Occurrence and berry production of Rubus chamaemorus L., Vaccinium oxycoccus L. & Vaccinium microcarpum Turcz. and Vaccinium vitis‐idaea L. on Swedish peatlands

During three consecutive years, 1978–1980, cloudberries (Rubus chamaemorus L.), cranberries (Vaccinium oxycoccus L. & Vaccinium microcarpum Turcz.) and lingonberries Vaccinium vitis‐idaea L.) growing wild in Swedish forests and mires were inventoried in the annual National Forest Survey. Both the coverage and fertility of these were estimated. Observations from 42 000 test sites (314 m² each) were processed according to geographical region, composition of tree and field layer, altitude and occurrence of draining ditches. Cloudberries cover 425 000 hectares or 1.5 % of the total investigated area (28.6 million hectares). The corresponding values for cranberries and lingonberries are 136000 hectares (0.5 %) and 1362000 ha (4.8%) respectively. Open mires have a greater degree of coverage by cloudberry and cranberry than wet forests on peat. The reverse situation is true for lingonberry. The total berry yield on peatland was estimated to 116.6 million kg (freshweight), distributed as 75.7 million kg cloudberries, 20.8 million kg cranberries and 20.1 million kg lingonberries. The corresponding production of lingonberries on mineral soils was 188.8 million kg. Both in wet forests and on mires, drained areas show lower berry production for the three species, with one exception. Lingonberries yielded better on drained mires. Productive stands of cloudberries and cranberries ought not to be drained for economic reasons.     

Forest structure classes in central Finnish Lapland

Structure classes and changes in the vegetation attributable to the altitude of the terrain were studied in the Hammastunturi virgin coniferous forest area. The area is located in Finnish Lapland, approximately 250–350 km to the north of the Arctic Circle (68°15'N; 68°45'N). The following forest classes were formed on the basis of the ground vegetation and stand coverage: (1) Pine stands, with birch admixture (n=14), (2) Vaccinium‐vitis‐idaea‐type pine stands (n = 24), (3) Vaccinium myrtillus‐type pine stands (n = 17), (4) mixed stands, dominated by pine (n = 8), (5) mixed stands, dominated by spruce (n=18), (6) paludified spruce stands (n = 3) and (7) vigorously growing spruce stands (n = 6). The forest structure classes were depicted using DCA ordinates. The differences were more distinct than those between the normal forest type classifications of the same sample plots. The basal area and volume of pine decreased with increasing altitude, while the proportion of spruce on those sample plots where it was present increased. Birch was present at an equal frequency at all altitudes. The floral composition and between‐species abundance changed along with increasing altitude. The change in floral frequencies could not be designated to a specific altitude zone.     

Ground vegetation under natural stress conditions in Scots pine forests on fixed sand dunes in southwest Estonia

Ecosystems on dunes are influenced by critical environmental factors (mineral nutrients, water deficiency, etc.) considered decisive for their existence. The present paper is based on studies carried out on dunes on the coastal area of the Baltic Sea, southwest Estonia. The nature of forest ecosystems on dunes was studied from the aspects of chemical characteristics of soil, vascular plant species richness and diversity. Sampling sites on the dunes with different heights were selected in Cladina and in Vaccinium vitis-idaea site-type Scots pine forests. Vascular plant species richness and diversity were related to edaphic gradients. On the dune with a height of 32.1 m a.s.l., significant relationships were revealed between the number of species of ground vegetation, pH, volumetric water content in soil and the position of the sample plots. No relationships were revealed between the number of vascular plant species, soil pH, volumetric water content and mineral nutrients on the dune with a height of 9 m a.s.l. The most frequent and abundant plant species on the higher dune were Deschampsia flexuosa, Vaccinium vitis-idaea and V. myrtillus; the highest number of species were found at the bottom of the dune, while on the top only some xeromorphic species such as Festuca ovina, Sedum acre and Crepis tectorum occurred. On the lower dune, the most frequent were Vaccinium vitis-idaea, V. myrtillus and Melampyrum pratense, while V. uliginosum was found only on the bottom and slope and Empetrum nigrum on the top of the dune.     

