Root biomass and carbon storage in oriental spruce and beech stands in Artvin, Turkey

In this study, influence of slope position (south-facing vs. north-facing), species type and sampling time on fine (0-2 mm), small (2-5 mm) and coarse (5-10 mm) root biomass and carbon storage of oriental spruce (Picea orientalis) and oriental beech (Fagus orientalis) were investigated. Mean total root biomass of oriental spruce was 20160 kg ha(-1) in south-facing slopes and 17140 kg ha(-1) in north-facing slopes. Mean total belowground C storage of oriental spruce was 7861 kg ha(-1) in south-facing slopes and 6840 kg ha(-1) in north-facing slopes. Similarly, biomass and C storage of oriental beech were 17190 and 6690 kg ha(-1) in south-facing slopes, and 13260 and 5200 kg ha(-1) in north-facing slopes, respectively. Oriental spruce had significantly higher fine root biomass than did oriental beech in south-facing slopes. Fine root biomass was significantly higher in fall than in spring in south-facing slopes.     

Potential parasitoid attractants,volatile composition throughout a bark beetle attack

Several hymenopteran parasitoids prey on mature bark beetle larvae (Scolytidae), concealed under the bark of conifers. According to previous results, certain oxygenated monoterpenes are crucial in host location. However, synthetic baits tested in laboratory bioassays are not quite as attractive to the parasitoids as the natural volatile bouquet from conifers containing susceptible bark beetle larvae. The aim of the current study was to identify the "missing components" in previously tested synthetic baits. Volatiles were sampled throughout bark beetle attacks (Ips typographus) on Norway spruce logs (Picea abies), and analyzed (qualitatively and quantitatively) by coupled gas chromatography-mass spectrometry (GC-MS). In addition, a pilot test was done employing the relatively new technique, fast GC-surface acoustic wave detector (SAW), zNose^TM, described in the methods. Quantitative differences in volatile composition were found between infested and uninfested logs, and between different stages of the bark beetle attack. In addition, the volatile composition of logs with or without mature bark beetle larvae (susceptible to parasitism) was compared, isolating odor differences at this most suitable host stage. In general, the quantity of monoterpenes (the predominant phytochemical volatiles in conifers) was found to decrease with time after initial infestation. In contrast, certain oxygenated monoterpenes and benzenoid compounds increased as susceptible bark beetle larvae developed, which therefore could be candidates for improving parasitoid baits. To the best of our knowledge, this is the first report on long-term dynamics of the volatile composition of bark beetle infested P. abies. The results should be interpreted in the light of previous electrophysiological and behavioral investigations of larval parasitoids, and present a number of compounds that could improve synthetic parasitoid baits.     

A resource-depletion model of forest insect outbreaks

Detailed analyses of thresholded ecological interactions can improve our understanding of the transition from aperiodic to periodic dynamics. We develop a threshold model of the population dynamics of outbreaking bark beetle populations that alternate between non-epidemic and epidemic behavior. The model involves accumulation of resources during low-density periods and depletion during outbreaks. The transition between the two regimes is caused by disturbance events in the form of major tree felling by wind. The model is analyzed with particular reference to the population dynamics of the spruce bark beetle (Ips typographus) in Scandinavia for which a comprehensive literature allows full parameterization. The fairly constant outbreak lengths and the highly variable waiting time between outbreaks that are seen in the historical records of this species agree well with the predictions of the model. The thresholded resource-depletion dynamics result in substantial variation in the degree of periodicity between stochastic realizations. The completely aperiodic tree colonizations are partly predictable when the timing of the irregular windfall events are known. However, the predictability of inter-outbreak periods is low due to the large variation of cases falling most frequently in the middle between the extremes of purely nonperiodic (erratic) and periodic (cyclic) fluctuations.     

