Vicinity Of Trees Research Articles

Living With Hyraxes: Biogeography and Comparative Ecology of West African Fornasinius Beetles

ABSTRACTAmong the flower beetles (Scarabaeidae, Cetoniinae), the Goliathini comprise several genera of medium‐ and large‐sized beetles widely distributed in sub‐Saharan Africa. In this tribe, the genus Fornasinius Bertoloni, 1853, includes two species found in West Africa: F. higginsi (Westwood) and F. klingbeili Zöller, Fiebig,and Schulze. In this study, we present new data on the comparative ecology and biogeography of these two species, including sex ratio, population structure by size, monthly activity patterns and habitat features at two different spatial scales. These observations were conducted, mostly opportunistically, over a 20‐year period in Cote d'Ivoire, Ghana and Togo. Both species exhibited similar overall population structure and morphometrics. They were characterised by a male‐skewed adult sex ratio (with possible bias), male‐larger sexual size dimorphism and consistent population structure by size; the two species are seemingly parapatric (with the potential contact zone being separated in eastern Ghana by the Volta River and Volta Lake). Both are primarily found in the vicinity of trees that contained middens of hyraxes, such as Dendrohyrax dorsalis (F. higginsi), Dendrohyrax interfluvialis (F. klingbeili) and Procavia capensis (F. klingbeili). F. higginsi has been primarily observed in forest habitat, while F. klingbeili was found in both forests and Guinea savannahs. Occurrence sites of F. higginsi were predominantly characterised by higher tree cover, less bare areas and built‐up zones. Although these beetles may be locally abundant within hyrax middens, they typically occur in only a relatively small number of sites within their preferred habitat. Monthly activity patterns differed between the two species. Although adults of both species were observed throughout the year, sightings of F. higginsi were more common during the wet season, whereas F. klingbeili sightings were more frequent in the dry season. The observed differences in monthly activity patterns between these ecologically and morphologically similar species may help to minimise interspecific competition in potential—yet unknown—sites of syntopy. Although some Fornasinius populations might be locally threatened by deforestation or overhunting of hyraxes, the careful management of hyrax populations should adequately ensure the conservation of these two beetle species.

Influence of an interview location on opinions about the ecosystem services provided by trees

Collecting opinions regarding environmental management is essential, particularly in urban areas where space is limited, and interests often collide. However, the impact of the conditions in which the research is conducted on opinions and preferences elicited via surveys and interviews about the environment is usually taken for granted. The recent development of computer-aided survey methods allows a simulation of an environment, which can create an artificial environment for interviews. Therefore, examining whether direct access to the environment impacts opinions and preferences becomes a significant issue when considering environmental policies and management design and execution. This study examines whether the location of an interview, indoors or outdoors (in the vicinity of trees), influences the opinion on the ecosystem services (ES) trees provide. A quasi-experimental method with a map-aided computer-assisted personal interview (CAPI) survey in two Polish cities, indoors and outdoors, in the vicinity of trees, shows that respondents’ location did not significantly affect the opinion on the ES provided by trees. However, on average, respondents answering the survey inside buildings marked more trees on a map than those answering outside. We argue that although an interview location does not have a significant impact on the results, from the perspective of various stakeholder groups in participatory processes, the convenience of place is more important than the character of the place (i.e., in the vicinity of trees) as long as the survey method is mediated by a virtual representation of the subject of the study.

