Statistical analysis for the spatial validity of a model to forecast the daily number of forest fires

In earlier papers a qualitative and quantitative model was developed for predicting the number of forest fires occurring per day. This model permits the forecast at 00.00 hours Universal Time Convention (UTC) of any day (d), the number of forest fires per day for a range of several days (d tod+5) over a particular region. Input data are the number of forest fires in the region during two preceding days (d–2 andd–1) and the type of day (real and evaluated from radiosonde ford–2,d–1,d and predicted from meteorological medium-range forecasts, i.e. of European Centre, ford+1,d+2,d+3,d+4 andd+5. As this model requires data obtained by radiosonde, particularly temperatures and geopotentials at 850 and 700 hPa and dew points (or specific humidity) at 850 hPa, this study investigates the spatial validity of the model in relation to the distance from the radiosonde station (RS). The highest quality forecast is obtained for the region immediately surrounding the RS, and diminishes with increasing distance from it, this being due to the data obtained from the RS not being representative of the atmospheric column over the region. Hence, the derivation of the critical distance for a particular quality level of measurement. Conversely, fixed quality level implies a specific separation between RS and the region for the prediction, with a higher predictive quality implying a shorter distance.     

Meteorological conditions are associated with physical activities performed in open-air settings

Meteorological conditions (MC) are believed to modify physical activity. However, studies in this area are limited and none have looked at the associations between MC and physical activity in open-air settings. Therefore, we examined the relationships between MC and physical activities performed on sidewalks/streets and outdoor oval tracks. Observation techniques were used to count individuals walking to school, exercising on oval tracks and walking/jogging/biking on sidewalks/streets. Meteorological conditions were obtained from an Automated Surface Observing System located at a nearby airport for the same time periods physical activities were observed. On weekdays, fewer children were seen walking to school and more bicyclists were observed on sidewalks/streets as wind speed increased (p < 0.05). Ambient and apparent temperatures were positively (p < 0.05) and humidity and barometric pressure negatively (p < 0.005) related to the number of individuals walking on the track. Meteorological conditions were not significantly associated with physical activities observed on weekends. Multiple linear regression analyses showed that apparent temperature (+), barometric pressure (−) and dew point (−) accounted for 58.0% of the variance in the number of walkers on the track. A significant proportion of the variance (>30%) in the number of joggers and the length of time they jogged was accounted for by apparent temperature (+) and dew point (−). We found that meteorological conditions are related to physical activity in open-air settings. The results embellish the context in which environmental–physical activity relationships should be interpreted and provide important information for researchers applying the observation method in open-air settings.     

Diversity of Vibrios associated with reared clams in Galicia (NW Spain)

The aim of the present study was to characterize and identify vibrios isolated from cultured clams in Galicia (NW Spain). A total of 759 isolates were obtained, phenotypically characterized, grouped and assigned to the genus Vibrio. Subsequently, the genomic diversity of 145 representative strains was analyzed by means of amplified fragment length polymorphism (AFLP), which revealed a high genetic diversity amongst these isolates. Only 57 out of 145 strains could be identified to the species level, and they were distributed in 13 AFLP clusters. V. cyclitrophicus, V. splendidus and V. alginolyticus were the most abundantly represented species. Eighty-eight isolates remained unidentified, 59 were distributed over 16 clusters, while 29 were unclustered. Sequencing of the 16S rRNA and two house-keeping genes (rpoA and recA) from representative strains belonging to eight unidentified clusters with the highest number of isolates confirmed their assignation to the Vibrionaceae family, and some of these probably represent new species within the genus. The present study confirmed that the phenotypic characterization of vibrios is not sufficient to identify them at the species level. A wide diversity of vibrios was found in cultured clams from all four geographic locations analyzed. In total, more than 12 Vibrio species and at least three potential new species in this genus were identified.     

Climate change-driven forest fires marginalize the impact of ice cap wasting on Kilimanjaro

The disappearing glaciers of Kilimanjaro are attracting broad interest. Less conspicuous but ecologically far more significant is the associated increase of frequency and intensity of fires on the slopes of Kilimanjaro, which leads to a downward shift of the upper forest line by several hundred meters as a result of a drier (warmer) climate since the last century. In contrast to common belief, global warming does not necessarily cause upward migration of plants and animals. Here, it is shown that on Kilimanjaro the opposite trend is under way, with consequences more harmful than those due to the loss of the showy ice cap of Africa's highest mountain.     

