Breeding territory selection in Prothonotary Warblers (Protonotaria citrea (Boddaert, 1783)) is thought to hinge on standing water, with a strong preference for low-lying areas prone to seasonal ...flooding. However, we have observed this species nesting in much drier areas than previously reported. We recently initiated a study of the Carolina Wren (Thryothorus ludovicianus (Latham, 1790)) using wooden nest boxes, and nearly 60% of all nests produced in these boxes during the initial study year were produced by Prothonotary Warblers, despite this species being absent from our field site during the year preceding nest-box availability. Most nests were produced in dense, closed-canopy forest with a thick shrub layer >100 m from any water body. There was no difference in the mean distance from water between nests of the Prothonotary Warbler and those of the Carolina Wren, a habitat generalist that does not nest over water. We then observed a 60% increase in the number of Prothonotary Warbler nests the following year, along with significant increases in breeding productivity. Although they nested on sites that they are not thought to prefer, our observations suggest that Prothonotary Warblers may nest in drier areas than usual if appropriate nest cavities are provided.
Photochemical processes in ambient air were studied using the atmospheric simulation chamber SAPHIR at Forschungszentrum Jülich, Germany. Ambient air was continuously drawn into the chamber through a ...50 m high inlet line and passed through the chamber for 1 month in each season throughout 2019. The residence time of the air inside the chamber was about 1 h. As the research center is surrounded by a mixed deciduous forest and is located close to the city Jülich, the sampled air was influenced by both anthropogenic and biogenic emissions. Measurements of hydroxyl (OH), hydroperoxyl (HO.sub.2 ), and organic peroxy (RO.sub.2) radicals were achieved by a laser-induced fluorescence instrument. The radical measurements together with measurements of OH reactivity (k.sub.OH, the inverse of the OH lifetime) and a comprehensive set of trace gas concentrations and aerosol properties allowed for the investigation of the seasonal and diurnal variation of radical production and destruction pathways. In spring and summer periods, median OH concentrations reached 6 x 10.sup.6 cm.sup.-3 at noon, and median concentrations of both HO.sub.2 and RO.sub.2 radicals were 3 x 10.sup.8 cm.sup.-3 . The measured OH reactivity was between 4 and 18 s.sup.-1 in both seasons. The total reaction rate of peroxy radicals with NO was found to be consistent with production rates of odd oxygen (O.sub.x = NO.sub.2 + O.sub.3) determined from NO.sub.2 and O.sub.3 concentration measurements. The chemical budgets of radicals were analyzed for the spring and summer seasons, when peroxy radical concentrations were above the detection limit. For most conditions, the concentrations of radicals were mainly sustained by the regeneration of OH via reactions of HO.sub.2 and RO.sub.2 radicals with nitric oxide (NO). The median diurnal profiles of the total radical production and destruction rates showed maxima between 3 and 6 ppbv h.sup.-1 for OH, HO.sub.2, and RO.sub.2 . Total RO.sub.X (OH, HO.sub.2, and RO.sub.2) initiation and termination rates were below 3 ppbv h.sup.-1 . The highest OH radical turnover rate of 13 ppbv h.sup.-1 was observed during a high-temperature (max. 40 .sup." C) period in August. In this period, the highest HO.sub.2, RO.sub.2, and RO.sub.X turnover rates were around 11, 10, and 4 ppbv h.sup.-1, respectively. When NO mixing ratios were between 1 and 3 ppbv, OH and HO.sub.2 production and destruction rates were balanced, but unexplained RO.sub.2 and RO.sub.X production reactions with median rates of 2 and 0.4 ppbv h.sup.-1, respectively, were required to balance their destruction. For NO mixing ratios above 3 ppbv, the peroxy radical reaction rates with NO were highly uncertain due to the low peroxy radical concentrations close to the limit of NO interferences in the HO.sub.2 and RO.sub.2 measurements. For NO mixing ratios below 1 ppbv, a missing source for OH and a missing sink for HO.sub.2 were found with maximum rates of 3.0 and 2.0 ppbv h.sup.-1, respectively. The missing OH source likely consisted of a combination of a missing inter-radical HO.sub.2 to OH conversion reaction (up to 2 ppbv h.sup.-1) and a missing primary radical source (0.5-1.4 ppbv h.sup.-1). The dataset collected in this campaign allowed analyzing the potential impact of OH regeneration from RO.sub.2 isomerization reactions from isoprene, HO.sub.2 uptake on aerosol, and RO.sub.2 production from chlorine chemistry on radical production and destruction rates. These processes were negligible for the chemical conditions encountered in this study.