The Use of Envi-Met for the Assessment of Nature-Based Solutions’ Potential Benefits in Industrial Parks—A Case Study of Argales Industrial Park (Valladolid, Spain)

Urbanization causes major changes in environmental systems, including those related with radiation balances and other meteorological conditions because of changes in surfaces and the physical environment. In addition, cities generate specific microclimates as a consequence of the diverse conditions within the urban fabric. Industrial parks represent vast urban areas, often neglected, contributing to the degradation of the urban environment, including poor thermal comfort as a result of soil sealing and low albedo surfaces. Nature-Based Solutions (NBS) can promote the mitigation of the anthropic effects of urbanization using nature as an inspiration. The present study, aimed at estimating the microclimate conditions in a fraction of the Argales industrial park in the city of Valladolid (Spain), with the use of the ENVI-Met software, assesses the current situation and a planned NBS scenario. Base scenario simulation results demonstrate different conditions across the simulations, with higher temperatures on sun-exposed surfaces with low albedo, and lower temperature spots, mostly associated with shadowed areas near existent buildings. After the simulation of the NBS scenario, the results show that, when compared with the base scenario, the projected air temperature changes reach reductions of up to 4.30 °C for the locations where changes are projected from impervious low albedo surfaces to shaded areas in the vicinity of trees and a water body.

Assessing soil carbon dioxide and methane fluxes from a Scots pine raised bog-edge-woodland

Scots pine bog edge woodland is a type of habitat typical on raised bogs where trees cohabitate with bog vegetation to form a low-density stand. Even though nowadays this habitat does not cover large areas, in a future scenario it is possible that this environment will expand, either naturally (drier climate) or anthropogenically, as the result of the application of new restoration strategies that could increase net landscape carbon benefits from both peatland and woodland environments. This study is the first reported investigation in Scotland exploring carbon flux dynamics from sparse woodlands on raised bogs. We examined how Scots pine trees directly or indirectly affected soil temperature and moisture, ground vegetation, and consequently carbon dioxide (CO2) and methane (CH4) soil fluxes. Soil CO2 and CH4 were measured at different distance from the tree and thereafter assessed for both spatial and temporal variability. Our results showed that these low-density trees were able to modify the ground vegetation composition, had no effect on soil temperature, but did affect the soil moisture, with soils close to tree roots significantly drier (0.25 ± 0.01 m3 m-3) than those on open bog (0.39 ± 0.02 m3 m-3). Soil CO2 fluxes were significantly higher in the vicinity of trees (34.13 ± 3.97 μg CO2 m−2 s−1) compared to the open bog (24.34 ± 2.86 μg CO2 m−2 s−1). On the opposite, CH4 effluxes were significantly larger in the open bog (0.07 ± 0.01 μg CH4 m−2 s−1) than close to the tree (0.01 ± 0.00 μg CH4 m−2 s−1). This suggests that Scots pine trees on bog edge woodland may affect soil C fluxes in their proximity primarily due to the contribution of root respiration, but also as a result of their effects on soil moisture, enhancing soil CO2 emissions, while reducing the CH4 fluxes. There is, however, still uncertainty about the complete greenhouse gas assessment, and further research would be needed in order to include the quantification of soil nitrous oxide (N2O) dynamics together with the analysis of complete gas exchanges at the tree-atmosphere level.

The ectomycorrhizal community of urban linden trees in Gdańsk, Poland.

The linden tree (Tilia spp.) is a popular tree for landscaping and urban environments in central and northwest European countries, and it is one of the most popular in cities in Poland. Ectomycorrhizal fungi form a symbiosis with many urban tree species and protect the host plant from heavy metals and against salinity. The aim of this study was to characterise the ECM fungal community of urban linden trees along the tree damage gradient. The study was performed on two sites located in the centre of the city of Gdańsk, in northern Poland. The vitality assessment of urban linden trees was made according to Roloff’s classification. Tree damage classes were related to soil characteristics using principal component analysis. The five ectomycorrhizal fungal species were shared among all four tree damage classes, and Cenococcum geophilum was found to be the most abundant and frequent ectomycorrhizal fungal species in each class. Soil samples collected in the vicinity of trees belonging to the R0 class had significantly lower pH Na, Cl and Pb content than other soils. Our knowledge of ectomycorrhizal communities in urban areas is still limited, and these findings provide new insights into ectomycorrhizal distribution patterns in urban areas.

