The effect of scalping on seedling establishment after seed tree cutting of Scots pine stands in drained peatlands in northern Finland

We studied the establishment of natural seedlings after seed tree cutting and scalping in two drained Scots pine peatland stands in northern Finland (Simo and Sievi). Approximately, 50?ha^?1 of Scots pine stems were retained on both sites. During the six subsequent years, five seedling surveys were conducted. The effect of site preparation was analysed using generalized linear mixed models (GLMM). The mean density of pine seedlings increased more quickly in the scalped plots and was ca. 1.1?m^?2 after six years compared to 0.87?m^?2 in the non-scalped plots, on average. Scalping increased the number of pine seedlings 2-fold compared to that in non-treated plots in Simo, however, in Sievi non-treated plots had 30% higher pine seedling density after six years. Downy birch seedling density was 9–10-fold compared to that of non-treated plots in both sites. In terms of seedling density, seed tree cutting led to satisfactory pine regeneration after just two growing seasons in drained pine peatlands, even without scalping. Scalping significantly increased the number of pine seedlings, but it also enhanced the germination of birch seedlings strongly.     

The maturation of Pinus sylvestris seeds in relation to temperature climate in Northern Finland

The probability of achieving an anatomically mature seed crop of Scots pine (Pinus sylvestris L.) in Northern Finland has been studied on the basis of earlier data and meteorological observations. The meteorological data over the period of 1951–1980 was used to calculate the probability of having a mature seed crop in various parts of Northern Finland. The climatic variables used were: (a) June‐August mean temperature (b) June—September mean temperature, and (c) annual temperature sum (+5°C base temperature). A non‐linear relationship between the percentage of mature seeds in a seed crop and the annual temperature sum was detected, indicating that 50% mature seed crop was achieved at appr. 890 degree days. The results suggest that the probability of having 50% mature seed crop is approximately 0.02–0.03 near the polar timber line. The probability of the occurrence of such years is, however, considerably higher in lowlands and lake districts even near the timber line.     

Optimal management of Korean pine plantations in multifunctional forestry

Korean pine is one of the most important plantation species in northeast China.Besides timber,it produces edible nuts and plantations sequester carbon dioxide from the atmosphere.This study optimized the management of Korean pine plantations for timber production,seed production,carbon sequestration and for the joint production of multiple benefits.As the first step,models were developed for stand dynamics and seed production.These models were used in a simulation–optimization system to find optimal timing and type of thinning treatments and optimal rotation lengths.It was found that three thinnings during the rotation period were optimal.When the amount or profitability of timber production is maximized,suitable rotation lengths are 65–70 years and wood production is 5.5–6.0 m~3 ha~(-1) a~(-1).The optimal thinning regime is thinning from above.In seed production,optimal rotation lengths are over 100 years.When carbon sequestration in living biomass is maximized,stands should not be clear-cut until trees start to die due to senescence.In the joint production of multiple benefits,the optimal rotation length is 86 years if all benefits(wood,economic profits,seed,carbon sequestration) are equally important.In this management schedule,mean annual wood production is 5.5 m~2 ha~(-1) and mean annual seed yield 141 kg ha~(-1).It was concluded that it is better to produce timber and seeds in the same stands rather than assign stands to either timber production or seed production.     

Tree regeneration in patch cutting in Norway spruce stands in northern Finland

The study focused on the success of regeneration on patch cuts in spruce-dominated stands in terms of stocking and tree height. It was based on an experiment in the Kainuu region in northern Finland. The experimental design included 8 stands with 58 clearcut patches of variable size (0.09–0.37?ha), on which either natural regeneration without site preparation or site preparation and planting of Scots pine was applied. A regeneration survey was conducted 13–15 growing seasons after treatments. Patches without site preparation had been restocked quite well from natural seed sources. The average number of trees was about 11,000?ha^?1, of which 1700?ha^?1 crop trees. With site preparation and planting, the stocking levels were also very high, 25,000 and 2100?ha^?1, respectively. One hundred percent of the planted patches and 75% of the naturally regenerated patches had an acceptable density. Restocking was equally good across the range of patch sizes. Tree growth had been somewhat slower in the smallest patches than in the largest ones in the range. Natural regeneration was capable of yielding good regeneration results in most patches, especially when site preparation was applied. Stocking levels and height development were higher yet in the planted patches.     

