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1
Fukasawa, Y., Y. Komagata e S. Ushijima. "Fungal wood decomposer activity induces niche separation between two dominant tree species seedlings regenerating on coarse woody material". Canadian Journal of Forest Research 47, n. 1 (gennaio 2017): 106–12. http://dx.doi.org/10.1139/cjfr-2016-0218.
Testo completoAbstract (sommario):
Decomposition subsystems have an essential role in forest dynamics but few studies demonstrate the effect of microbial decay traits on seedling regeneration. In the present study, we focused on seedling regeneration on coarse woody material (CWM), which is an important regeneration site for forest tree species, and the effects of wood decay type according to fungal decay preference for wood structural components on seedling colonization. Effects of log properties including wood decay type and other environmental variables on seedling density were evaluated by ordination methods and generalized linear models. In total, 22 woody species were recorded as seedlings on Pinus densiflora logs. By ordination analysis, white rot in heartwood and brown rot in sapwood, as well as canopy openness and log diameter, showed significant association with seedling communities. The factors selected for a generalized linear model for explaining seedling densities of the two dominant seedling species Cryptomeria japonica and P. densiflora included brown rot in sapwood and white rot in heartwood, but the effects were different: a positive effect of brown rot on C. japonica and a negative effect of white rot on P. densiflora. These results suggested that wood decay type could induce niche separation between dominant tree species regenerating on CWM.
2
Béland, Martin, Yves Bergeron e Richard Zarnovican. "Natural regeneration of jack pine following harvesting and site preparation in the Clay Belt of northwestern Quebec". Forestry Chronicle 75, n. 5 (1 ottobre 1999): 821–31. http://dx.doi.org/10.5558/tfc75821-5.
Testo completoAbstract (sommario):
A 36-ha experiment was carried out to assess the possibility of naturally regenerating jack pine stands following harvesting on clay soils of northwestern Quebec. Although differences between treatments were not statistically significant, there was a trend toward a positive effect of one treatment combining on-site delimbing and scarification with the Silva Wadell™ cone scarifier on jack pine seedling density (up to 10 000/ha) and distribution (50% of 1 m2 plots with at least one seedling, corresponding to 94% with 4 m2 plots), two years after harvest. However, scarified microsites contained fewer seedlings than expected and undisturbed humus contained more seedlings than expected. This result, contrary to what is generally reported in the literature may be explained either by the fairly humid conditions, favourable to germination and seedling establishment, occurring on clay sites or by the scarifier spreading the cone-bearing slash outward. Seedling abundance and distribution improved substantially from the first year to the second year following treatment. Although the irregular branch distribution over the cutover area appears to have limited regeneration success, combining on-site delimbing with soil scarification could lead to relatively good stocking of jack pine regeneration that could be enhanced by some fill-planting. This regeneration method could constitute an alternative to planting jack pine on clay. However, vegetation control to remove aspen competition might be necessary. Key words: jackpine, silviculture, natural regeneration, boreal mixed wood
3
Johnson e Yeakley. "Microsites and Climate Zones: Seedling Regeneration in the Alpine Treeline Ecotone Worldwide". Forests 10, n. 10 (3 ottobre 2019): 864. http://dx.doi.org/10.3390/f10100864.
Testo completoAbstract (sommario):
Microsites, local features having the potential to alter the environment for seedling regeneration, may help to define likely trends in high-elevation forest regeneration pattern. Although multiple microsites may exist in any alpine treeline ecotone (ATE) on any continent, some microsites appear to enhance density of seedling regeneration better than others. Known seedling regeneration stresses in the ATE include low temperature, low substrate moisture, high radiation, drought, wind, and both high and low snowfall amount. Relationships among various microsite types, annual temperature, annual precipitation, and tree genera groups were assessed by synthesizing 52 studies from 26 countries spanning six continents. By categorization of four main microsite types (convex, concave, object, and wood) by mean annual precipitation and temperature, four major climatic zone associations were distinguished: cold & dry, cold & wet, warm & dry, warm & wet. Successful tree recruitment varied among microsite types and by climatic zones. In general, elevated convex sites and/or decayed wood facilitated earlier snow melt for seedlings located in cold & wet climates with abundant snowfall, depressions or concave sites enhanced summer moisture and protected seedlings from wind chill exposure for seedlings growing in cold & dry locations, and objects protected seedlings from excessive radiation and wind in warm & dry high locations. Our study results suggest that climate change will most benefit seedling regeneration in cold & wet locations and will most limit seedling regeneration in warm & dry locations given likely increases in fire and drought. Study results suggest that high-elevation mountain forests with water-limited growing seasons are likely to experience recruitment declines or, at best, no new recruitment advantage as climate warms. Climate envelope models, generally focusing on adult trees rather than seedling requirements, often assume that a warming climate will move tree species upward. Study results suggest that climate models may benefit from more physically-based considerations of microsites, climate, and current seedling regeneration limitations.
4
Peters, Vernon S., e Darcy R. Visscher. "Seed Availability Does Not Ensure Regeneration in Northern Ecosystems of the Endangered Limber Pine". Forests 10, n. 2 (10 febbraio 2019): 146. http://dx.doi.org/10.3390/f10020146.
Testo completoAbstract (sommario):
Research Highlights: When biotic interactions such as disease alter both the seed production capacity of stands, and seedling survivorship, the relative importance of seed availability versus substrate specificity may alter future regeneration opportunities for plant populations. Background and Objectives: We investigated the importance of disease severity, seed availability, and substrate limitation to the regeneration dynamics of the endangered limber pine, Pinus flexilis, in two ecosystems with varying forest composition, and different histories of white pine blister rust infection (WPBR; Cronartium ribicola). Materials and Methods: A total of 17 stands from the montane ecoregion (Alberta, Canada) were sampled for seed production between 2007–2010, seedling density, and age structure. Model selection using an information theoretic approach compared a series of a priori models and their combinations, based on our hypotheses on the role biotic variables play in the regeneration process. Results: Despite higher rates of WPBR infection, 2.3 times more seed was available for avian dispersers in the southern ecosystem. Recent seedling regeneration did not correspond to seed production (83 versus 251 seedlings/ha, in southern versus northern ecosystems, respectively), resulting in a seven-fold difference in seed to seedling ratios between ecosystems. Models suggest that disease and vegetation cover were important factors explaining the absence of regeneration in 79.4% of the plots sampled, while basal area (BA) of live limber pine, rocky substrates, ecosystem, South aspects, and slope enhanced limber pine regeneration. Seedling age structures suggest that recent regeneration is less likely in more diseased landscapes, than it was historically (40% versus 72.8% of seedlings < 20 years old, respectively, in southern versus northern ecosystems). Conclusions: At the northern limits of limber pine’s range, seed availability does not ensure regeneration, suggesting that other environmental or biotic factors hinder regeneration. Regeneration was consistently predicted to be lower in the southern ecosystem than in the northern ecosystem, suggesting that natural regeneration and the potential for population recovery are ecosystem dependent. We recommend that monitoring recent seedlings will aid the identification of biotic and abiotic factors affecting regeneration.
5
St-Pierre, Hélène, Réjean Gagnon e Pierre Bellefleur. "Distribution spatiale de la régénération après feu de l'épinette noire (Picea mariana) et du pin gris (Pinus banksiana) dans la forêt boréale, Réserve faunique Ashuapmushuan, Québec". Canadian Journal of Botany 69, n. 4 (1 aprile 1991): 717–21. http://dx.doi.org/10.1139/b91-097.
Testo completoAbstract (sommario):
Post-fire spatial distribution of black spruce (Picea mariana (Mill.) BSP) and jack pine (Pinus banksiana Lamb.) regenerations were studied in the Réserve faunique Ashuapmushuan, Quebec. The main factors analysed were (i) effects of organic matter thickness on growth and regneration, (ii) spatial distribution type of the regeneration, (iii) effects of burned stems on this distribution, and (iv) links between spatial distribution of the regeneration and the thickness of the post-fire residual organic matter. A strong correlation was observed between the presence of seedlings and the thickness of the post-fire residual organic matter. However, jack pine was much more efficient in getting established on microsites with thicker organic matter. Spatial distribution of the regeneration has a tendency to spread, following Blackman's dispersion coefficient, while adult individuals of the original population follow a more random pattern; this suggests that some seedling mortality, induced by seedling density, is to be expected. Regeneration shows a spatial link (point correlation coefficient) with trees of the original population, thus showing up the post-fire perpetuation of the individuals on the same microsites. Finally, the residual organic matter thickness on the ground seems without significant influence on the overall growth of jack pine and black spruce seedlings. Key words: Picea mariana, Pinus banksiana, spatial distribution, fire, regeneration. [Journal translation]
6
Alfaro-Sibaja, Laura, Daniela Barquero-Salgado, Alicia Fonseca, Randall A. Montoya-Solano, Vanesa Morales-Cerdas e Daniel Ramírez-Arce. "Vegetation structure and composition of mangrove Palo Seco Quepos, Costa Rica". UNED Research Journal 7, n. 2 (15 dicembre 2015): 325–32. http://dx.doi.org/10.22458/urj.v7i2.1161.
