Canopy Types Research Articles

Tree—Open Grassland Structure and Composition Drive Greenhouse Gas Exchange in Holm Oak Meadows of the Iberian Peninsula

Iberian holm oak meadows are savannah-like ecosystems that result from traditional silvo-pastoral practices. However, such traditional uses are declining, driving changes in the typical tree—open grassland structure of these systems. Yet, there are no studies integrating the whole ecosystem—including the arboreal and the herbaceous layer—as drivers of greenhouse gas (GHG: CO2, CH4 and N2O) dynamics. Here, we aimed at integrating the influence of tree canopies and interactions among plant functional types (PFT: grasses, forbs, and legumes) of the herbaceous layer as GHG exchange drivers. For that purpose, we performed chamber-based GHG surveys in plots dominated by representative canopy types of Iberian holm oak meadows, including Quercus species and Pinus pinea stands, the last a common tree plantation replacing traditional stands, and unraveled GHG drivers through a diversity-interaction model approach. Our results show the tree–open grassland structure, especially drove CO2 and N2O fluxes, with higher emissions under the canopy than in the open grassland. Emissions under P. pinea canopies are higher than those under Quercus species. In addition, the inclusion of diversity and compositional terms of the herbaceous layer improve the explained variability, with legumes enhancing CO2 uptake and N2O emissions. Changes in the tree cover and tree species composition, in combination with changes in the structure and composition of the herbaceous layer, will imply deep changes in the GHG exchange of Iberian holm oak meadows. These results may provide some guidelines to perform better management strategies of this vast but vulnerable ecosystem.

Shrub canopy interception of diaspores dispersed by wind

AbstractInterception by plant canopies during wind dispersal can affect the final destination of diaspores. However, how the interaction of wind speed, canopy type and diaspore attributes affects interception of diaspores by the plant canopy has rarely been studied. We investigated canopy interception for 29 species with different diaspore attributes, six canopy types and six wind speeds in controlled experiments in a wind tunnel. Shrub canopy interception of diaspores were controlled by wind speed and diaspore attributes, but the latter had a greater influence on canopy interception than the former. At low wind speed, diaspore wing loading had a large influence on canopy interception, whereas at high wind speed, diaspore projection area had a large influence. The chance of canopy interception at a particular wind speed was additionally affected by the type of canopy. This study increases our knowledge of the dispersal process, corrects the previous understanding of diaspore dispersal potential and improves the theoretical basis for predicting spatial pattern and dynamics of plant populations.

The Environment and Textile Industry-Friendly Hirsute Cotton Variety, Indica

A short statured variety Indica with open type of canopy that matured in 130 days yielded 2246 kg of seed cotton ha-1 with better quality of fibres than the other popular varieties MCU5, MCU5 VT and Surabhi which recorded 6.50 to 12.15% lesser yield in the village farms with lower quality of fibres than Indica. The bleached fibres of variety Indica were brighter white in colour with lower tinge of yellowness than the other varieties. Upon dyeing with a blue and a red reactive dye to 0.5% shade, the uptake of dyes by Indica was more than the other varieties and it left lesser dye in the dye bath irrespective of the dye. The variety MCU 5VT recorded the lowest dye uptake and left more dye residue in the dye bath as compared to the other varieties. The dyed fibres of Indica were darkest in colour with better colour strength than the other varieties which may save some dye costs for the textile industries since a darker colour can be produced with lesser amount of dye. Since Indica left least residual dye, dye effluent from this variety will cause lesser damage to the environment and soil. It may also help the Textile industries to spend less on treatment of dye effluent as lesser quantity of residual dye is likely to be present in it. Use of this cotton variety may thus reduce the overall dyeing costs and make the garments made out of the fibres of this variety to cost less than the other popular cotton varieties.

Characteristics of Bird Nestling Trees in the Padang State University, West Air Tawar, West Sumatera

The purpose of this research is to describe the characteristic of the tree as birds nesting at State University of Padang , West Air Tawar, West Sumatra. This research conducted on March 2019. Data collection was using survey method. The results showed that found 14 species of tree is using by birds to nesting. The characteristic of tree is preferable by birds to using for nesting are tree and pole growth rate, monopodium and simpodium branching type, with round, oval and fountain canopy type, model leeuwenberg, attims and corner architecture model.

