Forest Health Status Research Articles

Biological Control of Cryphonectria parasitica in Romanian Protected Sweet Chestnut Forests

Asiatic fungus Cryphonectria parasitica has gradually infected all chestnut habitats, forest and horticulture plantations from the most important natural centres of sweet chestnut distribution in Romania. The objectives of this work were to understand the destruction rate of chestnut habitats under C. parasitica pressure, and to test the efficacy of pathogen control in revitalizing these protected forests. Successive inventories of forest health status were carried out in forest districts of Maramures and Gorj counties. C. parasitica biologic control using CHV1 virus has been tested. The methodology includes standard laboratory and field work techniques: local hipervirulent strain identification and conversion to hipovirulence, field canker inoculation, and treatment efficacy evaluation. The fungus killed all mature chestnut trees in roughly two decades. Field inoculation has been successful on chestnut and sessile oak (fungus secondary host) in experimental plots from both target zones. This is the first time in Romania when a forest habitat is recovered by means of biological control, after a severe dieback of the old forest caused by a lethal invasive pathogen.

Detecting Drought-Induced Tree Mortality in Sierra Nevada Forests with Time Series of Satellite Data

A five-year drought in California led to a significant increase in tree mortality in the Sierra Nevada forests from 2012 to 2016. Landscape level monitoring of forest health and tree dieback is critical for vegetation and disaster management strategies. We examined the capability of multispectral imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) in detecting and explaining the impacts of the recent severe drought in Sierra Nevada forests. Remote sensing metrics were developed to represent baseline forest health conditions and drought stress using time series of MODIS vegetation indices (VIs) and a water index. We used Random Forest algorithms, trained with forest aerial detection surveys data, to detect tree mortality based on the remote sensing metrics and topographical variables. Map estimates of tree mortality demonstrated that our two-stage Random Forest models were capable of detecting the spatial patterns and severity of tree mortality, with an overall producer’s accuracy of 96.3% for the classification Random Forest (CRF) and a RMSE of 7.19 dead trees per acre for the regression Random Forest (RRF). The overall omission errors of the CRF ranged from 19% for the severe mortality class to 27% for the low mortality class. Interpretations of the models revealed that forests with higher productivity preceding the onset of drought were more vulnerable to drought stress and, consequently, more likely to experience tree mortality. This method highlights the importance of incorporating baseline forest health data and measurements of drought stress in understanding forest response to severe drought.

Лесопатологическое состояние древостоя географического парка Ботанического сада им. проф. Б.М. Козо-Полянского Воронежского государственного университета

For the ecology of the big city it is very important to have such a significant woodland, as, for example, natural and artificial plantings of Prof. BM Kozo-Polyansky Botanical Garden, Voronezh State University. The article briefly characterizes the botanical garden, its origins and the present conditions. The main goal of the definition of forest pathology and health status of all the stand has been put on one of the key areas of the botanical garden referred to as "Northern ravine oak wood." In conducting research we use standard methods of forest inventory and forest pathology examination with appropriate post-processing. The detailed data on the composition, taxation rates and conditions of the studied plants are given. Complete loss of the composition of exotic species planted in 30-x – 70-ies of the last century is revealed and we determine an accelerated death of English oak and European white birch, which is actively being replaced by Norway maple and Scotch elm. Comparative analyzes of forestpathological characteristics of the main forest-forming species of this area is made, and conclusions about the lack of competitiveness of such artificially planted exotic species as the horse chestnut, bitternut walnut and European larch in natural groves stands is drawn. A list of found external characteristics of each species diseases in the surveyed forest stand is given. On English oak leading pathological features are: shrinkage of the skeletal branches and inboard hollows. On the Norway maple there are also a lot of dead skeletal branches, and a lot of trees with pathological forms of the barrel. The main conclusion of the work lies in the fact that the stock data on shrunken and especially drying trees testify to the strong weakening of the stand. Conducting sanitary measures in the form of selective sanitary cutting is required for its recovery.