Testo completoAbstract (sommario):
The Palo Seco mangrove in the Pacific coast of Costa Rica is in a tropical wet forest-perhumid forest transition. The nearby human population and tourism are threatening its borders. We studied mangrove’s structure, composition and regeneration as a base for future comparisons. We sampled eight 10m x 10m plots. Within them, 1m2 and 16 m2 plots were established to measure seedlings and saplings. We measured 153 trees in an 800 m2 area, with an average density of 0,19 ± 0,12 Ind/m2. Avicennia germinans was the dominant species, and Avicennia bicolor the less abundant. While seed- ling’s basal area and density were high, we found a low sapling density. We found a strong positive correlation between seedling density and trees richness and density, whereas that a strong significant negative correlation between the seedling regeneration index and tree stem height, diameter and basal area. We found a positive correlation be- tween the seedling regeneration index and mangrove tree’s richness and density. We conclude that several variables have an influence in the seedling’s establishment, survival and growth, intervening in the mangrove’s maintenance and regeneration. Strong competition with other vegetation can be a major factor in sapling growth. Palo Seco mangrove has a great potential for regeneration, and stem height and diameter evidence of an old-growth ecosystem.
7
Youngblood, Andrew P. "Effect of shelterwood removal methods on established regeneration in an Alaska white spruce stand". Canadian Journal of Forest Research 20, n. 9 (1 settembre 1990): 1378–81. http://dx.doi.org/10.1139/x90-182.
Testo completoAbstract (sommario):
Seedling damage during overstory removal was compared among different yarding methods; almost three times more mortality was associated with rubber-tired ground skidding than with skyline cable yarding. Seedlings ranging in height from 0.4 to 1.0 m generally received less damage or had lower mortality rates from cable yarding than did shorter or taller seedlings. Snowpack disturbance and percentage of seedling mortality were positively correlated. Results suggested that with attention to seedling height growth and yarding method, the shelterwood regeneration system is a viable option for white spruce (Piceaglauca (Moench) Voss) stand regeneration in interior Alaska.
8
Lunt, Ian D., Heidi C. Zimmer e David C. Cheal. "The tortoise and the hare? Post-fire regeneration in mixed Eucalyptus - Callitris forest". Australian Journal of Botany 59, n. 6 (2011): 575. http://dx.doi.org/10.1071/bt11151.
Testo completoAbstract (sommario):
Seedling regeneration after a high intensity wildfire was assessed in a mixed forest dominated by Eucalyptus species and Callitris endlicheri (Parl.) F.M. Bailey. Patterns were compared against the ‘slow seedling’ or ‘tortoise-and-hare’ theory of competitive interactions between gymnosperms and angiosperms. Browsing effects were documented using fenced plots, and seedling density, mortality and height were assessed over 6 years, from 2004–10. Consistent with expectations, Eucalyptus seedlings grew faster than Callitris seedlings in most situations. Callitris seedlings grew faster and produced seed cones sooner in plots with fewer Eucalyptus seedlings compared with plots with dense Eucalyptus seedlings. The local growth rates of Callitris seedlings were not associated with long-term site suitability for Callitris, as many plots with diminutive Callitris seedlings and dense Eucalyptus seedlings were dominated by Callitris trees before the 2003 fire. Contrary to expectations, few Callitris seedlings died during the 6-year period, so competition during the regeneration phase did not regulate co-existence. Strong drought tolerance and the ability to persist in dense, unthinned stands may enable Callitris to persist beneath dense Eucalyptus regeneration. Nevertheless, Callitris seedlings growing with dense Eucalyptus seedlings have a longer primary juvenile period than seedlings in sites with fewer seedling or adult eucalypts, which places these stands at greater risk of mortality in future fires and greater risk of browsing in the meantime.
9
Brose, Patrick H. "A comparison of the effects of different shelterwood harvest methods on the survival and growth of acorn-origin oak seedlings". Canadian Journal of Forest Research 41, n. 12 (dicembre 2011): 2359–74. http://dx.doi.org/10.1139/x11-143.
Testo completoAbstract (sommario):
Timely development of newly germinated oak (Quercus spp.) seedlings into competitive-sized regeneration is an essential part of the oak regeneration process. The amount of sunlight reaching the forest floor partly governs this development, and foresters often use the shelterwood system to expose oak seedlings to varying degrees of insolation. To further understand the seedling development–sunlight–shelterwood relationships, I conducted a multiyear study at five locations in Pennsylvania. Each location had four stands either uncut or recently treated with one of three shelterwood harvest methods (preparatory cut, first removal cut, or final removal cut) resulting in four different levels of sunlight reaching the forest floor. In each stand, four 32 m2 plots were prepared, and each was planted with 400 acorns of black (Quercus velutina Lam.), chestnut (Quercus montana Willd.), northern red (Quercus rubra L.), or white oak (Quercus alba L.) and protected from wildlife. Germination success was universally high and for the next 8 years, I monitored seedling survival and measured seedling growth. The final and first removal cut treatments had higher seedling survival than the preparatory cut and uncut treatments. Oak seedling growth was positively related to sunlight availability; seedlings in the final removal cut grew the most, followed in descending order by those in the first removal cut, preparatory cut, and uncut treatments. These findings provide insight into the subtleties of regenerating oak forests with the shelterwood system.
10
Jones, Robert H., Ralph D. Nyland e Dudley J. Raynal. "Response of American Beech Regeneration to Selection Cutting of Northern Hardwoods in New York". Northern Journal of Applied Forestry 6, n. 1 (1 marzo 1989): 34–36. http://dx.doi.org/10.1093/njaf/6.1.34.
Testo completoAbstract (sommario):
Abstract Root sprout and seedling regeneration of American beech was sampled in two maple-dominated northern hardwood stands 13-14 years after single-tree selection cutting. The largest stems had been advance regeneration, and seedlings comprised a substantial and well-distributed portion of these. Among stems established after the cut, root sprouts outnumbered seedlings. Total beech regeneration abundance was correlated with basal area of overstory beech. For long-term beech control, it may be useful to reduce beech seedling populations before selection cutting, and to cut large diameter beech trees. North. J. Appl. For. 6:34-36, March 1989.
11
Burton, Philip J., Jesy Simons, Steve Brittingham, Daniel B. Thompson, Darin W. Brooks e Lawrence R. Walker. "Regeneration dynamics of Great Basin bristlecone pine in southern Nevada". Canadian Journal of Forest Research 50, n. 6 (giugno 2020): 589–94. http://dx.doi.org/10.1139/cjfr-2019-0404.
Testo completoAbstract (sommario):
Great Basin bristlecone pine (Pinus longaeva D.K. Bailey) is an important and long-lived tree species found at high elevations in the interior southwest of the United States, but little is known about its regeneration requirements and response to disturbance. We conducted extensive surveys of seedling regeneration and environmental attributes of regeneration sites in undisturbed forest dominated by this species in the Spring Mountains of southern Nevada. Additional surveys tallied new seedling densities and site attributes 4 years after a wildfire in the same area. Seedlings, saplings, and juvenile trees were less abundant than adult trees in the unburned forest, and soils had lower bulk density and greater depth, moisture, and soil organic matter under adult trees than in open areas. Seedling distributions in both unburned and burned forest showed a negative relationship to a heat load index governed by aspect. The density of new seedlings after the fire was negatively related to distance from unburned forest edges. Seedlings were found in clusters and were associated with adult trees (live or dead) in both unburned and burned stands. Seedling emergence from animal-dispersed caches was more frequent in burned habitats than in unburned habitats. These natural regeneration dynamics provide potential guidance for restoration efforts in this ecosystem.
12
Taylor, Alan H., Zisheng Qin e Jie Liu. "Tree regeneration in an Abiesfaxoniana forest after bamboo dieback, Wang Lang Natural Reserve, China". Canadian Journal of Forest Research 25, n. 12 (1 dicembre 1995): 2034–39. http://dx.doi.org/10.1139/x95-220.
Testo completoAbstract (sommario):
Bamboos in the understory of Abiesfaxoniana Render & Wilson forests in China impede tree regeneration when they are mature. However, bamboos die back every few decades and may synchronize tree seedling establishment on the forest floor. Tree seedling regeneration patterns were studied beneath 20 canopy gaps and adjacent closed forest in an old-growth A. faxoniana forest where understory bamboos died back in 1976. Most seedlings of A. faxoniana, Acercaudatum Wallich, and Betulautilis D. Don in gaps established 2 years after dieback of the bamboo Fargesiadenudata Yi. Acercaudatum seedlings in gaps were taller than those of B. utilis or A. faxoniana, and B. utilis seedlings were fourfold more abundant in gaps than the other species. All species (except A. caudatum) had greater seedling densities in gaps, but there were no density differences among species beneath closed forest. Bamboo cover and maximum culm height were greater under gaps than forest, and it takes bamboo seedlings about 18 years to grow to full height. Bamboo seems to reduce the success of an advanced regeneration strategy and promotes synchronized seedling establishment in gaps after it dies back.
