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[en] Aim of study: To analyze the susceptibility of Eucalyptus and hybrids species to Leptocybe invasa through field assays. Area of study: The north of the Argentine province of Misiones (Colonia Delicia). Material and methods: A total of 11 Eucalyptus species and 2 hybrids were surveyed for damage and severity of L. invasa infestation. Six evaluations were made during an annual period. Main results: The susceptibility ranking to L. invasa from highest to lowest was E. tereticornis > E. propinqua > E. dunni > E. camaldulensis > E. grandis > E. major > E. longistrata >E. grandis × E. camaldulensis. However, E. moluccana, E. urophylla × E. grandis and E. urophylla were tolerant to L. invasa. Research highlights: This study suggests that in Misiones, E. tereticornis is the most sensible eucalyptus species to gall wasp attack, whereas other species and hybrids presented low damage levels or tolerance to L. invasa region.
[en] Aim of study: The main objective is to determine the best machine-learning algorithm to classify the stand types of Monteverde forests combining LiDAR, orthophotography, and Sentinel-2 data, thus providing an easy and cheap method to classify Monteverde stand types. Area of study: 1500 ha forest in Monteverde, North Tenerife, Canary Islands. Material and methods: RF, SVML, SVMR and ANN algorithms are used to classify the three Monteverde stand types. Before training the model, feature selection of LiDAR, orthophotography, and Sentinel-2 data through VSURF was carried out. Comparison of its accuracy was performed. Main results: Five LiDAR variables were found to be the most efficient for classifying each object, while only one Sentinel-2 index and one Sentinel-2 band was valuable. Additionally, standard deviation and mean of the Red orthophotography colour band, and ratio between Red and Green bands were also found to be suitable. SVML is confirmed as the most accurate algorithm (0.904, 0.041 SD) while ANN showed the lowest value of 0.891 (0.073 SD). SVMR and RF obtain 0.902 (0.060 SD) and 0.904 (0.056 SD) respectively. SVML was found to be the best method given its low standard deviation. Research highlights: The similar high accuracy values among models confirm the importance of taking into account diverse machine-learning methods for stand types classification purposes and different explanatory variables. Although differences between errors may not seem relevant at a first glance, due to the limited size of the study area with only three plus two categories, such differences could be highly important when working at large scales with more stand types.
[en] Aim of study: The identification of material of forest tree species using genetic markers was carried out. Two promising chloroplast barcode markers, matK and ycf1, were tested for species identification and reconstruction of phylogenetic relationships in pines. Area of study: The present study included worldwide Pinus species, with a wide representation of European taxa. Material and methods: All matK sequences longer than 1600 base pairs and ycf1 sequences for the same species were downloaded from GenBank, aligned and subsequently analyzed to estimate alignment statistics, phylogenetic trees and substitution saturation signals. Main results: We confirm the usefulness of the ycf1 marker for barcoding purposes and phylogenetic studies in pines, especially in studies focusing at the within-genus level relationships, but caution in the use of the matK marker is recommended. Research highlights: Incongruent phylogenetic signals between these two chloroplast markers are demonstrated in pines for the first time.
[en] Aim of study: To better estimate the annual allowable cut reserve (AACR), taking into consideration the endemic windthrows (EW), we combined a series of existing algorithms into a coherent methodology to use the data available at district level, without any additional fieldworks. Area of study: The algorithm was tested on the EW occurred in the last 20 years in Brosteni FD (Eastern Carpathians, Romania) that covers 21,013 ha and we found that every year from an AAC of 37,000 m3 no more than 2,700 m3 shall be spared for EW that might occur next year. Material and methods: We considered three EW enabling factors (stand slenderness, location on pits and mounds, and the vicinity of canopy gap) and three contingency tables of the EW produced between 1999 and 2008, one for each 40-year age group. Then we calculated a Bayesian model for all six permutations of enabling factors, each of them being tested on the data referring to 2008-2017 period. Results: Plugging the posterior EW likelihoods into a Markov chains (MC) model, we produced a formula that enables a better estimation of the optimal AACR that could be replaced with salvage cuttings every next year. Other options of using the EW likelihoods are also presented at length, such as the type of age-class structure that requires no AACR, that is a “U” shape age structure, as well as a rough assessment of the additional demand for seedlings needed to re-plant the stands affected by EW. The relatively short period of time the input data refer to, which is ten years, equals the time window of the forest planning and this parity allows a ten-year forecast period, enough for modeling the stationary age-structure of even-aged forests. Research highlights: A new model for optimizing the annual allowable cut (AAC) in even-age forests in the context of endemic windthrows (EW) scenario has been developed and evaluated.