Effects of urbanization intensity on forest structural-taxonomic attributes, landscape patterns and their associations in Changchun, Northeast China: Implications for urban green infrastructure planning

Understanding the associations between urbanization intensity and urban forest structural-taxonomic attributes is a central theme of urban ecology, biodiversity conservation and forest management for maximizing ecological services to design proper urban green infrastructure. By selecting a typical provincial capital city of Changchun as an example, the effects of urbanization intensity (low, medium and heavy urbanization as measured by impervious surface area, ISA) on landscape patterns and structural-taxonomic attributes of urban forests were investigated in this study. The results showed that the urban forest Patch Density (PD), Landscape Shape Index (LSI), Interspersion & Juxtaposition Index (IJI), Tree Density (TD), Canopy Density (CD), Species Richness (SR) and Species Diversity (H’ index) exhibited strictly monotonic increases with urbanization intensity, increasing by 162%, 60%, 44%, 37%, 50%, 85%, and 84% from low to heavy urbanization areas, respectively. In contrast, the forest Mean Euclidian Nearest Neighbor Distance (ENN-MN) and Health Condition grade (HC) monotonically decreased by 12% and 37%, respectively. Furthermore, regression analysis suggested that structural-taxonomic attributes were closely associated with forest-related landscape patterns, but urbanization intensity dramatically influenced these associations. Our findings highlight that the planning of urban green infrastructure, in particular, urban afforestation and associated management, should be different at different urbanization intensities. In low urbanization areas, low Total area (TA, forest area) requires construction of larger forest patches and the protection of large remnant trees, and TD and above ground biomass (AGB) could be increased by enhancing the Mean Fractal Dimension (FRAC-MN) and PD, respectively. In medium urbanization areas, the same increases in TD and AGB could be more effectively achieved by decreasing the IJI and Area-Weighted Mean Contiguity (CONTIG-MN). Moreover, in heavy urbanization areas, more attention should be paid to increasing forest patch aggregation and contiguity, and both tree diversity and evenness could be increased by enhancing the FRAC-MN index. Because these structural-taxonomic attributes are the basis of various forest ecological services, our findings indicate that regulation of some of these landscape metrics could improve urban forest services in Changchun.

Discrimination between acute and chronic decline of Central European forests using map algebra of the growth condition and forest biomass fuzzy sets: A case study

Forest decline is either caused by damage or else by vulnerability due to unfavourable growth conditions or due to unnatural silvicultural systems. Here, we assess forest decline in the Czech Republic (Central Europe) using fuzzy functions, fuzzy sets and fuzzy rating of ecosystem properties over a 1×1km grid. The model was divided into fuzzy functions of the abiotic predictors of growth conditions (Fpred including temperature, precipitation, acid deposition, soil data and relative site insolation) and forest biomass receptors (Frec including remote sensing data, density and volume of aboveground biomass, and surface humus chemical data). Fuzzy functions were designed at the limits of unfavourable, undetermined or favourable effects on the forest ecosystem health status. Fuzzy sets were distinguished through similarity in a particular membership of the properties at the limits of the forest status margins. Fuzzy rating was obtained from the least difference of Fpred−Frec. Unfavourable Fpred within unfavourable Frec indicated chronic damage, favourable Fpred within unfavourable Frec indicated acute damage, and unfavourable Fpred within favourable Frec indicated vulnerability. The model in the 1×1km grid was validated through spatial intersection with a point field of uniform forest stands. Favourable status was characterised by soil base saturation (BS)>50%, BCC/Al>1, Corg>1%, MgO>6g/kg, and nitrogen deposition<1200mol(H+)/ha·year. Vulnerable forests had BShumus 46–60%, BCC/Al 9–20 and NDVI≈0.42. Chronic forest damage occurs in areas with low temperatures, high nitrogen deposition, and low soil BS and Corg levels. In the Czech Republic, 10% of forests were considered non-damaged and 77% vulnerable, with damage considered acute in 7% of forests and chronic in 5%. The fuzzy model used suggests that improvement in forest health will depend on decreasing environmental load and restoration concordance between growth conditions and tree species composition.

Лесопатологическое состояние древостоя северной байрачной дубравы Ботанического сада им. проф. Б.М. Козо-Полянского Воронежского государственного университета

The article shows the urgency of such significant woodlands as, for example, natural and artificial planting of the Prof. B.M. Kozo-Polyansky Botanical Garden, Voronezh State University, for the environment of big city. We briefly characterize the botanical garden, its origins and the present conditions. The main goal of the definition of forest pathology and health status of all the stand has been put on one of the key areas of the botanical garden referred to as &amp;#34;Northern ravine oak wood.&amp;#34;

Gnomoniopsis castaneae associated with Dryocosmus kuriphilus galls in chestnut stands in Sardinia (Italy)