13
Rahman, Md Rayhanur, MK Hossain, Md Akhter Hossain e Mohammad Emran Hasan. "Natural regeneration potential of Madhupur National Park, Bangladesh". Bangladesh Journal of Botany 49, n. 4 (31 dicembre 2020): 989–96. http://dx.doi.org/10.3329/bjb.v49i4.52515.
Testo completoAbstract (sommario):
Natural regeneration is an essential tool to evaluate the overall health of a forest ecosystem. Natural regeneration of the tree species in Madhupur National Park showed 47 regenerating tree species among which Shorea robusta has maximum density (18,046 seedlings per ha) followed by Aporosa sp., whereas minimum density (19 seedling per ha) was recorded for Cassia nodosa, Litsea glutinosa, Grewia asiatica and Syzygium cumini, respectively. Relative density, relative frequency and relative abundance were estimated to assess the Importance Value Index (IVI) of the seedlings of different tree species. IVI of S. robusta was highest (66.25 out of 300) followed by Mallotus philippensis (27.33). G. asiatica, Derris robusta, and L. glutinosa showed the lowest IVI (0.93) among the regenerating tree species. Distribution of seedlings into different height classes showed that maximum number (31.4%) of seedlings in the height range of 50 - <100 cm. Among the recorded seedlings, Protium serratum showed maximum (11%) recruitment success. Alien invasive species, pineapple and banana based participatory agroforestry, frequent occurrence of fire, extensive collection of fuelwood and litter are the potential threats to the natural regeneration of Madhupur National Park.
14
Kingery, J. L., e R. T. Graham. "The Effect of Cattle Grazing on Ponderosa Pine Regeneration". Forestry Chronicle 67, n. 3 (1 giugno 1991): 245–48. http://dx.doi.org/10.5558/tfc67245-3.
Testo completoAbstract (sommario):
During the summer and fall of 1982, a study was established on the Nez Percé National Forest in central Idaho to assess the effects of cattle grazing on the performance of a new ponderosa pine (Pinus ponderosa Laws.) plantation. Three study sites were located in a Douglas-fir/ninebark (Pseudotsuga menziesii/Physocarpus malvaceus) habitat type. Results after six years showed that livestock use can influence tree seedling establishment. Mortality and damage to tree seedlings from cattle resulted primarily from trampling rather than from browsing. Five and one-half percent of the seedlings were damaged by cattle, of which 3.6% died. Browsing by deer and elk caused the most growth loss. Overall damage was greatest from non-animal causes. Seedling quality at the time of planting, handling of the seedling, and droughty conditions during the first two years of the study contributed to this type of damage. Overall performance of the tree seedlings were relatively poor. Total mortality to tree seedlings resulting from all sources of damage was 43.6% for the grazed treatment and 25.3% for the non-grazed treatment.
15
Štícha, V., I. Kupka, D. Zahradník e S. Vacek. "Influence of micro-relief and weed competition on natural regeneration of mountain forests in the Šumava Mountains". Journal of Forest Science 56, No. 5 (28 maggio 2010): 218–24. http://dx.doi.org/10.17221/28/2009-jfs.
Testo completoAbstract (sommario):
Natural regeneration and its relationship to micro-relief and weed competition were studied on 6 research plots in mountain spruce forests in the Šumava Mountains. The data on density regeneration, total height and height increment of each seedling were recorded on 50 by 5 m transects. The position of each seedling was adjusted by a satellite system "Field map". The data show that an elevation is a significantly (significance level P = 0.99) preferable micro-relief for seedlings in most cases (7 of the total 9 cases). The regeneration density is low in a high-competition environment, i.e. in grass and ferns, where the number of seedlings is significantly low on all surveyed plots. But dead wood, which is also an elevation in terms of the micro-relief, is the most preferable micro-site. The data show no significant differences in seedling heights due to differently dominant competing plants. Neither was the hypothesis about the beneficial influence of stem or stump in close surroundings on seedlings confirmed by our data.
16
Battaglia, L. L., B. S. Collins e P. B. Weisenhorn. "Quercus michauxii regeneration in and around aging canopy gaps". Canadian Journal of Forest Research 34, n. 6 (1 giugno 2004): 1359–64. http://dx.doi.org/10.1139/x04-019.
Testo completoAbstract (sommario):
Floodplain forests are subject to frequent windstorms, which create canopy gaps and microtopographic heterogeneity. Forest regeneration may be enhanced when light and microtopographic conditions are both favorable, but slower growing canopy species may still require multiple disturbance events to reach the canopy. In 2001, we revisited a cohort of Quercus michauxii Nutt. seedlings planted in 1995 on pitmound microsites that were constructed in and around canopy gaps to determine patterns of seedling persistence and investigate the effects of canopy openness and microtopography on seedling survival and growth. After 7 years, canopy openness in gap centers had decreased to levels that did not differ from levels in forest canopy. Seedling height and maximum root depth were greatest in gap centers, where light was initially greater but seedling growth rates declined over time. Soil moisture was greater in pits, where establishment and survival were very low. Roots of some seedlings reached from mound surfaces to depths and moisture levels comparable to those of adjacent pits, which might facilitate survival in both floods and droughts. Quercus michauxii can persist on elevated sites in aging gaps, and positive feedback in sites favorable for recruitment can enhance seedling growth; ascent into the canopy will likely require additional canopy-opening events.
17
Vasconcelos, Heraldo L., e J. Malcolm Cherrett. "Leaf-cutting ants and early forest regeneration in central Amazonia: effects of herbivory on tree seedling establishment". Journal of Tropical Ecology 13, n. 3 (maggio 1997): 357–70. http://dx.doi.org/10.1017/s0266467400010567.
Testo completoAbstract (sommario):
ABSTRACTThe effects of herbivory by the leaf-cutting antAtta laevigataFr. Smith on the re-establishment of forest trees in an abandoned farm near Manaus, central Amazonia, were investigated. Experimental seedling transplants and observations on seedlings which emerged naturally in the study area showed that damage by leaf-cutting ants negatively affected tree seedling survival and growth. However, excluding leaf-cutting ants from experimental plots for 20 mo did not significantly increase tree seedling densities. The number of seedlings emerging varied considerably between plots and this obscured any effect the ants may have had on seedling survivorship. Taller seedlings, and seedlings attacked only once, suffered less mortality than smaller seedlings and seedlings attacked twice or more. In general, mortality was greater for those species preferred by the ants, indicating that selective herbivory by leaf-cutting ants affects tree species composition. The number of seedlings attacked byA. laevigataremained approximately constant throughout the period of this study in spite of the fact that the number available for attack increased. Thus, the chance of any individual seedling being attacked declined with time, suggesting that the effect ofAttaherbivory on tree establishment is stronger during the first few years of forest regeneration.
18
Côté, Sylvie, e Louis Bélanger. "Variations de la régénération préétablie dans les sapinières boréales en fonction de leurs caractéristiques écologiques". Canadian Journal of Forest Research 21, n. 12 (1 dicembre 1991): 1779–95. http://dx.doi.org/10.1139/x91-246.
Testo completoAbstract (sommario):
The renewal of boreal fir stands after harvesting is related to the abundance of fir advanced regeneration. The objective of this study was to compare the advanced regeneration in 45-years-old balsam fir stands of second growth to determine if ecological site conditions could explain some regeneration problems noted in the balsam fir – white birch ecoclimatic domain. Seven ecological phases were studied; these are among the most common in the Laurentians north of Québec. On the basis of fir seedling densities (2 years old and more), three groups could be distinguished using a cluster analysis method for grouping means. Dry balsam fir – herb-and-moss type on well drained tills formed a first group characterized with very high seedling densities (> 60 000 seedlings/ha). A second group, characterized with high seedling densities (25 000 – 40 000 seedlings/ha), was constituted of three phases with an important moss cover:the mesic balsam fir – moss-and-herb type on moderately well drained tills, the humid balsam fir – moss-and-herb type on imperfectly drained tills with seepage, and the humid balsam fir – moss type on imperfectly drained tills. A third group, with low seedling densities (< 15 000 seedlings/ha), included three phases recognized by their important herb cover associated with a less abundant moss cover: the dry balsam fir – herb type on well drained till, the mesic balsam fir – white birch – herb type on moderately well drained till, and the mesic rich balsam fir – herb type on moderately well drained tills with seepage. Low densities of fir advanced regeneration seemed to be related to the abundance of leaf litter on the forest floor that could hinder fir regeneration. Insufficient natural coniferous regeneration can be anticipated in this last group if harvesting follows the 45-year rotation currently used now in Quebec.