Seed viability of selected tree,shrub, and vine species stored in the field

Seeds from 10 species were collected, sealed in fiberglass screen pouches, and stored under hardware-cloth cages on both a forest and cleared site for up to five years. At each site, half of the pouches were placed under leaf litter and the other half were planted in mineral soil. Liquidambar styraciflua and Callicarpa americana seeds had high germination rates under all conditions. Quercus falcata, Sassafras albidum, Rhus copallina, and Vaccinium arboreum required planting in mineral soil to ensure germination. Planted Myrica cerifera and Vitis aestivalis seeds germinated well on both sites. Myrica cerifera also germinated well if placed under litter on the forest floor and Vitis aestivalis if placed under litter on the cleared site. Germination of Crataegus uniflora seeds was erratic. Most Lonicera japonica were unsound when collected. Germination rates generally decreased over time, but some Sassafras albidum, Myrica cerifera, and Vaccinium arboreum seed germinated after four years, and Rhus coppalina, Callicarpa americana, Crataegus uniflora, and Vitis aestivalis seeds germinated after five years in the field.     

First report of Phytophthora pseudosyringae recovered from aquatic ecosystems in Bulgaria

Two Phytophthora pseudosyringae isolates were recovered from aquatic ecosystems in Bulgaria during a two‐year investigation of Phytophthora distribution in water sources in the country. Isolate RVit2016/6d was derived from Boyana Lake at the Vitosha Mountain, whereas isolate RTr2016/32d was obtained from Erma River at the Ruy Mountain. Both isolates belong to P. pseudosyringae species according to their morphological and physiological characteristics, as well as to the DNA sequence analysis of the internal transcribed spacer (ITS) region. The pathogenicity of the isolates to wild cranberry plants (Vaccinium vitis‐idea) was studied by detached leaves experiments and in planta. Both P. pseudosyringae isolates were able to cause leaf necrosis and death of plants within 3 months. The ability of the pathogens to infect cranberry leaves at different temperatures was also investigated. The significance of P. pseudosyringae species and its potential threat for forest ecosystems is discussed. To our knowledge, this is the first report of P. pseudosyringae isolation in Bulgaria.     

Sulphate adsorption and acidification of Calluna heathland and Scots pine forest podzol soils in north-east Scotland

Three sites in north-east Scotland were selected to compare soil characteristics of acidification-sensitive sites under Calluna vulgaris heathland and afforestation. At each site, fences separate Calluna heathland from Scots pine plantation on podzol profiles evolved from granitic parent material on gentle slopes in the altitude range 200–500 m. In total, 30 soil pits were dug, with five for each land use-type at each of the three sites. Samples of each horizon were analysed for pH, sulphate adsorption/desorption characteristics, cation exchange properties, carbon and nitrogen contents, bulk density and texture. As expected, acidification to depth had occurred in the forest sites. However, although the forest soils at depth showed less capacity for sulphate adsorption, as might be expected from increased atmospheric aerosol and pollutant trapping and greater water interception loss under trees, they did not contain more PO³⁻₄-extractable sulphate. This may reflect the combined effects of soil pH differences and changes in concentrations and composition of soluble organic matter upon sulphate adsorption, although interpretation is also complicated by textural differences between forest and heathland soils.     

Regeneration niches of Norway spruce (<Emphasis Type="Italic">Picea abies</Emphasis> [L.] Karst.) saplings in small canopy gaps in mixed mountain forests of the Bavarian Limestone Alps

Natural regeneration measurements are the main silvicultural objective in overaged protective forests of the Bavarian Limestone Alps. While manifold problems with these stands, especially the impact of browsing, are widely recognised, the regeneration niches of Norway spruce (Picea abies [L.] Karst.) are insufficiently known. The purpose of this study was to determine favourable combinations of site factors for the development of spruce in small, unfenced canopy gaps, located on Aposerido-Fagetum caricetosum albae forest sites. We recorded the occurrence of spruce saplings (as dependent variable) and of six site factors (as independent variables) on 480 0.5 m²-subplots. In addition, we estimated the coverage of six acid adapted plant species to determine correlations with the humus depth. A binary logistic regression analysis was used to predict the probability of the occurrence of a spruce sapling in dependency of the different site factors. Supported by other studies, we assumed that the supply of solar radiation was adequate for the sufficient regeneration of spruce within the canopy gaps. Other site factors significantly determined the regeneration niches of spruce saplings. More spruce saplings were found near hindrances and on rough surfaces than would be expected from a random occurrence of saplings. These microsite types may have characteristics, especially protection against snow gliding that promotes spruce establishment. A calculated “hindrance index”, which accounted for the number, and the distance of surrounding hindrances might be a good specific value to describe the influence of hindrances on steep slopes. The sapling establishment decreased on thin humus layers. Our assumption for the sites was that thick organic layers might represent a good seedbed for spruce. Decayed dead wood was scarce, but was exceedingly favoured by spruce saplings. Results obtained suggest that the natural regeneration establishment of spruce on steep slopes can be successfully influenced by site factors which inhibit the influence of snow gliding. According to a “positive microsite” concept, we recommend for artificial regeneration measurements with spruce, microsites close to hindrances (e.g. stumps, downed trees) and Vaccinium myrtillus as a predictor for thick, acid humus layers.     

