Aerial Tree Research Articles

Conceptualization and First Realization Steps for a Multi-Camera System to Capture Tree Streamlining in Wind

Forests and trees provide a variety of essential ecosystem services. Maintaining them is becoming increasingly important, as global and regional climate change is already leading to major changes in the structure and composition of forests. To minimize the negative effects of storm damage risk, the tree and stand characteristics on which the storm damage risk depends must be known. Previous work in this field has consisted of tree-pulling tests and targets attached to selected branches. They fail, however, since the mass of such targets is very high compared to the mass of the branches, causing the targets to influence the tree’s response significantly, and because they cannot model dynamic wind loads. We, therefore, installed a multi-camera system consisting of nine cameras that are mounted on four masts surrounding a tree. With those cameras acquiring images at a rate of 10 Hz, we use photogrammetry and a semi-automatic feature-matching workflow to deduce a 3D model of the tree crown over time. Together with motion sensors mounted on the tree and tree-pulling tests, we intended to learn more about the wind-induced tree response of all dominant aerial tree parts, including the crown, under real wind conditions, as well as dampening processes in tree motion.

Green Mapper: An AI-Driven Initiative for Aerial Tree Mapping, Maintaining Environmental Balance

Green Mapper: An AI-Driven Initiative for Aerial Tree Mapping, Maintaining Environmental Balance

Potential for carbon sequestration in severely degraded temperate climate sites: Acrisol and Andosol gullies in Mexico

Aim of study: We assessed potential carbon (C) sequestration in gullies formed in Acrisols and Andosols, on the basis of long-term field restoration trials and GIS analysis. Area of study: Two field trials in Michocán, Mexico, restored with Pinus pseudostrobus, Pinus greggii and Pinus devoniana in 2005 and 2009. Material and methods: Soil C content was analyzed from field samples, and C content of aerial tree biomass of the three Pinus species was estimated by means of allometric equations. The potential restoration area was calculated with a GIS using available layers from the INEGI (Mexican National Institute for Geography and Statistics). Main results: The spatial analysis showed that 1.83% of the Mexican territory are Acrisols and 1.18% are Andosols. From which, 40.87% of Acrisols and 42% of Andosols are eroded. The area with gullies was 2810 km² for both groups of soils within the elevational range of conifer forests in Mexico. C content at the two restored sites was on average of 1.27 t/ha. Soil C content in a 30-cm depth profile was 4.25 t/ha. The potential C sequestration for an average period of 13 years for an area of 2810 km² was 3.947 megatons of C (MtC). A total of four states ‒ Michoacán, Chiapas, Oaxaca, and Puebla ‒ concentrate 89% of the possible capture. Research highlights: Severely degraded sites where gullying is dominant have a high potential for C sequestration once erosion has been controlled and plant cover has been restored.

TreeMMoSys: A low cost sensor network to measure wind-induced tree response

Severe storms caused the largest amount of damaged timber in European forests in the past 70 years. Storm damage occurs when wind loads exceed the failure limits of trees. A decisive factor in assessing storm damage is comprehensive knowledge of interactions between the aerial parts of trees and the high-impact airflow. This paper describes the inexpensive multiple sensor system TreeMMoSys that can measure aerial tree parts' wind-induced reactions, including branches and the stem. The output of TreeMMoSys includes acceleration and angular rate data converted to tilt angles in the post-processing. The system consists of a scalable number of light-weight tree response sensors and ground receivers that communicate through a WLAN network. The weatherproofed system is highly portable, reusable, and allows for an efficient monitoring and a maximization of the number of study trees. Due to the stable measurement performance and accuracy of TreeMMoSys, it can be deployed in the field for long-term monitoring of single tree reactions or neighboring trees' reactions to wind excitation.