One-dimensional models of radiation transfer in heterogeneous canopies: a review, re-evaluation, and improved model

Abstract. Despite recent advances in the development of detailed plant radiative transfer models, large-scale canopy models generally still rely on simplified one-dimensional (1-D) radiation models based on assumptions of horizontal homogeneity, including dynamic ecosystem models, crop models, and global circulation models. In an attempt to incorporate the effects of vegetation heterogeneity or “clumping” within these simple models, an empirical clumping factor, commonly denoted by the symbol Ω, is often used to effectively reduce the overall leaf area density and/or index value that is fed into the model. While the simplicity of this approach makes it attractive, Ω cannot in general be readily estimated for a particular canopy architecture and instead requires radiation interception data in order to invert for Ω. Numerous simplified geometric models have been previously proposed, but their inherent assumptions are difficult to evaluate due to the challenge of validating heterogeneous canopy models based on field data because of the high uncertainty in radiative flux measurements and geometric inputs. This work provides a critical review of the origin and theory of models for radiation interception in heterogeneous canopies and an objective comparison of their performance. Rather than evaluating their performance using field data, where uncertainty in the measured model inputs and outputs can be comparable to the uncertainty in the model itself, the models were evaluated by comparing against simulated data generated by a three-dimensional leaf-resolving model in which the exact inputs are known. A new model is proposed that generalizes existing theory and is shown to perform very well across a wide range of canopy types and ground cover fractions.

Coarse Woody Debris’ Invertebrate Community is Affected Directly by Canopy Type and Indirectly by Thinning in Mixed Scots Pine—European Beech Forests

Research Highlights: Thinning and tree species alter the forest floor microclimate by modifying canopy cover, radiation, wind, and humidity. Thus, forest management can directly influence the edaphic mesofauna responsible for decomposing coarse woody debris (CWD). Background and Objectives: This research was carried out in the Southwestern Pyrenees Mountains (Northern Spain) and aimed to determine the influence of forest thinning and canopy type (pure Pinus sylvestris L. or a mix of P. sylvestris and Fagus sylvatica L.) on CWD colonization by edaphic fauna. Materials and Methods: CWD samples were collected belonging to intermediate and advanced decomposition stages, approximately 10 cm long and 5 cm in diameter. Using a design of three thinning intensities (0%, 20%, and 40% of basal area removed), with three replications per treatment (nine plots in total), four samples were taken per plot (two per canopy type) to reach 36 samples in total. Meso- and macrofauna were extracted from CWD samples with Berlese–Tullgren funnels, and individuals were counted and identified. Results: 19 taxonomic groups were recorded, the most abundant being the mesofauna (mites and Collembola). Mixed canopy type had a significant positive influence on richness, whereas advanced decay class had a positive significant influence on total abundance and richness. In addition, there were non-significant decreasing trends in richness and abundance with increasing thinning intensity. However, interactions among thinning intensity, canopy type, and decay class significantly affected mesofauna. Furthermore, some taxonomic groups showed differential responses to canopy type. CWD water content was positively correlated with total invertebrate abundance and some taxonomic groups. Our results suggest that stand composition has the potential to directly affect invertebrate communities in CWD, whereas stand density influence is indirect and mostly realized through changes in CWD moisture. As mesofauna is related to CWD decomposition rates, these effects should be accounted for when planning forest management transition from pure to mixed forests.

