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Land use/land cover (LULC) changes driven by human activities are major environmental challenges in many developing regions. This study assessed local community perceptions and household-level drivers of LULC change in northwest Ethiopia. The study combined remote sensing analysis of LULC change with household surveys to understand local perspectives and the socioeconomic, biophysical, and institutional factors influencing household engagement in deforestation activities. The household survey data was collected from 384 randomly selected household heads, as well as from focus group discussions and key informant participants. The remote sensing component used ERDAS IMAGINE 2014 software to classify satellite images and assess LULC changes over time. The quantitative socio-economic data was analyzed using descriptive statistics and econometric methods of the multivariate probit (MVP) model. The study revealed that population growth, poverty, and food insecurity were the major proximate driving factors, while agricultural land expansion, settlement growth, fuelwood collection, overgrazing, and forest fires were the major underlying causes of LULC change. The MVP model result indicated that gender, off-farm income, access to training, family size, educational level, and agroecology were key determinants of households’ involvement in deforestation drivers such as forestland clearing for agriculture, fuelwood collection, timber harvesting, and overgrazing. These findings highlight the need for integrated land use policies and programs that address the socioeconomic and biophysical root causes of LULC change. This study recommends supporting alternative livelihoods, promoting fuel-efficient technologies, and tailoring interventions to different agroecological contexts of sustainable land use planning and natural resource management in the study site. Future studies should compare perceptions and drivers of land use change across different regions to identify common patterns and unique challenges. This approach will enhance understanding and inform targeted interventions for sustainable land management.

The present work proposes a new model based on a convolutional neural network (CNN) to retrieve solar shortwave (SW) irradiance via the estimation of the cloud modification factor (CMF) from daytime sky images captured by all-sky cameras; this model is named CNN-CMF. To this end, a total of 237,669 sky images paired with SW irradiance measurements obtained by using pyranometers were selected at the following three sites: Valladolid and Izaña, Spain, and Lindenberg, Germany. This dataset was randomly split into training and testing sets, with the latter excluded from the training model in order to validate it using the same locations. Subsequently, the test dataset was compared with the corresponding SW irradiance measurements obtained by the pyranometers in scatter density plots. The linear fit shows a high determination coefficient (R2) of 0.99. Statistical analyses based on the mean bias error (MBE) values and the standard deviation (SD) of the SW irradiance differences yield results close to −2% and 9%, respectively. The MBE indicates a slight underestimation of the CNN-CMF model compared to the measurement values. After its validation, model performance was evaluated at the Antarctic station of Marambio (Argentina), a location not used in the training process. A similar comparison between the model-predicted SW irradiance and pyranometer measurements yielded R2=0.95, with an MBE of around 2% and an SD of approximately 26%. Although the precision provided by the SD at the Marambio station is lower, the MBE shows that the model’s accuracy is similar to previous results but with a slight overestimation of the SW irradiance. Finally, the determination coefficient improved to 0.99, and the MBE and SD are about 3% and 11%, respectively, when the CNN-CMF model is used to estimate daily SW irradiation values.

Aerosol optical depth (AOD) at night-time has become a hot topic in recent years due to the development of new instruments recording accurate ground-based lunar irradiance measurements, and the development of calibration methods and extraterrestrial irradiance models adapted to lunar photometry. This study uses all daytime and night-time AOD data available at Valladolid (Spain) from October 2016 to March 2022 in order to analyze its behavior and the added contribution of night data. The annual, monthly and daily AOD evolution is studied comparing daytime and night-time values and checking the correlation between them. For this purpose, the daily averages are computed, showing an annual pattern, with low AOD values throughout the year (mean value of AOD at 440 nm: 0.122), where winter months have the lower and summer the higher values, as observed in previous studies. All these AOD values are modulated by frequent desert dust events over the Iberian Peninsula, with a strong influence on daily and monthly mean values in February and March, where the strongest desert outbreaks occurred. The added new data confirm these results and the good correlation between daytime and night-time data. Also, a complete daily evolution is shown, observing that AOD and Ångström exponent (AE) mean values vary by only ±0.02 in 24 h, with a maximum value at 06:00 UTC and minimum at 18:00 UTC for both parameters.