Primeiro registro de bivaque arbóreo para a espécie de formiga de correição Eciton rapax Smith, 1855 (Formicidae: Dorylinae)

A formiga de correição Eciton rapax é uma espécie de formiga ainda muito pouco conhecida quanto à sua história natural. Os hábitos de nidificação de E. rapax ainda permanecem pouco estudados, sendo uma importante lacuna para a compreensão da ecologia dessa espécie. Nosso estudo registrou e descreveu locais de nidificação de E. rapax. O estudo foi realizado em uma região de mata primária, no município de Bragança, no estado do Pará. Colunas de forrageio de E. rapax foram encontradas e seguidas até seu local de nidificação, entre julho de 2018 e janeiro de 2020. Foram encontrados 5 bivaques, que foram descritos e localizados. Quatro bivaques eram subterrâneos, embaixo de troncos caídos, buracos deixados por outros animais ou entre raízes aéreas de árvores. Um bivaque situava-se na parte oca de uma árvore, a aproximadamente 3 metros de altura. Nossos dados mostram que além de hábitos subterrâneos de nidificação já descritos na literatura para a espécie, Eciton rapax também pode nidificar fora do subsolo, em cavidades situadas nas partes altas das árvores, em um local seguro e livre das inundações das estações chuvosas.

A Hierarchical Urban Forest Index Using Street-Level Imagery and Deep Learning

We develop a method based on computer vision and a hierarchical multilevel model to derive an Urban Street Tree Vegetation Index which aims to quantify the amount of vegetation visible from the point of view of a pedestrian. Our approach unfolds in two steps. First, areas of vegetation are detected within street-level imagery using a state-of-the-art deep neural network model. Second, information is combined from several images to derive an aggregated indicator at the area level using a hierarchical multilevel model. The comparative performance of our proposed approach is demonstrated against a widely used image segmentation technique based on a pre-labelled dataset. The approach is deployed to a real-world scenario for the city of Cardiff, Wales, using Google Street View imagery. Based on more than 200,000 street-level images, an urban tree street-level indicator is derived to measure the spatial distribution of tree cover, accounting for the presence of obstructing objects present in images at the Lower Layer Super Output Area (LSOA) level, corresponding to the most commonly used administrative areas for policy-making in the United Kingdom. The results show a high degree of correspondence between our tree street-level score and aerial tree cover estimates. They also evidence more accurate estimates at a pedestrian perspective from our tree score by more appropriately capturing tree cover in areas with large burial, woodland, formal open and informal open spaces where shallow trees are abundant, in high density residential areas with backyard trees, and along street networks with high density of high trees. The proposed approach is scalable and automatable. It can be applied to cities across the world and provides robust estimates of urban trees to advance our understanding of the link between mental health, well-being, green space and air pollution.

Modelización de biomasa forestal aérea mediante técnicas deterministas y estocásticas

Mediante la estimación de la biomasa forestal es posible determinar la cantidad de recursos forestales existentes en un determinado territorio, sin embargo, este es un proceso costoso y que consume gran cantidad de tiempo. Por ello, el objetivo del presente estudio fue modelar la biomasa arbórea aérea de un ecosistema forestal ubicado en la región centro sur del estado de San Luis Potosí. Para definir este proceso se compararon métodos determinísticos (distancia inversa ponderada) y estocásticos (kriging y cokriging), con los que se determinó la biomasa forestal con base en datos de campo y espectrales. Los datos de campo correspondieron a 50 conglomerados del Inventario Nacional Forestal y de Suelos, a partir de los cuales se calculó la biomasa mediante el empleo de ecuaciones alométricas. Los datos espectrales (NDVI tradicional -bandas roja e infrarroja del espectro electromagnético) se derivaron de una imagen Landsat 5TM del año 2009. Con los resultados del cálculo de la biomasa y del NDVI, se probaron semivariogramas y variogramas cruzados con los modelos esférico, exponencial y gausiano para analizar el que resultara en el mejor ajuste. Posteriormente, se seleccionó el modelo exponencial derivado de la técnica cokriging, con base en el cual se obtuvo un valor de la raíz cuadrada del error cuadrático medio de 32.01 Mg ha-1. Finalmente, con base en el modelo seleccionado, se generó un mapa de la distribución de la biomasa aérea, en el cual se presentan resultados que van de 0.85 Mg ha-1 a 157 Mg ha-1.