Abstract: Invasive fungal pathogens and pests of sweet chestnut (Castanea sativa Mill.) forests drastically reduce their productivity. The recently described Gnomoniopsis castaneae is one of the main agents involved in the epidemic of brown rot of chestnut nuts worldwide. In 2014, during an investigation aimed at evaluating the health status of chestnut forests in Sardinia, a high incidence of necrotic galls induced by the Asian gall wasp Dryocosmus kuriphilus Yasumatsu (Hymenoptera, Cynipidae) was observed. Several fungal isolates were consistently isolated from necrotic gall tissues. Based on their morphological characters and analyses of both the ITS and EF1-α-coding gene sequences, all isolates were identified as Gnomoniopsis castaneae.

Effect of fungal pathogens and climatic factors on production, biodiversity and health status of ash mountain forests

Effect of fungal pathogens and climatic factors on production, biodiversity and health status of ash mountain forests

Norway spruce (Picea abies/L./Karst.) health status on various forest soil ecological series in Silesian Beskids obtained by grid or selective survey

The values of characteristics of forest health status (FHS) depend on design of monitoring plot selection. The aim of the work was to compare the dependence of FHS on various ecological site conditions on research plots with different selection designs. The differences of Norway spruce (Picea abies/L./Karst.) defoliation, discoloration and total damage variance were investigated in the Silesian Beskids (Czech Republic; 297 km2; 304–1067 m a. s.l.) during 1999–2008. FHS results on 187 plots at 400×400 m grid were obtained through routine methods according to EMEP-LRTAP. In addition, forest health status on 18 plots of selective survey design was obtained by estimation of defoliation and crown structure transformation. The comparison of ecological series proportion in individual survey designs was carried out through Mann-Whitney U-test, the comparison of health status feature occurrence in ecological series between different survey designs through analysis of variance. The survey design did not influence ecological series proportion, but influenced FHS feature variance. FHS features on sites of various ecological series have different rate of tree damage in individual survey designs. The selective survey significantly decreased data variance in contrast to low plot frequency.

Effects of parent material, stand type and oak species on defoliation of coppice-originated oak (Quercus spp.) forests in Northern Turkish Thrace

Cases of significant defoliation in oak (Quercus spp.) forests have been reported in Turkey and throughout the world. Oak trees are important in Turkish forests and forestry and cover vast pieces of land in Thrace. In this study, in a quest to determine the general health condition of pure oak forests in Northern Turkish Thrace, the defoliation rate of tree crowns was evaluated for 8,769 trees in 336 sample plots corresponding to different geological parent materials, regions, oak species and stand types. The defoliation rates were designated and assessed based on the criteria of the European Union Forest Health Monitoring Program (UNECE-ICP Forests). The defoliation rate was, to a significant extent, affected by stand type, the geological parent material, and oak species. In general, 47 % of trees exhibited defoliation. The highest ratio of defoliation was found in Kirklareli Region, where water deficit was the highest, and the parent material was schist-calcschist. Medium diameter forests (MDF, mean dbh: 8-20 cm, ratio of defoliated trees = 65 %) among stand types, and sessile oaks (ratio of defoliated trees = 53 %) among oak species, had the highest defoliation rates. Achieved results demonstrated that the defoliation classes in observed oak stands have a significant relation with variables concerning stand types, oak species and geological parent materials.

In situ data supporting remote sensing estimation of spruce forest parameters at the ecosystem station Bílý Kříž

Remote sensing offers an effective way of mapping vegetation parameters in a spatially continuous manner, at larger spatial scales and repeatedly in time compared to traditional in situ mapping approaches that are typically accurate, but limited to a few distributed location and few repetitions. In case of forest ecosystems, remote sensing allow to assess quantitative parameters or indicators related to forest health status such as leaf area index, leaf pigment content, chlorophyll fluorescence, etc. Development, calibration and validation of remote sensing-based methods, however, still rely on supportive in situ data. The aim of this contribution is to introduce the individual in situ components in the framework for the retrieval of forest quantitative parameters from airborne imaging spectroscopy data. All measurements were acquired during an extensive in situ/flight campaign that took place at the Norway spruce dominated study site Bílý Kříž (Moravian-Silesian Beskydy Mts., Czech Republic) during August 2016. In addition to airborne remote sensing data acquisition, the in situ activities included terrestrial laser scanning for tree 3D modelling, measurements of needle biochemical and optical properties, leaf area index measurements and spectral measurements of various natural and artificial surfaces. Leaf pigments varied between 25.2 and 49.1 µg cm-2 for chlorophyll a+b content, 4.9 – 10.6 µg cm-2 for carotenoid content depending on needle age and its adaptation to sun illumination, whereas ratio between the two pigments was stable around 4.6 – 5. 3. Specific leaf area of spruce needles varied between 49.3 and 105.8 cm2 g-1, being the highest for the shade adapted needles of the current year. Leaf area index of spruce stands of various age and densities varied between 5.3 and 9. 3.