[en] Aim of study: To understand throughfall (TF) sensitivity to variability in rainfall amount (Pg ) for typical forest sites across the main climate types of Iran. Area of study: Nine forest stands of several common native and introduced tree species situated in all common Iranian climate types, but located primarily in northern Iran. Material and methods: A nondimensional relative sensitivity coefficient was employed to predict responses of TF to Pg changes. Projected Pg changes over the measurement sites for the period 2020-50 were estimated using one of the Coupled Model Intercomparison Project phase 5 (CMIP5) known as HadGEM2-ES under low and high emission scenarios (RCP 2.6 and 8.5). Main results: TF displayed strong positive linear relationships with Pg at all sites [TF=0.66 Pg -0.16; R2 =0.91]. The sensitivity coefficient ranged from 0.96-2.35 across the nine forest sites and large sensitivity coefficient differences were found between small (< mean annual Pg) and large (> mean annual Pg ) storms for arid and Mediterranean plantations. Shifts in Pg and increased small storm frequency are predicted for these regions (2020-50) under low and high emission scenarios. Research highlights: TF sensitivity may be a useful variable when selecting tree species for afforestation to buffer expected shifts in Pg due to climate change.
[en] Aim of study: Edible products from tree species were identified in Burkina Faso and their contribution to the diet in the lean season was assessed. The main threats affecting most consumed food tree species were also documented. Area of study: Six villages across two phytogeographic regions of Burkina Faso Material and methods: Focus group discussions and semi-structured interviews, including a 7-day dietary intake recall targeting women; semi-structured interviews targeting key male informants. Main results: The number of edible tree products consumed was found to vary according to phytogeographic region and ethnic group. A few tree species played a disproportionally greater role in the diet and were characterized by very high frequency of consumption by the majority of households in both phytogeographic regions and across ethnicities: Adansonia digitata, Parkia biglobosa and Vitellaria paradoxa. These species are not critically endangered at country level but they are perceived as scarcely available at local level. Considering that the main threats on priority tree species (fires, drought, pest and diseases) vary across regions, to maintain sustainable sources of nutrients in the landscape, mitigation measures should be diversified and adapted to local pressures. Research highlights: Priorities for conservation are emerging clearly, but research efforts should also target underutilized tree species for their potential to diversify nutrient-poor diets.
[en] Aim of study: To verify how well near infrared (NIR) spectroscopy is able to discriminate wood specimens from natural and planted forests. This study was carried out using tropical trees from Brazil. Area of study: Wood specimens coming from Lavras (21°10′S, 44°54′W), Paraopeba (19°16′S, 44°24′W) and Belo Oriente (19°17′S, 42°23′W) cities, Minas Gerais state, southeastern Brazil were insvetigated. Material and methods: NIR spectra were recorded in the radial surface of wood specimens of four native species (Cedrela sp., Apuleia sp., Aspidosperma sp. and Jacaranda sp.) and two commercial clones (Eucalyptus for bioenergy and pulp & paper). Main results: The principal component analysis (PCA) of spectral information revealed that it is possible to distinguish wood from planted and native forests. The dispersion of scores in the graphic formed by the first and second principal component formed two groups allowing differentiating very clearly the Eucalyptus clones from the native woods. The partial least squares discriminant analysis (PLS-DA) allowed the prediction of group of species with a high degree of correct classification. The PLS-DA models performed from untreated NIR spectra obtained 86 to 100% accuracy for the natural wood species. Research highlights: From PLS-DA of treated NIR spectra, no Eucalyptus wood sample was classified as a natural forest species and vice versa. NIR technique associated with multivariate statistics are promising to discriminate wood specimens from native or planted forests and thus identify frauds.