Biomass and carbon budgeting of sustainable agroforestry systems as ecosystem service in Indian Himalayas

Adoption of agroforestry is paramount as a climate change mitigation and adaptation strategy. The assessment of plant biomass is crucial for understanding the vulnerability of biological systems to climate change. In the present study, agroforestry systems viz., agrisilviculture (AS), agrihorticulture (AH), agrihortisilviculture (AHS) and agrisilvihorticulture (ASH) were investigated for biomass production and carbon stock in vegetation as well as in soil in the Indian central Himalaya along the elevation i.e. E₁ (<1100 m), E₂ (1100–1400 m), E₃ (1400–1700 m), E₄ (1700–2000 m) and E₅ (>2000 m). Mean aboveground and belowground biomass were 73.9% and 26.1%, respectively, of total biomass (64.4 t ha^?1) in agroforestry systems. Fodder and/or timber trees accounted for 31% (in AHS) to 74% (in AS) of total biomass, while fruit trees accounted for 18% (in ASH) to 73% (in AH) of total biomass. The contribution of agriculture crops to total biomass fluctuated between 19% (in ASH) and 26% (in AH). Total vegetation biomass, soil carbon and total carbon density in agroforestry systems increased significantly along the elevation, with maximum biomass at elevation E₅ (32.0 t ha^?1, 64.7 t C ha^?1 and 96.7 t C ha^?1). Total biomass of vegetation among agroforestry systems differed significantly. Soil carbon stock was highest in AHS (59.5 t C ha^?1) and total carbon density (vegetation + soil) was highest in ASH (93.0 t C ha^?1). Thus, in Indian Himalayas, vegetation biomass, carbon stock, soil and total carbon (vegetation + soil) stock increased along the elevation.

Abbrviations: AG: aboveground; BG: belowground; WD: wood density; VOB: volume over bark; BEF: biomass expansion factor; AS: agrisilviculture; AH: agrihorticulture; ASH: agrisilvihorticulture; AHS: agrihortisilviculture; E: elevation; C: carbon; CO₂: carbon-di-oxide; IPCC: Intergovernmental Panel on Climate Change; DBH: diameter at breast height; AGBD: aboveground biomass density; BGBD: belowground biomass density; GSVD: growing stock volume density     

Natural tree collectives of pure oriental spruce [Picea orientalis (L.) Link] on mountain forests in Turkey

Distribution area of oriental spruce [Picea orientalis (L.) Link.] in the world is only in the north-east of Turkey and Caucasian. Because of being the semi monopoly tree with respect to its distribution and representing the upper forest line, it is necessary to analyse, evaluate and model the stand structures of oriental spruce forests in Turkey. In this research, some sampling plots were selected in timberline and treeline in the subalpine forest zone in Turkey. In these sampling plots some information about occurrence and development of the tree collectives was obtained. A total of 12 sampling plots (6 in timberline and 6 of them in treeline) were studied and horizontal and vertical stand profiles were obtained, while number of trees ranges between 2-86 in the tree collectives in treeline and in timberline 3-12. According to this, area per tree in treeline and in timberline is determined as 1.02 m2 and 3.75 m2 on an average respectively. Mean age of trees to reach breast height is 43 years in treeline sampling plots and 22 years in timberline sampling plots. According to the ratio of h (mean height) / d1.30 (diameter at breast height), stand stability values were calculated and it was determined if the stands were stable on the basis of the sampling plots. Stability values of the sampling plots changed between 33 and 75.     

Climate variability and spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska

We used tree ring data (AD 1601-2007) to examine the occurrence of and climatic influences on spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska and found evidence of regional-scale outbreaks dating from the mid-1700s, related to climate variability at multiple temporal scales. Over interannual time scales (approximately 1-3 years), El Ni?o years, combined with severe late-summer drought, appeared to contribute significantly to spruce beetle outbreaks in the study area. Over multidecadal time scales (up to approximately 40 years), cool-phase Pacific Decadal Oscillation (PDO) conditions tended to precede beetle outbreaks, regardless of the phase of El Ni?o-Southern Oscillation (ENSO). All sites showed low-severity disturbances attributed to spruce beetle damage, most notably during the 1810s. During other major periods of disturbance (i.e., 1870s, 1910s, 1970s), the effects of spruce beetle outbreaks were of moderate or higher severity. The highly synchronized timing of spruce beetle outbreaks at interannual to multidecadal scales, and particularly the association between cool-phase PDO conditions and beetle disturbance, suggests that climate (i.e., temperature, precipitation) is a primary driver of outbreaks in the study area. Our disturbance chronologies (mid-1700s to present) suggest that recent irruptions (1990s to present) in south-central and southwest Alaska are within the historical geographic range, but that outbreaks since the 1990s show greater spatiotemporal synchrony (i.e., more sites record high-severity infestations) than at any other time in the past approximatly 250 years.     

Volatile attractants for three Pteromalid parasitoids attacking concealed spruce bark beetles

Summary. The odour perceptive abilities, and preferences, of three bark beetle parasitoid species; Rhopalicus tutela (Walker), Roptrocerus mirus (Walker), and Roptrocerus xylophagorum (Ratzeburg) (Hymenoptera: Pteromalidae), were investigated to isolate and identify the essential compounds involved in host location. These parasitoids attack several economically important bark beetle species and oviposit preferentially on late larval stages concealed under the bark of conifers. Odours were collected from Norway spruce logs (Picea abies L. Karst.) containing Ips typographus L. (Coleoptera: Scolytidae) larvae. Biologically active compounds were isolated by coupled gas chromatographic-electroantennographic detection (GC-EAD), and identified by GC-mass spectrometry (GC-MS). Based on these analyses, four different synthetic baits were prepared and tested in a Y-tube walking bioassay. In the complex odour samples from spruce logs, only 16 compounds were EAD-active. The tested R. tutela and R. mirus females displayed similar trends in antennal activity to EAD-active compounds, responding mainly to oxygenated monoterpenes that indicate damaged conifers. Consequently, the synthetic baits were exclusively prepared with oxygenated monoterpenes. Parasitoid females (R. tutela and R. mirus) preferred spruce logs containing susceptible hosts over fresh logs, while male parasitoids (R. mirus) did not show any preference. However, when odours from fresh logs were mixed with synthetic baits (mimicking the odour composition of logs containing susceptible hosts), these combinations attracted female parasitoids (R. tutela, R. mirus, and R. xylophagorum). All synthetic baits seemed to be equally attractive to female parasitoids. Received 12 October 2000; accepted 18 January 2001     

The aggregation pheromone ofIps duplicatus and its role in competitive interactions withI. typographus (Coleoptera: Scolytidae)

Summary Ips duplicatus withI. typographus co-inhabiting Norway spruce (Picea abies (L.) Karst.) would benefit from a pheromone blend distinct from that of the larger competitorI. typographus. GC-MS analysis showed thatI. duplicatus males feeding in the host produced ipsdienol (Id),cis-verbenol (cV),trans-verbenol (tV), myrtenol (Mt), andE-myrcenol (EM) and traces of 2-methyl-3-buten-2-ol (MB).I. duplicatus produced Id in approximately racemic form (48.9-54.5% (+)-(S)-isomer). The amounts of Id and EM released over a 9 day period had a maximum of 250 and 5 ng/h/male, respectively, on day 2. Exposure ofI. duplicatus males to myrcene and -pinene resulted in the production of small amounts of Id, cV, tV, Mt, andtrans-pinocarveol, but not of EM. In laboratory bioassays with walking beetles, the pheromone component Id alone was weakly attractive while EM was inactive, but in binary combination with Id strongly synergized attraction. A combination of EM and Id at a release rate equivalent to 100–200 males was more attractive in the field than 70 unmated males in a spruce log. The addition of myrcene ( a suggested pheromone precursor of Id) to Id did not enhance trap caches, while addition of EM increased catches > 10-fold. Subtracting EM from a blend of Id, EM, cV and MB drastically reduced trap catches while subtraction of cV or MB or both had no significant effect. Addition of EM over a wide concentration range to the synthetic pheromone ofI. typographus did not reduce the attraction of females of this species in the laboratory. A two-species pheromone interaction field test releasingI. typographus pheromone components (MB + cV) at 10–1000 male equivalents (ME) andI. duplicatus pheromone (Id + EM) at 0, 10–1000 ME in all possible combinations showed both positive intraspecific dose-response effects and an interspecific inhibition. Higher release rates of EM appeared to inhibitI. typographus, especially males. In a tree colonization model, the response of the two competing species to their respective pheromones show a good separation during the mass-attack with a small initial cross-attraction. It remains to be shown whether either of the two pheromone systems have in fact evolved in the present sympatry, or if they are an incidental effect of ancestry of these phylogenetically distantIps.     