MAPPING ROBINIA PSEUDOACACIA FOREST HEALTH CONDITIONS BY USING COMBINED SPECTRAL, SPATIAL AND TEXTUREAL INFORMATION EXTRACTED FROM IKONOS IMAGERY

Abstract. In this study grey-level co-occurrence matrix (GLCM) textures and a local statistical analysis Getis statistic (Gi), computed from IKONOS multispectral (MS) imagery acquired from the Yellow River Delta in China, along with a random forest (RF) classifier, were used to discriminate Robina pseudoacacia tree health levels. The different RF classification results of the three forest health conditions were created: (1) an overall accuracy (OA) of 79.5% produced using the four MS band reflectances only; (2) an OA of 97.1% created with the eight GLCM features calculated from IKONOS Band 4 with the optimal window size of 13 × 13 and direction 45°; (3) an OA of 94.0% created using the four Gi features calculated from the four IKONOS MS bands with the optimal distance value of 5 and Queen’s neighborhood rule; and (4) an OA of 96.9% created with the combined 16 spectral (four), spatial (four), and textural (eight) features. The experimental results demonstrate that (a) both textural and spatial information was more useful than spectral information in determining the Robina pseudoacacia forest health conditions; and (b) IKONOS NIR band was more powerful than visible bands in quantifying varying degree of forest crown dieback.

Analysis of multitemporal aerial images for fenyőfő Forest change detection

This study evaluated the use of 40 cm spatial resolution aerial images for individual tree crown delineation, forest type classification, health estimation and clear-cut area detection in Fenyőfő forest reserves in 2012 and 2015 years. Region growing algorithm was used for segmentation of individual tree crowns. Forest type (coniferous/deciduous trees) were distinguished based on the orthomosaic images and segments. Research also investigated the height of individual trees, clear-cut areas and cut crowns between 2012 and 2015 years using Canopy Height Models. Results of the research were examined based on the field measurement data. According to our results, we achieved 75.2% accuracy in individual tree crown delineation. Heights of tree crowns have been calculated with 88.5% accuracy. This study had promising result in clear cut area and individual cut crown detection. Overall accuracy of classification was 77.2%, analysis showed that coniferous tree type classification was very accurate, but deciduous tree classification had a lot of omission errors. Based on the results and analysis, general information about forest health conditions has been presented. Finally, strengths and limitations of the research were discussed and recommendations were given for further research.

Examination on the State of Health Regarding a Protected Sessile Oak Stock

It can be observed in more and more fields of science that the results of other disciplines are utilised in order to achieve new results; it is true for nature conservation as well. Global climate change is to be considered as one of the most thoroughly studied topic; scientists pay special attention to the responses given by species and communities to climate change. In case of field examinations the accuracy of samplings and measurements is of key importance. Often solely estimated data is available which deteriorates the accuracy of the assessment. The health status of forests is usually determined by visual observations that imply errors due to human subjectivity. In this examination we surveyed the health status of a protected sessile oak stock within the Botanical Garden of Szent István University in Gödöllő by using not only conventional methods but also instrumental measurements. We have used FAKOPP 3D Acoustic Tomograph. It is an instrument developed in Hungary that is able to determine – in percentage – the extent of deterioration in tree trunks. The method of measurement is the following: this instrument measures the speed of sound propagation in the tree matter, since rotten and healthy tissues conduct sound differently. Prior to the examination we surmised that a predominantly healthy stock would be examined. Nevertheless, instrumental measurements proved that the trees of this stock are considerably decayed; therefore constant instrumental monitoring is required. We found that the extent of decomposition was the most significant in the lowest measurement level (i.e. 40 cm – Layer 1) and it steadily decreased in the higher regions.