Scots pine (Pinus sylvestris L.) plantations contribute to the regeneration of holly (Ilex aquifolium L.) in mediterranean central Spain

The aim of this study is to evaluate the recruitment possibilities of holly (Ilex aquifolium L.) populations under Pinus sylvestris plantations in the mountains of Central Spain. Population recruitment of holly under P. sylvestris L. plantations was studied at two localities. We sampled holly seed rain, seed bank, and seedling emergence and survival (of both emerged and planted seedlings) in both localities. Seed germination was analysed by randomly sowing Ilex seeds and their subsequent recollection and analysis over the following 3 years (only in one locality). Seed rain, seed bank and emerged seedling densities did not differ between localities. Seed bank density was between 10 and 20 seeds m⁻², considerably higher than the observed seed rain (0.4–1.2 seeds m⁻²), and also higher than the emerged seedling density (0–4 seedlings m⁻²). But Ilex is not very efficient in germinating under pine forests (29.1% germination after 3 years). This may indicate a seed accumulation process of at least 5 years. Seedling survival for the first year differed among the studied sites (50–60 vs. 17%). Nevertheless these survival rates are higher than those found for the same seedling populations in different forest habitats (not Scots pine forests) from near locations. Differences in summer water stress between the study sites are proposed as the main cause of the observed differences in seedling survival. It is concluded that P. sylvestris forests may provide one of the best regeneration habitats for holly in the Mediterranean area, where this species is close to the Southern limit of its distribution.     

不同产地厚朴种子性状的变异分析

厚朴(Magnolia officinalis Rehd. et Wils.)为木兰科(Magnoliaceae)落叶乔木.正品药用厚朴为厚朴的根皮、干皮和枝皮,其中的有效成分(厚朴酚(magnolol)、和厚朴酚(honokiol)及β-桉叶油醇等)具有多方面的药理作用(如燥湿消痰、下气除满),用于湿滞伤中、脱痞吐泻、食积气滞、腹胀便秘、痰饮喘咳等[1-4].厚朴主要分布于102NFA48122°E、22NFA4834°N之间,分布区内的不同气候及土壤条件,致使形成大量不同的遗传类型,其中种子形态必然存在很大的差异.     

A stochastic spatial regeneration model for Pinus sylvestris

A simulation model of pine regeneration is presented, based on earlier models and research for natural regeneration of Scots pine in Finland. The model is stochastic, reflecting the unpredictable variation in regeneration results observed in nature. Geographic area, site and stand characteristics and soil preparation affect the simulated regeneration result. The model predicts the amount and quality of seed crop, germination and predation of seeds, and survival and growth of seedlings. The effect of parent trees on seed dispersal, and growth and survival of seedlings is accounted for. At the stand level, the model gives results similar to empirical measurements. The simulation example provided illustrates the effect of density and spatial distribution of the parent tree stand on the regeneration result.     

Variation in seed rain from Widdringtonia whytei growing in different conditions on Mulanje Mountain in Malawi