Slope aspect modifies community responses to clear-cutting in boreal forests

Slope aspect modifies microclimate and influences ecological processes and spatial distribution of species across forest landscapes, but the impact of slope aspect on community responses to disturbance is poorly understood. Such insight is necessary to understand landscape community dynamics and resilience. We compared bryophyte (liverworts and mosses) communities in matched 0.02-ha plots of four boreal stand types in central Sweden: recently clear-felled and mature stands dominated by Norway spruce in south-facing and north-facing slopes. Differences between forests and clear-cuts were interpreted as effects of clear-cutting, and differences between south- and north-facing slopes as effects of aspect. In response to clear-cutting, bryophyte cover and composition changed more in south-facing slopes. Only one out of ten significantly declining species in south-facing slopes also declined significantly in north-facing slopes. North-facing slopes lost fewer bryophyte species, and among those, fewer forest species and fewer species associated with wood and bark. In north-facing slopes, the average proportions of mosses and liverworts shared between the forest and the clear-cut plot were 88% and 74%, respectively. Corresponding numbers for south-facing slopes were 79% and 33%. In addition, more bryophyte species were added in north- than south-facing slopes after clear-cutting, somewhat reducing the difference in compositional change between aspects. South- and north-facing mature forests differed in species composition, mostly due to higher richness of mosses in south-facing slopes. The smaller changes in bryophyte communities on north-facing slopes in response to clear-cutting have implications for ecosystem dynamics and management as high local survival may enhance landscape-level resilience.     

Impacts of changing frost regimes on Swedish forests: Incorporating cold hardiness in a regional ecosystem model

Understanding the effects of climate change on boreal forests which hold about 7% of the global terrestrial biomass carbon is a major issue. An important mechanism in boreal tree species is acclimatization to seasonal variations in temperature (cold hardiness) to withstand low temperatures during winter. Temperature drops below the hardiness level may cause frost damage. Increased climate variability under global and regional warming might lead to more severe frost damage events, with consequences for tree individuals, populations and ecosystems. We assessed the potential future impacts of changing frost regimes on Norway spruce (Picea abies L. Karst.) in Sweden. A cold hardiness and frost damage model were incorporated within a dynamic ecosystem model, LPJ-GUESS. The frost tolerance of Norway spruce was calculated based on daily mean temperature fluctuations, corresponding to time and temperature dependent chemical reactions and cellular adjustments. The severity of frost damage was calculated as a growth-reducing factor when the minimum temperature was below the frost tolerance. The hardiness model was linked to the ecosystem model by reducing needle biomass and thereby growth according to the calculated severity of frost damage. A sensitivity analysis of the hardiness model revealed that the severity of frost events was significantly altered by variations in the hardening rate and dehardening rate during current climate conditions. The modelled occurrence and intensity of frost events was related to observed crown defoliation, indicating that 6-12% of the needle loss could be attributed to frost damage. When driving the combined ecosystem-hardiness model with future climate from a regional climate model (RCM), the results suggest a decreasing number and strength of extreme frost events particularly in northern Sweden and strongly increasing productivity for Norway spruce by the end of the 21st century as a result of longer growing seasons and increasing atmospheric CO₂ concentrations. However, according to the model, frost damage might decrease the potential productivity by as much as 25% early in the century.     