19
Gratzer, G., P. B. Rai e G. Glatzel. "The influence of the bamboo Yushania microphylla on regeneration of Abies densa in central Bhutan". Canadian Journal of Forest Research 29, n. 10 (1 ottobre 1999): 1518–27. http://dx.doi.org/10.1139/x99-125.
Testo completoAbstract (sommario):
To assess the impact of a dense understory of the bamboo Yushania microphylla Munro on tree regeneration in monospecific Abies densa Griff. stands of the central Bhutan Himalayas, the age-class distribution of fir regeneration, the microsite preferences, and height growth as well as the relationship between height of the bamboo, gap fraction, and tree seedling density were studied. Seedling densities were much lower on sites with bamboo. Recruitment was more or less continuous, and there was no indication of overall synchronized single-cohort regeneration in bamboo plots. On sites with bamboo understory, the light regime at the forest floor is strongly influenced by the height of the bamboo. A large portion of the variance of tree seedling density could be explained by the height of the bamboo. The mortality of fir seedlings is considerably reduced at elevated microsites. Fir establishment on the forest floor is restricted to sites where bamboo density is low and light levels are higher. On sites with dense, unbrowsed bamboo, light levels are too low for long-term survival of fir seedlings, resulting in a lack of suppressed regeneration with minimal height growth. Because of the absence of this fraction, the average height increment of fir seedlings is higher on sites with bamboo.
20
Bakken, Peter N., e James E. Cook. "Regeneration Potential of Six Habitat Types Common to North-Central Wisconsin". Northern Journal of Applied Forestry 15, n. 3 (1 settembre 1998): 116–23. http://dx.doi.org/10.1093/njaf/15.3.116.
Testo completoAbstract (sommario):
Abstract The arboreal regeneration of 24 mature, fully stocked forests distributed among 6 common habitat types (Kotar et al. 1988) in north-central Wisconsin were studied. Nineteen of the stands were inventoried in 1992 and 1993; in 1993 an additional 5 stands were included. The density and composition of small (<25 cm) and large (25-150 cm) seedlings were determined, and the relationships of the understory and overstory were investigated. No significant (P < 0.05) differences were found for seedling densities of either size class among habitat types. This was due, in part, to the large variation within most habitat types; this in turn is primarily a function of the temporally variable nature of seedlings. The average densities per habitat type ranged from 3,125-20,200/ha for large seedlings and from 20,208-152,083/ha for the small seedlings. Red and sugar maple strongly dominated the regeneration. Red maple was the most common (88-96%) species in the small seedling size class on the three driest habitat types, and sugar maple (88-99%) on the two most mesic habitat types. In the middle of the site quality gradient, the two maples shared dominance with northern red oak. The level of maple dominance was lower in the large seedling class, ranging from 53-93%. The small seedling size class was significantly related to the amount of maple basal area each year, but the strength of this relationship weakened from 1992 to 1993. The widespread domination by red and sugar maple is a function of their regeneration ecology, shade tolerance, fire suppression, and deer browsing. The seedling composition and densities have important implications for the management of these forests. The regeneration and overstory characteristics suggest that it would be easiest to direct the composition one of several ways on the PMV and AVVib habitat types. Fairly heavy overstory treatments, in conjunction with seedbed preparation, are probably necessary to regenerate significant amounts of species other than sugar maple on the two most mesic habitat types. North. J. Appl. For. 15(3):116-123.
21
Kimambo e Naughton-Treves. "The Role of Woodlots in Forest Regeneration outside Protected Areas: Lessons from Tanzania". Forests 10, n. 8 (25 luglio 2019): 621. http://dx.doi.org/10.3390/f10080621.
Testo completoAbstract (sommario):
Promoting forest regeneration outside protected forests is an urgent challenge in densely settled, biodiverse areas like the East African Rift. Regenerating forests entails managing complex processes of ecological recovery as well as understanding the needs and motivations of local land users. Here, we evaluate pathways for attaining native tree regeneration across variable site conditions. We investigate two common strategies for attaining native tree regeneration—setting aside land for forest regeneration (‘Protect and Wait’) and native tree planting (‘Native Tree Planting’)—and a possible third, smallholder exotic tree-planting (‘Woodlots’). We measured native seedling regeneration patterns for each of the three strategies, all underway at a single site in Southern Tanzania. We also used historical aerial photograph analysis and interviews with smallholder farmers to understand past and present land use. Our results show that forest regeneration has been arrested for decades on land under ‘Protect and Wait’, and seedling survival appears to be limited under ‘Native Tree Planting’. In contrast, we found saplings of 28 native species growing spontaneously within pine, eucalyptus, and cypress woodlots planted <400 meters from native forest boundaries. Interviews showed that the citizens most likely to plant woodlots near the protected forest were those who owned additional land parcels elsewhere. Some saw woodlots as a means to avoid losing crops to wildlife at the forest edge. Our findings suggest: 1) Simply setting aside land for regeneration does not guarantee forest regrowth, even if it is adjacent to natural forest, 2) native seedlings will be more likely to survive if planted near shade trees, and 3) smallholders’ woodlots could hasten native tree regeneration at forest park edges if farmers have incentives to protect the native tree seedlings in their woodlots and they can find land elsewhere to plant food crops.
22
Chesterfield, CJ, e RF Parsons. "Regeneration of Three Tree Species in Arid South-Eastern Australia". Australian Journal of Botany 33, n. 6 (1985): 715. http://dx.doi.org/10.1071/bt9850715.
Testo completoAbstract (sommario):
Grazing effects by introduced mammals on tree seedlings in the arid zone have caused concern for the long-term future of some tree species. This was investigated by measuring stem girths of Casuarina cristata Miq., Heterodendrum oleifoliurn Desf. and Myoporum platycarpum R.Br. in arid-zone wood- lands. Episodic seedling regeneration of Myoporum is inferred following series of wet years in the 1950s and 1970s. Although young Myoporum plants appear unpalatable to stock, regeneration may be sup- pressed by rabbit-grazing in some areas. Almost no Heterodendrurn seedlings were found but suckering was common after burning and clearing. This species is highly palatable to grazing mammals and suckers may grow to safety above the browse line only where stock are absent. Evidence for recent Casuarina seedling regeneration was limited to one cohort, on a site that had been flooded. While suckers can be found locally where surface roots become exposed, suckering appears insufficient to perpetuate many Casuarina stands. Mammal-grazing seems important in strongly limiting regeneration. While Casuarina and Heterodendrum stand densities decline due to natural senescence and occasional fire, the only species regenerating into gaps is Myoporum. There is concern for the future of Casuarina and Heterodendrum, given their widespread failure to regenerate despite the wettest 3 years ever recorded, in 1973-75. On pastoral land, at least 10 years without stock-grazing might be needed for successful regeneration of Heterodendrurn. In reserves, some nature conservation programs for woodlands might require virtual eradication of all exotic mammalian herbivores, including goats.
23
Kneeshaw, Daniel D., e Yves Bergeron. "Ecological factors affecting the abondance of advance regeneration in Quebec's southwestern boreal forest". Canadian Journal of Forest Research 26, n. 5 (1 maggio 1996): 888–98. http://dx.doi.org/10.1139/x26-097.
Testo completoAbstract (sommario):
Boreal forest disturbance regimes have changed during the past century, in turn changing regeneration and stand dynamics of these forests. This is occurring at the same time that the forest industry is emphasizing operations that take advantage of pre-established natural regeneration. This study has therefore investigated the effect of various ecological factors on the abundance of Abiesbalsamea (L.) Mill., Piceaglauca (Moench) Voss, Piceamariana (Mill.) BSP, Thujaoccidentalis L., Betulapapyrifera Marsh., and Populustremuloides Michx. natural regeneration in some boreal stands in the Abitibi region of Quebec. Abiotic ecological site classification variables were found to be poorly correlated with seedling densities for most species. Parent trees, as a seed source, and stand type, for its influence on the quality of the seedbed, were strongly correlated with abundant conifer regeneration. As expected, time since fire was positively correlated with seedling abundance for late successional species, whereas it was not related to the abundance of early successional species. Post-fire disturbances, such as those due to spruce budworm (Choristoneurafumiferana (Clem.)) outbreaks, accounted for the variations in seedling densities observed with respect to stand age. The presence of budworm-caused gaps was positively correlated with regeneration abundance, whereas shrub competition, which was greatest in large gaps, was negatively correlated with advance regeneration density. Forest management based on abundance of pre-established regeneration should focus mainly on mixed stands because seedling density is very low in hardwood stands and because of the strong competition found in large gaps of resinous forests. The low number of seedlings observed, especially in coniferous stands, may limit the effectiveness of operations that take advantage of advance regeneration. The large variability observed among site and stand types limits their operational use in predicting seedling densities.
24
Taylor, GB. "Effect of tillage practices on the fate of hard seeds of subterranean clover in a ley farming system". Australian Journal of Experimental Agriculture 25, n. 3 (1985): 568. http://dx.doi.org/10.1071/ea9850568.