Mulanje Mountain is one of the examples of tropical montane landscapes with plant populations varying in size from small fragments of less than 1 ha to riverine strips and stands of more than 100 ha. Seed availability is a potential limiting factor in vegetation recovery in such landscapes. Field observation on seed rain and seed limitation was conducted in 2008 and 2009 in three sizes of forest fragments at three sites on the mountain to investigate: (1) whether size of Widdringtonia whytei forest patches influences seed-rain density; (2) whether W. whytei seed rain occurs in a specific season; and (3) if seed limitation differs from within forest patches to the adjacent non-forest patch habitats. The results showed that there was a distinct difference in seed-rain density among fragments where large fragments (>20 trees) collected higher seed-rain density (10.4 ± 0.9 seeds m^?2 y^?1) than small fragments (1.1 ± 0.4 seeds m^?2 y^?1). The seed-rain density differed significantly between 2008 (2.1 ± 0.6 seeds m^?2 y^?1)and 2009 (6.1 ± 1.1 seeds m^?2 y^?1). Seed rain was recorded every month of the year but the densities were not significantly different among months. Seed-rain density was highest inside the forest fragments (12.04 ± 2.3 seeds m^?2 y^?1) and decreased drastically and very significantly at the edges (1.0 ± 0.8 seed m^?2 y^?1) and outside the forest fragments (0.11 ±0.1 seed m^?2 y^?1). Seed limitation was strong (0.98) on all sites; 0.95 in large fragments and 0.99 in medium and small fragments, respectively. Therefore, it can be concluded from this study that the presence and retention of more seed trees ensures the continued availability of W. whytei seed on the forest floor within the context of limited seed dispersal.     

Effects of drought stresses induced by polyethylene glycol on germination of Pinus sylvestris var. mongolica seeds from natural and plantation forests on sandy land

Effects of drought stresses induced by polyethylene glycol (PEG) (0.0%, 10%, 15%, 20%, 25%, and 30%, with four replicates) on germination of Mongolian pine (Pinus sylvestris var. mongolica) seeds produced in plantations (southern Keerqin sandy land) and natural forests (Hulunbeier sandy plain) were observed. The results indicated that the seeds from both provenances did not germinate when PEG concentration was more than 25%. The time of initial germination and that of its completion of stressed seeds from both provenances were delayed when compared with the unstressed seeds. The germination capacity and germination rate of natural seeds were significantly higher than those of plantation seeds for all treatment levels (P < 0.05). The mean growth rates of radicle and hypocotyl from natural seeds were significantly higher than those from plantation seeds at all treatment levels below 20% PEG treatment (P < 0.05). The ratios of radicle to hypocotyl of 20% PEG treatment were significant higher than those of the corresponding controls for both provenances (P < 0.05). These results suggested that Mongolian pine seeds/seedlings had stronger resistance to PEG drought stresses; 10% PGE stress did not significantly influence germination. Natural seeds exhibited more resistance to PEG stress than plantation seeds. It was concluded that drought stress on seed germination might be one cause of obstructed natural regeneration of Mongolian pine plantations on sandy land. It is recommended that natural seeds be used for afforestation, and light drought stress (e.g., 10% PEG stress) may be useful in improving seed germination and the growth of radicles and hypocotyls.     

Comparative mast seed production in unmanaged and shelterwood white pine (Pinus strobus L.) stands in central Ontario

The effect of the seed cut of the uniform shelterwood silvicultural system on white pine seed production, seed characteristics, and seed viability during 2 mast seeding events was examined in operationally harvested second growth, white pine-dominated forest stands in central Ontario. Seed traps placed along transects in unmanaged and shelterwood stands in each of 3 blocks were used to monitor seed production in 2000 and 2006 (4 and 10 years after harvesting). During these 2 mast seed years between 386,000 and 2,730,600 seed ha^?1 were produced among study stands. Total seed production expressed on a per hectare and unit pine basal area basis did not differ by harvest treatment or among blocks in either year. Variability in seed production among stands was primarily due to differences in stand structure, with seed production positively related to white pine basal area. Seed characteristics were largely similar between harvested and unmanaged stands and between seed years. Seed viability was relatively high in both years, with seed from shelterwoods germinating slightly slower than those from unmanaged stands. Seed quality, as estimated by laboratory germination performance, was higher in 2006 than 2000, likely due to improved seed development and maturation in the warmer, wetter growing season of 2006. Our results suggest that the seed cut of the uniform shelterwood system applied to second growth white pine stands is unlikely to adversely affect white pine seed production, seed quality, or potential for natural regeneration during mast seeding events.     