The effect of tree water uptake on suction distribution in tropical residual soil slope

This study provided an investigation of active root tree zone which is located at the toe of a slope. This section of slope generated matric suction due to tree water uptake. A field monitoring program was carried out to collect matric suction data at slope with two conditions; in absent of a tree and with a tree (Acacia Mangium) located at toe of slope on a tropical residual soil. This soil suction collection is very important to determine the moisture content in soil. When the soil suction is low, it means that the soil is lack of water, which increase the shear strength of the soil compare to soil with more water content. The variation in matric suction values and matric suction profiles response to the tree water uptake and rainfall are investigated. Three soil instruments known as tensiometer and gypsum block (both for suction collection) together with rain gauge (for rainfall collection). Matric suction significantly increased at vicinity of tree at toe of slope compared to slope without tree. The variations of matric suction response due to climate change occur significantly at swallow of the slope and decrease gradually with depth. The decreases of matric suction occur after long duration of intense rainfall. This act as an initial condition before the water uptake driven by active root tree generate to maximum matric suction (low moisture content). Analyses from matric suction profiles revealed that majority of matric suction changes were greater near tree trunk (<4 m) and at shallow depth (0.5 m). The contours of matric suction profiles are presented to reveal moisture flow due to tree water uptake. This investigation provides the viewed contribution of single mature tree significantly alter the matric suction or moisture variation distribution driven by transpiration in an unsaturated soil slope. It takes consideration that preserving mature tree can improved soil properties in modern slope designs.

Evaluation of the influence of the windbreak trees on the change of wind shear in weakly complex terrains

The turbulent nature of the wind above the earth’s surface depends on both the topology of the terrain and the presence of natural obstacles along the way such as low grasses and shrubs, as well as medium-tall trees. When the wind passes through the indicated obstacles, detachment is observed i.e. formation of large eddies, which are carried away by the main flow, after which they dissipate. The size of the vortices, as well as the period of dissipation, depends on the wind speed, as well as the type of obstacle. The presence of windbreak trees significantly changes the wind shear over the surface, and hence the energy potential of the wind in the vicinity of trees. In present work, the influence of the tree belt on the wind shear at the adopted prevailing wind direction is investigated. The degree of deformation of the speed profile after the obstacle in weakly complex terrain is shown. Relevant prescriptions for the location of wind turbines in the vicinity of windbreak trees are presented in view of minimum shading and maximum energy output.

Novel Isoprene-Degrading Proteobacteria From Soil and Leaves Identified by Cultivation and Metagenomics Analysis of Stable Isotope Probing Experiments.

Isoprene is a climate-active gas and one of the most abundant biogenic volatile organic compounds (BVOC) released into the atmosphere. In the terrestrial environment, plants are the primary producers of isoprene, releasing between 500 and 750 million tons per year to protect themselves from environmental stresses such as direct radiation, heat, and reactive oxygen species. While many studies have explored isoprene production, relatively little is known about consumption of isoprene by microbes and the most well-characterized isoprene degrader is a Rhodococcus strain isolated from freshwater sediment. In order to identify a wider range of bacterial isoprene-degraders in the environment, DNA stable isotope probing (DNA-SIP) with 13C-labeled isoprene was used to identify active isoprene degraders associated with soil in the vicinity of a willow tree. Retrieval by PCR of 16S rRNA genes from the 13C-labeled DNA revealed an active isoprene-degrading bacterial community dominated by Proteobacteria, together with a minor portion of Actinobacteria, mainly of the genus Rhodococcus. Metagenome sequencing of 13C-labeled DNA from SIP experiments enabled analysis of genes encoding key enzymes of isoprene metabolism from novel isoprene degraders. Informed by these DNA-SIP experiments and working with leaves and soil from the vicinity of tree species known to produce high amounts of isoprene, four novel isoprene-degrading strains of the genera Nocardioides, Ramlibacter, Variovorax and Sphingopyxis, along with strains of Rhodococcus and Gordonia, genera that are known to contain isoprene-degrading strains, were isolated. The use of lower concentrations of isoprene during enrichment experiments has revealed active Gram-negative isoprene-degrading bacteria associated with isoprene-emitting trees. Analysis of isoprene-degradation genes from these new isolates provided a more robust phylogenetic framework for analysis of isoA, encoding the α-subunit of the isoprene monooxygenase, a key molecular marker gene for cultivation-independent studies on isoprene degradation in the terrestrial environment.