Formation and growth of stem cankers caused by Gremmeniella abietina on young Pinus contorta

From 1990 to 1995, the formation and growth of stem cankers caused by Gremmeniella abietina on Pinus contorta var. latifolia was studied in three stands in northern Sweden. The stands were planted in 1976–80. The total number of cankers on 756 trees that were individually followed increased from 233 to 477 during the 5‐year period. With 42.0% of the cankers, the pathogen entered through or from the base of diseased branches, and 33.6% through visually undamaged bark. Most of the cankers were within 100 cm of the ground. In one of the three areas, the cankers were evenly distributed within 180 cm of the ground. The frequency of cankers facing north exceeded those facing south. The average vertical length of cankers had increased, 55.6% of cankers had increased their percentage coverage of the stem girth; 13.8% had fully girdled the stem. At two of the sites, there was a negative correlation between canker coverage of the stem circumference and tree height increment.     

Logicality of expert evaluations of berry yields by the experience and interests of forest planners

Abstract

In Finland, expert knowledge has been widely utilized when developing models that facilitate predicting the impacts of alternative forest management options on non-wood forest products. However, expert modelling has been criticized because of the uncertainty and inconsistencies it includes. In this study, expert evaluations regarding bilberry (Vaccinium myrtillus L.) and cowberry (Vaccinium vitis-idaea L.) yields of different imaginary forest stands were analysed to find out whether the assessments were logically consistent. In particular, the consistency of the evaluations concerning berry production capacity of different stand densities and site fertilities was examined. The evaluations were made by 266 forest planners and other people whose work was related to field work in forest planning. The study also assessed whether the level of expertise (measured by two different variables, i.e. interest in berry picking and forest planning experience) affected the logic of the evaluations. It was found that on average both bilberry and cowberry yield assessments were in line with empirical research results found in literature. In addition, interest in berry picking was a more reasonable measure of berry yields in different forest stands than planning experience. The results of this study encourage the use of expert knowledge as a tool for forest planning and management.     

Height growth of young larch (Larix kaempferi) in relation to the frequency of deer browsing damage in Hokkaido, Japan

The effect of browsing frequency by Sika deer (Cervus nippon yezoensis) on the height growth of Japanese larch (Larix kaempferi) in Hokkaido, Japan, was analyzed. Tree heights at the time of the census and at the start of the current growing season were determined for 100 trees selected randomly at each site. The tallest shoot on each tree was identified and the number of browsing occurrences on the current-year shoot was determined. Young larches browsed by deer repeatedly develop new shoots during a growing season. Larch is a browsing-tolerant species, and the average height growth of the most heavily browsed trees was >15 cm. Although resprouting partly compensated for decreased height growth caused by browsing, the annual increase in height decreased with increased browsing frequency. Thus, browsing frequency during a growing season best reflects the intensity of browsing damage to larch trees.     