Resolving intractable soil constraints in urban forestry through research–practice synergy

In compact urban areas, grey infrastructure tends to prevail over green infrastructure. The tight urban fabric challenges tree growth and restricts development of greener and healthier cities. The admirable forest-city goal demands innovative methods and solutions tailor-made to tackle inherent constraints. Research findings could be more proactively transformed and transferred into practices. The aerial tree growth space, relatively less difficult to ameliorate, attracts more attention. The more intractable subterranean constraints of confined soil volume acutely restrict root growth, root spread and tree health and contribute extensively to premature decline and tree hazard. Soil surface sealing by impermeable paving is associated with compaction, organic matter deficit, low nutrient and water holding capacity and meagre nutrient stock. Scanty application of research findings has kept practice quality at a low level, rendering the persistent soil problems in the bane of urban forestry. A systematic survey of state of play provides hints on novel solutions derived from existing knowledge and proposes new research practice. A package of measures with generic connotations has been distilled from the survey of chronic, critical yet widely neglected urban soil management issues. Urban forest managers and researchers can jointly adopt out-of-the-box thinking and generate actionable translational research. Policy makers and practitioners can more promptly be informed by new harvests of research–practice synergy. Intimate and reciprocal interactions between science and practice can be proactively nurtured to raise the quality of urban landscape.

Inventory of Organic Carbon in a Pterogyne nitens Tul. Plantation in Southwest Bahia, Brazil

ABSTRACT Carbon binding capacity varies between forest plantations, mainly in terms of species and climate and soil conditions. The objective of this study was to estimate the amount of organic carbon stored in aerial tree biomass in the litter and soil of a homogeneous planting of Pterogyne nitens Tul. located in the Southwest Bahia region of Brazil. The woody biomass was obtained by destructive method. Litter collection was carried out using a wooden template (0.25 m2). Soil samples were collected at four depths (0-5, 5-10, 10-20 and 20-40 cm). The carbon stored in all studied compartments totaled 47.1 Mg ha-1 with a greater contribution from the ground (31.4 t ha-1). The accumulated litter was the lowest carbon compartment, storing about 1.4% of the total. Among the different fractions of the biomass, the stem is the largest carbon reservoir, representing about 46% of fixed C biomass.

Elevated root retention of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in coniferous trees

For decades, the explosive RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) has been used for military and industrial applications. Residues of RDX pollute soils in large areas globally and the persistence and high soil mobility of these residues can lead to leaching into groundwater. Dendroremediation, i.e. the long-term use of trees to clean up polluted soils, is gaining acceptance as a green and sustainable strategy. Although the coniferous tree species Norway spruce and Scots pine cover large areas of military land in Central Europe, the potential of any coniferous tree for dendroremediation of RDX is still unknown. In this study, uptake experiments with a (14)C-labelled RDX solution (30 mg L(-1)) revealed that RDX was predominantly retained in the roots of 6-year-old coniferous trees. Only 23 % (pine) to 34 % (spruce) of RDX equivalents (RDXeq) taken up by the roots were translocated to aboveground tree compartments. This finding contrasts with the high aerial accumulation of RDXeq (up to 95 %) in the mass balances of all other plant species. Belowground retention of RDXeq is relatively stable in fine root fractions, since water leaching from tissue homogenates was less than 5 %. However, remobilisation from milled coarse roots and tree stubs reached up to 53 %. Leaching from homogenised aerial tree material was found to reach 64 % for needles, 58 % for stems and twigs and 40 % for spring sprouts. Leaching of RDX by precipitation increases the risk for undesired re-entry into the soil. However, it also opens the opportunity for microbial mineralisation in the litter layer or in the rhizosphere of coniferous forests and offers a chance for repeated uptake of RDX by the tree roots.

Responses of an individual deciduous broadleaved tree to wind excitation

Although responses of aerial tree parts to wind excitation are of crucial importance for deciduous broadleaved tree stability against wind loading, only a few field studies have been conducted that explore wind–tree part interactions. Therefore, responses of aerial parts of an individual Norway maple tree (Acer platanoides) to wind excitation were measured in a field study near the city of Freiburg (Southwest Germany) between July 2009 when the tree was in leaf and March 2010 when the tree was out of leaf. Using Fourier analysis, for most of the sampled tree parts six frequencies associated with the first three vibration modes in two motion directions were identified. In agreement with previous studies, vibration frequencies were lower when the tree was in leaf compared to the leafless period. The results indicate the importance of the foliage for the seasonal variation in aerial tree part motion damping. For the analyzed wind speed range, it is shown that the importance of higher order vibration modes localized on the sampled tree parts for total tree part response to wind excitation decreases with increasing wind speed. Results from wavelet analysis demonstrate that tree part response strongly covaried in the time frequency-space only with wind components having frequencies much lower than the frequencies associated with the dominant tree part vibration modes.

