•Aerosol fluxes over a forest showed a strong seasonal and size-dependent variation.•Leaf-presence drove fine particles deposition and ultrafine particles emission.•Deposition velocity of ultrafine ...and fine particles correlated with leaf area index.•Plant stomatal activity seemed to influence the emission of ultrafine particles.•Deposition of accumulation mode aerosols was related to impaction processes.
Eddy covariance measurements of aerosol fluxes were performed above an oak-hornbeam forest in the Po Plain (Northern Italy), from February to May and from September to December 2019. Measurements aimed at assessing the influence of forest phenology and leaf presence/absence on the seasonal evolution of size-segregated aerosol fluxes. The size-resolved aerosol concentration in the range 0.006-10 μm was sampled with a 14-stage impactor (ELPI+, Dekati, FI), and the filters exposed in May were subjected to chemical analysis. Over the whole sampling period, the forest removed from the atmosphere an average of 3.12 mg of aerosol m−2 d−1. The direction and the intensity of the aerosol fluxes were not constant through the year, as a strong seasonal and size-dependent variability emerged. In particular, leaf-presence drove a net deposition of the accumulation mode aerosol (100 nm< particle diameter Dp<1000 nm) and an emission of the Aitken (10 nm< Dp<100 nm) and coarse mode (Dp>1000 nm) aerosols. On the contrary, in absence of leaves all the sub-micrometer aerosol size-classes showed net daily upward fluxes, while coarse mode aerosol fluxes were prevalently downward. Monthly averages of deposition velocities of Aitken and accumulation mode aerosols correlated with the Leaf Area Index (LAI) seasonal trend, thus indicating an important role of the amount of the leaf surface area on the deposition and emission of these size-classes. Furthermore, an influence of the stomatic activity was suggested for the Aitken mode aerosol, since its deposition velocity followed the same diel course of the stomatal conductance to water. The analysis of the influence of meteorological parameters on aerosol deposition velocities highlighted that dynamic and convective turbulence (described by friction velocity, u* and Deardorff velocity, w*) enhanced the vertical aerosol exchanges, both upward and downward, while the approaching of condensing conditions reduced the flux intensities.
Resprouting of non-native tree invaders is a threat to tropical montane cloud forests and particularly to periurban forests. Resprouting is a common response of trees to disturbance in many ...ecosystems; however, little is known about the resprouting of woody exotic species with shade-tolerant characteristics that can slowly invade those forests. Furthermore, resprouting of woody invaders is a complex challenge for the control of invasive species since it is a major driver of reinvasion and persistence. In this study, we focus on the resprouting ability of a potential invader, Eriobotrya japonica, in a periurban cloud forest reserve of Xalapa, Mexico. We experimentally cut trees and juveniles in the secondary forest and clipped seedlings at the forest edge, and assessed resprout number, dimensions, emergence position, survival, and leaves per resprout. We then determined foliar traits of the newly produced leaves (leaf area (LA), specific leaf area (SLA), leaf mass area (LMA), leaf dry mass content (LDMC), and thickness). Our results show that resprouting occurred within a month in both tree stumps and clipped seedlings. Resprout survival was 50-80% in stumps, and 63-88% in clipped seedlings. Resprouts were produced mostly in the upper 5 cm below the cut. Leaf number was positively related to dimensions of the longest resprout. Some leaf traits of E. japonica were similar to those of shade-tolerant trees, but there is a combination of strategies since the species presents higher LA and thicker leaves than other native tree species, yet its LMA and LDMC are within the range presented by shade-tolerant species. Eriobotrya japonica is a woody invasive that partly behaves as a shade-tolerant tree and resprouts profusely and rapidly from stumps and clipped seedlings. Its resprouting ability is therefore a key trait by which to explain the invasive potential of this woody species.
Remnants of Semideciduous Atlantic Forest surrounded by numerous industries, intense road traffic and agricultural lands in Southeast Brazil have been affected by trace elements. We implemented a ...passive biomonitoring with the three most abundant native tree species (Astronium graveolens, Croton floribundus and Piptadenia gonoacantha) to answer these questions: 1) which species has the greatest potential to accumulate trace elements?; 2) does the leaf accumulation level of trace elements vary between the edge and interior of the forest remnants, between dry and wet periods or due to the distance from the industrial area?; 3) which species, among the most abundant in the forest remnants, would better indicate the spatial variations in trace elements pollution and which elements would be the most relevant for such spatial discrimination? Leaf samples were collected during the dry and wet seasons, at the edge and interior of four forest remnants. Trace elements were determined using inductively coupled plasma mass spectrometry (ICP MS). Few edge effects were evidenced in the leaf concentrations in all species. Higher concentrations of most trace elements were measured during dry season. Although C. floribundus showed the most accumulating capacity, A. graveolens was the most appropriate species to discriminate spatial variations. The forest closer to the industrial area was distinguished from the others by Mn and Ni from oil burning, but the metal pollution from the industrial area did not interfere on the leaf concentrations in A. graveolens sampled in the urban and rural forests.
•Leaves of Croton floribundus showed higher content of most trace elements.•Astronium graveolens better indicated spatial variations of trace element pollution.•Higher leaf contents of trace elements were observed during the dry season.•The trace element leaf contents of closest forest was influenced by industrial area.•There were no clear edge effects on the trace element leaf contents.
