampling protocols in order to produce results that are both statistically defensible and useful for science-based management. © 2018 The Authors

Evaluación de daños y escombros provocados por el huracán en los bosques urbanos de Florida

A random 10% sample of communities in highly-impacted counties from the 2004 and 2005 Florida, U.S. hurricane seasons were used to study tree debris generation and damage from seven hurricanes. Woody debris amounts in cubic meters (m3 ) (cubic yards; yd3 ) as well as rates and costs for cleanup, tree removal and pruning were obtained for these events. Average debris generation per 30.5 m (100 ft) of street segment ranged from 0.59 m3 (0.77 yd3 ) for low damage, 3.4 m3 (4.44 yd3 ) for moderate damage, and 17.47 m3 (22.85 yd3 ) for high damage levels; cost of removal and disposal averaged $28.25 per m3 ($21.47 per yd3 ). Most communities used unit costing to account for tree removal and pruning rates, averaging 2% and 28% of street trees, respectively. Tree canopy, wind speed, and percentage of urban developed land all had a significant effect on debris amount. Florida communities with a greater tree density generated decreased amounts of debris during the 2004 and 2005 hurricane season. These results can be used to help communities plan for hurricane management activities and estimate potential damages to their tree resource

Biomasa de árboles, rendimiento de residuos de madera y cambios en el almacenamiento de carbono en un bosque urbano

Urban tree biomass studies are important for estimating urban wood waste yield, carbon sequestration, and other ecosystem goods provided by urban forests. This study quantified urban tree wood waste yield and temporal changes in carbon storage for different land uses using data from permanent monitoring plots and locally developed urban tree and regional allometric biomass equations. Drivers influencing wood waste yields and carbon (C) sequestration were analyzed as was accuracy of available urban tree C storage models. We estimated annual urban tree stem and crown biomass removals at 2 Mega grams (Mg) per hectare, equivalent to approximately 5% of the annual requirements of a 100 MegaWatt bioenergy plant. Urban tree C storage changes, or annual C sequestration, was 29,280 Mg which is equivalent to 5% of all anthropogenic local C emissions in 2008 and twice as much as estimated by an available carbon sequestration model. Greater amounts of wood waste were generated in forests and commercial/institutional areas than residential areas, but differences were not significant and amount removed was only significantly related to the amount of impervious surfaces and maintained grass. Available urban tree C storage models can have errors of 40%. Results can be used to estimate the potential annual supply of city-wide urban wood waste from management, maintenance, land clearing activities, and post-hurricane tree debris removal. Wood waste can be a sustainable urban forest ecosystem service and good; but tradeoffs such as esthetics, soil quality and community preferences should be accounted for as well