In forests, the residence time of air - the inverse of first-order exchange rates - influences in-canopy chemistry and the exchanges of momentum, energy, and mass with the surrounding atmosphere. ...Accurate estimates are needed for chemical investigations of reactive trace species, such as volatile organic compounds, some of whose chemical lifetimes are on the order of average residence times. However, very few observational residence-time estimates have been reported. Little is known about even the basic statistics of real-world residence times or how they are influenced by meteorological variables such as turbulence or atmospheric stability. Here, we report opportunistic investigations of residence time of air in a free-air carbon dioxide enrichment (FACE) facility in a mature, broadleaf deciduous forest with canopy height of h.sub.c â25 m. Using nearly 50 million FACE observations, we find that median daytime residence times in the tree crowns range from around 70 s when the trees are in leaf to just over 34 s when they are not. Residence times increase with increasing atmospheric stability, as does the spread around their central value. Residence times scale approximately with the reciprocal of the friction velocity, u.sub.â . During some calm evenings in the growing season, we observe distinctly different behaviour: pooled air being sporadically and unpredictably vented - evidenced by sustained increases in CO.sub.2 concentration - when intermittent turbulence penetrates the canopy. In these conditions, the concept of a residence time is less clearly defined. Parameterisations available in the literature underestimate turbulent exchange in the upper half of forest crowns and overestimate the frequency of long residence times. Robust parameterisations of residence times (or, equivalently, fractions of emissions escaping the canopy) may be generated from inverse-gamma distributions, with the parameters 1.4less than or equal toαless than or equal to1.8 and β=hc/uâ estimated from widely measured flow variables. In this case, the mean value for Ï becomes formally defined as Ï-=β/(α-1). For species released in the canopy during the daytime, chemical transformations are unlikely unless the reaction timescale is on the order of a few minutes or less.
Introducción. Los municipios de San Sebastián del Oeste y Mascota, parte del territorio del Paisaje Biocultural de Sierra Occidental de Jalisco (PBSOJ), presentan una diversidad de ecosistemas como ...el bosque de pino-encino (BP-E), bosque mesófilo de montaña (BMM), bosque tropical caducifolio (BTC) y bosque de galería (BG) (Aragón-Parada et al., 2021). Como parte del subproyecto de ríos, se propone la implementación de sistemas agroforestales basados en tipos de vegetación nativa, incluyendo especies de la NOM-059-SEMARNAT-2010 (Acosta-Pérez, 2021). Este modelo permitirá establecer y fortalecer prácticas que reconozcan y promuevan la resiliencia de los ecosistemas a través de la conservación y el manejo productivo. Objetivo. Generar modelos regionales para el programa de Unidades de Producción Agroforestal ProSAF en el territorio PBSOJ. Métodos. A través de entrevistas etnográficas, recorridos y colectas etnobotánicas, talleres participativos diagnósticos y revisión bibliográfica; se trabaja en la generación de diferentes modelos agroforestales. Para la generación de modelos se toman en cuenta además dos criterios: La implementación de las especies vegetales nativas en el sitio a intervenir será de, por lo menos, 80% (Fisher-Ortíz et al., 2021). Se deberá incluir una o varias de las 10 especies vegetales con alguna categoría de riesgo de la NOM 059 2010 DE SEMARNAT, contempladas en el marco del subproyecto de ríos. Resultados y discusión. Se proponen los siguientes modelos ProSAF adaptados a microrregiones y actividades productivas: BP-E forestal, BMM cafetal bajo sombra, BMM Solar, BTC de restauración, BTC solar y BG como modelo de amortiguamiento para su posterior implementación en parcelas demostrativas en el territorio del PBSOJ. Conclusiones. Los modelos propuestos son importantes ya que son modelos socialmente aceptados, pues integran la agrobiodiversidad de la región aunado al conocimiento tradicional y de manejo sobre el paisaje, así como la conservación de especies nativas amenazadas.
The annual patterns of precipitation in the dry deciduous forest of Madagascar are characterized by a dry season when the majority of trees lose their leaves and a wet season with full foliage ...development. Such variation allows the examination in shifts in the vertical distribution of birds and to their response to changing environmental conditions. Patterns of birds in the dry deciduous forest of Kirindy CNFEREF, central western Madagascar, were analyzed related to the vertical variation of vegetation structure and microclimate during 2 study periods: the dry (24 Aug to 16 Sep 2017) and wet seasons (25 Jan to 17 Feb 2018). Six line transects in forest habitat of 1,000 m each were used to survey birds, and each was associated with linear sampling to quantify vegetation structure. Data loggers were employed to record temperature and relative humidity across the vertical strata. During the dry season, associated with the microclimate aridity and reduction in vegetation cover in the upper strata, the number of species and individual birds found on the ground increased. During the wet season, fewer birds occurred on the ground, and abundance and species richness increased in the canopy. These results show the sensitivity of birds with regard to environmental fluctuations. However, regardless of the season, birds frequented mainly the mid-story, which had the highest abundance of species as compared to upper and lower vertical strata. Received 25 July 2020. Accepted 4 August 2021.