In outskirts of Kinshasa, the capital of the Democratic Republic of Congo, increasing anthropic pressure on the periurbans forest ecosystems threat the perenniality of the goods and services that ...they are able to furnish. Shifting agriculture, bush fires and production of wood-energy are the leading causes. In nine villages of the Batéké Plateau, the Makala project (European project of sustainable management of the wood-energy resource project, 2009-2013) accompanied more than 180 farmers in the implementation of assisted natural regeneration. In order to restore the forest fallow, it appeared convenient to study the composition of recruitment, in particular for Albizia adianthifolia, a local leguminous tree with rapid growth, used for the restoration of the soil fertility and the production of wood-energy. An inventory of natural regeneration (seedlings, stump sprouts) were carried out initially. It was supplemented by a preliminary test of rootsuckering induction. The observations show that the saplings result from basal sprouts and rootsuckers; the seedlings are almost non-existent. The major impact of agricultural practises and of bush fires is underlined. These factors must most probably support the regeneration of this species at the expense of others not having the same capacities of vegetative propagation in condition of post-farming fallows.
Urbanization processes increased dramatically in the past century leading to the emission of large quantities of air pollutants over relatively small areas. The consequent high concentration of ...pollutants and particulate matter (PM) have clear detrimental effects not only on human health, but also on urban and peri-urban vegetation. In this context, the Castelporziano Presidential Estate, a protected natural area located at the southeastern edge of the large conurbation of Rome (Italy), represents an ideal site to study the interaction between vegetation and atmospheric pollutants. Here we present an overview of the international field campaigns carried out in Castelporziano during the past 20 years, and of the ongoing research activities aimed to understanding the role of the estate in the provision of ecosystem services to the Metropolitan area of Rome. The exposure and potential detrimental effects of air pollutants such as tropospheric ozone and PM on natural vegetation have been assessed, investigating also the potential capacity of vegetation to ameliorate air quality under Mediterranean climatic condition. The results show that a correct assessment of the Ecosystem Services (ESs) provided by Mediterranean vegetation must consider the functional strategies that different species adopt to cope with drought stress, including the species-specific response of stomatal conductance to atmospheric water pressure difference, as well as the length of the drought period and its inter annual variability. Our results highlight the need to adopt managements strategies to mainten and implement the ESs provided by the important peri-urban natural area of Castelporziano.
Periurban forests are key to offsetting anthropogenic carbon emissions, but they are under constant threat from urbanization. In particular, secondary Neotropical forest types in Andean periurban ...areas have a high potential to store carbon, but are currently poorly characterized. To address this lack of information, we developed a method to estimate periurban aboveground biomass (AGB)-a proxy for multiple ecosystem services-of secondary Andean forests near Bogotá, Colombia, based on very high resolution (VHR) GeoEye-1, Pleiades-1A imagery and field-measured plot data. Specifically, we tested a series of different pre-processing workflows to derive six vegetation indices that were regressed against in situ estimates of AGB. Overall, the coupling of linear models and the Ratio Vegetation Index produced the most satisfactory results. Atmospheric and topographic correction proved to be key in improving model fit, especially in high aerosol and rugged terrain such as the Andes. Methods and findings provide baseline AGB and carbon stock information for little studied periurban Andean secondary forests. The methodological approach can also be used for integrating limited forest monitoring plot AGB data with very high resolution imagery for cost-effective modelling of ecosystem service provision from forests, monitoring reforestation and forest cover change, and for carbon offset assessments.
In France and in Europe, periurban forests are subject to high social demands for recreational purposes. These demands take the form of frequent visits for sports or rest. Local governments have ...succeeded in creating new wooded parks close to cities that are highly appreciated by the population. A survey was run on visitors to forests around three mid-sized cities, addressing what they do in the forests and why. The answers revealed differences between suburban parks and larger national forests located farther from the cities. New approaches targeting health may also be observed on the part of both individuals and the health sector. These new approaches indicate the existence of a wellness function in periurban forests.
En France, les espaces boisés périurbains font l'objet d'une forte demande sociale en tant qu'espaces récréatifs. Ces nouvelles demandes sont exprimées notamment par des pratiques ...renouvelées,sportives ou de ressourcement. De leur côté, les collectivités territoriales ont su aménager de nouveaux espaces forestiers plus proches des villes, très appréciés des habitants. Des usagers ont été interviewés dans les espaces boisés de trois villes moyennes, sur leurs usages et sur la justification de ces pratiques. Cela a permis de préciser des différences entre les espaces boisés suburbains et les forêts domaniales plus vastes mais plus éloignées des villes. De même, on observe l'émergence d’un nouvel usage lié à la santé, tant au niveau des individus qu’au niveau des établissements de soins.Ces nouvelles pratiques conduisent à considérer les espaces forestiers périurbains comme des espaces prophylactiques.
In France and in Europe, periurban forests are subject to high social demands for recreationalpurposes. These demands take the form of frequent visits for sports or rest. Local governmentshave succeeded in creating new wooded parks close to cities that are highly appreciated by thepopulation. A survey was run on visitors to forests around three mid-sized cities, addressingwhat they do in the forests and why. The answers revealed differences between suburban parksand larger national forests located farther from the cities. New approaches targeting health mayalso be observed on the part of both individuals and the health sector. These new approachesindicate the existence of a wellness function in periurban forests.
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