Impact of the spatial uncertainty of seed dispersal on tree colonization dynamics in a temperate forest

An aggregated distribution of dispersed seeds may influence the colonization process in tree communities via inflated spatial uncertainty. To evaluate this possibility, we studied 10 tree species in a temperate forest: one primarily barochorous, six anemochorous and two endozoochorous species. A statistical model was developed by combining an empirical seed dispersal kernel with a gamma distribution of seedfall density, with parameters that vary with distance. In the probability density, the fitted models showed that seeds of Fagaceae (primarily barochorous) and Betulaceae (anemochorous) were disseminated locally (i.e. within 60 m of a mother tree), whereas seeds of Acer (anemochorous) and endozoochorous species were transported farther. Greater fecundity compensated for the lower probability of seed dispersal over long distances for some species. Spatial uncertainty in seedfall density was much greater within 60 m of a mother tree than farther away, irrespective of dispersal mode, suggesting that seed dispersal is particularly aggregated in the vicinity of mother trees. Simulation results suggested that such seed dispersal patterns could lead to sites in the vicinity of a tree being occupied by other species that disperse seeds from far away. We speculate that this process could promote coexistence by making the colonization rates of the species more similar on average and equalizing species fitness in this temperate forest community.

Field monitoring of suction in the vicinity of an urban tree: exploring termite infestation and the shading effects of tree canopy

The objective of this short communication is to explore spatial distribution of soil suction in the vicinity of an urban tree considering effects of termite infestation and also radiant energy interception by canopy. A site in an urban landscape containing a mix of species cover (grass cover in the vicinity of trees) was selected for monitoring. A field monitoring program was designed to monitor soil (soil suction, moisture), vegetation parameters (tree height, grass leaf area), and meteorological parameters during drying/wetting cycles. As expected, before termite infestation, suction magnitude and rate of change were highest near the tree stem and at shallower depths, reflecting the dominance of transpiration over evaporation. However, after termite infestation, soil suction diminished significantly near the tree stem and increased farther from the tree stem, a phenomenon accompanied by loss of canopy area, as captured by a color analysis technique (i.e., an image processing method). These findings reflected a reduction in stomatal conductance, itself an indicator of transpiration loss through the stomata—likely because reduced canopy shading effects caused increased evaporation. Soil suction at deeper depths seemed not to be significantly affected, generally due to canopy and termite infestation. In summary, the study sheds new light on issues of tree maintenance by showing how termite infestation can significantly affect the performance of green infrastructure.

Intra-annual Ips typographus outbreak monitoring using a multi-temporal GIS analysis based on hyperspectral and ALS data in the Białowieża Forests

