Fungal biodiversity in the air of Turin

The qualitative fungal composition of Turin 's atmospheric environment was surveyed, carrying out a twelve-month study and collecting with a single stage volumetric sieve sampler on Dermasel agar supplemented with 0.4 g l^–1 cycloheximide and 0.05 g l^–1 chloramphenicol. We isolated 165 species and 2 varieties of mesophilic fungi from 58 genera and 26 thermotolerant species from 12 genera. Penicillium, Aspergillus, Acremonium, Chrysosporium, Scopulariopsis, Malbranchea, Paecilomyces, Phialophora and Cladosporium were in sequence the genera most rich in mesophilic species; Aspergillus, Penicillium, Chrysosporium and Scopulariopsis the most rich in thermotolerant species. Many of the species isolated are rarely or never recorded in the atmospheric environment. Cycloheximide can thus be said to select among airborne fungi, giving a characteristic picture.Abbreviation CH Cycloheximide - cfu colony forming unit     

Immunoblotting of mite aeroallergens collected with an indoor Burkard air sampler

We examined the kinetics of airborne levels of mite allergen particles in a house by combined use of an indoor Burkard air sampler and immunoblotting. Airborne mite allergens collected on the Burkard sampling tape were transferred onto a nitrocellulose membrane, reacted with mouse monoclonal anti-mite allergen (Der pI) antibody, then treated with alkaline phosphatase conjugated anti-mouse IgG. Finally, the blotted allergen on the membrane was reacted with BCIP/NBT phosphatase, and purple spots visible by the naked eye were produced. The shape of the spots was observed under a microscope, and the spot area was measured by an image processor. This technique might be useful for analyzing the behavior of airborne allergen particles in indoor environments.     

Airborne grass pollen in Granada (Spain)

We have carried out a study on the annual and daily pollen concentrations from Gramineae over four consecutive years in the atmosphere of Granada (Spain). Samples of pollen grains were collected by the volumetric method with the aid of a Burkard sporetrap. Gramineae, according both to their high sensitizing capacity and to data from allergologists, are responsible for many pollinoses diagnosed in this area. In this work, daily pollen levels from April to July are monitored and the variations identified are interpreted in relation to meteorological conditions. Results indicated that the highest airborne concentrations of Gramineae pollen were found in May and June, although the beginning and intensity of pollination have been variable during these 4 years.     

基于地面LiDAR数据的塔里木河下游胡杨林结构参数反演

以塔里木河下游天然胡杨林为研究对象,利用Riegl VZ-1000型地面激光扫描仪(Terrestrial Laser Scanning, TLS)获取离河道不同距离的8个样方内513棵胡杨的三维点云数据,通过建立冠层高度模型、Hough变换等方法获取单木株数和结构参数,并与传统的每木检尺实测数据和无人机(Unmanned Aerial Vehicle, UAV)低空影像进行对比,验证激光雷达方法的测树精度;对TLS获取的胡杨树形参数进行相关性分析,并建立关系模型;探讨不同水胁迫条件(不同离河道距离,不同地下水埋深)对胡杨单木结构参数的影响;最后按不同径级划分胡杨的年龄,得出各龄级胡杨所占比例。结果表明:(1)TLS能够高精度获取不同密度和长势的胡杨单木株数和结构参数,单株准确分割比率为94%—100%,相对于UAV低空影像更为准确;(2)TLS获取的胡杨树高(Tree height,TH)、胸径(Diameter at breast height, DBH)、冠幅直径(Crown diameter,CD)和冠幅面积(Crown area,CA)与传统实测值拟合度R~2较高,分别为0.95、0.97、0.77和0.84,表明实测数据和TLS获取数据无明显差异;(3)胡杨CD、CA分别与TH呈显著正相关,其相关性系数为0.73、0.67;基于此构建了胡杨TH与CD的关系模型,即TH=2.6274×CD~(0.706),R~2为0.64;(4)根据径级划分胡杨年龄段可知,DBH为15—30 cm的近熟林比例最大,占8个样方内监测胡杨总株数的47%,表明胡杨种群年龄结构相对稳定并总体态势良好,呈现了生态输水对塔河下游胡杨种群恢复有明显的促进作用。总之,激光雷达技术能够客观反映胡杨树形结构参数,可替代耗力、耗费、耗时的传统实测方法,为时时掌握胡杨林生长发育、长势动态以及多尺度、多时相生态耗水研究提供高精度信息,为干旱区荒漠河岸林的有效保护与可持续管理提供科学依据。     