Testo completoAbstract (sommario):
In a rotation of 1 year pasture/l year crop, a subterranean clover (Trifolium subterraneum cv. Daliak) pasture was either left untilled or subjected to minimum or conventional tillage. One set of tillage treatments was imposed in each ofthree crop years while another set of treatments was imposed in only the first crop year. Regenerating clover plants were prevented from setting seed. In the first crop, 44% of the clover seeds were buried below 2 cm of soil by minimum tillage; this proportion was 65% in the conventional tillage treatment. In the first pasture regeneration year, seedling densities were highest in the no-tillage treatment. Conversely, there were more residual seeds in the tilled treatments and, in the second and third pasture regeneration years, this led to higher seedling densities than in the no-tillage treatment. The effects of tillage were more marked in the conventional than in the minimum-tillage treatment. Clover establishment was improved by repeat tillage operations which returned some of the buried seeds closer to the soil surface. Although more seedlings overall were obtained from the no-tillage treatment, the disadvantage of fewer seedlings in the tilled treatments was offset by the spread of seedling establishment over a number of pasture years. This spread, which would be more marked with harder-seeded cultivars, could be desirable in environments in which clover seed production is unreliable.
25
Weisberg, Peter J., e William L. Baker. "Spatial variation in tree regeneration in the forest-tundra ecotone, Rocky Mountain National Park, Colorado". Canadian Journal of Forest Research 25, n. 8 (1 agosto 1995): 1326–39. http://dx.doi.org/10.1139/x95-145.
Testo completoAbstract (sommario):
Ecotone vegetation may be especially sensitive to climate change. In particular, the invasion of subalpine meadows by tree seedlings has been well documented. However, there has been no systematic analysis of tree regeneration across the environmental heterogeneity of the alpine forest–tundra ecotone (FTE). Also, the position of the FTE may be relictual from more favorable climates of the past and therefore unresponsive to changing climate. To assess the environmental controls on FTE tree regeneration, to determine whether the ecotone might be relictual, and to determine whether tree invasion of nonforested FTE areas is occurring, we measured tree regeneration in various environments within the FTE of Rocky Mountain National Park, Colorado. Generally, seedling establishment appears to be controlled by patterns of soil moisture. Little seedling establishment was observed in krummholz openings, except for high seedling densities in willow wetlands. Tree seedling invasion of tundra is rare. Therefore, the upper limits of the FTE in Rocky Mountain National Park may be relictual from more favorable climates of the past. Abundant seedling establishment in patch forest openings suggests that patch forest may be poised to change to closed forest.
26
Schroder, Thomas, Anna Paula Lora Zimmermann, Lílian Daniel Pereira, Noé dos Santos Ananias Hofiço, Dilson Sousa Rocha Júnior, Frederico Dimas Fleig e Evandro Alcir Meyer. "USING BARE-ROOT AND ROOTSTOCK SEEDLINGS FROM NATURAL REGENERATION OF CEDRELA FISSILIS". CERNE 22, n. 3 (settembre 2016): 309–16. http://dx.doi.org/10.1590/01047760201622032203.
Testo completoAbstract (sommario):
ABSTRACT The success of forest creation relies on seedling availability and quality. The aim of this research is to assess the possible use of rootstock and bare-root seedlings of Cedrela fissilis obtained from natural regeneration for direct field planting. We used Generalized Linear models to assess survival and Hierarchical Models to assess height growth over one year after planting. Initial root-collar diameter (RCD) and treatment (rootstock or bare-root) affected survival and growth. Rootstock and larger seedlings presented higher levels of survival and growth. Higher seedling quality in the rootstock treatment is due to higher water stress tolerance. Rootstock seedlings with more than 1 cm of initial RCD had over 80% of survival probability, while small bare-root seedlings had mean survival probability as low as 20%. Rootstock seedlings grew as much as fourfold more than bare-root. Using natural regeneration of C. fissilis as a source of rootstock seedlings may be a cheap alternative for forest restoration and enrichment planting projects.
27
Fukasawa, Yu, Yoko Ando, Satoshi N. Suzuki, Mineaki Aizawa e Daisuke Sakuma. "Climate influences the effect of fungal decay type on regeneration of Picea jezoensis var. hondoensis seedlings on decaying logs". Canadian Journal of Forest Research 50, n. 1 (gennaio 2020): 73–79. http://dx.doi.org/10.1139/cjfr-2019-0147.
Testo completoAbstract (sommario):
Hondo spruce (Picea jezoensis var. hondoensis (Mayr) Rehder)) is separately distributed among several mountainous regions in central Japan as remnant populations of the last glacial period. To identify factors that affect Hondo spruce seedling regeneration on decaying logs, we investigated the relationships between climatic conditions, log properties, including decay type by fungi, and Hondo spruce seedling density on logs using data from seven subalpine Hondo spruce forests in central Japan. The results showed that the presence of soft rot was associated with higher seedling density, and the effect of brown rot in sapwood and white rot in heartwood on the predicted number of spruce seedlings on logs switched from positive to negative with increasing temperature and precipitation. Because soft rot occurs under humid conditions, the use of forest management techniques that increase the number of logs with soft rot in sapwood (e.g., by keeping the forest floor moist) are recommended for the sustainable regeneration of Hondo spruce. However, the relationships between wood decay type and seedling regeneration can also be affected by climate condition and thus are more complex than previously thought.
28
Kreider, Mark R., Karen E. Mock e Larissa L. Yocom. "Methods for Distinguishing Aspen Seedlings from Suckers in the Field". Journal of Forestry 118, n. 6 (6 luglio 2020): 561–68. http://dx.doi.org/10.1093/jofore/fvaa030.
Testo completoAbstract (sommario):
Abstract Quaking aspen is a common component of postdisturbance landscapes, in part because of its ability to regenerate via asexual suckers. Previously viewed as exceedingly rare in the western United States, sexual seedling establishment is increasingly seen as another important natural regeneration pathway for aspen, because sexual regeneration increases genetic diversity and facilitates long-distance dispersal. However, aspen seedling research is hampered by difficulties in visually distinguishing seedlings from suckers in the field, and few resources exist to guide managers and researchers. We present methods for distinguishing aspen seedlings from aspen suckers, suitable for use in field studies. Using these methods, we achieved 99 percent predictive accuracy in a recently burned area in southern Utah, although accuracy decreased to 90 percent following one summer’s growth, as seedlings and suckers became more similar in appearance. Study Implication: Sexual regeneration may play an important role in aspen’s response to climate change, as it increases genetic diversity and adaptive capacity, and allows aspen populations and their ecological associates to better track changing climate through increased dispersal distances. The methods we present allow managers and researchers to accurately identify aspen seedling populations, which can then be protected and monitored through time to better understand aspen demography and the factors limiting establishment and survival of new clones. Aspen seedling ecology is an area with many knowledge gaps currently, and these methods remove a barrier that has hindered research in the past.
29
Fromm, Michael, Matthias Schubert, Guillermo Castilla, Julia Linke e Greg McDermid. "Automated Detection of Conifer Seedlings in Drone Imagery Using Convolutional Neural Networks". Remote Sensing 11, n. 21 (4 novembre 2019): 2585. http://dx.doi.org/10.3390/rs11212585.
Testo completoAbstract (sommario):
Monitoring tree regeneration in forest areas disturbed by resource extraction is a requirement for sustainably managing the boreal forest of Alberta, Canada. Small remotely piloted aircraft systems (sRPAS, a.k.a. drones) have the potential to decrease the cost of field surveys drastically, but produce large quantities of data that will require specialized processing techniques. In this study, we explored the possibility of using convolutional neural networks (CNNs) on this data for automatically detecting conifer seedlings along recovering seismic lines: a common legacy footprint from oil and gas exploration. We assessed three different CNN architectures, of which faster region-CNN (R-CNN) performed best (mean average precision 81%). Furthermore, we evaluated the effects of training-set size, season, seedling size, and spatial resolution on the detection performance. Our results indicate that drone imagery analyzed by artificial intelligence can be used to detect conifer seedling in regenerating sites with high accuracy, which increases with the size in pixels of the seedlings. By using a pre-trained network, the size of the training dataset can be reduced to a couple hundred seedlings without any significant loss of accuracy. Furthermore, we show that combining data from different seasons yields the best results. The proposed method is a first step towards automated monitoring of forest restoration/regeneration.
30
Castro, Jorge, e Alexandro Leverkus. "Effect of Herbaceous Layer Interference on the Post-Fire Regeneration of a Serotinous Pine (Pinus pinaster Aiton) across Two Seedling Ages". Forests 10, n. 1 (20 gennaio 2019): 74. http://dx.doi.org/10.3390/f10010074.