Habitats and tidal accessibility of the marine foods of dabbling ducks and brant in Boundary Bay,British Columbia

The role of birds in intertidal food webs is mediated by effects of tides on the habitat, distribution, and accessibility of food organisms. We studied effects of elevation, sediment characteristics, vegetation, and tidal cycles on waterfowl feeding and food organisms in Boundary Bay, British Columbia, Canada from September to March 1990–1992. Percent dry mass of esophageal contents was mainly Zostera japonica leaves (84%) for American wigeon (Anas americana Gmelin), and leaves of Z. japonica (57%) and Z. marina (41%) for brant (Branta bernicla L.). Northern pintails (A. acuta L.) and mallards (A. platyrhynchos L.) ate mostly the leaves, seeds, and rhizomes of Z. japonica (48 and 72%, respectively) and gastropods (12 and 28%). Green-winged teal (A. crecca L.) ate mainly amphipods (68%) and saltmarsh seeds (19%). The well-sorted fine sand (median 0.125 mm) to medium sand (0.25 mm), and the low organic carbon content (1.31±0.12% dry mass), did not appear to vary sufficiently along 2.1- and 2.6-km transects to affect macroinvertebrate distributions. Three habitat zones were recognized: (1) upper intertidal (sandflats); (2) mid-intertidal (largely monotypic Z. japonica); and (3) lower intertidal (mixed Z. japonica and Z. marina). These zones, although related to elevation, had greater influence on amphipod distributions than did elevation alone or detrital biomass. Biomass and numbers of most invertebrate foods of waterfowl were greatest in the eelgrass zones, with the upper elevational limit of Z. japonica occurring at about Mean Water Level (MWL). Accordingly, wigeon, pintails, and mallards fed mostly below MWL. Because of seasonal tidal cycles, daily accessibility of areas below MWL but within reach of surfacefeeding waterfowl decreased from a mean of 10.8 h in October to 9.6 h in December. In October only 10 d and <12 h available feeding time, whereas in December and January every day had <12 h available feeding time. Seasonal effects of tides on accessibility might limit sufficient feeding by some waterfowl species in intertidal areas, increasing their reliance on alternative feeding sites.     

Characterizing the landscape dynamics of an invasive plant and risk of invasion using remote sensing.

Improved understanding of the spatial dynamics of invasive plant species may lead to more effective land management and reduced future invasion. Here, we identified the spatial extents of nonnative cheatgrass (Bromus tectorum) in the north central Great Basin using remotely sensed data from Landsat MSS, TM, and ETM+. We compared cheatgrass extents in 1973 and 2001 to six spatially explicit landscape variables: elevation, aspect, hydrographic channels, cultivation, roads, and power lines. In 2001, Cheatgrass was 10% more likely to be found in elevation ranges from 1400 to 1700 m (although the data suggest a preferential invasion into lower elevations by 2001), 6% more likely on west and northwest facing slopes, and 3% more likely within hydrographic channels. Over this time period, cheatgrass expansion was also closely linked to proximity to land use. In 2001, cheatgrass was 20% more likely to be found within 3 km of cultivation, 13% more likely to be found within 700 m of a road, and 15% more likely to be found within 1 km of a power line. Finally, in 2001 cheatgrass was 26% more likely to be present within 150 m of areas occupied by cheatgrass in 1973. Using these relationships, we created a risk map of future cheatgrass invasion that may aid land management. These results highlight the importance of including land use variables and the extents of current plant invasion in predictions of future risk.     

