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  • Open access
  • 26 Reads
First report on infection of Eucalyptus pellita seeds by Ralstonia solanacearum

Forest plantation in Indonesia has been rapidly increasing since the last few decades. Ecologically, forest plantations are able to reduce pressure on natural forests, quickly fix carbon and stimulate the restoration of natural vegetation. However, monoculture plantations are challenged to sustainably manage pest and disease risks. Traditionally, the use of healthy (pathogen-free) seeds is one approach that can be taken to reduce the risk of disease. So far, most of the reports on seed-borne pathogens on forest trees have dealt with fungi only. Information on seed transmission of other pathogens, especially bacteria, was very limited. Take for example the bacterial wilt pathogen of eucalyptus, Ralstonia solanacearum. The pathogen has previously been reported to be a seed-borne pathogen in many agricultural plants including eggplant, tomato, chili, potato, and ginger. However, it was yet to be proved as seed-transmitted in eucalyptus. Bacterial wilt is one of major threats in eucalyptus plantations which can cause significant losses. Until now, study about bacterial wilt on Eucalyptus pellita in Indonesia is still very limited, especially regarding the presence of the pathogen on or in the seeds. This study aims to provide evidence of existence of the R. solanacearum bacterium on or in E. pellita seeds. Result of our study indicated that R. solanacearum can be detected from eucalyptus seeds using early growth seed germination, universal and selective medium in laboratory, nursery growing test, and molecular-based detection using the enrichment-PCR method. The bacterial inoculum is also proven to exist both on the surface of and inside the eucalyptus seeds. This is the first report that R. solanacearum is a seed-borne pathogen in E. pellita seeds. Previous studies in different agricultural systems show that the effective method used to control the pathogen is through seed treatments using biological, physical, and chemical approaches.

  • Open access
  • 79 Reads

Development of Biocontrol Agents to Manage Major Diseases of Tropical Plantation Forests in Indonesia: A Review

In 2018 the area of plantation forests in Indonesia reached 8,668,670 ha. Pests and diseases have been considered as critical factors in sustainable production of plantation forests in the humid tropic areas. With the introduction of new plant species such as fast-growing plants of acacias and eucalypts, new pests and diseases have become emerging threats. Several pathogenic fungi and bacteria have been recorded in plantation forests in Indonesia since their early establishment. The fungal species associated with the most common diseases include Ceratocystis manginecans (Ceratocystis wilt and dieback), Ganoderma philippii (red root rot), Phellinus noxius (brown root rot and heart rot) and Fusarium spp. (Fusarium wilt), whereas the major bacterial pathogens are Ralstonia spp. (bacterial wilt) and Xanthomonas spp. (leaf streak). As one key component of integrated pest management, biocontrol measure plays significant roles in managing major diseases of tropical plantation forests in Indonesia. A number of forestry companies have put development of biocontrol agents as one of their priority research programs. For this scenario, antagonists have been collected and isolated from different ecosystems. This paper reviews development of biocontrol agents to manage major diseases of tropical plantation forests in Indonesia.

  • Open access
  • 43 Reads
Carbon footprint of thermal energy production from poplar short-rotation coppice plantations

The use of agroforestry biomass represents a relevant aspect in the world debate on the issue of reducing the climate-altering gases into the atmosphere. in fact, as a renewable energy source, woody biomass can play an important role in replacing fossil fuel in the production of thermal and electrical energies. One of the possible sources of wood biomass production is represented by poplar SRC plantations. In the present work the Global Worming Potential (GWP) of the entire supply chain of four different cutting shifts (2, 3, 4, and 5-years) have been evaluated according to the IPCC method. The productive cycle of the plantation was 16 years (2- and 4-years shifts), and 15 years (3- and 5-years shifts). For production cycles of 2- and 3-years, two biomass harvesting systems were considered: the first one by carrying out a single step with a dedicated machine (forage harvester); the second one using different machines to perform first the felling, then the logging of whole trees and subsequently, the chipping of staked trees. Two options were considered also for 4- and 5-years shifts: the first one involves manual felling with a chainsaw, logging of whole trees with winch and subsequent chipping of them; the second one considers the use of a feller-buncher for felling, a skidder for logging and a chipper before using the woodchips in the boiler. It was considered that the biomass produced was used in a biomass plant for heating a public building. The environmental impact of 1 GJ of heat energy produced by the various forest rotation plants were assessed considering the entire life cycle, from the field stage to the thermal energy production. The results were compared with the production of the same thermal energy using a diesel boiler. The field stage has contributed to greater environmental impact due above all to fertilization and fuel consumption for the execution of mechanical processing, the collection and chipping of the biomass produced. The comparison between the two systems has shown that the production and use of biomass to generate thermal energy can reduce the Global Worming Potential by more than 50% compared to the use of fossil fuels.