Testo completoAbstract (sommario):
Herbaceous vegetation is a major source of interference with the regeneration of woody species. This is particularly the case after forest fires, as a dense herbaceous layer usually regenerates naturally. Although the competitive effect of the herbaceous vegetation upon tree seedlings has been widely studied, there are still gaps in knowledge for management related to the effect of tree seedling age and size on the outcome of the interaction. In this study, we seek to determine the response of maritime pine (Pinus pinaster Aiton) seedlings to herbaceous competition at two different seedling ages. For that, two treatments of herbaceous competition were implemented, namely unweeded (no action around pine seedlings) and weeded (herbaceous cover removed around pine seedlings). Treatments were conducted twice (2 and 4 years after the fire), and we monitored seedling survival and growth at the end of each growing season. The treatments were implemented across three adjacent landscape units that differed in the management of burned wood and that are representative of common post-fire scenarios: no intervention, salvage logging, and an intermediate degree of intervention. Weeding increased seedling survival from 44.7% to 67.8% when seedlings were 2 years old, but had no effect for four-year-old seedlings, which showed 99% survival. Seedling growth also increased in the weeding treatment, but only slightly. Moreover, growth (and survival for two-year-old seedlings) was strongly correlated with initial seedling size, particularly in the case of two-year-old seedlings. Initial pine seedling height was strongly and positively correlated with the height of the herbaceous layer, supporting the existence of microsite features that promote plant growth above competitive effects. The results support that management actions conducive to foster post-fire pine forest restoration in this Mediterranean ecosystem should reduce herbaceous competition at early stages after fire (second or third year) and focus on larger seedlings.
31
Mendel, Z., F. Assael, N. Saphir, A. Zehavi, D. Nestel e G. Schiller. "Seedling Mortality in Regeneration of Aleppo Pine Following Fire and Attack by the Scale Insect Matsucoccus josephi". International Journal of Wildland Fire 7, n. 4 (1997): 327. http://dx.doi.org/10.1071/wf9970327.
Testo completoAbstract (sommario):
Mortality of Pinus halepensis seedlings was investigated in Israel during the first years of natural regeneration after fire, with special emphasis on the role of Matsucoccus josephi, drought and competition. The investigations were conducted in the native natural forest on Mt. Carmel, and in a plantation severely damaged by the scale insect at Horeshim in Samaria. M josephi was the dominant mortality agent during the first five years after regeneration, killing almost 73 % and 54% of the seedlings at Mt. Carmel and Horeshim, respectively. Neither injury nor mortality due to the scale insect was recorded during the first year after regeneration, but subsequently mortality occurred during the third and the fourth years. About 23% of the seedlings died due to drought, interspecific and intraspecific competition. Mortality due to other biotic agents, i.e., Hylastes linearis and Pityophthorus pubescens was practically nil. It is shown that resistance of regenerating population of native P. halepensis on Mt. Carmel to the scale did not differ significantly from that of regeneration of a planted Aleppo pine forest of unknown seed sources at Horeshim, despite differences in the level of injury to the adult trees on each site. Five years after natural seeding seedling density in scale-infested plots is high enough to ensure stand development. This second growth possibly displays lower susceptibility to M. josephi than the present adult population.
32
Kreyling, Juergen, Andreas Schmiedinger, Ellen Macdonald e Carl Beiekuhnlein. "Potentials of Natural Tree Regeneration after Clearcutting in Subalpine Forests". Western Journal of Applied Forestry 23, n. 1 (1 gennaio 2008): 46–52. http://dx.doi.org/10.1093/wjaf/23.1.46.
Testo completoAbstract (sommario):
Abstract Regeneration of interior mountain forests still is not adequately understood, although these forests are subject to intensified use over the last decades. We examined factors influencing the success of natural tree regeneration after harvesting in the Engelmann spruce–subalpine fir zone of the Monashee Mountains, British Columbia, Canada. Distance from the forest edge was an important factor for regeneration; at distances exceeding 70 m from the forest edge only 50% of plots showed sufficient natural regeneration to meet stocking targets compared with 90% of plots closer to forest edges. Seedling density and growth were superior in the more protected southern portions of clearcuts. Seedling growth was less in plots containing high cover of downed woody debris. There was no relationship between understory plant diversity or composition and tree seedling regeneration. However, cover of fireweed (Epilobium angustifolium) had a significant negative relationship with density but not growth of tree seedlings, particularly for lodgepole pine (Pinus contorta var. latifolia). Cover of fireweed decline substantially within the first 10 years after clearcutting. We conclude that natural regeneration of trees has potential to help achieve stocking targets and also to maintain natural diversity of tree species if spatial constraints, especially thresholds in clearcut size, are considered.
33
Densmore, Roseann V., e James C. Page. "Paper Birch Regeneration on Scarified Logged Areas in Southcentral Alaska". Northern Journal of Applied Forestry 9, n. 2 (1 giugno 1992): 63–66. http://dx.doi.org/10.1093/njaf/9.2.63.
Testo completoAbstract (sommario):
Abstract Density and growth of naturally regenerated paper birch seedlings were examined in relation to substrate and vegetative competition on two scarified logged sites on the Matanuska Valley Moose Range in southcentral Alaska. Seedling density was inversely related to extent of thick O horizon, grass cover, herb cover, distance to the nearest seed tree, and the extent of B horizon substrate, and positively related to seedling density and the extent of A horizon and moss cover. Paper birch seedlings did not establish on organic layers more than 2 cm thick. Paper birch seedlings grew much more rapidly on the edges of scarified areas or on A horizon substrate than on B horizon substrate. The principal recommendation is that scarification should remove the organic layer and expose the A horizon, but should not be so deep as to expose the B horizon. North. J. Appl. For. 9(2):63-66.
34
Dinis, Cati, Peter Surovy, Nuno A. Ribeiro, Rui Machado e Maria R. G. Oliveira. "Cork Oak Seedling Growth under Different Soil Conditions from Fertilisation, Mycorrhizal Fungi and Amino Acid Application". Journal of Agricultural Science 8, n. 1 (7 dicembre 2015): 55. http://dx.doi.org/10.5539/jas.v8n1p55.
Testo completoAbstract (sommario):
<p class="TESE">Regeneration process deals with some constrains related with the livestock management, pasture rotations, and dependence of a sequence of favourable climatic years, among others, which can lead to a continuous delay in the initiation of the regeneration process. The purpose of this study is to promote an increase of cork oak seedling growth in order to decrease the time required for regeneration and also to contribute to avoid the effect of post-transplant stress on cork oak. With this objective, a study was carried out on a greenhouse, where the effect of fertilisation, mycorrhizal fungi inoculation, and amino acid supply were tested. Results showed that cork oak seedling capability to growth, expressed as total seedling dry weight, was positively affected by treatments, except when only fertilisation was applied. We verified that cork oak seedlings inoculated with mycorrhizal fungi presented better results in terms of aerial structures growth. Any of the treatments was suitable to contribute positively for tap root and total belowground dry weight accumulation. Only fine roots structures were sensitive to treatments effects; it was verified that both inoculated and non-inoculated seedlings subjected to fertilisation were capable to invest largely on the production of these structures (33 and 30%, respectively). To reinforce the cork oak seedling growth, the equilibrium between fertilisers and mycorrhizal fungi inoculation would probably be the better option to enhance the cork oak regeneration process. Thus, the balance between shoot and root systems growth would be guaranteed, fertilisation mainly for root system and mycorrhizal fungi inoculation for shoot growth.</p>
35
Margolis, Hank A., e David G. Brand. "An ecophysiological basis for understanding plantation establishment". Canadian Journal of Forest Research 20, n. 4 (1 aprile 1990): 375–90. http://dx.doi.org/10.1139/x90-056.
Testo completoAbstract (sommario):
Forest plantations in the early stages of establishment are considered as hierarchical biological systems, and some implications for the design of research projects and the education of regeneration foresters and scientists are discussed. Since less than optimum environmental conditions convey stress to seedlings, seedlings will in turn exhibit a strain response at either the biochemical, physiological, or morphological level. Environmental conditions in a clear-cut are contrasted with other regeneration niches, and implications for the performance of different plantation species are discussed. The important physiological and biochemical limitations on the absorption of water, nitrogen, and carbon by seedlings during their establishment phase are described. Methods of quantifying stress at the plantation site, including simple ways to separate seedling growth into its different physiological components, are shown. An example of an eastern white pine (Pinusstrobus L.) plantation grown under different levels of soil temperature, fertilization, and brush control is presented to illustrate the concepts. An approach to silvicultural research is proposed that determines the effects of silvicultural treatment on the seedling environment and then relates these environmental conditions to seedling biochemistry, physiology, and growth.
36
Mao, Peili, Hongxiang Mu, Banghua Cao, Yuhong Liu, Zhaofei Fan e Shumei Wang. "Effects of sand burial and overstory tree age on seedling establishment in coastal Pinus thunbergii forests in the northern Shandong Peninsula, China". Forestry Chronicle 92, n. 03 (giugno 2016): 357–65. http://dx.doi.org/10.5558/tfc2016-062.