大兴安岭2001-2010年森林火灾碳排放的计量估算

林火是森林生态系统重要的干扰因子,是导致植被和土壤碳储量减少的重要路径之一。森林火灾总碳和含碳气体的排放对气候变化具有重要影响,科学有效地对其进行计量,对了解全球的碳平衡和碳循环,以及森林火灾对大气碳平衡的影响机理均有重要意义。大兴安岭是我国唯一的寒温带针叶林区,又是森林火灾的多发区,科学计量该区森林火灾的碳排放量,对了解区域碳平衡具有重要意义。根据大兴安岭2001—2010年森林火灾统计资料和森林资源清查中各林型可燃物载量数据,通过野外调查和采样,并结合野外火烧迹地调查与室内控制环境实验相结合的方法确定各种计量参数,从林分水平上计量大兴安岭2001—2010年间森林火灾所排放的总碳和含碳气体排放量。结果表明:大兴安岭在10a间森林火灾所排放的总碳量为5.36×106t;含碳气体排放量CO2、CO、CH4和NMHC分别为1.73×107t、1.10×106t、7.10×104t和3.50×104t。通过分析可知3种兴安落叶松林型(杜鹃-落叶松林、杜香-落叶松林和草类-落叶松林)对该区的碳排放具有重要贡献,占总碳排放量的83.08%,占含碳气体排放量CO2、CO、CH4和NMHC分别为83.36%、82.25%、57.96%、81.00%。同时研究表明,该区年均的碳排放对区域碳平衡产生重要影响。     

黑龙江省温带森林火灾碳排放的计量估算

森林火灾干扰作为森林生态系统重要的干扰因子,剧烈地改变着森林生态系统的结构、功能、格局与过程,对区域乃至全球的碳循环与碳平衡产生重要影响。随着全球气候变暖,森林火灾干扰的频率和强度进一步加剧,其排放的含碳气体对大气中温室气体浓度的贡献率更大,进而加快气候变暖的速率。科学有效地对森林火灾碳排放及含碳气体排放量进行计量估算,对了解区域乃至全球的碳循环及碳平衡具有重要的理论价值和实践意义。根据黑龙江省温带森林1953—2012年火灾统计资料和森林调查数据,结合地理信息系统GIS技术,通过野外火烧迹地调查以及实验室的控制环境实验来确定森林火灾碳排放计量中的各种参数,在林分水平上,利用排放因子的方法,估算了黑龙江省温带森林60年间火灾碳排放量和含碳气体排放量。结果表明:黑龙江省温带森林60年间火灾碳排放量为5.88×107t,年均排放量为9.80×105t,约占全国年均森林火灾碳排放量的8.66%;含碳气体CO2、CO、CH4和非甲烷烃(nonmethane hydrocarbons,NMHC)的排放量分别为1.89×108、1.06×107、6.33×105和4.43×105t,含碳气体CO2、CO、CH4和NMHC的年均排放量分别为3.15×106、1.77×105、1.05×104和7.38×103t,分别占全国年均森林火灾各含碳气体排放量的7.74%、6.52%、9.42%和6.53%。研究发现针阔混交林型的森林火灾面积占总过火林地面积的57.54%,由于其燃烧效率较低,在森林火灾中的碳排放量仅占排放总量的38.57%;尤其是针阔混交林森林火灾面积占总过火林地面积的20.71%,而碳排放量仅占总排放量的9.67%;且CO2的排放因子较低,其CO2排放量仅占总排放量的8.95%。同时研究表明,黑龙江省温带森林年均的碳排放对该区域的碳循环与碳平衡产生重要影响,并针对研究结果提出了应对气候变化的森林经营可持续管理策略,亦提出了科学的林火管理策略及其合理化的林火管理路径。     

Geochemical aspects of aluminium in forest soils in Galicia (N.W. Spain)

The aqueous speciation of Al was studied in acid forest soils in N.W. Spain. Aluminum concentrations were 10–70 mol L^–1, with variable proportions oflabile, nonlabile, andacid-soluble Al. Almost all thelabile Al was found complexed with F^–, Al³⁺ concentrations being low. The importance of organic matter was seen in the formation of Al-organic complexes in the solid soil fraction and the presence of aqueous alumino-organic complexes in superficial horizons (umbric epipedons) rich in organic matter.     