大兴安岭4种杜鹃花科植物的DSE真菌分布

深色有隔内生真菌在寒温带地区的研究在国内还属空白。本研究首次对内蒙古大兴安岭兴安落叶松林下笃斯越橘、越橘、杜鹃和杜香的DSE真菌进行了研究。结果表明,这4种杜鹃花科植物都有DSE真菌定殖,但DSE定殖率都小于10%。DSE菌根定殖率与全氮呈极显著负相关。依据菌落形态特征和菌丝体的显微结构特征将这4种植物的根样中分离得到的187个DSE菌株分为15个菌株类型,并对这4种植物进行回接实验,其中有8种DSE菌株类型可以定殖这4种植物,8个菌株类型属于子囊菌门的Phialocephala属,分属4个种。     

Biomass,decomposition and nutrient release of Vaccinium myrtillus leaf litter in four forest stands

Biomass and nutrient transfer (N, P, K, Ca, Mg) of bilberry (Vaccinium myrtillus L.) leaf litter fall, as well as decomposition and nutrient release, were studied in four mature forest stands situated in Central and South Sweden. Bilberry leaf litter fall amounted to between 33 and 55 kg ha^‐1 yr^‐1 in the four stands. Only minor differences between sites were noted for litter concentrations of N, P and Ca, whereas K and Mg showed somewhat larger variability. Relative amounts of the five nutrient elements in the litter fall were generally in the order N > Ca > K > Mg > P. The amounts of nutrients returned to the forest floor by the annual leaf litter fall in the stands ranged from 0.4 to 0.8 kg ha^‐1 for N, 0.4 to 0.6 kg ha^‐1 for Ca, 0.2 to 0.7 kg ha^‐1 for K, 0.1 to 0.2 kg ha^‐1 for Mg and 0.04 to 0.08 kg ha^‐1 for P.

The decomposition of the local bilberry leaf litter was followed by means of litterbags during three years. At all sites there was an extremely rapid mass loss from the litter (between 45% and 54%) during the first four to five months of decomposition. After this initial phase, the decomposition rates decreased markedly and after three years the accumulated mass losses of the litters varied between 64% and 78% at the studied sites. After two and three years of decomposition, three of the sites exhibited almost similar litter mass losses whereas at the fourth site the litter was decomposed to a significantly lower degree. The pattern of nutrient release from the decomposing bilberry leaf litter differed somewhat from site to site. Minor differences were, however, noted for P, Ca and Mg while N and K were more strongly retained in the litter at one of the sites.     

Modelling the incidence of Heterobasidion annosum butt rots and related economic losses in alpine mixed naturally regenerated forests of northern Italy

A total of 2257 recently felled stumps were sampled from 22 mixed naturally regenerated forest stands in the Aosta Valley, western Italian Alps, and examined for Heterobasidion annosum butt rots. Disease incidence ranged from 6% to 71% depending on sites, and H. annosum accounted for 92% of the total number of diseased stumps. H. annosum incidence was significantly higher (Chi‐squared multiple comparison tests, p < 0.05) on Norway spruce (44%) than on the other tree species (silver fir = 18%, larch = 12% and Scots pine = 6%). Based on the information on the airborne inoculum composition of the fungus, all the three European species of H. annosum were present, with a variable frequency, depending on site. A partial least squares regression analysis showed that the relative abundance of Norway spruce and four variables describing the size of trees were the best predictors for the incidence of H. annosum butt rots. A model having these variables as predictors was developed (r² = 0.75; p < 0.001) and successfully validated on five additional forest stands. An estimate of the losses in yield and value of timber associated with the disease, i.e. direct losses, was also carried out in the forests included in the survey. The percentage of direct financial losses was either comparable or lower than the average level of disease incidence.     

Yield Potential of Quercus robur Stands in Finland

Yield potential of common oak (Quercus robur L.) stands in Finland was examined by estimating the site index value with a Swedish model of a sample of 23 existing stands in southern Finland, and studying its correlation with site fertility and geographical location. Stand structure and yield parameters were compared with those suggested by the Swedish management regimes to assess their condition and potential for quality oak production. External wood quality and sawlog volume were examined in sample tree data. The study stands scored high site index values on the reference site index curves from southern Sweden. The most fertile sites showed an average site index value of H ₁₀₀=28-30 m, and the common Oxalis-Myrtillus type H ₁₀₀=24-26 m. In the absence of thinning and pruning, the external quality of the trees was poor. Defects had reduced the sawlog proportion on average by 40% from the estimated maximum allowed by tree dimensions.     