Phenology affects differentiation of crop and weed species using hyperspectral remote sensing

AbstractThe effect of plant phenology and canopy structure of four crops and four weed species on reflectance spectra were evaluated in 2016 and 2017 using in situ spectroscopy. Leaf-level and canopy-level reflectance were collected at multiple phenologic time points in each growing season. Reflectance values at 2 wk after planting (WAP) in both years indicated strong spectral differences between species across the visible (VIS; 350–700 nm), near-infrared (NIR; 701–1,300 nm), shortwave-infrared I (SWIR1; 1,301–1,900 nm), and shortwave-infrared II (SWIR2; 1,901–2,500 nm) regions. Results from this study indicate that plant spectral reflectance changes with plant phenology and is influenced by plant biophysical characteristics. Canopy-level differences were detected in both years across all dates except for 1 WAP in 2017. Species with similar canopy types (e.g., broadleaf prostrate, broadleaf erect, or grass/sedge) were more readily discriminated from species with different canopy types. Asynchronous phenology between species also resulted in spectral differences between species. SWIR1 and SWIR2 wavelengths are often not included in multispectral sensors but should be considered for species differentiation. Results from this research indicate that wavelengths in SWIR1 and SWIR2 in conjunction with VIS and NIR reflectance can provide differentiation across plant phenologies and, therefore should be considered for use in future sensor technologies for species differentiation.

Detecting Vegetation Recovery after Fire in A Fire-Frequented Habitat Using Normalized Difference Vegetation Index (NDVI)

Research Highlights: Fire-frequented savannas are dominated by plant species that regrow quickly following fires that mainly burn through the understory. To detect post-fire vegetation recovery in these ecosystems, particularly during warm, rainy seasons, data are needed on a small, temporal scale. In the past, the measurement of vegetation regrowth in fire-frequented systems has been labor-intensive, but with the availability of daily satellite imagery, it should be possible to easily determine vegetation recovery on a small timescale using Normalized Difference Vegetation Index (NDVI) in ecosystems with a sparse overstory. Background and Objectives: We explore whether it is possible to use NDVI calculated from satellite imagery to detect time-to-vegetation recovery. Additionally, we determine the time-to-vegetation recovery after fires in different seasons. This represents one of very few studies that have used satellite imagery to examine vegetation recovery after fire in southeastern U.S.A. pine savannas. We test the efficacy of using this method by examining whether there are detectable differences between time-to-vegetation recovery in subtropical savannas burned during different seasons. Materials and Methods: NDVI was calculated from satellite imagery approximately monthly over two years in a subtropical savanna with units burned during dry, dormant and wet, growing seasons. Results: Despite the availability of daily satellite images, we were unable to precisely determine when vegetation recovered, because clouds frequently obscured our range of interest. We found that, in general, vegetation recovered in less time after fire during the wet, growing, as compared to dry, dormant, season, albeit there were some discrepancies in our results. Although these general patterns were clear, variation in fire heterogeneity and canopy type and cover skewed NDVI in some units. Conclusions: Although there are some challenges to using satellite-derived NDVI, the availability of satellite imagery continues to improve on both temporal and spatial scales, which should allow us to continue finding new and efficient ways to monitor and model forests in the future.

Effects of decadal experimental drought and climate extremes on vegetation growth in Mediterranean forests and shrublands

AbstractIncreased drought combined with extreme episodes of heatwaves is triggering severe impacts on vegetation growth, particularly for plant communities in arid and semiarid ecosystems. Although there is an abundance of short‐term field drought experiments in natural ecosystems, remaining knowledge gaps limit the understanding and prediction of vegetation growth to ongoing and future climate scenarios. Here, we assessed the impacts of long‐term (1999–2016) experimental drought (ca. −30% rainfall) on the vegetation growth of a Mediterranean high (H) and low (L)‐canopy forests and an early‐successional shrubland, as indicated by above‐ground biomass increment (ABI) and standing density, respectively. We found habitat context (impact of historical climate change, soil depth and successional status) of the study sites significantly affected the magnitude of climate impacts; there were synergistic effects of experimental drought and meteorological drought (Standardised Precipitation–Evapotranspiration Index, SPEI) as well as extreme dry years on vegetation growth. Long‐term experimental drought decreased the ABI for the two forest canopy types and the standing density for the shrubland. Water availabilities in winter–spring (SPEIs) were positively correlated with the ABI and standing density. Moreover, experimental drought decreased the vegetation growth in extreme dry years for the shrubland. We propose that future work not only study the vegetation dynamics with physiological, phenological and demographical changes in long‐term processes and across climate gradients, but also should explore the changes of multiple functions simultaneously (e.g. multifunctionality) under long‐term processes and extremes. This type of analysis of long‐term data is essential to understand and predict biodiversity loss, composition shifts, declines in ecosystem function and carbon budgets at temporal and spatial scales, to enable policy makers to design and implement strategies for the maintenance of sustainable ecosystem function under future climate change scenarios.