Removal of stumps and suppression of sprouts after harvesting by conventional methods, such as using heavy machinery or herbicides, alters the physico-chemical characteristics of soil, may cause environmental damage and can be very costly. In this study, the performance of inoculation with edible fungi as a biological alternative for stump degradation, has been examined in walnut plantations of five Spanish provinces. Stumps were inoculated with two species of edible fungi: Pleurotus ostreatus (Jacq. Ex Fr.) P. Kumm and Lentinula edodes (Berk) Pené. Compared with untreated controls, the two biological treatments resulted in a significant and evident reduction of the sprouting probability, which was stronger than the result obtained with chemical treatments. Inoculated stumps also produced edible sporocarps, averaging 15.58 g per stump during the first year. This article constitutes the basis for the development of a sustainable, environmentally friendly and cost-effective product, which is a bioeconomy-based solution for stump degradation in intensive plantations.

Aim of the study: Understanding post-fire germination of tree species in arid and semi-arid zones of sub-Saharan Africa. Area of study: Ethiopian Acacia senegal L. and Acacia seyal Del. forests. Material and methods: Seeds were subjected to heat shocks at combinations of four temperatures (60º, 90º, 120º and 150ºC) and three exposure times (1, 5 and 10 minutes). A control was also included, resulting in a total of thirteen treatments. After the application of the heat shocks, the viability of no germinated seeds was assessed after immersion in a Tetrazolium solution. A mixed and a logistic model were used to analyse the influence of heat shock on germination. Main results: Results showed that germination depended on the species, the heat shock treatment and their interaction. Both species showed similar germination results at temperatures below 90ºC in all exposure times, however, germination in Acacia senegal was statistically higher in most of the heat shocks. On the other hand, germination probability decreased in both species, when the exposure time increased, although with a different behaviour. In 1 minute of time of exposure, the germination probability was higher than 60% in the two species throughout the temperature range. However, at 5 minutes of time and temperature smaller than 90°C, the probability of germination was higher than 70% in A. senegal and 50% in A. seyal. Although germination in both species was impacted by the different heat shocks, non-germinated seeds were viable. Research highlights: This paper showed, according to these results, that heat shock would negatively influence the regeneration of both species, and especially for A. seyal. Key words: germination, Acacia, heat shock, logistic model.

Aim of study: The aim of this study was to 1) estimate the amount of dead wood in managed beech (Fagus sylvatica L.) stands in northern Iberian Peninsula and 2) evaluate the most appropriate volume equation and the optimal transect length for sampling downed wood. Area of study: The study area is the Aralar Forest in Navarra (Northern Iberian Peninsula). Material and methods: The amount of dead wood by component (downed logs, snags, stumps and fine woody debris) was inventoried in 51 plots across a chronosequence of stand ages (0-120 years old). Main results: The average volume and biomass of dead wood was 24.43 m3 ha-1 and 7.65 Mg ha-1, respectively. This amount changed with stand development stage [17.14 m3 ha-1 in seedling stage; 34.09 m3 ha-1 inpole stage; 22.54 m3 ha-1 in mature stage and 24.27 m3 ha-1 in regular stand in regeneration stage], although the differences were not statistically significant for coarse woody debris. However, forest management influenced the amount of dead wood, because the proportion of mass in the different components and the decay stage depended on time since last thinning. The formula based on intersection diameter resulted on the smallest coefficient of variation out of seven log-volume formulae. Thus, the intersection diameter is the preferred method because it gives unbiased estimates, has the greatest precision and is the easiest to implement in the field. Research highlights: The amount of dead wood, and in particular snags, was significantly lower than that in reserved forests. Results of this study showed that sampling effort should be directed towards increasing the number of transects, instead of increasing transect length or collecting additional piece diameters that do not increase the accuracy or precision of DWM volume estimation. Keywords: snags; downed logs; stumps; fine woody debris; beech; line intersect sampling.