[en] Forest ecosystems provide a host of services and societal benefits, including carbon storage, habitat for fauna, recreation, and provision of wood or non-wood products. In a context of complex demands on forest resources, identifying priorities for biodiversity and carbon budgets require accurate tools with sufficient temporal frequency. Moreover, understanding long term forest dynamics is necessary for sustainable planning and management. Remote sensing (RS) is a powerful means for analysis, synthesis and report, providing insights and contributing to inform decisions upon forest ecosystems. In this communication we review current applications of RS techniques in Spanish forests, examining possible trends, needs, and opportunities offered by RS in a forestry context. Currently, wall-to-wall optical and LiDAR data are extensively used for a wide range of applications—many times in combination—whilst radar or hyperspectral data are rarely used in the analysis of Spanish forests. Unmanned Aerial Vehicles (UAVs) carrying visible and infrared sensors are gaining ground in acquisition of data locally and at small scale, particularly for health assessments. Forest fire identification and characterization are prevalent applications at the landscape scale, whereas structural assessments are the most widespread analyses carried out at limited extents. Unparalleled opportunities are offered by the availability of diverse RS data like those provided by the European Copernicus programme and recent satellite LiDAR launches, processing capacity, and synergies with other ancillary sources to produce information of our forests. Overall, we live in times of unprecedented opportunities for monitoring forest ecosystems with a growing support from RS technologies.
[en] Aim of study: The objective of this study was to present statistical information pertaining to recurrent inconsistencies found in the literature of the last 25 years that involve calculation of the GR and the errors that this may entail when interpreting the seed vigor of different botanical materials. Materiales y métodos: After filtering articles that did not present numerical results or in which the application of Maguire's formula was not clearly indicated, a total of 124 papers were ultimately used in this study. Main results: Germination rate (GR) represents the potential of seeds to germinate and, along with germination percentage (GP), are the two most important measurements when evaluating seed quality. The correct calculation of GR allows the seeds classification according to their vigor and capacity to produce healthy seedlings, so it is very important to rely on the adequate mathematical formula for this purpose. According to the formula developed by Maguire, this parameter is calculated by the sum of values obtained when dividing the GP at different times (i.e. daily) by the total time elapsed since the start of the test. We have found from the relevant literature that different authors have been using different ways of applying the formula, which makes it difficult to directly compare the results. Research highlights: A total of 54.8 % of the papers reviewed, belonging mainly to the theme of forestry, presented objectionable application of the formula. Publication of this warning may help to reduce the occurrence of this situation in the future.
[en] The TTS Institute has carried out a study concerning forest owners' timber sales. The material was collected in 2002 via a mail inquiry that targeted forest owners who sold timber during the years 1997-1999 and 1999-2002. Three quarters of the forest owners sold timber to the same timber buying company during both periods of 1997-1999 and 1999-2002. The most important reasons for selling to the same buyer were that they purchased all timber assortments, reliability and good timber price. Mainly the same reasons also applied when changing the timber buying company. The most sensitive groups to changing timber buyer were 60-69 year old, entrepreneurs, men, and owners of forest holdings between 20-29 hectares, owners of inherited forests and joint forest ownerships. The forest owners assessed the timber buying company's operations and its staff on the basis of the last timber sale. The forest owners gave best values for the timber buyer's reliability, the purchase of all timber assortments and the timber buyers' reputation. The worst values were given for cross-cutting and response to complaints. No less than 95 percent of forest owners were prepared to recommend their timber trade partner to acquaintances, friends or other forest owners. Yet only half of the forest owners recognized that their last timber sale experience would not affect which company will be selected for the nest timber sale process