Growth and survival of lodgepole pine and Scots pine after 25 years in a reciprocal transplant experiment in Canada and Sweden

Lodgepole pine is native to western North America, but it is also planted as a fast-growing alternative to Scots pine in Sweden. The production of these two species, when grown as native and as exotic species, was compared in a transcontinental two-species provenance experiment. The tests were planted in 1986 on five sites in northwestern Canada and two sites in Sweden, and included full-sib families, half-sib families, seed orchard collections and natural stand seed collections of both species. After 25 years, lodgepole pine produced 48% more volume (m³ha^?1) and had 27% higher survival than Scots pine at one Swedish site, and had similar volume production and survival at a second. In the five Canadian sites, Scots pine produced on average 22% more volume than lodgepole pine. The variation between sites was, however, large. This higher volume of Scots pine in Canada could be due to higher survival (+28%) and less frequent damage; but higher top height for lodgepole pine in Canada indicated higher potential productivity. The results indicate that an exotic species may produce more than the native species, possibly thanks to higher survival, but it is also possible to increase production with successful population selection of the native species.     

Spatial variation in tree seedling density after the site preparation for planting in a cleared coniferous plantation in Hokkaido,northern Japan

To study spatial variation in natural tree seedling density and the relationship between variation in seedling density and seed dispersal mode at a cleared site, we surveyed natural tree seedlings after the site preparation for planting in a coniferous plantation cleared by a typhoon disturbance in 2004. The site was located near Sikotsuko Lake, Hokkaido, northern Japan. Twenty-five tree seedling species were found and the mean seedling density was 9.8 seedlings/m². Seedlings of non-animal-dispersed species (7.2 seedlings/m²) were approximately five times more abundant than those of animal-dispersed species (1.4 seedlings/m²), and 87% of all seedlings were current. The seedling density of non-animal-dispersed species (almost all wind-dispersed) decreased with distance from a natural forest; however, this trend did not hold for animal-dispersed species (almost all bird-dispersed). The spatial variation in seedling density was lower in animal-dispersed species than in non-animal-dispersed species. Seed dispersal patterns and the viability duration of buried seeds likely affected the variation in seedling density by seed dispersal mode.     

Seasonal and interannual variation in net ecosystem production of an evergreen needleleaf forest in Japan

Carbon dioxide (CO₂) flux was measured above the forest at the Fujiyoshida site on the northern slope of Mount Fuji in Japan in 2000?C2008 using an eddy covariance technique. The forest mainly consists of Japanese red pine (Pinus densiflora) and Japanese holly (Ilex pedunculosa). The 9-year average of monthly mean net ecosystem production (NEP) ranged from ?0.1?g?C?m^?2?day^?1 in January to 2.5?g?C?m^?2?day^?1 in May. The maximum net uptake was observed in May, although gross primary production (GPP) was highest in July. Variation in the leaf amount did not notably affect seasonal variation in GPP. This site was characterized by carbon uptake even in winter, if the meteorological conditions were conducive for photosynthesis and a resulting long period of carbon uptake. The 9-year averages of annual NEP, GPP, and ecosystem respiration (RE) were 388, 1,802, and 1,413?g?C?m^?2?year^?1, respectively. The annual NEP was lowest in 2003 and highest in 2004 over the 9?years. Year-to-year variability of NEP mainly depended on air temperature and photosynthetically active radiation in summer, and the dependence of the deviation of annual NEP on that of GPP was greater than that of RE. Long-term observational data indicated that the carbon uptake ability at the study site was at a moderate level in comparison with other temperate humid evergreen forests around the world. These data also indicated that the site had a high carbon uptake ability compared with other deciduous forests in Japan because of the duration of carbon uptake.     