First Report of Pilidiella granati Causing Dieback and Fruit Rot of Pomegranate (Punica granatum) in Iran.

Iran is the largest producer of pomegranate (Punica granatum) in the world, with more than 60,000 ha currently in production. In the spring of 2011, a decline and dieback of young pomegranate trees (7 to 10 years old) were observed in the Kheir area of Fars Province. Dieback and twig blight developed toward the lower part of the stem, resulting in death of aerial tree parts and growing suckers from roots. Surface-disinfected tissues of diseased plants were plated on potato dextrose agar (PDA) and malt extract agar media. Isolates were separated into two groups that had either pale green or white aerial mycelia and sporulated after 5 to 7 days at 25°C. Pycnidia were globose and black with thin, membranous, pseudoparenchymatic walls, 80 to 140 μm in diameter. Conidia were hyaline, one-celled, elongate to fusiform, straight, and 11 to 17 × 4 to 6 μm (average 14 × 4.7 μm). Cardinal minimum growth temperatures were 8 to 10°C, optimum at 27 to 30°C, and maximum at 35°C. Radial growth rate at 30°C was 8 to 9 mm per day. Representative isolates were deposited in the CBS-KNAW Fungal Biodiversity Centre, the Netherlands (CPC 19625 = CBS 130974 and CPC 19626 = CBS 130975; GenBank JN815312 and JN815313, respectively). Genomic DNA was extracted with the UltraClean Microbial DNA Isolation Kit (MoBio Laboratories, Inc., Solana Beach, CA) and the internal transcribed spacer (ITS) region of the nrDNA operon of two isolates were sequenced as described previously (1). On the basis of morphology (3), the causal organism was identified as Pilidiella granati Sacc. This identification was corroborated by the ITS sequence data, which was identical for both colony types to GenBank HQ166057 (identities = 614 of 614 [100%]). Pathogenicity tests were conducted using two representative isolates from each group on 5-month-old P. granatum trees with 10 replicates under greenhouse conditions; 5-mm mycelial plugs from the edge of 7-day-old colonies on PDA were placed under the bark of twig wounds. Uncolonized PDA plugs were used as noninoculated controls. Pathogenicity was also tested on nonwounded fruit by placing colonized 5-mm-diameter mycelial plugs on surface-disinfected pomegranate fruits; noncolonized PDA plugs were used as controls. All treated fruit were placed in plastic bags and maintained at 25°C for 10 days. Isolates were found to be pathogenic on twigs after 2 months, giving rise to brown lesions that were 2 to 5 cm long. No lesions were observed on the controls. Furthermore, the fungus was reisolated from all infected tissues, satisfying Koch's postulates. On pomegranate fruit, the fungus colonized the fruit after 5 to 8 days, followed by the appearance of fruit rot symptoms leading to the formation of abundant pycnidia covering the skin after 10 days. No decay was observed in control inoculations. Pilidiella granati has previously been reported as a pathogen of P. granatum fruit from Europe, Asia, and the United States (2). To our knowledge, this is the first report of this pathogen causing dieback and fruit rot of pomegranate in Iran.

Seasonal colonisation of apple trees by ‘Candidatus Phytoplasma mali’ revealed by a new quantitative TaqMan real-time PCR approach