Characterization of an alpine tree line using airborne LiDAR data and physiological modeling

Understanding what environmental drivers control the position of the alpine tree line is important for refining our understanding of plant stress and tree development, as well as for climate change studies. However, monitoring the location of the tree line position and potential movement is difficult due to cost and technical challenges, as well as a lack of a clear boundary. Advanced remote sensing technologies such as Light Detection and Ranging (LiDAR) offer significant potential to map short individual tree crowns within the transition zone despite the lack of predictive capacity. Process‐based forest growth models offer a complementary approach by quantifying the environmental stresses trees experience at the tree line, allowing transition zones to be defined and ultimately mapped. In this study, we investigate the role remote sensing and physiological, ecosystem‐based modeling can play in the delineation of the alpine tree line. To do so, we utilize airborne LiDAR data to map tree height and stand density across a series of altitudinal gradients from below to above the tree line within the Swiss National Park (SNP), Switzerland. We then utilize a simple process‐based model to assess the importance of seasonal variations on four climatically related variables that impose non‐linear constraints on photosynthesis. Our results indicate that all methods predict the tree line to within a 50 m altitudinal zone and indicate that aspect is not a driver of significant variations in tree line position in the region. Tree cover, rather than tree height is the main discriminator of the tree line at higher elevations. Temperatures in fall and spring are responsible for the major differences along altitudinal zones, however, changes in evaporative demand also control plant growth at lower altitudes. Our results indicate that the two methods provide complementary information on tree line location and, when combined, provide additional insights into potentially endangered forest/grassland transition zones.     

Effects of group size and group density on trade-offs in resource selection by a group-territorial central-place foraging woodpecker

Trade-offs in resource selection by central-place foragers are driven by the need to balance the benefits of selecting resources against the costs of travel from the central place. For group-territorial central-place foraging birds, trade-offs in resource selection are likely to be complicated by a competitive advantage for larger groups at high group density that may limit accessibility of high-quality distant resources to small groups. We used the group-territorial, central-place foraging Red-cockaded Woodpecker Leuconotopicus borealis (RCW) as a case study to test predictions that increases in group density lead to differences in foraging distances and resource selection for groups of different sizes. We used GPS tracking and LiDAR-derived habitat data to model effects of group size on foraging distances and selection for high-quality pines (≥ 35.6 cm diameter at breast height (dbh)) and lower quality pines (25.4–35.6 cm dbh) by RCW groups across low (n = 14), moderate (n = 10) and high group density (n = 10) conditions. At low and moderate group density, all RCW groups selected distant high-quality pines in addition to those near the central place because competition for resources was low. In contrast, at high group density, larger groups travelled further to select high-quality pines, whereas smaller groups selected high-quality pines only when they were close to the central place and, conversely, were more likely to select lower quality pines at greater distances from the central place. Selection for high-quality pines only when close to the cavity tree cluster at high group density is important to long-term fitness of small RCW groups because it allows them to maximize benefits from both territorial defence and selecting high-quality resources while minimizing costs of competition. These relationships suggest that intraspecific competition at high group density entails substantive costs to smaller groups of territorial central-place foragers by limiting accessibility of distant high-quality foraging resources.     

Seed hairs of poplar trees as natural airborne pollen trap for allergenic pollen grains

The present article deals with the efficacy of seed hairs of poplar trees (Populus spp.) as a potent natural airborne pollen trap. Different species of Populus are commonly found planted along the streets in the cities of North China. The seed hairs and pericarp of poplar trees were collected from the trees and on the ground in Beijing Botanical Garden of Chinese Academy of Sciences and around Miyun Reservoir during May 2005 for pollen analysis. Different pollen spectra are recorded from different samples and are characterised by dominant occurrence of pollen grains of arboreal and anemophilous plants. In addition, pollen grains of non‐arboreal plants including grasses are also found trapped. Among the 46 trapped pollen grains, 26 are known to be allergenic. This study suggests that poplar seed hairs possibly make people feel uncomfortable due to the presence of allergenic pollen trapped in the hairs.