喀斯特断陷盆地不同植被恢复模式土壤水分动态变化

[目的]以喀斯特断陷盆地小流域中典型植被恢复模式,即桉树(Eucalyptus maideni)林、冲天柏(Cupressus duclouxiana)林、马尾松(Pinus massoniana)林以及天然次生灌丛、高盖度车桑子(Dodonaea viscosa)灌丛和低盖度车桑子灌丛为研究对象,探究断陷盆地不同植被恢复模式土壤水分时空变异规律,为该地区植被生态恢复工作提供参考。[方法]利用自动气象观测系统和土壤水分传感器同步监测2016年5月—2017年4月期间小流域降雨量与各林地土壤水分,采用变异系数与克里金插值分析方法,对6种植被恢复模式林地的土壤水分时空异质性以及持续干旱条件下土壤水分衰减特征进行研究。[结果]表明:(1)同一植被类型不同土层雨季和旱季土壤体积含水量垂直变化趋势相同,且雨季土壤水分含量显著高于旱季(P0.05),均为中等变异(Cv:12.88%28.66%)。(2)同一乔木林雨季和旱季的土壤活跃层与次活跃层垂直分布不同,但同一灌丛雨季和旱季分布相同。(3)6种植被恢复模式土壤体积含水量均在降雨量较充足的8—9月达到最大值,其变化范围介于26.25%44.08%之间,在降雨量明显不足的3—4月达到最小值,土壤体积含水量介于9.48%17.47%之间。(4)3种乔木林0 30 cm土层、3种灌丛0 10 cm土层充分降雨后约10 d土壤水分恢复为降雨前1 d水平,低盖度和高盖度车桑子灌丛10 30 cm土层土壤水分降雨后15 d恢复为降雨前1 d水平,并且接近植物萎蔫系数。[结论]不同植被恢复模式间雨季、旱季和月均土壤体积含水量均表现为桉树林天然次生灌丛冲天柏林马尾松林高盖度车桑子灌丛低盖度车桑子灌丛。喀斯特断陷盆地季节性干旱和临时性干旱问题严峻,乔木林和灌丛经充足降雨,达到田间持水量后,在连续放晴天气下林地土壤水分可供植物10 15 d的消耗。     

European pear rust on Juniperus excelsa L. in south‐western Turkey

In this study, the frequency of European pear rust (Gymnosporangium fuscum) lesions on Juniperus excelsa was investigated both on seedlings in a nursery and on forest trees in six juniper stands located in south‐western Turkey. In the nursery, lesions occurred on 0.7% of 5510 1‐year‐old seedlings and 29% of 200 2‐year‐old potted seedlings. In each of the juniper forests, 50 trees were chosen within a square of approximately 400 m² in size. In general, rust lesions were common on the trees. On average, 49.0% of the trees had lesions; on 17.3% of the trees, the lesions were located on the trunk, on 43.3% on the branches and on 11.7% on both. In lesion‐bearing trees, the average number of lesions was 1.47–3.59 and the maximum number of lesions per tree were six to 11. Most of the lesions (85.1%) were on branches. There were significant differences between the stands, which can be attributed to different age of the trees, site factors and the presence of alternate hosts. The rust identified from stem lesions in forest trees and from nursery seedlings was European pear rust (G. fuscum), but possible co‐occurrence of other Gymnosporangium spp. cannot be excluded.     

Site index variation with latitude and altitude in IUFRO Pinus contorta provenance experiments in western Canada and northern Sweden

Site index was calculated for 66 experimental plantations in western Canada and northern Sweden, containing a wide range of Pinus contorta provenances drawn from seed lots belonging to the IUFRO international provenance testing program. Growth data from recommended provenances were used to calculate the site index. Site index was defined as predicted average height of the 100 largest trees by diameter ha^‐1 at age 50.

Latitude and altitude explained 56% of site index variation by fitting the function:

Site Index (m) = 99.8 ‐ 1.226 ? Latitude (°N) ‐ 0.01205 ? Altitude (m).

The site index pattern indicated that forest productivity of the sites investigated decreased approximately by 0.8 m³ ha^‐1 yr^‐1 per one‐degree latitude northwards and per 100 m increase in altitude.     