The effects of walnut and pine leaves on bread wheat growth and frequence of common weed species in the East-Mediterranean region

A field experiment was carried out to determine the effects of walnut (Juglans regia L.) and pine (Pinus sp.) leaves on bread wheat (Triticum aestivum L.) growth and weed control, during 2001-02 and 2002-03 growing seasons in East Mediterranean region of Turkey. In this research, the treatments were: applications of ground walnut leaves (GWL) and ground pine leaves (GPL) at 19 g/m2 dose at Zadoks-11, applications of 200, 400 and 800 cc/m2 of walnut leaves extract (WLE2, WLE4 and WLE8 respectively), pine leaves extract (PLE2, PLE4 and PLE8 respectively), mixture extract of 200 cc walnut and 200 cc pine (ME), herbicide application (HA) at 8 g/m2 dose at Zadoks-21, and control (C) without any treatment. The results have indicated that the effects of treatments were significant for grain yield (GY), plant height (PH), flag leaf length (FLL), weed number per square meter (WN), but non significant for grain number per head (GN), grain weight per head (GW), 1000 grain weight (1000 GW), flag leaf width (FLW), head number per square meter (HN), vegetative period (VP), grain filling period (GFP) and days to maturity (DM).     

Antennal responses of four species of tree-killing bark beetles (Coleoptera: Scolytidae) to volatiles collected from beetles,and their host and nonhost conifers

Summary. Host selection in tree-killing bark beetles (Coleoptera: Scolytidae) is mediated by a complex of semiochemical cues. Using gas chromatographic-electroantennographic detection (GC-EAD) and GC-mass spectrometric analyses, we conducted a comparative study of the electrophysiological responses of four species of tree-killing bark beetles, the Douglas-fir beetle, Dendroctonus pseudotsugae, Hopkins, the mountain pine beetle, D. ponderosae Hopkins, the spruce beetle, D. rufipennis Kirby, and the western balsam bark beetle, Dryocoetes confusus Swaine, to volatiles captured by aeration of 1) bole and foliage of four sympatric species of conifers, Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, lodgepole pine, Pinus contorta var. latifolia Engelm., interior spruce, Picea engelmannii x glauca, and interior fir, Abies lasiocarpa x bifolia, and 2) con- and heterospecific beetles at three stages of attack. We identified 13 monoterpenes in the conifers and nine compounds in the volatiles of beetles that elicited antennal responses. There was no qualitative difference in the terpene constitution of the four species of conifers and very little difference across beetle species in their antennal response to compounds from conifers or beetles. The lack of species-specific major or minor components in conifers suggests that beetles would need to detect differences in the ratios of different compounds in conifers to discriminate among them. Attraction to hosts and avoidance of nonhost conifers may be accentuated by perception of compounds emitted by con- and heterospecific beetles, respectively. The 22 compounds identified are candidate semiochemicals with potential behavioural roles in host location and discrimination.     

粤北亚热带山地森林土壤有机碳沿海拔梯度的变化

选择位于南岭国家级自然保护区的广东第一峰——石坑崆,从海拔300 m起到山顶部1 900 m范围,每隔100 m高程设置1条10 m×120 m的样带,共17条样带,研究土壤有机碳含量沿海拔梯度的变化规律及其与植被类型和凋落物层厚度的关系。结果表明,0～20 cm和>20～40 cm土层有机碳含量均随海拔梯度变化呈极显著差异(P<0.001),并随林分类型不同而呈高度显著差异(P<0.01),土壤有机碳含量总体上呈随海拔上升而升高的变化趋势。凋落物层厚度仅对0～20 cm土层有机碳含量有显著影响(P<0.05)。可见,海拔梯度变化是影响土壤有机碳含量的综合和主导因素,而最表层土壤有机碳含量还易受林分因子的影响,这些因子反映了土地利用变化及自然保护历史。该研究结果提示,减少人类活动的干扰和保持林地适合的凋落物层厚度有助于增加森林生态系统的碳储量。     

Photographic and acoustic tracking observations of the behaviour of the grenadier Coryphaenoides (Nematonurus) armatus the eel Synaphobranchus bathybius,and other abyssal demersal fish in the North Atlantic Ocean