Structure,biomass and production of a resprouted holm-oak (Quercus ilex L.) forest in NE Spain

When considered as a compartment of nutrients (biomass) and as a flux between compartments (production) vegetation plays an important role in the biogeochemical forest research that is carried out at the Prades research station in two adjacent catchments: L'Avic (51.6 ha) and La Teula (38.5 ha). The forest density at the Prades site, considering both the tree and shrub layers, is 9182 stems ha^–1, with 4527 stems ha^–1 being the tree layer. The predominant species is Quercus ilex with Arbutus unedo and Phillyrea media less common. The structure of the population, estimated by grouping the numbers of the stems in classes of 2.5 cm, shows a distribution which conforms, in both catchments, to a negative exponential equation following the Yoda law. The distribution observed at different altitudes shows great heterogeneity, the number of stems of Q. ilex increases with altitude, from 4000 stems ha^–1 at 800 m, to 14000 stems ha^–1 at 1000 m of altitude. The upper and the lower parts of the watershed show differences in forest production that explain this variation. In this paper the influence of human activities and physical factors on the origin of this structure is discussed. The tree and shrub biomass was calculated by applying allometric regressions for the three predominant species and has been estimated as 113.2 t ha^–1. The tree layer accounts for 92%. Net production was calculated from annual increases (by differences between the 1981 and 1986 basal area measures) of the woody part and the litterfall. The above-ground net production was about 6.5 t ha^–1 year^–1, 95.4% of it being from trees and shrubs and only 4.6% from grasses.     

Branchial lesions associated with abundant apoptotic cells in oysters Ostrea edulis of Galicia (NW Spain)

An experiment to evaluate differences in growth, mortality and disease susceptibility among Ostrea edulis stocks was performed. Five families were produced from each of 4 oyster populations (Irish, Greek and 2 Galician). The spat were transferred to a raft in the Ria de Arousa (Galicia, Spain) for grow-out. Monthly samples of each family were histologically processed from 2001 to 2003. One of the pathological conditions discovered by this study was the occurrence of extensive branchial lesions characterized by haemocytic infiltration and loss of branchial architecture. Furthermore, abundant atypical cells occurred among the haemocytes in the lesions in the branchial connective and epithelial tissues, but rarely in the mantle. These cells were contracted in size with nuclei showing chromatin condensation and fragmentation. Some nuclear chromatin aggregated under the nuclear membranes into crescent shapes, whereas others were uniformly dense. Those characteristics suggested that the cells were apoptotic haemocytes, which was confirmed by transmission electron microscopy (TEM) and by a terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labelling (TUNEL) assay using the Apoptag Kit on paraffin sections. A low prevalence of gill lesions was detected in some, but not all, families of every origin peaking in July 2002 and April 2003. No etiologic agent was identified by either histology or TEM; thus, the cause of the abundance of apoptotic cells remains unclear.     

Correlation between meteorological conditions and Parietaria pollen concentration in Alassio,north-west Italy

The pollen grains in the atmosphere in different geographical areas differ according to the species present, the pollination seasons and pollen grain concentrations, but possibly the greatest contributors to this variability are the meteorological conditions. The aim of our research is to establish a possible correlation between Parietaria pollen concentration and meteorological conditions during the period from 1991 to 1995 in the town of Alassio (north–west Italy). As far as vegetation is concerned, the Mediterranean climatic conditions support the blooming of extensive grasslands in the environment surrounding the town; these grasslands mainly comprise Urticaceae and shrubs. The study demonstrates that the most influential parameters affecting the Urticaceae grain concentration upsurge are the absence of rainfall, a maximum daily temperature of about 21 °C, and a diurnal temperature range of about 5 °C. Moreover, our aeropalinological study indicates that this last parameter has the greatest influence on Urticaceae pollination. In fact, an increase in diurnal temperature range could be responsible for a dehydration of pollens resulting in a loss in mass. This grain lightness and volatility would ultimately permit atmospheric dispersion if there is a significant wind speed. On the other hand, days with rain or high relative humidity make pollens heavier, preventing them from flying long distances and therefore partially explaining the decline in airbone pollen concentration.     

Effects of fire recurrence in Quercus coccifera L. shrublands of the Valencia Region (Spain): II. plant and soil nutrients

The consequences of fire recurrence (1, 2 and 3 fires in 16 years) on plant and soil C, N, P and K from Quercus coccifera garrigues were analysed in the Valencia Region (E Spain). Plant and forest floor (L horizon) nutrient concentrations either changed weakly or showed no change with fire recurrence. At the soil surface (0-2.5 cm), soil potential mineralisable nitrogen increased and available P decreased after an initial increase, whereas exchangeable K was not affected by successive fires. However, the significance of those observed trends for N and P was site-dependent. Despite the rapid formation of the L soil horizon, fire recurrence did not permit the development of the whole forest floor profile observed in the unburned garrigues. These organic layers contained a great proportion of the total nutrient pool, especially for N. Forest-floor and aboveground plant combustion by fire may produce significant losses of N and P compared with those available in mineral soil, whereas soil exchangeable K is large enough to replace these losses. Belowground nutrient reserves may account for the quick recovery of the Quercus coccifera aboveground biomass although successive fires could deplete these reserves and produce a loss of biomass and productivity in this species.     