Disturbances caused by biotic and abiotic agents are inherent processes of forest ecosystems and often play a key role in forming the ecosystems themselves. However, they also may negatively affect wood production and alter ecosystem services. Thus, precise and up-to-date spatial information on invasion presence and dynamic is essential when planning protective and sanitary actions. Gathering such data is still challenging if large areas, with limited access, are affected.This study addresses this issue by suggesting a GIS-workflow based on high-resolution multi-temporal remote sensing data to describe the spread of a bark beetle outbreak by mapping dead trees on a single tree level and estimating timber losses associated with the infestations in the Polish part of the Białowieża Forest (BF) in 2015.Along with field inventories, airborne hyperspectral data were collected in 2015 at three acquisition dates: 2–4 July, between August 24th and 27th and between 1st and 2nd October with a HySpex VNIR-1800 camera. Airborne laser scanning data were collected during 2–5 July 2015 using a Riegl LMS-Q680i scanner. The analysis consisted of three steps: (i) hyperspectral images were used to stratify the area into living vegetation and all other classes (including dead trees); (ii) a single tree delineation was performed and individual tree volumes were calculated based on a volume ∼ height allometry; (iii) the delineated trees were assigned as either living trees or dead trees (snags). Based on these data bark beetle dynamics between the three time steps were analysed.The results show that the Ips typographus outbreak in BF in 2015 was very dynamic. The volume of dead standing spruce detected in subsequent dates was as follows: July – 503 410 m3; August – 640 692 m3; October – 737 978 m3 New groups of dead trees in the flat landscape of Białowieża forest appeared preferably but not only in the immediate vicinity of trees classified as dead in the previous period. New infestations were also identified over 100 m away from earlier infested trees. On the other hand, we could not identify any tendencies in terms of the spread direction which makes the prediction of the spread-dynamics challenging in our study area.

Seedling emergence in uneven-aged Norway spruce stands in Finland

ABSTRACTThe emergence of Norway spruce seedlings on different types of germination sites in uneven-aged Norway spruce dominated stands four years after selection harvesting was studied. The data were collected from 20 stands in southern Finland. In each stand, ground cover was measured from a set of 64 one square metre subplots on a permanent experimental plot of 1600 m2. Correlation analysis, direct comparison of subplots with and without seedlings and mixed-effects models were used to estimate the influence of ground and tree cover on seedling occurrence. Grass cover, dwarf shrub cover, cover of certain moss species and close vicinity of trees decreased the occurrence probability and number of seedlings, while greater stand and local basal area around the subplots increased the seedling number. The cover of vegetation free surfaces, usually considered as good germination sites, was rather low. Variation in seedling emergence between plots was high. We concluded that spruce regeneration was slightly more abundant in stands with greater overall stand density and local density within a stand in postharvest conditions.

The Research of Gmelin Larch (Larix gmelinii (Rupr.) Rupr.) Gum

The samples of Gmelin larch (Larix gmelinii (Rupr.) Rupr.) gum, selected from a variety of trees and from different parts of the tree in vicinity of Ulan-Ude (Buryatia), were investigated with GPC, IR, quantitative NMR 13C spectroscopy and spectrophotometry methods. The samples were dissolved in distilled water at room temperature. The mechanical impurities were filtered, the transparent solutions were evaporated to dryness, and the dry residues were purified by reprecipitation from water to ethanol. The content of mechanical impurities was 0.1–4.8% of the mass of absolutely dry gum. Aqueous solutions of gum were weakly acidic, as well as arabinogalactan (AG) isolated from wood of Siberian and Gmelin larches. It is established that Gmelin larch gum is a high purity arabinogalactan (~99%) with minor impurities of flavonoids, tannins and mineral substances. Molecular-mass characteristics and monosaccharide composition of Gmelin larch gum arabinogalactan is similar to arabinogalactan obtained from wood of all previously studied species of larch growing in Siberia and the Far East. The data suggest recommending Gmelin larch gum for application in medicine and the veterinary, food and cosmetic industries.

Effects of ground surface permeability on the growth of urban linden trees

Street trees are an important part of urban vegetation due to their provisioning of different types of ecosystem services such as local climate regulation and contribution to aesthetical and recreational values. In order to provide these services, urban trees need to endure many stress factors not present in natural environments, such as the widespread use of impervious surfaces in the vicinity of street trees. However, few studies have evaluated the effect of this potential stress factor on urban tree growth. The aim of this study was therefore to investigate how ground surface permeability affects stem and current-year shoot growth of linden (Tilia europaea) street trees in Gothenburg, Sweden. We found that a small fraction of permeable ground surface in the vertically projected tree crown area caused lower stem growth and strongly suppressed current-year shoot growth. This finding can guide future city planning, demonstrating that the vitality of street trees is compromised when the permeable surface area in the vicinity of the tree is small.