Aim of study: The aim of the study was to determine the baseline carbon stock in forest floor and mineral soils in pine and oak stands in acid soils in Northern Spain. Area of study: The study area is situated in northern Spain (42° N, 4° W) on “Paramos y Valles” region of Palencia Material and methods: An extensive monitoring composed of 48 plots (31 in pine and 17 in oak stands) was carried out. Litter layers and mineral soil samples, at depths of 0-30 cm and 30-60 cm, were taken in each plot. An intensive monitoring was also performed by sampling 12 of these 48 plots selected taken in account species forest composition and their stand development stage. Microbial biomass C (CMB), C mineralization (CRB), and soil organic C balance at stand level were determined in surface soil samples of intensive monitoring. Main results: No differences in soil C content were detected in the two forest ecosystems up to 60 cm depth (53.0±25.8 Mg C ha-1 in Pinus spp. plantations and 60.3±43.8 Mg C ha-1 in oak stands). However, differences in total C (CT), CMB and CRB were found in the upper 10 cm of the soils depending on the stand development stage in each species forest composition (Pinus nigra, Pinus pinaster, Pinus sylvestris and Quercus pyrenaica). Plots with high development stage exhibited significant lower metabolic quotient (qCO2), so, meant more efficient utilization of C by the microbial community. The C content in the forest floor was higher in pine stands (13.7±0.9 Mg C ha-1) than in oak stands (5.4±0.7 Mg C ha-1). A greater turnover time was found in pine ecosystems vs. oak stands. In contrast, forest floor H layer was nonexistent in oak stands. Research highlights: Results about litterfall, forest floor and mineral soil dynamics in this paper can be used strategically to reach environmental goals in new afforestation programs and sustainable forest management approaches. Keywords: C stocks; pine; Quercus pyrenaica; litter; metabolic quotient (qCO2).

This work introduces CAECENET, a new system capable of automatically retrieving columnar and vertically-resolved aerosol properties running the GRASP (Generalized Retrieval of Atmosphere and Surface Properties) algorithm using sun-sky photometer (aerosol optical depth, AOD; and sky radiance measurements) and ceilometer (range corrected signal; RCS) data as input. This method, so called GRASPpac, is implemented in CAECENET, which assimilates sun-sky photometers data from CÆLIS database and ceilometer data from ICENET database (Iberian Ceilometer Network). CAECENET allows for continuous and near-real-time monitoring of both vertical and columnar aerosol properties. The main characteristics and workflow of CAECENET are explained in detail. This work also explores the potential of CAECENET to monitor and analyze the evolution of transported aerosol events on a regional scale by means of the distribution of CAECENET stations across the Iberian Peninsula. As an example, this paper analyzes, using the CAECENET products, the case of a Saharan dust outbreak that occurred between the 3rd and 5th of October 2022. This was an intense event, with AOD at 440 nm values around 0.5 in Madrid and Valladolid, and reaching 1.55 in Granada. Transport from the Canadian wildfires at the end of June 2023 is also studied. Despite the long-range transport of the smoke particles in this event, measured volume concentrations reached and surpassed 80 μ m3/ μ m2 in some stations. The results obtained point to the utility of this CAECENET tool for analyzing changes in the height and speed of the event propagation, in the aerosol concentration, and how this affects the optical properties. [ABSTRACT FROM AUTHOR]