Loss in macronutrient pools in bilberry and lingonberry in mesic Scots pine forests after Northern red oak introduction

Forest transformation from coniferous monocultures to mixed stands is being promoted worldwide, including the introduction of fast-growing broadleaved tree species within native stands. Here, we studied how enrichment of temperate European Scots pine (Pinus sylvestris) forest by North-American northern red oak Quercus rubra impacted macronutrient concentrations in two long-lived and dominant components of the forest understory: bilberry Vaccinium myrtillus and lingonberry V. vitis-idaea. Study sites were located in forest complexes (central Poland) which occupy continuously reforested lands (hereafter ancient forests) as well as post-agricultural lands (recent forests), all suitable for mesic pine forests. Samples of bilberry and lingonberry leaves, stems, and fruits were collected in pine stands and in adjacent Scots pine-red oak stands, in both ancient and recent forests. Concentrations of macronutrients (C, N, P, K, Ca, S, and Mg) in aboveground biomass components were analysed using standardized chemical procedures. The study revealed intra- and interspecific (bilberry vs. lingonberry) differences in concentrations of all nutrients in leaves, stems, and fruits, except for invariable C concentrations. Macronutrient accumulations in plants were decreased by land-use discontinuity and favoured by enrichment of tree stands by Q. rubra. The estimated macronutrient pools were much higher for V. myrtillus than V. vitis-idaea in all forest types studied. They were lower in forests enriched with Q. rubra, both ancient (up to 25.5% for bilberry and 99.9% for lingonberry) and recent (46.9% and 99.9%, respectively), as well as in recent pine forest (46.6% and 81.1%, respectively) than in ancient pine forest. Higher K and S pools (39.3% and 6.5%, respectively) noted for bilberry in an ancient forest with Q. rubra were exceptions. Despite more effective accumulations of elements at the species level, macronutrient pools of Vaccinium myrtillus and V. vitis-idaea decreased significantly in the presence of introduced Q. rubra due to negative impacts of this broadleaved tree on bilberry and lingonberry cover and biomass. Therefore, the limitation of alien Q. rubra planting in sites of mesic pine forest with the abundant occurrence of V. myrtillus and/or V. vitis-idaea is recommended.

Graphic abstract

     

伊犁吐尔根农场沟不同地形对新疆野杏分布特征的影响

采用2019年WorldView-3卫星遥感影像与SRTM数字高程模型（DEM）数据,通过遥感面向对象提取、地理信息系统数字地形分析等,研究新疆伊犁吐尔根农场沟流域新疆野杏（Prunus armeniaca）的生长分布特征。结果表明,新疆野杏主要分布于吐尔根农场沟流域上游海拔1 000~1 900 m的山地坡面,分布面积2.57 km²,覆盖率为2.58%;新疆野杏垂直地带性空间分布特征明显,其分布面积、覆盖率均随海拔升高呈先增大后减小趋势,在海拔1 300~1 400 m出现最大值;新疆野杏分布面积西风迎风阳坡大于背风阴坡、15°~35°坡大于其他更缓和更陡坡,覆盖率西风迎风阴坡高于背风阳坡、陡坡高于缓坡;随海拔升高,同一海拔内不同坡向、坡度上新疆野杏覆盖率的差异均呈先减小后增大趋势,海拔1 300 m附近各坡向、各坡度间新疆野杏分布差异最小,相对最适宜其生存。     

Productivity of single-grip harvesters in clear-cutting operations in the northern European part of Russia

A field-based study was carried out to broaden our knowledge of fully mechanized cut-to-length harvesting productivity in naturally grown forests in the northern European part of Russia (NEPR). The recorded data comprised 38 midsized single-grip harvesters (JD 1270D) in clear-cutting operations in the Karelia, Komi, Vologda, Leningrad, Tver, and Kirov regions in NEPR, 4.3 million felled trees, and 1.4 million m³ u.b. (under bark) of processed timber. Harvesting operations were conducted in forest stands composed of spruce (48% on average), pine (19%), birch (22%), and aspen (11%), with an average stem volume 0.31 m³ u.b. The cut-to-length harvesters produced from 4.3 to 14.9 m³ u.b./productive machine hour (PMH) and 16.0–49.5 m³ u.b./stem processing machine hour (S _proc MH). A machine evaluation analysis and a regression analysis were used to formulate models for predicting cutting productivity of modern single-grip harvester. The regression models were developed to estimate the productivity of the harvesters in the regions taking into account two significant factors influencing the productivity: the stem volume and tree species of the felled trees. Productivity/cubic meter u.b. of processed timber/PMH was calculated according to stem volume and tree species distributions in most forest-covered NEPR regions. Further research is suggested to improve the developed productivity models and to allow prediction of system performance over a broad range of stand and site conditions.