Vegetation impacts soil water content patterns by shaping canopy water fluxes and soil properties

AbstractSoil water content is a key variable for biogeochemical and atmospheric coupled processes. Its small‐scale heterogeneity impacts the partitioning of precipitation (e.g., deep percolation or transpiration) by triggering threshold processes and connecting flow paths. Forest hydrologists frequently hypothesized that throughfall and stemflow patterns induce soil water content heterogeneity, yet experimental validation is limited. Here, we pursued a pattern‐oriented approach to explore the relationship between net precipitation and soil water content. Both were measured in independent high‐resolution stratified random designs on a 1‐ha temperate mixed beech forest plot in Germany. We recorded throughfall (350 locations) and stemflow (65 trees) for 16 precipitation events in 2015. Soil water content was measured continuously in topsoil and subsoil (210 profiles). Soil wetting was only weakly related to net precipitation patterns. The precipitation‐induced pattern quickly dissipates and returns to a basic pattern, which is temporally stable. Instead, soil hydraulic properties (by the proxy of field capacity) were significantly correlated with this stable soil water content pattern, indicating that soil structure more than net precipitation drives soil water content heterogeneity. Also, both field capacity and soil water content were lower in the immediate vicinity of tree stems compared to further away at all times, including winter, despite stemflow occurrence. Thus, soil structure varies systematically according to vegetation in our site. We conclude that enhanced macroporosity increases gravity‐driven flow in stem proximal areas. Therefore, although soil water content patterns are little affected by net precipitation, the resulting soil water fluxes may strongly be affected. Specifically, this may further enhance the channelling of stemflow to greater depth and beyond the rooting zone.

Spatial and temporal variation of hydraulic conductivity and vegetation growth in green infrastructures using infiltrometer and visual technique

Hydraulic conductivity of a vegetated soil (i.e., mixed grass cover) is an important parameter governing the hydrological performance of green infrastructure (GI). This paper focuses on GI with mixed grass cover in the presence of trees. Due to shading effects (interception of radiant energy) of tree canopy, mixed grass cover in the vicinity of trees may not receive direct photosynthetically active radiation (PAR). This can hinder the growth rates resulting in the low grass cover (i.e., in density). The hydraulic conductivity and the performance of GI can be further affected. Several field studies were conducted to investigate hydraulic conductivity in different types of vegetated covers. However, any variation in growth and hydraulic conductivity of mixed grass cover in the vicinity of trees was rarely investigated. The objective of this study is to quantify spatial and temporal variation of vegetation growth and hydraulic conductivity in a mixed grass cover in the vicinity of a tree. Field monitoring of a mixed grass cover in the vicinity of a tree in a GI was conducted for about six months. Hydraulic conductivity tests were carried out using mini disk infiltrometer (MDI) at 149 locations in a selected site once every month. Vegetation density was quantified using image analysis and the images were captured by a DJI Phantom drone. The growth of mixed grass cover around tree vicinity (within 5m radial distance) was found to be more uniform during months characterized by high rainfall depth. Spatial heterogeneity in both vegetation density and hydraulic conductivity is found to be more significant during a dry period than wet period. Variation of hydraulic conductivity with respect to the change in vegetation density is found to be significant in a wet period than dry period. It is also found that hydraulic conductivity is higher at the portions where shredded leaves are present. The obtained dynamic spatio-temporal relationship of soil, vegetation and atmospheric parameters can support the design of green infrastructures and contribute to a better understanding of the maintenance practices.