A multitude of disturbance agents, such as wildfires, land use, and climate‐driven expansion of woody shrubs, is transforming the distribution of plant functional types across Arctic–Boreal ...ecosystems, which has significant implications for interactions and feedbacks between terrestrial ecosystems and climate in the northern high‐latitude. However, because the spatial resolution of existing land cover datasets is too coarse, large‐scale land cover changes in the Arctic–Boreal region (ABR) have been poorly characterized. Here, we use 31 years (1984–2014) of moderate spatial resolution (30 m) satellite imagery over a region spanning 4.7 × 106 km2 in Alaska and northwestern Canada to characterize regional‐scale ABR land cover changes. We find that 13.6 ± 1.3% of the domain has changed, primarily via two major modes of transformation: (a) simultaneous disturbance‐driven decreases in Evergreen Forest area (−14.7 ± 3.0% relative to 1984) and increases in Deciduous Forest area (+14.8 ± 5.2%) in the Boreal biome; and (b) climate‐driven expansion of Herbaceous and Shrub vegetation (+7.4 ± 2.0%) in the Arctic biome. By using time series of 30 m imagery, we characterize dynamics in forest and shrub cover occurring at relatively short spatial scales (hundreds of meters) due to fires, harvest, and climate‐induced growth that are not observable in coarse spatial resolution (e.g., 500 m or greater pixel size) imagery. Wildfires caused most of Evergreen Forest Loss and Evergreen Forest Gain and substantial areas of Deciduous Forest Gain. Extensive shifts in the distribution of plant functional types at multiple spatial scales are consistent with observations of increased atmospheric CO2 seasonality and ecosystem productivity at northern high‐latitudes and signal continental‐scale shifts in the structure and function of northern high‐latitude ecosystems in response to climate change.
Climate change and disturbances are rapidly altering Arctic–Boreal land cover, but such changes are poorly quantified, confounding studies of northern high‐latitude change. We used multidecadal time series of 30 m satellite remote sensing to map and quantify areas of vegetation change across NASA's Arctic–Boreal Vulnerability Experiment (ABoVE), spanning much of western Canada and Alaska, and found that 13% of the domain experienced land cover change. Fire and logging drove net declines of Evergreen Forest area by 15%, while post‐disturbance recovery expanded Deciduous Forest area by 15% and climate warming expanded Shrub and Herb area by 7%.
Although richness and distribution of woody species in the Cerrado physiognomies have been extensively studied, the shifts of woody species from savanna physiognomies to dry forests have not yet been ...addressed. Here, we investigate the effect of soil physical-chemical traits on the woody species turnover between adjacent cerrado stricto sensu and dry forest physiognomies. Woody species were surveyed, and soil and topographic variables measured, in 30 10*40 m plots systematically distributed, with 15 plots in each physiognomy. We found a spatially structured distribution of woody species, and differences of soil traits between cerrado stricto sensu and dry forest areas, mainly related to the aluminum saturation, base saturation, and available phosphorus. Aluminum saturation increased toward the savanna area, while base saturation increased toward the dry forest. Most woody species predominated in one physiognomy, such as Callisthene major in the cerrado stricto sensu and Anadenanthera colubrina in the dry forest. Only 20% of the species were widely distributed across both physiognomies or, not often, restricted to the intermediary values of the soil gradient. General results indicate that contrasting soil traits between cerrado stricto sensu and dry forest produce a strongly spatially organized and sharp transition in terms of species distribution between these physiognomies.
The longevity of a single 22.4 Mg * ha.sup.-1 application of dolomitic limestone at four northern hardwood stands was evaluated over 30 years (1986-2016) to determine whether changes in soils, ...foliage, and tree growth were sustained on the unglaciated Allegheny Plateau in northern Pennsylvania, USA. In limed plots, soils, sampled to 45-55 cm depth, and sugar maple (Acer saccharum Marsh.) and black cherry (Prunus serotina Ehrh.) foliage had significantly (P less than or equal to 0.05) greater concentrations of calcium (Ca) and magnesium (Mg) through 2016 compared with samples from unlimed plots. Ca and Mg capitals (g * m.sup.-2) in the Oi through A horizons combined were greater on limed plots than unlimed plots, largely due to increases in the thickness and nutrient concentration in the A horizon. Over 30 years, sugar maple basal area increment (cm.sup.2 * year.sup.-1 BAINC) was greater in limed plots (30.6 cm.sup.2 * year.sup.-1 vs unlimed 13.3), American beech (Fagus grandifolia Ehrh.) BAINC was unaffected by lime application, and black cherry BAINC was reduced in limed plots compared with unlimed plots. The sustained effect of this one-time lime treatment shows the strong role of efficient nutrient cycling in forests and suggests that the benefits over a substantial portion of a stand rotation may increase the feasibility of operational liming.
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