Development of forest cover mask to monitor the health condition of forests in Poland using long-term satellite observations

Abstract The work presented here aims at developing cover mask for monitoring forest health in Poland using remote sensing data. The main objective was to assess the impact of using the mask on forest condition monitoring combined with vegetation indices obtained from long-term satellite data. In this study, a new mask developed from the CORINE Land Cover 2012 (CLC2012) database is presented and its one-kilometer pixel size matched to low-resolution data derived from SPOT VEGETATION satellite registrations. For vegetation mapping, only pixels with a cover ≥ 50% of broad-leaved and mixed forests defined by CLC2012 were taken into account. The masked pixels were used to evaluate spatial variability in eight Natural-Forest Regions (NFRs). The largest coverages by masked forests were obtained in Sudetian (65.7%), Carpathian (65.9%) and Baltic (51.3%) regions. For other forest regions the coverage was observed to be around 30-50%. Time-series of the Normalized Difference Vegetation Index (NDVI) comprising SPOT VEGETATION images from 1998 until 2014 were computed and cross-comparison analyses on ≥ 50% and &lt; 50% forest cover masks brought up frequent differences at a level higher than 0.05 NDVI in seven out of eight NFRs. An exception is the Sudetian region, where the data was highly consistent. Furthermore, the Mann-Whitney U non-parametric test revealed statistically significant differences in two regions: Baltic and Masurian-Podlasie NFR. The comparative analysis of NDVI confirmed that there is a need for additional investigation of the quality of newly developed forest mask combined with vegetation and meteorological data.

Disturbance Agents and Their Associated Effects on the Health of Interior Douglas-Fir Forests in the Central Rocky Mountains

Interior Douglas-fir is a prevalent forest type throughout the central Rocky Mountains. Past management actions, specifically fire suppression, have led to an expansion of this forest type. Although Douglas-fir forests cover a broad geographic range, few studies have described the interactive effects of various disturbance agents on forest health conditions. In this paper, we review pertinent literature describing the roles, linkages, and mechanisms by which disturbances, including insect outbreaks, pathogens, fire, and other abiotic factors, affect the development, structure, and distribution of interior montane forests primarily comprised of Douglas-fir. We also discuss how these effects may influence important resource values such as water, biodiversity, wildlife habitat, timber, and recreation. Finally, we identify gaps where further research may increase our understanding of these disturbance agents, their interacting roles, and how they influence long-term forest health.

Classification of riparian forest species and health condition using multi-temporal and hyperspatial imagery from unmanned aerial system.

Riparian forests are critically endangered many anthropogenic pressures and natural hazards. The importance of riparian zones has been acknowledged by European Directives, involving multi-scale monitoring. The use of this very-high-resolution and hyperspatial imagery in a multi-temporal approach is an emerging topic. The trend is reinforced by the recent and rapid growth of the use of the unmanned aerial system (UAS), which has prompted the development of innovative methodology. Our study proposes a methodological framework to explore how a set of multi-temporal images acquired during a vegetative period can differentiate some of the deciduous riparian forest species and their health conditions. More specifically, the developed approach intends to identify, through a process of variable selection, which variables derived from UAS imagery and which scale of image analysis are the most relevant to our objectives.The methodological framework is applied to two study sites to describe the riparian forest through two fundamental characteristics: the species composition and the health condition. These characteristics were selected not only because of their use as proxies for the riparian zone ecological integrity but also because of their use for river management.The comparison of various scales of image analysis identified the smallest object-based image analysis (OBIA) objects (ca. 1 m(2)) as the most relevant scale. Variables derived from spectral information (bands ratios) were identified as the most appropriate, followed by variables related to the vertical structure of the forest. Classification results show good overall accuracies for the species composition of the riparian forest (five classes, 79.5 and 84.1% for site 1 and site 2). The classification scenario regarding the health condition of the black alders of the site 1 performed the best (90.6%).The quality of the classification models developed with a UAS-based, cost-effective, and semi-automatic approach competes successfully with those developed using more expensive imagery, such as multi-spectral and hyperspectral airborne imagery. The high overall accuracy results obtained by the classification of the diseased alders open the door to applications dedicated to monitoring of the health conditions of riparian forest. Our methodological framework will allow UAS users to manage large imagery metric datasets derived from those dense time series.