ANALYSIS OF SUCTION DISTRIBUTION RESPONSE TO RAINFALL EVENT AND TREE CANOPY

This study provides an exploration of matric suction influenced by tree canopy interception on a single rainfall event. A field monitoring was carried out to measure matric suction at slope with two conditions; at toe of slope without tree and with a tree at toe of slope on a tropical residual soil. The variation in matric suction values and matric suction profiles response to the rainfall events on slope with and without a tree at toe were analysed to reveal the effect of the tree canopy. At initial condition, the matric suction was significantly higher at vicinity of tree compared to that of area without tree at toe of slope. However, a typical short and intense tropical rainfall has caused the matric suction to drop dramatically to a minimum value on slope without tree. This condition did not occur on slope with tree. Although, both slopes (with and without tree at toe) received the same amount of precipitation rainfall but the different responses in matric suction valueswere clearly shown at slope with tree at the slope toe. The short and intense rainfalls appeared to be the dominant factor to the suction variation at slope without tree, but not at slope with the tree. The tree canopy can be a factor to influence the suction variation at slope with tree as canopy interception reduced the amount of precipitation to the ground/sloping surface

Tree Water Uptake And Suction Distribution On Tropical Residual Soil Slope

This paper present an exploration of soil matric suction effected by water uptake via tree root at toe of slope on various condition between wet condition (high rainfall) and dry condition (prolonged no rainfall). Matric suction generated by active root tree has substantial influence soil moisture content on residual soil slope. A field monitoring was carried out to collect matric suction data at slope in two conditions; with a tree located at toe of slope and absent of a tree. The installations of instruments particularly at slope with tree at toe were placed within vicinity of the tree with certain depths and distances. The matric suction data from field monitoring was influence by the rainfall events that lead to the instability of soils slope. Analysis of soil matric suction distribution pattern indicates that the highest matric suction value was at shallower depth and proximity of tree. The matric suction profiles obtained from field monitoring are applied as an input data to develop soil matric suction contour. The effect of transpiration driven by active root zone generated matric suction on soil at vicinity of tree may create dry soil to increase soil shear strength.

Příspěvek k poznání vlivu drobných hlodavců na obnovu lesních dřevin ve vybraných porostech Kelečské pahorkatiny (okres Přerov, Česká republika)

Effects of small mammals were studied on the regeneration of trees in a forest reserve and on forest plantation in the area of the Kelečská pahorkatina Upland with a view to stands of European beech (Fagus sylvatica). Inspection of bark damage was carried out and artificial regeneration was markedly more susceptible to damage (p &lt; 0.01). Of the total number of monitored beech trees 57.5% were damaged in artificial regeneration compared to 12.7% in natural regeneration and 15% died as against 0%. The only pest proved by trapping was Myodes glareolus although damage of tree bases could mean damage caused by species of the genus Microtus. With respect to the large crop of seeds (beech nuts) in 2006, it is possible to expect increase in the population of rodents in the next season and thus increased damage to trees. Results obtained show that it is very important to support natural regeneration and as for planting to minimize the herb layer cover in the vicinity of trees, which represents the optimum environment for the occurrence of rodents.

THE INFLUENCE OF TREE INDUCE SUCTION ON SOIL SUCTION PROFILES

This study provided an investigation of active root tree zone located at the toe of the slope. This section of slope generated suction due to tree water uptake during dry season. A field mon itoring set up program was carried out to collect m atric suction data at slope with absent of a tree and with a tree located at toe of the slope. The installations of Jet-fill tensiometer and Gypsum blocks to measured matric suction were placed at vicinity of tree with certain depths and distances. The distribution in matric suction values and matric suction profiles responses to tree water uptake and rainfall were investigated. The decreased of soil matric suction after intense rainfall in this monitoring period as a function of an initial condition before the water uptake drive n by active root tree substantially increased matric suction (low moisture content). Ma tric suction significantly increased at vicinity of tree trunk located at toe of slope compared to the slope without tree. This exploratio n provides the viewed of mature tree can significan tly alter the suction distribution driven by transpiration in an unsaturated soil slop e. It takes consideration by preserved mature tree can improved soil properties in geotechnical slope design.