This study explores the potential to retrieve aerosol properties with the GRASP algorithm (Generalized Retrieval of Atmosphere and Surface Properties) using as input measurements of zenith sky radiance (ZSR), which are sky radiances measured in the zenith direction, recorded at four wavelengths by a ZEN-R52 radiometer. To this end, the ZSR measured at 440, 500, 675 and 870 nm by a ZEN-R52 (ZSRZEN), installed in Valladolid (Spain), is employed. This instrument is calibrated intercomparing the signal of each channel with coincident ZSR values simulated (ZSRSIM) at the same wavelengths with a radiative transfer model (RTM). These simulations are carried out using the GRASP forward module as RTM and the aerosol information from a collocated CE318 photometer belonging to the AERONET network (Aerosol and Robotic Network) as input. Dark signal and the signal dependence on temperature are characterized and included in the calibration process. The uncertainties on each channel are quantified by an intercomparison with a collocated CE318 photometer, obtaining lower values for shorter wavelengths; between 3 % for 440 nm and 21 % for 870 nm. The proposed inversion strategy for the aerosol retrieval using the ZSRZEN measurements as input, so-called GRASP-ZEN, assumes the aerosol as an external mixture of five pre calculated aerosol types. A sensitivity analysis is conducted using synthetic ZSRZEN measurements, pointing out that these measurements are sensitive to aerosol load and type. It also assesses that the retrieved aerosol optical depth (AOD) values in general overestimates the reference ones by 0.03, 0.02, 0.02 and 0.01 for 440, 500, 675, 870 nm, respectively. The calibrated ZSRZEN measurements, recorded during two and half years at Valladolid, are inverted by GRASP-ZEN strategy to retrieve some aerosol properties like AOD. The retrieved AOD shows a high correlation with respect independent values obtained from the collocated AERONET CE318 photometer, with a determination coefficient (r2) about 0.86, 0.85, 0.79 and 0.72 for 440, 500, 675 and 870 nm, respectively, and finding uncertainties between 0.02 and 0.03 with respect to the AERONET values. Finally, it is studied the goodness of other retrieved aerosol properties like aerosol volume concentration for total, fine and coarse modes. [ABSTRACT FROM AUTHOR]

The main objective of this study was to analyse biomass production and distribution among the constituent parts of 4-year-old Pinus pinaster and Pinus halepensis trees. Young trees were harvested from a Nelder wheel experimental site and their biomass weight was determined. With the Nelder design, the effect of stand density can be included in the biomass analysis. We analysed biomass production at test densities ranging from 1000 to 80 000 seedlings/ha by fitting two types of equations: (1) Dirichlet regressions to estimate the biomass proportions of constituent tree parts and (2) allometric equations to simultaneously predict the biomass content of constituent tree parts. Results from this innovative approach showed that the effect of stand density in tree-level biomass was significant for P. halepensis but not for P. pinaster. We observed a general increase of total biomass from P. halepensis at lower densities. More precisely, the proportion of root biomass increased at the expense of aboveground biomass, which is considered a positive effect in terms of resilience and adaptation. This new set of equations fills a fundamental knowledge gap for these species in central Spain and can readily be used by silviculturists and scientists to quantify carbon stocks for young planted forests. [ABSTRACT FROM AUTHOR]

Information regarding carbon concentration and wood density are lacking in Chilimo dry Afromontane forest. The aim of this study was to estimate carbon concentration and wood density for Allophyllus abyssinicus, Olea europaea, Olinia rochetiana, Rhus glutinosa, and Scolopia theifolia. A total of 105, 30–50 mm thick wood discs were collected and oven dried at 102°C and 67°C to constant weight, chopped and finally grinded into 0.2 mm with a grinding mill. Carbon concentration was analyzed using the ash method, while wood density was estimated using the water displacement method. The highest carbon concentration (57.12%) was found for O. rochetiana, however, the lowest carbon concentration (56.43%) was found for A. abyssinicus. Stem parts had higher carbon concentration (56.98%) than branch (56.74%) and leave (54.53%) parts. O. europaea exhibited the highest wood density (0.67 g cm−3) value than other species. However, the lowest wood density (0.42 g cm−3) was exhibited for A. abyssinicus. Wood density was also showed a decreasing trend along with increases in stem height and maximum wood density (0.62 g cm−3) was found under stump position, while, the minimum wood density (0.4 g cm−3) was found under tree commercial height. [ABSTRACT FROM AUTHOR]

Density management diagrams are valuable tools for managing specific forest species. The aim of this study was to obtain a density management diagram for teak (Tectona grandis L.) plantations in the State of Tabasco in Mexico. To achieve this objective, a set of 10 plantations were studied, in which 42 plots were established. Two equations were fitted simultaneously, including one related to the quadratic mean diameter, stand density and dominant height and the other which related the total stand volume to the quadratic mean diameter, stand density and dominant height. The results showed that the diagram had an acceptable predictability, thus indicating its usefulness and accuracy in planning silvicultural interventions. This diagram is a very powerful tool that can enable stakeholders to manage teak plantations in the State of Tabasco. [ABSTRACT FROM AUTHOR]