Using an autonomous free-fall vehicle (AU-DOS), observations were made of demersal fish attracted to baits and baited acoustic transmitters at two stations in the North Atlantic Ocean. A comparison was made between Station PAP (48°50N; 16°30W), 4800 m deep on the Porcupine Abyssal Plain which is relatively eutrophic, and Station MAP (31°N; 20°W), 4900 m deep on the Madeira Abyssal Plain, which is oligotrophic. Experiments were conducted during summer, in 1989 and 1990. Four species of fish were observed at Station MAP, the grenadier, Coryphaenoides (Nematonurus) armatus, the eel, Synaphobranchus bathybius, and the ophidiids Spectrunculus grandis, and Barathrites sp. At Station PAP, C. (N.) armatus and H. (S.) bathybius were attracted to bait on all deployments and only two other individuals of different species, probably ophidiids, were seen. The mean first grenadier arrival time was 30 and 138 min at Stations PAP and MAP, respectively. Mean first eel arrival time was 29 and 151 min at Stations PAP and MAP, respectively. Estimated population densities of fish were 167 grenadiers km^-2 and 180 synaphobranchid eels km^-2 at Station PAP and 8 grenadiers km^-2 and 7 eels km^-2 at Station MAP. Only the grenadier C. (N.) armatus definitely ingested transmitters, and this species dominated fish activity around the baits. Mean time of departure of grenadiers with transmitters in their stomachs across an acoustic horizon at 1000 m range was 371 and 488 min at Stations PAP and MAP, respectively. Grenadiers had a longer mean staying time at the food source at the more oligotrophic Station MAP (364 min) than at Station PAP (141 min). This corresponds with predictions of optimal foraging theory.     

Sanitary felling of Norway spruce due to spruce bark beetles in Slovenia: A model and projections for various climate change scenarios

A model is presented to predict sanitary felling of Norway spruce (Picea abies) due to spruce bark beetles (Ips typographus, Pityogenes chalcographus) in Slovenia according to different climate change scenarios. The model incorporates 21 variables that are directly or indirectly related to the dependent variable, and that can be arranged into five groups: climate, forest, landscape, topography, and soil. The soil properties are represented by 8 variables, 4 variables define the topography, 4 describe the climate, 4 define the landscape, and one additional variable provides the quantity of Norway spruce present in the model cell. The model was developed using the M5′ model tree. The basic spatial unit of the model is 1 km², and the time resolution is 1 year. The model evaluation was performed by three different measures: (1) the correlation coefficient (51.9%), (2) the Theil's inequality coefficient (0.49) and (3) the modelling efficiency (0.32). Validation of the model was carried out by 10-fold cross-validation. The model tree consists of 28 linear models, and model was calculated for three different climate change scenarios extending over a period until 2100, in 10-year intervals. The model is valid for the entire area of Slovenia; however, climate change projections were made only for the Maribor region (596 km²). The model assumes that relationships among the incorporated factors will remain unchanged under climate change, and the influence of humans was not taken into account. The structure of the model reveals the great importance of landscape variables, which proved to be positively correlated with the dependent variable. Variables that describe the water regime in the model cell were also highly correlated with the dependent variable, with evapotranspiration and parent material being of particular importance. The results of the model support the hypothesis that bark beetles do greater damage to Norway spruce artificially planted out of its native range in Slovenia, i.e., lowlands and soils rich in N, P, and K. The model calculation for climate change scenarios in the Maribor region shows an increase in sanitary felling of Norway spruce due to spruce bark beetles, for all scenarios. The model provides a path towards better understanding of the complex ecological interactions involved in bark beetle outbreaks. Potential application of the results in forest management and planning is discussed.     