Background pollination in Pinus sylvestris seed orchards

The proportion of background pollen grains in the seed crops of two Pinus sylvestris seed orchards in Central Finland was estimated with the aid of multilocus allozyme markers. The orchards studied were more than 30 years old and in full pollen production. For the bulked seed crops of the seed orchard with southern clones the estimated average of background pollination over four years was 26%. There were statistically significant differences between years. No significant heterogeneity in the degree of background pollination between clones was found. Among single ramets there was significant heterogeneity in the estimated contamination rates, but the variation was not related to position in the orchard. For the seed orchard with northern clones the bulked seed crop was studied only for one year and the level of background pollination was found to be 33 %. These estimates are fairly high, but lower than for many other orchards. Background pollination at this level will cause losses in expected genetic gains. Part of the seeds from northern orchards will not be adapted to the intended area of use.     

Effects of temperature on the site productivity of Pinus sylvestris and lodgepole pine in Finland and Sweden

The influence of temperature regime on forest production in the northern boreal forest was studied by analysing the variation in site index for 20 provenance tests of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) in Finland and Sweden with respect to temperature. The site indices were regressed with several different temperature variables, which were obtained from interpolated monthly averages over 30 years from permanent meteorological stations nearby. There were strong correlations between all tested temperature variables and site index (r = 0.80–0.94). Site fertility influenced site index to some extent but the slope of the test sites did not. An increase in temperature sum from 600 to 1200 degree days (corresponding to an increase of the mean temperature in July from 13 to 15°C) was associated with an increase in site index of Scots pine (Pinus sylvestris L.) from 12.2 to 21.6 m (77%). Such an increase in site index can be assumed to correspond to an increase of 6.5 m³ ha^?1 wood (183%) in mean annual increment. The effect of temperature was greater on poor sites than on fertile sites, and in harsh temperature regimes than in mild.     

Revealing past needle density in Pinus spp.

The number of short shoots per shoot length, or needle density, is species typical, and it shows year‐to‐year variation within species. By modification of the needle trace method, long‐term needle density chronology was produced in a Scots pine (Pinus sylvestris L.) stand, located at the northern timberline in Finland. Treewise, needle density varied between 9 and 14 short shoots per long shoot (stem internode) centimetre, the annual minimum and maximum values being 5 and 37 short shoots cm^?1. The stand‐specific long‐term average was 10.5 short shoots cm^?1, and the mean annual value varied between 17 and 8 short shoots cm^?1 in 1951 and 1984, respectively. The long‐term pattern in needle density was one of decline with time between 1950 and the mid‐1970s, then to slightly increase on entering the 1990s. The years when the density was relatively high were 1957, 1968 and 1981, indicative of some climatic extremes.     

Seed bank and regeneration dynamics of <Emphasis Type="Italic">Emmenopterys henryi</Emphasis> population on the western side of Wuyi Mountain,South China

Emmenopterys henryi Oliv. (Rubiaceae) is an endangered tree species that is native to China. The wild populations of E. henryi have declined rapidly because of its poor natural regeneration, but the actual regeneration processes are not yet understood. In field tracking surveys and experiments in the Wuyishan Nature Reserve in Southeast China to determine the most important stage that affects the regeneration process, seed bank characteristics, seed germination, and seedling growth dynamics were studied in the typical habitats of E. henryi, Phyllostachys pubescens and broad-leaved forests. Results showed that in both P. pubescens and broad-leaved forests, more than 70% of the E. henryi seeds were distributed in moss and litter layers, and few were found in the soil beneath them. However, seed germination in the soil layer was significantly higher than in the moss and litter layers. Seed density, overall seed quality, and germination rate in the broad-leaved forest were significantly higher than in P. pubescens forest. Seed germination was highest in the microsites around the edge of the crown projection area of E. henryi mother trees. The order of survival rate of the seedlings on different ground surfaces was soil > moss > litter. In both habitats, the average seed density was 24.9 seeds m^?2, and the total germination rate was less than 3.5‰. However, seedlings developed from only 1% of the germinated seeds, indicating that the seed germination is the most important stage in the natural regeneration of E. henryi.     