  • Open access
  • 27 Reads
Technical and economic aspects of Stone Pine (Pinus pinea L.) maintenance in urban environments

The Italian Stone Pine (Pinus pinea L.) is one of the most employed ornamental trees in towns with Mediterranean climates. For example, in the city of Rome, according to Rome municipality, Pinus is the most common genus, with more than 51,000 trees. Due to several reasons (size of plants, historical importance of some trees, wrong plantation sites, etc.) the maintenance of this species may constitute a serious issue for the owners, both private and public subjects. Pruning and felling are the most frequent management operations of trees in towns and this study analyzes the technical and economic features of these operations carried out in 14 work sites (with a total of 25 trees observed). The operations were carried out either with aerial platforms (19 trees) or ascending the crown by tree-climbing (6 trees). The operations were sampled with time studies (12 trees for pruning and 13 for felling). Work time was measured from the beginning of operations to the transport of the residual biomass to the collection and loading point, using centesimal stopwatches and video recording. Total observation time amounted to 63.1 hours. Moreover, the total residual biomass was weighed or assessed. The evaluation of the costs of each work site considered the fixed and the variable costs and the costs for the labor force. A Multiple Linear Regression modelling was adopted to predict the total operation cost. This paper can contribute to optimize trees maintenance methods in urban sites and to assess the potential residual wood biomass attainable from urban forestry maintenance.

  • Open access
  • 30 Reads
Occurrence and activity of roe deer in urban forests of Warsaw

Although ungulates avoid human disturbances, roe deer (Capreolus capreolus) is recently observed more often in cities. Human presence or activities are perceived by animals as those associated with predation risk so activity and exploration patterns of animals should be shaped by indices of anthropogenic disturbances. The high level of human disturbances is noticed in big cities, therefore, the aim of the study was to determine the occurrence of roe deer in the capital of Poland and it’s activity in the urban forests of Warsaw, one of the biggest capital cities of Europe. We hypothesized that (1) roe deer inhabits more often forests than other habitats in the city, (2) daily activity of roe deer is higher in nights (between 10:00 pm and 06:00 am), when the level of human disturbances is lower, (3) considering moon phases, roe deer is more active during dark nights than bright nights. We used snow tracking on transect routes (winter seasons 2016, 2017, 2018, 115.1 km in total) to determine roe deer occurrence in four habitats, potentially used by this species in the city: forests, open areas, parks, and built-up areas. The number of tracks was highest in forests (4,6 tracks/1km/24hr), followed by open areas, built-up areas, and parks. We used camera traps to determine the activity of roe deer in selected urban forests. We collected 697 observations of roe deer in Warsaw forests in the years 2016-2019 (per 4826 trap-days in total). The peak of roe deer activity was noticed between 04:00 and 05:00 am. The animals were least active at 1:00-2:00 pm and between 11:00 pm-01:00 am. Roe deer was more active during dark nights than bright nights (42% and 30% observations, respectively). Our research showed that roe deer inhabiting the urban area avoided human presence by using well-covered habitats and being active in periods when humans' disturbances level is lower.

  • Open access
  • 29 Reads
Models to estimate the bark volume for Larix sp. in Poland

Bark constitutes significant part of the trees volume for some species, being also one of the main residues and by-products of the mechanized tree harvest. Therefore, in order to conduct effective forest management, it is essential to estimate the possible amount of that product which can be obtained during the harvest process. Our objective was to develop a model to estimate two basic parameters of bark: its volume and its share in the total volume of a tree. For the study we choose larch (Larix sp.) that is a rare but valuable forest raw material in Poland.

The research material was collected in northern (2 sites), central (1 site), and southern (2 sites) Poland. In total, we obtained data from 700 trees. We used geographical location and site type as well as tree’s age, breast height diameter, height and volume as an independent variables.

Bark volume increased, while share of bark in total volume of a tree decreased along with increasing breast height diameter, height or tree volume. The previous parameter was strongly related to tree’s age and site type, while in case of the latter one these relationships were significant for age and not that evident for site type. As geographical location turned to significantly influence investigated bark parameters (p < 0.01 in both cases), we developed models separately for each region. Obtained formulae might be applied in harvest planning or in software utilised during the process of felling and assortments production.

  • Open access
  • 30 Reads
Infection and spread of root rot caused by Heterobasidion parviporum in Picea abies stands after thinning: case studies on former pasture and meadow lands

Afforestation of former agricultural lands is well established practice in several countries. It is beneficial to avoid previous-generation forest diseases and expand forest areas. However, several biotic and abiotic risks have been reported for such stands, also higher risk of Heterobasidion root rot after thinning. Therefore, this study investigates the spread patterns of Heterobasidion root rot in three Picea abies (L.) Karst. plantations established on former pasture and meadow lands and subjected to forest management practices. First of all, to get an insight of average infection rate we sampled all standing trees (157 in total) within transect all along sampling area. It showed slightly lower infection in pastures and higher in former meadows (16 % vs. 29 and 33%, respectively). Based on those data and observed dieback all over the stand we established circle sample plots in disease centres where all trees and stumps were analysed and average infection rate there was from 34 to 41%. All obtained Heterobasidion isolates belonged to Heterobasidion parviporum Niemelä & Korhonen. Isolates were paired to detect genotype sizes and infection origin. Of 141 genets examined, 99 were single-tree indicating primary infection and 42 formed territorial clones (160 trees and (or) stumps) indicating spread of infection through root contacts. The following conclusions were reached: ((i) on average, primary infection in such stands is essential but with a stand age secondary infection dominates; (ii) H. parviporum can form large (up to 137 m2) territorial clones in forests on former pasture and meadow lands causing extensive tree dieback and mortality. This study was financially supported by European Regional Development Fund's Post-doctoral Research project No. “Determining the risk of Heterobasidion root-rot and fungal communities in roots of Norway spruce stands on former agricultural land”.