Heat and chill requirements of Fraxinus flowering in Galicia (NW Spain)

Fraxinus pollen data from eight Galician localities (1999-2003), recorded using 7-day Lanzoni VPPS pollen traps, were studied to determine their temporal and spatial distribution. The determination of the chill and heat required to trigger flowering and the start cumulative date were calculated using ten years of pollen data from Ourense. The sum of maximum temperatures from the 55 days before the peak date showed the lowest standard deviation coefficient and the mean quantity of accumulated heat was 741. Temperatures below 0°C and/or rainfall at the beginning of flowering caused a longer period before the peak date was registered. Temperatures recorded in November were very important for chill accumulation and determine the heat requirement needed to trigger Fraxinus flowering in Galicia.     

半干旱地区河滩宜林地立地条件研究

采用对应分析、回归分析方法对半干旱地区河滩宜林地土壤基本性质进行了研究．结果表明,河滩地土壤理化性质的差异主要表现为土壤质地的差异,有机质含量、ＣａＣＯ３含量、全盐量、田间持水量等与土壤机械组成中细粒级含量（尤其是＜０．００１ｍｍ、０．００１～０．００５ｍｍ两个粒级）呈正相关．半干旱地区河滩宜林地立地条件主导因子为地下水位、土壤质地和有效土层厚度．采用最优分割法对地下水位、有效土层厚度进行了分级．以主导因子分级组合法综合考虑当地具体情况,将河滩宜林地划分为２０个立地类型,并对其进行了多树种综合评价．     

Diversity measurements in shrubland communities of Galicia (NW Spain)

Diversity was studied in 10 communities, including the understory of native oak woodland, planted woodlands (pine and eucalypt), and shrublands in the strict sense (heathlands, broom shrublands, gorse shrublands).In each community, species richness, diversity, dominance and evenness were analysed. Differences were observed among communities with regard to species composition, richness in annual herbs, perennial herbs and shrubs, dominant plant families (Ericaceae, Papilionaceae) and diversification of shrub species.The possible relations between environmental stress and/or human influences on differences in diversity are discussed.     

Herb layer changes (1954-2000) related to the conversion of coppice-with-standards forest and soil acidification

Question: Did the composition of the herb layer of a deciduous forest on loamy soils sensitive to soil acidification change between 1954 and 2000? How are these change related to the abandonment of traditional coppice-with-standards forest management and increased soil acidification? Location: Central Belgium (Europe). Methods: Twenty semi-permanent phytosociological quadrats from an ancient deciduous forest (Meerdaal forest) were carefully selected out of a total of 70 plots dating from 1954 and were revisited in 2000. Species composition and soil pH H₂O were recorded using an analogous methodology. The studied period coincides with a period of forest conversion from coppice-with-standards towards a high forest structure and with an increase in acidifying and eutrophying deposition. Results: Between 1954 and 2000, species composition of the herb layer changed significantly. Redundancy analysis pointed to increased shade resulting from shifts in cover and species composition of the shrub and tree layer as the main driving force. Soil acidity increased and the majority of plots entered the aluminium buffer range, which potentially affected herb layer composition. Observations at the species level, especially a strong decrease in cover of the vernal species Anemone nemorosa supported this hypothesis. Conclusions: Our results show significant shifts in the forest herb layer in less than five decades. These shifts were related to an alteration in the traditional forest management regime and increased soil acidity. Whereas the effect of a changed management regime can be mitigated, soil acidification is less reversible. Testing the generality of these patterns on more extensive data sets is certainly needed.     

森林植物的一些特殊环境功能

本文从植物对大气、水体和土壤化角度分析了森林的特殊环境功能,有些植物能吸收空气中各种有害气体,如SO₂、Cl₂、HF以及放射性物质,可用于治理大气污染,或用于环境污染监测;许多森林植物对各种污染物有一定的吸收、积累和分解作用,因而,可以用于污染环境的修复治理;植物通过蒸腾作用向大气中释放大量的水分,带走了热量,降低了大气的温度;森林还能保持水土、防风固沙、涵养水源.因而,森林具有美化环境,清理环境污染物,稳定气候等重大的环境功能.     

Decomposition rate of Quercus rotundifolia leaves in an evergreen oak forest of the Duero Basin (Province of Zamora,Spain)

Experimental litter decomposition of Quercus rotundifolia leaves in an evergreen oak forest of the semiarid area of the Duero Basin has been carried out. The loss of weight of the decomposing oak leaves was 62% after 24 months. In general, it is physical factors (mainly precipitation) which limit the decomposition of the evergreen oak leaves. Different patterns of bioelement losses were observed, increasing the relative content of N and P, and decreasing the amounts of Mg, K and Na in the decomposing leaves.