Multi-Scale Evaluation of the TSEB Model over a Complex Agricultural Landscape in Morocco

An accurate assessment of evapotranspiration (ET) is crucially needed at the basin scale for studying the hydrological processes and water balance especially from upstream to downstream. In the mountains, this term is poorly understood because of various challenges, including the vegetation complexity, plant diversity, lack of available data and because the in situ direct measurement of ET is difficult in complex terrain. The main objective of this work was to investigate the potential of a Two-Source-Energy-Balance model (TSEB) driven by the Landsat and MODIS data for estimating ET over a complex mountain region. The complexity is associated with the type of the vegetation canopy as well as the changes in topography. For validating purposes, a large-aperture scintillometer (LAS) was set up over a heterogeneous transect of about 1.4 km to measure sensible (H) and latent heat (LE) fluxes. Additionally, two towers of eddy covariance (EC) systems were installed along the LAS transect. First, the model was tested at the local scale against the EC measurements using multi-scale remote sensing (MODIS and Landsat) inputs at the satellite overpasses. The obtained averaged values of the root mean square error (RMSE) and correlation coefficient (R) were about 72.4 Wm−2 and 0.79 and 82.0 Wm−2 and 0.52 for Landsat and MODIS data, respectively. Secondly, the potential of the TSEB model for evaluating the latent heat fluxes at large scale was investigated by aggregating the derived parameters from both satellites based on the LAS footprint. As for the local scale, the comparison of the latent heat fluxes simulated by TSEB driven by Landsat data performed well against those measured by the LAS (R = 0.69, RMSE = 68.0 Wm−2), while slightly more scattering was observed when MODIS products were used (R = 0.38, RMSE = 99.8 Wm−2). Based on the obtained results, it can be concluded that (1) the TSEB model can be fairly used to estimate the evapotranspiration over the mountain regions; and (2) medium- to high-resolution inputs are a better option than coarse-resolution products for describing this kind of complex terrain.

Underground deserts below fertility islands? Woody species desiccate lower soil layers in sandy drylands

Woody plants in water‐limited ecosystems affect their environment on multiple scales: locally, natural stands can create islands of fertility for herb layer communities compared to open habitats, but afforestation has been shown to negatively affect regional water balance and productivity. Despite these contrasting observations, no coherent multiscale framework has been developed for the environmental effects of woody plants in water‐limited ecosystems. To link local and regional effects of woody species in a spatially explicit model, we simultaneously measured site conditions (microclimate, nutrient availability and topsoil moisture) and conditions of regional relevance (deeper soil moisture), in forests with different canopy types (long, intermediate and short annual lifetime) and adjacent grasslands in sandy drylands. All types of forests ameliorated site conditions compared to adjacent grasslands, although natural stands did so more effectively than managed ones. At the same time, all forests desiccated deeper soil layers during the vegetation period, and the longer the canopy lifetime, the more severe the desiccation in summer and more delayed the recharge after the active period of the canopy. We conclude that the site‐scale environmental amelioration brought about by woody species is bound to co‐occur with the desiccation of deeper soil layers, leading to deficient ground water recharge. This means that the cost of creating islands of fertility for sensitive herb layer organisms is an inevitable negative impact on regional water balance. The canopy type or management intensity of the forests affects the magnitude but not the direction of these effects. The outlined framework of the effects of woody species should be considered for the conservation, restoration or profit‐oriented use of forests as well as in forest‐based carbon sequestration and soil erosion control projects in water‐limited ecosystems.