Apple proliferation (AP), caused by ‘Candidatus Phytoplasma mali’, is an economically important disease affecting many apple-growing areas in Europe. A new TaqMan real-time PCR assay was established for absolute quantification of ‘Ca. P. mali’ by using a single-copy gene of the host plant as a reference, which is amplified with the pathogen DNA in a single-tube reaction. Normalised estimates of phytoplasma concentration are ultimately expressed as the number of phytoplasma cells per host plant cell. The assay was used to monitor the ‘Ca. P. mali’ titre over the course of two growing seasons in roots and branches of symptomatic and asymptomatic but AP-positive apple trees. All 252 root samples from symptomatic and asymptomatic trees tested positive, with an average number of 59.8 ± 5.68 (standard error) and 55.1 ± 9.83 ‘Ca. P. mali’ per host cell, respectively. From the 378 shoot samples analysed, 81% of the symptomatic and only 20% of the asymptomatic samples were AP-positive with an average number of 9.4 ± 1.04 and 0.7 ± 0.13 ‘Ca. P. mali’ per host cell, respectively. This strengthens evidence that not the pathogen occurrence alone but the presence of a certain quantity of ‘Ca. P. mali’ in the aerial tree sections is involved in symptom expression. In addition, pronounced seasonality of the phytoplasma concentration was found, not only in branches, but also for the first time in roots of symptomatic and asymptomatic apple trees. Highest phytoplasma levels in roots were detected from December to May.

Can we detect a west Norwegian tree line from modern samples of plant remains and pollen? Results from the DOORMAT project

In the DOORMAT (Direct Observation of Recent Macrofossils Across Treeline) project, the modern representation of local vegetation by pollen and plant remains (plant macrofossils) across a west Norwegian tree line, composed of Betula pubescens and Pinus sylvestris, has been studied over 2 years. The aim was to discover if the modern tree line could be detected and therefore how precisely past tree-line movements could be reconstructed and related to Holocene climate changes by using one proxy or a combination of both. Traps were placed in the vegetation from 663 to 1,120 m a.s.l., spanning the pine altitudinal species limit, the birch tree-line ecotone, and the vegetation zones up to the mid-alpine zone. Three traps were also set in the small lake Trettetjorn close to the modern tree line at 800 m a.s.l. Traps were emptied twice a year to sample both summer and winter seasons. Macrofossils represent their local vegetation well. However, tree Betula remains were trapped above the tree line and Pinus and Picea remains were recorded 1.0–1.5 km away from their sources, demonstrating considerable dispersal capacity. This shows that rare macrofossil remains do not necessarily represent the local presence of these trees. Aerial tree pollen deposition in traps at the upper limit of pine woodland and in the subalpine birch woodland was unexpectedly low, whereas pollen accumulation rates (PAR) were orders of magnitude higher in the lake traps. We hypothesise that the lake receives regional pollen rain washed in from its catchment by snow meltwater and that high values in traps are due to continuous suspension of pollen in the lake water during summer. The interpretation of tree-line changes from existing Holocene pollen and plant macrofossil data from Trettetjorn was supported and refined by the DOORMAT macrofossil data, but the modern pollen data were anomalous.

Aerial tree volume functions for eucalypts in Western Australia

Large-scale, fixed-base aerial photography is being used together with ground sampling in a major inventory of eucalypt forest in Western Australia. This paper describes the aerial tree volume functions derived for that inventory, covering species in the jarrah (Eucalyptusmarginata) forest. The equations, derived from ground measurements, predict gross bole volume from estimates of total height and vary with the site quality of the forest. They are used to predict volume from photomeasurements of total height that have been corrected for measurement error. The functions appear suitable for this forest type, although the volumes of veteran trees with severely damaged crowns are underestimated.

Fungi in healthy stems and branches of American beech and aspen: a comparative study

SUMMARYFungi inhabiting healthy stems and branches of American beech and aspen were induced to develop within the wood by drying sections of these organs. The two tree species were similar in that tile water content of the wood strongly determined fungal development, with a high water content preventing fungal growth for at least 25 weeks, fast drying resulting in poor development and slow drying inducing very fast growth of fungi within the wood. Fungal assemblages thus obtained were strongly dominated by ascomycetes and coelomycetes.Although some fungal species appeared on both tree species, assemblages of fungi obtained from each tree species were clearly different, even though samples of each were obtained from the same site and all experimental conditions were identical for both.All the characteristics mentioned above strongly resemble those documented for endophytes on smaller aerial tree organs such as leaves, petioles and twigs, and for this reason the fungi obtained here were termed‘xylotropic endophytes'.Among the dominant species found on aspen, three species with presumed pathogenic abilities were isolated. These were Cryptosphaeria populina, Cytospora chrysosperma and Hypoxylon mammatum. Hypoxylon fragifarme was the most frequently and abundantly isolated species obtained from beech.