Physical attributes as indicator of seed maturity and germination enhancement in Himalayan Wild Cherry (<Emphasis Type="Italic">Prunus cerasoides</Emphasis> D. Don.)

Prunus cerasoides has poor regeneration in its natural habitat due to its hard seed coat. The information about maturity time of fruit/seed is scanty and studies on seed germination enhancement lacking. In the present study, the main focus has been given to the physical fruits/seeds attributes which are reliable indicators of maturity and seed pretreatments which help to enhance germination. The fruits/seeds were collected from low and high elevational sites covering the altitudinal range of the species during the period of fruit/seed development (last week of February–mid April) for two consecutive years (2003–2004). The change in fruit colour from dark green to pale red or red was a useful indicator of seed maturity in P. cerasoides. Fruit moisture content between 46.57 ± 0.45% and 56.81 ± 1.14% and seed moisture content between 29.8 ± 1.35% and 34.13 ± 1.50% coincided with maximum germination (41.11 ± 13.96% and 59.99 ± 12.05%) across sites. The removal of seed coat (mechanical treatment) enhanced the germination of seeds to 70 ± 0% at low elevation and 100 ± 0% at high elevation in comparison of control or untreated seeds (germination range between 5.83 ± 0.83% and 31.68 ± 25.02%). Positive correlation existed between seed size and germination (r = 0.280; P < 0.01).     

Cone and seed production from stone pine (<Emphasis Type="Italic">Pinus pinea</Emphasis> L.) stands in Central Range (Spain)

Natural regeneration of stone pine (Pinus pinea L.) stands in the Central Range of Spain can be difficult to attain. The success of this regeneration is affected by factors such as the total amount of seed available, the short dispersal ability of the pinyon, the conditions required for germination, specific problems associated with the establishment, early survival of the seedlings due to severe summer heat and drought, competition for water and mineral resources and grazing damage. This study focuses on seed availability. The amount of available seeds depends on the number and size of the cones and the number of viable pinyons within the cones. In stone pine stands, both variables show great year to year variability. Both cone and seed production, for a given year, are also conditioned by the vigour and health of the tree, its size, the condition and attributes of the stand and the loss of seed through pests or predation. In this study, the main factors which influence cone and pinyon production are identified and a multivariate model to predict annual cone and viable seed production is developed. To consider the correlation among observations coming from the same tree, stand or year, random components are included in the model. The multivariate random structure allows for future calibration of the model for a given year from a small additional sample of observations. It is important to know the total amount of viable seed produced in a stand for a given year since regeneration cuttings for Stone pine should be concentrated in high crop years.     

Long-term effect of wood and peat ash on the growth of Pinus sylvestris on drained peatland

The effect of ash fertilization on height growth and volume production of Scots pine (Pinus sylvestris L.) was studied on oligotroph peatland in southeast Norway. In the year 1944, plots 15 m × 15 m size were fertilized with 0, 4, 7, and 10 tons ha^?1 of wood or peat ash. The area was treeless, but a satisfactory number of pine seedlings were present. All measurements were confined to the central inner plot, 10 m × 10 m area. Most plots were re-fertilized with 10 tons of wood ash ha^?1 in the year 1993. Wood ash had higher content of nutrients, and generally, it had greater growth enhancement effect than peat ash. When the amount of ash was increased, volume production significantly increased for the age period 38–50 years and the total production at age 50 years. The mean annual increment during the first 50 years was about 6 m³ ha^?1 for the plots applied with 10 tons of ash ha^?1. Trees on plots fertilized with 7 or 10 tons in 1944 and replenished with 10 tons ha^?1 at age 50 years (1993) had a mean annual increment of 14 m³ ha^?1 for the stand age period 51–68 years. Over time some tree roots from control plots and plots fertilized with 4 tons ha^?1 have captured nutrients from richer plots. Such effect is to a smaller extent relevant for treatment 7 tons. It is concluded that the content of mineral nutrients of wood and peat ash makes these ashes well suited as fertilizers on peatland.