A field experimental study on the impact of Acer platanoides, an urban tree invader, on forest ecosystem processes in North America

BackgroundInvasive species affect community dynamics and ecosystem functions, but the mechanisms of their impacts are poorly understood. Hypotheses on invasion impact range from Superior Competitor to Novel Function, from Enemy Escape to Microbial Mediation. In this study, we examined the effects of an urban tree invader, Acer platanoides (Norway maple, NM), on a mesic deciduous forest in contrast to its native congener Acer rubrum (red maple, RM) with a split-plot design experiment. A total of 720 maple seedlings were transplanted to 72 plots under 24 trees of three canopy types. The three experimental treatments were removal of resource competition at above- and belowground and removal of leaf-litter effect. Soil moisture and nitrogen-related microbial activities were followed for each plot.ResultsWe found that partial canopy removal increased canopy openness and light transmission to the forest floor, but to a greater extent under NM than under RM trees. NM seedlings were more shade tolerant than RM seedlings in height growth. During the reciprocal transplantation in the mixed forest, biomass accumulation of NM seedlings under RM trees were twice as much as under NM, while that of RM seedlings under NM trees was 23.5% less than under RM. Soil net nitrification and relative nitrification were significantly higher, but mineralization rate was much lower under NM than under RM trees, which would lead to faster N leaching and lower N availability in the soil. Plots with litter removal had significantly higher seedling mortality due to herbivory by the end of 2 years, especially for NM seedlings under NM trees. Trenching enhanced soil water availability but there was no difference among canopy types.ConclusionsOur results demonstrated that invasion of NM not only altered forest canopy structure but also changed herbivory rate for seedlings and N dynamics in the soils. NM seedlings were more shade tolerant under NM canopies than RM seedlings and were more protected by NM litter under NM canopies than under RM canopies. These altered biotic and abiotic environments will likely facilitate further invasion of NM in the forests, hence positive feedbacks, and make it an increasingly serious tree invader in North America.

STUDI HABITAT BUAYA SENYULONG (Tomistoma schlegelii) DI SUNGAI SEKONYER TAMAN NASIONAL TANJUNG PUTING KALIMANTAN TENGAH

Senyulong (Tomistoma schlegelii) are crocodiles that have a unique morphology with shape of the snout in its mouth. This species based on IUCN Red List classified by endangered category (IUCN 2004). This study aim to determine characteristics ofSenyulong Habitat in Sekonyer river, Tanjung Puting National Park Central Kalimantan using by Purposive Sampling in discovery spot or ex crocodile nest, Parameter analyzed by important value index (INP), dominance index (C), index species diversity (H), species abundance index (e), and species similarity index. The results showed the abiotic water habitats in the river water pH 6 which indicated normal, an average of depth 4.5 meters and a water temperature 23.90 ºC. Biotically False Gharial likes the habitat of aquatic plants such as Rasau (Pandanus tectorious), water lily (Hanguana malayana) for sheltering. False gharial aquatic food habitats such as Toman fish (Channa gachua), Gabus (Channa striata) and Runtuk (Channa luchius) Baung (Mystus wyckii), Lais (Lais hexamena). Abiotically terrestrial habitats contain sandy clay texture and histosol soil types with 6 soil acidity, with 78% air humidity and the average temperature of 29ºC. Biologically, Senyulong terrestrial habitat formed by buffer zone with large tree with wide canopy and several types of terrestrial animals Senyulong food such as long-tailed monkeys, orangutans, and wild pigs. The terrestrial habitat of False Gharial is an important place to spawning ground by placing its eggs under a large buttress tree and covering the nest with leaf litter to keep it warm to camouflage egg predators such as to monitor lizards.Keyword: Terrestrial Habitat, Aquatic Habitat, Senyulong, Tanjung puting National Park

Wildfire‐Smoke Aerosols Lead to Increased Light Use Efficiency Among Agricultural and Restored Wetland Land Uses in California's Central Valley