Testo completoAbstract (sommario):
Coastal Pinus thunbergii (Japanese black pine) forests in the northern Shandong Peninsula of China recently experienced widespread natural regeneration failure. This study identifies critical factors that affect natural regeneration of P. thunbergii. Seeds from trees of various ages (13–32 years) were used to investigate the effects of age and burial depth in sand on germination and seedling establishment. Results show that seed density in 2–5 cm soil decreased with increased distance from the shoreline. Sand burial decreased seed germination but did not affect the relative growth rate of seedlings at depths from 0.5 to 3 cm. Germination, leaf mass ratio, and relative growth rates were higher with seedlings originating from older trees, all of which enhanced seedling resistance to sand burial. Tree age and seed burial were found to be determining factors for natural regeneration of the coastal P. thunbergii forest. Silvicultural treatments that promote quality of seed sources and mitigation of sand burial can be used in the future to improve the regeneration of these coastal forests.
37
Buermeyer, Karl R., e Constance A. Harrington. "Fate of Overstory Trees and Patterns of Regeneration 12 Years After Clearcutting with Reserve Trees in Southwest Washington". Western Journal of Applied Forestry 17, n. 2 (1 aprile 2002): 78–85. http://dx.doi.org/10.1093/wjaf/17.2.78.
Testo completoAbstract (sommario):
Abstract Changes in management objectives for some forestlands in the Pacific Northwest have spurred interest in the creation of multistoried stands and the use of natural regeneration systems, but data on such systems are lacking. We assessed the status of the overstory trees and the regeneration 12 yr after a clearcut harvest with reserve trees in an even-aged, 145-yr-old Douglas-fir stand on a moderately productive site (site class 3) in southwest Washington. The 15 ha harvest unit was superimposed over two areas differentially thinned 15 and 34 yr before clearcutting. The clearcut harvest retained 18 trees/ha with a mean diameter of 63 cm. The reserved overstory trees had a 93% survival rate after 12 yr; most dead trees had been windthrown. Diameter growth for the reserved trees averaged 3.3 cm and was greatest during the most recent 3 yr period, which also had the highest growing-season precipitation. In a 1 ha mapped area, there were 5,854 seedlings/ha, and more than 99% of the regeneration was Douglas-fir. Most seedlings were less than 2 m tall. Seedling density was somewhat clumped (value of 2.1 for Pielou's index of nonrandomness), but 79% of randomly located 4.04 m2 (mil-acre) plots and 98% of 5 × 5 m grid cells had at least one conifer seedling. There was no obvious pattern of regeneration based on direction from the reserved trees, but both seedling density and seedling size within the drip lines of reserved tree crowns were less than in the rest of the area. The number of seedlings was similar on the two halves of the plot corresponding to the original thinning blocks, but seedling size and age differed. In the half of the study plot that had been twice lightly thinned, only 14% of the seedlings were >0.5 m tall; however, 41% of the seedlings were >0.5 m in the block that had been thinned more heavily. There was no difference between the thinning blocks in the ages of seedlings ≤0.5 m tall (mean age of 5 yr). This example of clearcutting with reserve trees resulted in reasonable survival of the overstory trees and adequate stocking but slow growth rates in the naturally regenerated Douglas-fir. Heavier thinning before harvest was associated with more advance regeneration, more shrub cover, and less windthrow of the reserved trees than in the more lightly thinned block. If an abundance of tree species other than Douglas-fir was desired on this site, interplanting would be required. West. J. Appl. For.17(2):78–85.
38
Collins, Byron J., Charles C. Rhoades, Jeffery Underhill e Robert M. Hubbard. "Post-harvest seedling recruitment following mountain pine beetle infestation of Colorado lodgepole pine stands: a comparison using historic survey records". Canadian Journal of Forest Research 40, n. 12 (dicembre 2010): 2452–56. http://dx.doi.org/10.1139/x10-172.
Testo completoAbstract (sommario):
The extent and severity of overstory lodgepole pine ( Pinus contorta var. latifolia Engelm. ex Wats.) mortality from mountain pine beetle ( Dendroctonus ponderosae Hopkins) has created management concerns associated with forest regeneration, wildfire risk, human safety, and scenic, wildlife, and watershed resources in western North America. Owing to the unprecedented nature of the outbreak and associated management in the southern Rocky Mountains, it is unknown if the forests that regenerate after this current period of extensive change will differ from those that regenerated in the past. Here, we compare the density and species composition of post-harvest seedling recruits in pre-outbreak (1980–1996) and outbreak stands (2002–2007). Lodgepole pine accounted for more than 95% of post-harvest seedling recruitment and the density of seedlings colonizing clearcuts was equal during both the pre-outbreak and outbreak periods. Compared with harvested areas, the density of tree regeneration was 75% lower in uncut forests and was more evenly distributed among subalpine fir ( Abies lasiocarpa (Hook.) Nutt.) and lodgepole pine. This comparison provides evidence that the density of seedling recruitment will be at least as high after extensive pine beetle caused mortality as under healthy, pre-outbreak conditions and that the species composition of stands regenerating after this outbreak will differ between treated and untreated areas.
39
Youngblood, Andrew P., e John C. Zasada. "White spruce artificial regeneration options on river floodplains in interior Alaska". Canadian Journal of Forest Research 21, n. 4 (1 aprile 1991): 423–33. http://dx.doi.org/10.1139/x91-057.
Testo completoAbstract (sommario):
Reforestation options for artificial regeneration of white spruce (Piceaglauca (Moench) Voss) were tested on three floodplain sites near Fairbanks, Alaska. Survival of containerized seedlings after outplanting was above 96%, regardless of harvest cutting method or mechanical site preparation, and declined little between the third and fifth growing seasons. Establishment and survival after direct seeding on seed spots was more variable and differed by harvest cutting method, by type of site preparation, and by the use of plastic seed shelters for seedling protection. Maximum terminal leader growth, seedling total height, and basal diameter were found on planted seedlings in clear-cut units on the better site. In clear-cut units prepared by blading on one site, basal diameter of seedlings five seasons after outplanting was almost 50% more than on similar surfaces in shelterwood units. Planted seedlings on unscarified surfaces and in small scalped patches generally had similar basal diameters. Results suggested that similar interior Alaska floodplain forests of white spruce can be successfully regenerated by using the clear-cutting harvest method and planting nursery-reared seedlings without mechanical site preparation.
40
Alverson, William S., Marian V. Lea e Donald M. Waller. "A 20-year experiment on the effects of deer and hare on eastern hemlock regeneration". Canadian Journal of Forest Research 49, n. 11 (novembre 2019): 1329–38. http://dx.doi.org/10.1139/cjfr-2019-0071.
Testo completoAbstract (sommario):
Eastern hemlock (Tsuga canadensis (L.) Carrière) is a shade-tolerant, slow-growing tree once common in forests across the Great Lakes region. It was heavily exploited in the late 19th and early 20th centuries and now experiences limited regeneration across much of its range. This failure to regenerate has been ascribed to poor seedbed conditions, insufficient canopy openings, warmer climate, and browsing by white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) or snowshoe hare (Lepus americanus Erxleben, 1777). To test whether deer or hare limit hemlock regeneration, we studied >2000 hemlock seedlings inside and adjacent to experimental deer exclosures at 59 sites randomly distributed across hemlock and hemlock-component stands in northern Wisconsin and the western Upper Peninsula of Michigan in the United States. We monitored local deer and hare abundance, seedling growth, and seedling survival for 20 years. Two First Nations reservations showed lower deer density and greater survival and growth of unprotected seedlings than three national forests of the United States. Cohorts of hemlock seedlings protected from deer survived at a rate four times higher than those exposed to deer (59.3% vs. 15.0%) and shared a combined height 5.2 times greater. Hare densities significantly affected seedling survival only within exclosures. This extensive, long-term study identifies deer as the primary factor constraining hemlock regeneration in the region.
41
Burney, Owen, Michael G. Wing e Robin Rose. "Microsite Influences on Variability in Douglas-Fir Seedling Development". Western Journal of Applied Forestry 22, n. 3 (1 luglio 2007): 156–62. http://dx.doi.org/10.1093/wjaf/22.3.156.