Coastal inundation in the north-eastern mediterranean coastal zone due to storm surge events

Low-elevation coastal areas and their populations are at risk during and after the appearance of a storm surge event. Coastal flooding as a result of storm surge events is investigated in this paper for a number of areas around the north-eastern (NE) Mediterranean coastal zone (Adriatic, Aegean and north Levantine seas). The sea level rise (SLR) due to storm surge events is examined for the period 2000?C2004. Wind data, atmospheric pressure and wave data for this period as well as in situ sea elevation measurements (from stations around the Mediterranean coasts) were used. Potential inundation zones were then identified using a 90-m horizontal resolution digital elevation model (DEM). At these zones, the sea surface elevations were calculated for the study period, using the collected data and a 2D storm surge simulation model (1/10^o??1/10^o) output, examining the sea level alteration in specific coastal areas, where in situ measurements are absent and are characterised as ??risky?? in inundation areas, due to their topography. In order to determine the level of storm track implication on major SLR incidents, the trajectories of the respective storm events were computed. The aim of this paper is to investigate the major storm surge events that appeared during the study period, identify the major ??risky?? costal regions along the north-eastern Mediterranean coast and determine their hazard level due to inundation caused by storm surge phenomena. The combination of the risk level determination of an area and the calculation of sea level alteration is an important tool in terms of predicting and protecting the coastal area from extreme meteorological incidents.     

Biodiversity Consequences of Genetic Variation in Bark Characteristics within a Foundation Tree Species

Abstract: The developing field of community genetics has the potential to broaden the contribution of genetics to conservation biology by demonstrating that genetic variation within foundation plant species can act to structure associated communities of microorganisms, invertebrates, and vertebrates. We assessed the biodiversity consequences of natural patterns of intraspecific genetic variation within the widely distributed Australian forest tree, Eucalyptus globulus. We assessed genetic variation among geographic races of E. globulus (i.e., provenances, seed zones) in the characteristics of tree‐trunk bark in a 17‐year‐old common garden and the associated response of a dependent macroarthropod community. In total, 180 macroarthropod taxa were identified following a collection from 100 trees of five races. We found substantial genetically based variation within E. globulus in the quantity and type of decorticating bark. In the community of organisms associated with this bark, significant variation existed among trees of different races in composition, and there was a two‐fold difference in species richness (7–14 species) and abundance (22–55 individuals) among races. This community variation was tightly linked with genetically based variation in bark, with 60% of variation in community composition driven by bark characteristics. No detectable correlation was found, however, with neutral molecular markers. These community‐level effects of tree genetics are expected to extend to higher trophic levels because of the extensive use of tree trunks as foraging zones by birds and marsupials. Our results demonstrate the potential biodiversity benefits that may be gained through conservation of intraspecific genetic variation within broadly distributed foundation species. The opportunities for enhancing biodiversity values of forestry and restoration plantings are also highlighted because such planted forests are increasingly becoming the dominant forest type in many areas of the world.     

Recherches sur la situation trophique d'un groupe d'organismes pélagiques (Euphausiacea). III. Potentiel alimentaire du groupe

The position of a group of pelagic organisms among the food webs depends upon (1) its abundance in the biomass; (2) the factors allowing its utilization by predators; among these, the size distribution of animals and their bathymetric repartition appear to prevail. In the equatorial and southtropical Pacific Ocean, euphausiids represent 8% of the total macroplanktonic and micronektonic biomass, i.e., approximately 13 g/1000 m³ wet weight (somewhat less in oligotrophic tropical zones, a little more in the richer equatorial belt); Euphausia diomedae accounts for more than 50% of this biomass. Individuals measuring 9 to 18 mm in total length (4 to 37 mg wet weight) constitute 84% of the whole biomass of the group; the importance of each species in terms of size groups is discussed. Depth distribution is examined at the specific level. By night, 75% of the biomass concentrates in the 0 to 160 m water layer (ca. 10 g/1000 m³ wet weight; main species Euphausia diomedae), 22% between 160 and 300 m (3 g/1000m³ main species Nematoscelis spp.), and 3% (0.3g/1000 m³) in deeper layers. During the day, the only species abundant at depths less than 400 m belong to the genera Stylocheiron and Nematoscelis; specimens smaller than 15 mm and 20 mg remain at depths shallower than 200 m, individuals between 15 and 22 mm (20 to 65 mg) appear around 200 to 400 m, and larger animals are restricted to depths below 400 m.