AbstractThere are few observational studies measuring the ecosystem‐scale productivity effects of changes in incident diffuse photosynthetically active radiation (PARdiffuse), especially related to wildfire smoke. Climate change‐induced increases to the duration and intensity of fire conditions have made smoke a common occurrence across western North America, with largely unquantified ecosystem feedbacks. Under equivalent amounts of radiation, increased atmospheric particulate matter could lead to a boost in productivity as scattering redistributes photons throughout multilayer canopies. In this work, we leverage a meso‐network of eddy covariance measurement sites across a unique array of managed and restored C3 and C4 canopy types to understand how recent wildfire smoke affected ecosystem productivity during the summer of 2018, an especially smoky year in the agriculturally productive Central Valley. We find that diffuse PARdiffuse increased by more than a third compared to the previous growing season, while total PAR was only slightly diminished. These conditions caused nearly a doubling of light use efficiency over the range of diffuse fraction observed, with the highest sensitivity to diffuse fraction exhibited by corn and alfalfa crops. We utilized an empirical model to assess the trade‐off between enhanced diffuse fraction and reduced total PAR. Under mean radiation conditions, daily integrated gross ecosystem productivity increased by 1.2–4.2% compared to the previous growing season. Finally, we explore the potential negative effect of heightened ozone, a copollutant often associated with wildfire. In addition to the effects of wildfire smoke, the results of this natural experiment can help validate future predictions of aerosol‐productivity feedbacks.

KEANEKARAGAMAN JENIS BURUNG DI KAWASAN PENYANGGA TAMAN HUTAN RAYA SULTAN SYARIF HASYIM PROVINSI RIAU

The existence and spread of birds are closely related to the availability of food and habitat for birds while showing the existence of an individual or group of individuals. Species of birds and how the spread of bird species is based on habitat in the buffer zone of Tahura Sultan Syarif Hasyim. The method used is to use the Point Count method while calculating existing vegetation using anveg (vegetation analysis). The composition of birds in various vegetation cover is divided into 2 namely secondary forest and agroforestry land, in secondary forests there are 292 individuals, 41 species, 25 families from 9 orders while on agroforestry land there are 213 individuals, 25 species, 16 families of 6 orders. Thus, in the buffer zone of Tahura Sultan Syarif Hasyim, there were 505 individuals, 48 ​​species, 28 families of 10 orders with diversity included in the category of "High Diversity" with a value of 3.54, in the distribution of 14 species of land species, 27 types of lower canopy, 37 types of middle canopy and 26 types of top canopy.

Design and Selection Criteria of Main Parachute for Re entry Space Payload

Parachutes are used as a decelerator in the re-entry, descent, and landing of space recovery payloads, providingstability and desired descent rate for a safe landing. The selection of the main parachute is the most critical andimportant part of the space module recovery system. Parachute size is restricted by the required landing speed,materials, and weight of the payload. Parachute materials are selected based on the various forces experienced bythe parachute. An investigation has been carried out to design a parachute system which gives less impact velocity, less angle of oscillation and less impact load for the landing of a crew module. Therefore, in this paper, selection criteria for the main parachute have been discussed considering recovery of re-entry space payload of 500 kg (unmanned) and 3500 kg (manned) class. Based on analysis carried out on the parachute size, canopy filling time, velocity reduction, peak deceleration, and opening shock, authors have proposed a unique type of solid canopy with slots (slots of the minimum area equivalent to geometry porosity) for the main parachute rather than a complex ringsail or disk-band type canopy. With this new concept, the parachute has been designed, developed and qualified through testing, trials and maiden flight of space capsule in LEO and is propose to use in the next manned space mission program.

Small-mammal abundance differs between pipelines, edges, and interior boreal forest habitat

Oil and gas development alters boreal forests by creating early-successional habitat and an increased amount of edge. We evaluated which small-mammal species used pipeline rights of way, the influence of vegetation recovery on pipelines, and edge effects in the adjacent forest. Meadow voles (Microtus pennsylvanicus (Ord, 1815)) were the most common species on pipelines, whereas adjacent forest was dominated by southern red-backed voles (Myodes gapperi (Vigors, 1830)), northern red-backed voles (Myodes rutilus (Pallas, 1779)), and North American deer mice (Peromyscus maniculatus (Wagner, 1845)). Deer mouse abundance was greater along pipeline transects with greater vegetation recovery. Within the forest, irrespective of vegetation recovery on pipelines, meadow voles and deer mice increased near edges. Red-backed voles showed a mixed (i.e., neutral or positive) response to edge. Vegetation variables (i.e., canopy type and cover, ground cover, stem counts, and volume of downed woody material) were important predictors of small-mammal abundance in the forest, but they could not fully account for observed edge effects. Altered small-mammal communities on and adjacent to pipelines may have implications for boreal forest management and conservation through potential changes in predator–prey dynamics and boreal food webs; these implications require further study.