  • Open access
  • 74 Reads
Invertebrate Community of Scots’ pine Coarse Woody Debris in the Southwestern Pyrenees under different thinning intensities and tree species

Thinning and tree species alter microclimate by modifying canopy cover, radiation, wind and humidity in the forest floor. Thus, forest management can directly influence edaphic microfauna responsible for decomposing coarse woody debris (CWD). 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 sylvetris L. or mixed of P. sylvestris - Fagus sylvatica L.) on CWD colonization by edaphic fauna. CWD samples were in intermediate and advanced decomposition stages, approximately 10 cm long and 5 cm in diameter were collected. 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. Microfauna was extracted from CWD samples with Tullgren-Berlese funnels, and individuals were counted and identified. Nineteen taxonomic groups were recorded, being the most abundant the microinvertebrates (mites and Collembola). Canopy type had a significant influence on richness, whereas decay class had a 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 microfauna. Furthermore, some taxonomic groups showed differential responses to canopy type. CWD water content was 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 microfauna is related to CWD decomposition rates, these effects should be accounted for when planning forest management transition from pure to mixed forests.

  • Open access
  • 38 Reads
Quantifying Tree Cover Loss in Urban Forests within Nairobi City Metropolitan Area from Earth Observation Data

Urban forests contribute significantly to the ecological integrity of urban areas and the quality of life of urban dwellers through air quality control, energy conservation, improving urban hydrology, and regulation of Land Surface Temperatures (LST). However, urban forests are under threat due to human activities, natural calamities, and bio-invasion continually decimating forest cover. Few studies have used fine-scaled earth observation data to understand the dynamics of tree cover loss in urban forests and the sustainability of such forests in the face of increasing urban population. The aim of this work was to quantify the spatial and temporal changes in urban forest characteristics and to assess the potential drivers of such changes. We used data on tree cover, Normalized Difference Vegetation Index (NDVI), and land cover change to quantify tree cover loss and changes in vegetation health in urban forests within the Nairobi Metropolitan Area in Kenya. We also used land cover data to visualize the potential link between tree cover loss and changes in land use characteristics. From approximately 6600 hectares (ha) of forest land, 720 ha have been lost between 2000 and 2019, representing about 11% loss in 20 years. In 6 of the urban forests, the trend of loss was positive, indicating a continuing disturbance of urban forests around Nairobi. Conversely, there was a negative trend in the annual mean NDVI values for each of the forests, indicating a potential deterioration of the vegetation health in the forests. A preliminary, visual inspection of high-resolution imagery in sample areas of tree cover loss, showed that the main drivers of loss are the conversion of forest lands to residential areas and farmlands, implementation of big infrastructure projects that pass through the forests, and extraction of timber and other resources to support urban developments. The outcome of this study reveals the value of earth observation data in monitoring urban forest resources.

  • Open access
  • 98 Reads
Single trees stability assessment in beech high forest and factors that could induce windbreak

Wind in Europe is the main disturbing factor and the greatest damaging agent of forest stands, causing three times the annual damage caused by fires each year. The amount of trees destroyed by wind annually in Europe is over 38 million cubic meters. Given the importance and extent of the phenomenon of windbreak, this has been one of the main topics on which forestry scientists have focused over time, so much so that already in the mid-90s of the century last there were more than 200 scientific papers. However, most of these studies focused on the prediction of possible wind damage paying attention on the population level and not on a single tree; moreover, almost all of the studies were carried out on conifers. Studies concerning the single tree have been carried out above all in urban forestry, where the trees live in unfavorable contexts and very distant from what could be their optimal living conditions found in forests. The aim of this research was to search for possible correlations between the tree conformation and the crashes caused by windy events. This in order to assess the characteristics predisposing to the crash, in such a way as to provide the forest engineer with useful information in choosing the trees to be take priority in order to reduce the damage caused by windy events. In conjunction with the "Vaia windstorm", which affected much of Northern Italy, another meteoric event also occurred which caused the crash of numerous individuals inside the beech forest located on the summit of Monte Amiata, in Tuscany. In this occasion, an attempt was made to investigate the possible existence of single-tree scale indicators relating to a greater susceptibility to crash, in beech forests of the same age treated to shelterwood system, under the same phytosanitary, edaphic and topographical conditions. The research methodology applied is the same as in other studies carried out on the subject, in such a way as to allow comparison between the results obtained. Various parameters were analyzed, in particular: maximum height, crown insertion height, castle height, height corresponding to the maximum crown width, crown volume and surface. The findings showed that the main variables that had a significant influence on wind crashes were: tree height, crown surface and volume. In particular, the standing trees were taller than those crashed and with a larger crown.