Detection of Spatio-Temporal Changes of Norway Spruce Forest Stands in Ore Mountains Using Landsat Time Series and Airborne Hyperspectral Imagery

The study focuses on spatio-temporal changes in the physiological status of the Norway spruce forests located at the central and western parts of the Ore Mountains (northwestern part of the Czech Republic), which suffered from severe environmental pollution from the 1970s to the 1990s. The situation started improving after the pollution loads decreased significantly at the end of the 1990s. The general trends in forest recovery were studied using the tasseled cap transformation and disturbance index (DI) extracted from the 1985–2015 time series of Landsat data. In addition, 16 vegetation indices (VIs) extracted from airborne hyperspectral (HS) data acquired in 1998 using the Advanced Solid-State Array Spectroradiometer (ASAS) and in 2013 using the Airborne Prism Experiment (APEX) were used to study changes in forest health. The forest health status analysis of HS image data was performed at two levels of spatial resolution; at a tree level (original 2.0 m spatial resolution), as well as at a forest stand level (generalized to 6.0 m spatial resolution). The temporal changes were studied primarily using the VOG1 vegetation index (VI) as it was showing high and stable sensitivity to forest damage for both spatial resolutions considered. In 1998, significant differences between the moderately to heavily damaged (central Ore Mountains) and initially damaged (western Ore Mountains) stands were detected for all the VIs tested. In 2013, the stands in the central Ore Mountains exhibited VI values much closer to the global mean, indicating an improvement in their health status. This result fully confirms the finding of the Landsat time series analysis. The greatest difference in Disturbance Index (DI) values between the central (1998: 0.37) and western Ore Mountains stands (1998: −1.21) could be seen at the end of the 1990s. Nonetheless, levelling of the physiological status of Norway spruce was observed for the central and western parts of the Ore Mountains in 2013 (mean DI values −1.04 (western) and −0.66 (central)). Although the differences between originally moderately-to-heavily damaged, and initially damaged stands generally levelled out by 2013, it is still possible to detect signs of the previous damage in some cases.

Effects of Soil on Degradation of Robinia pseudoacacia Forests in the Yellow River Delta in China

Soil quality has significant importance for the growth and sustainability of plants. However, due to the variability and diversity of soil characteristics, many trees suffered death according to their confrontation degree. Over the past several decades, Robinia pseudoacacia forests in the Yellow River delta of China, lose health and died without an obvious cause. This study focuses on evaluating the role of soil characteristics (moisture content, soil salinity content, soil bulk density, soil texture (the percentages of soil sand, soil silt, and soil clay) and pH value on the deterioration of health level of Robinia pseudoacacia forests in the area. To do so, three health levels such as healthy, medium dieback, and severe dieback forest were firstly classified based on the United States Department of Agriculture Forestry Bureau of crown condition classification guide and in situ survey, then soil properties in vertical direction were analyzed by five sampling points for each forest type from surface to the depth of 260 cm with eight layers (0-20 cm, 20-40 cm, 40-60 cm, 60-100 cm, 100-140 cm, 140-180 cm, 180-220 cm and 220-260 cm) for healthy and moderate dieback and 0- 220 cm depth with seven layers for severe dieback because the water occurred after 220 cm depth. The results indicated that there are significant differences in soil moisture content and soil conductivity among three forest health conditions. For a vertical change of soil characteristics only soil particle sizes (sand, silt and clay) had a significant difference in three forest health conditions. For system roots, absorptive roots were observed down to 230 cm depth for healthy Robinia pseudoacacia forest but moderate and severe dieback Robinia pseudoacacia forests, roots are found in the surface layer.

État sanitaire des peuplements de Pin d’Alep (Pinus halepensis Mill.) dans le massif forestier de Senalba (Djelfa, Algérie)

Health status of Aleppo pine stands (Pinus halepensis Mill.) in the natural Senalba forest (Djelfa -Algeria). This study aimed to analyse the health status of the natural Senalba Aleppo pine forest (Pinus halepensis Mill.) located in the semi-arid zone of Djelfa (Algeria). A stratified systematic sampling was adopted and 80 plots were set up along two transects established on south and north-facing slopes. Various dendrometric (tree height ; circumference at 1.30 m ; bark thickness ; age) and site parameters (exposure ; altitude ; soil depth ; calcareous rate ; soil pH) were measured. Results showed that the decline process preferentially impacted the trees located on the southern slope of Senalba Chergui forest and old trees located on the northern slope of Senalba Gharbi forest. However, the other parameters have no significant effect on the process of decline.