Modeling operative temperature in desert tortoises and other reptiles: Effects imposed by habitats that filter incident radiation.

We challenged the common practice of using a single mean absorptance based on unfiltered skylight spectra to model operative temperature for reptiles in filtered light habitats by examining the effects of plant canopies on light transmittance. To assess differences in light filtration over a range of microhabitats, spectra were recorded under canopies of desert plants, tropical plants, and under unfiltered skylight. Spectra were then integrated with absorptivity curves of desert reptiles to determine if differences in light quality among microhabitat types changed integrated mean absorptance. Finally, we used the desert tortoise (Gopherus agassizii) as a case study to investigate the effects of filtered microhabitats on paint choice for physical operative temperature models and determined the magnitude of error that could result from discrepancies between paint and animal absorptance. We found that light energy was partitioned similarly among microhabitats with like canopy types and that most variation was explained by differences in transmittance between the visible and near infrared wavelengths. Mean absorptance for reptiles was similar among microhabitats with the greatest differences observed between animals in unfiltered skylight and under tropical canopies. In most microhabitats paint and tortoise absorptances differed, but operative temperatures were nearly identical within microhabitats no matter the absorptance used in the model. The findings of this study support the use of a single mean absorptance in modeling operative temperature for reptiles in a variety of habitats.

Diversity and population dynamic of Tabanidae (Diptera) in the cerrado-pantanal ecotone

Tabanid (Diptera) species are associated with the mechanical transmission of several pathogens to both domestic and wild animals around the world. The aim of this study was to evaluate the diversity, abundance, and seasonal dynamic of tabanids in the Cerrado-Pantanal ecotone in Miranda, state of Mato Grosso do Sul, Brazil. Tabanids were collected once a month, from June 2001 to May 2003, for seven consecutive days per collection, using canopy and nzi type traps baited with a chemical attractant (1-octen-3-ol). A total of 6,492 individuals from 39 species and 18 genera was collected, which increases from 25 to 34 the number of tabanid species reported for the studied region. Tabanus occidentalis Linnaeus, 1758 (62.21%) was the most abundant species throughout the collection period, followed by Lepiselaga crassipes (Fabricius, 1805) (7.19%) and Tabanus sorbillans Wiedemann, 1828 (5.68%). The peak of the tabanid population was reached during the rainy season, which is the period of the highest potential risk of mechanical transmission of pathogens by these insects in the studied region.

Defining and assessing urban forests to inform management and policy

The context in which trees and forests grow in cities is highly variable and influences the provision of ecological, social, and economic benefits. Understanding the spatial extent, structure, and composition of forests is necessary to guide urban forest policy and management, yet current forest assessment methodologies vary widely in scale, sampling intensity, and focus. Current definitions of the urban forest include all trees growing in the urban environment, and have been translated to the design of urban forest assessments. However, such broad assessments may aggregate types of urban forest that differ significantly in usage and management needs. For example, street trees occur in highly developed environments, and are planted and cared for on an individual basis, whereas forested natural areas often occur in parkland, are managed at the stand level, and are primarily sustained by natural processes such as regeneration. We use multiple datasets for New York City to compare the outcomes from assessments of the entire urban forest, street trees, and forested natural areas. We find that non-stratified assessments of the entire urban forest are biased towards abundant canopy types in cities (e.g. street trees) and underestimate the condition of forested natural areas due to their uneven spatial arrangement. These natural areas account for one quarter of the city’s tree canopy, but represent the majority of trees both numerically and in terms of biomass. Non-stratified assessments of urban forest canopy should be modified to accurately represent the true composition of different urban forest types to inform effective policy and management.