Testo completoAbstract (sommario):
Abstract We examined the microsite characteristics of 6,048 Douglas-fir seedlings at three regeneration sites in Washington state. Our objective was to determine the microsite characteristics that were most influential on seedling growth change over time. We analyzed microsite influences both individually and in concert with one another through regression-based techniques. Microsite parameters included soil impedance, topographic, and physical parameter measurements that were recorded at each seedling's location. Akaike's information criterion (AIC) was used to determine combinations of microsite parameters that were most strongly correlated with seedling growth. Multiparameter models explained between 15 and 39 percent of the variance in diameter growth. Prevalent terms from the strongest multiparameter models included soil penetration, log presence, stump presence, skid road presence, and topography. Individual microsite parameters for each regeneration site were also assessed for importance in explaining diameter growth using two additional methods. The first approach was to isolate the parameters that appeared in the strongest multiparameter models and to sum and contrast the AIC weights of all models in which they appeared. The second approach was to regress single parameters against seedling diameter growth. Results varied by site for both methods. AIC weight sums revealed that topographical depression and berms, the presences of logs and stumps, and soil penetration (pounds per square inch) as measured by a penetrometer were most influential, with values ranging from 0.31 (berm) to 0.82 (log). Regression analysis revealed that topographical depression, log presence, and soil penetration were significantly related to diameter growth, explaining between 6 and 29 percent of the variance in diameter growth. Combined results from the three regeneration sites suggest that preferred planting locations are near berms, in the transition zone associated with skid roads, and in soil that is neither too loose nor too compacted. Results from the Randle and Orting sites indicate that planting in topographical depressions should be avoided. Results from Orting indicate that seedlings should not be placed near logs, and Randle findings suggest not planting next to stumps.
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Barna, M. "The effects of cutting regimes on natural regeneration in submountain beech forests: species diversity and abundance". Journal of Forest Science 54, No. 12 (15 dicembre 2008): 533–44. http://dx.doi.org/10.17221/42/2008-jfs.
Testo completoAbstract (sommario):
The paper summarizes the results of 15-year natural regeneration for beech of five plots with different densities situated in the Western Carpathians Mts. Three of the plots were subjected to differently intensive shelterwood cuttings (plots L, M, H), one plot was clear-cut (CC), and one was left without intervention – as a control (C). The number of one-year-old seedlings decreased proportionally with increasing cutting intensity. The ANOVA results document a significant influence of cutting intensity on the abundance of both one-year-old and older seedlings. The abundance of beech seedlings was initially increasing with increasing cutting intensity, and, having reached the peak on plot M (medium intensity), there followed a decrease in the seedling abundance. Lower numbers of beech seedlings on plots subjected to less intensive cutting (C, L) result from less favourable growth conditions in comparison with plot M. On the other hand, cutting of higher intensity (H, CC) resulted in lower numbers of fructifying parent trees. The medium cut intervention having provided the plot M with stocking of 0.5 (50% of the stand) resulted in a lower number of seed resources (limiting factor for natural regeneration). However, for the other factor – seedling establishment (survival and recruitment) this plot (M) represents an ecological optimum in beech regeneration in the given conditions.
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Vickers, Lance A., William H. McWilliams, Benjamin O. Knapp, Anthony W. D’Amato, Daniel C. Dey, Yvette L. Dickinson, John M. Kabrick et al. "Are Current Seedling Demographics Poised to Regenerate Northern US Forests?" Journal of Forestry 117, n. 6 (28 agosto 2019): 592–612. http://dx.doi.org/10.1093/jofore/fvz046.
Testo completoAbstract (sommario):
Abstract Securing desirable regeneration is essential to sustainable forest management, yet failures are common. Detailed seedling measurements from a forest inventory across 24 northern US states were examined for plausible regeneration outcomes following overstory removal. The examination included two fundamental regeneration objectives: 1) stand replacement- securing future forest and 2) species maintenance- securing upper canopy species. Almost half the plots lacked adequate seedlings to regenerate a stand after canopy removal and over half risked compositional shifts. Based on those advance reproduction demographics, regeneration difficulties could occur on two-thirds of the plots examined. The remaining one-third were regeneration-ready. However, compared to historical norms, increased small-tree mortality rates reduces that proportion. Not all forest types rely on advance reproduction and results varied among the forest types examined. Some variability was associated with browsing intensity, as areas of high deer browsing had a lower proportion of regeneration-ready plots.
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Côté, Mathieu, Jean Ferron e Réjean Gagnon. "Impact of seed and seedling predation by small rodents on early regeneration establishment of black spruce". Canadian Journal of Forest Research 33, n. 12 (1 dicembre 2003): 2362–71. http://dx.doi.org/10.1139/x03-167.
Testo completoAbstract (sommario):
Black spruce (Picea mariana (Mill.) BSP) postdispersal seed and juvenile seedling predation by small rodents (Peromyscus maniculatus (Wagner), Clethrionomys gapperi (Vigor), and Phenacomys intermedius (Merriam)) was assessed in three boreal habitats over a 2-year period using an extensive exclosurecontrol experiment. Small rodent relative abundance was measured during six periods using snap trapping. We found that seed and juvenile seedling predation by small rodents varied according to habitat type and over time. Indeed, seed predation was higher in sprucemoss forests than in other habitats, notably during the winter of 2002. During this period, seedling predation was higher in recent burns. This period of higher seed and juvenile seedling predation corresponded to an increase in small rodent abundance in our study area. We suggest that seeds and juvenile seedlings can become important food sources for small rodents during winter when fresh and succulent vegetation is rare, as shown by results of seed predation. The impact of small rodents on the early regeneration of black spruce in the eastern Canadian boreal forest is thus an important factor to consider to better understand the forest regeneration process in this particular biome. Rodents can have a major effect on regeneration following a burn and can also contribute to poor seedling establishment from natural seed rain under mature cover.
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Hart, V., M. Nentvichová-Hartová e P. Tauchman. "Analysis of herbicide effects on Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) natural regeneration". Journal of Forest Science 56, No. 5 (28 maggio 2010): 209–17. http://dx.doi.org/10.17221/77/2009-jfs.
Testo completoAbstract (sommario):
Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) natural regeneration under parent stand after weed suppression was investigated in the area of the Training Forest Enterprise in Kostelec nad Černými lesy. The study evaluates two measurements made in a two-year interval. The parent stand, where Douglas fir grows in mixture with our domestic tree species, is one of the oldest and most productive stands at the Training Forest Enterprise in Kostelec nad Černými lesy. Herbicides for the control of weeds were applied onto three permanent experimental plots under the parent stand. Measurements done on the plots show a high potential of natural regeneration in areas where the negative impact of forest weeds was suppressed. This conclusion is acknowledged by the high seedling number found on research plots treated with herbicides. The number of Douglas fir seedlings varied from 21,600 per hectare counted on the plot treated with Dominator to 26,650 seedlings on the plot with Velpar treatment even six years after the soil preparation. Statistical analysis confirmed that the seedling number on the plot without any chemical preparation was significantly lower, only 950 individuals per hectare (χ<sup>2</sup> = 926.84, df = 3, P << 0.01).
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., Istomo, e Mia Afriyani. "PENDUGAAN POTENSI PEREKRUTAN PERMUDAAN ALAM OLEH POHON INDUK DI HUTAN MANGROVE IUPHHK-HA PT. BUMWI, TELUK BINTUNI, PAPUA BARAT Potential Estimation of Seedling Recruitment by Seed Trees in Mangrove Forest IUPHHKHA PT. BUMWI Bintuni Bay, West Papua". Journal of Tropical Silviculture 9, n. 1 (4 maggio 2018): 69–77. http://dx.doi.org/10.29244/j-siltrop.9.1.69-77.
Testo completoAbstract (sommario):
Since 1978 one of the legal silviculture systems in Indonesian regard to managing mangrove forest is seed tree method. The ability of this silviculture system to recruit the seeds to fulfill the regeneration is one of the importantaspects. The research is conducted to get the information about regeneration condition and the ability of seed tree method to recruit the regeneration in any various plot with different agecutting. Vegetation analysis for naturalregeneration (seedlings and saplings) were conducted at four different age logged-over area with the total 640 plots. The plot size is 78.5 m2. The result showed that existence of seed tree can affect the type of regeneration for seedlings recruitment with percentage between 59.52% to 83.37%.Key words: mangrove, natural regeneration, seed tree, seedling recruitment
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Riikonen, Johanna, e Jaana Luoranen. "Seedling Production and the Field Performance of Seedlings". Forests 9, n. 12 (27 novembre 2018): 740. http://dx.doi.org/10.3390/f9120740.
Testo completoAbstract (sommario):
The rapid establishment of seedlings in forest regeneration or afforestation sites after planting is a prerequisite for successful reforestation. The relationship between the quality of the seedling material and their growth and survival after outplanting has been recognized for decades. Despite the existence of a substantial amount of information on how to produce high-quality seedlings, there is still a need to develop practices that can be used in nurseries and at planting sites to be able to produce well-growing forest stands in ever-changing environments. This Special Issue of Forests is focused on seedling quality and how it can be manipulated in a nursery as well as how the quality of the seedlings affects their field performance after planting.
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Lodge, GM. "The effects of native grass cover, species, herbicide and sowing method on legume establishment on the northern slopes of New South Wales". Australian Journal of Experimental Agriculture 31, n. 4 (1991): 485. http://dx.doi.org/10.1071/ea9910485.
Testo completoAbstract (sommario):
The effects of sowing method (direct drilling or broadcasting), level of cover of native grass and pre-sowing herbicide application on pasture legume introduction were evaluated from 1984 to 1987 at a low elevation (425 m) site on the Northern Slopes of New South Wales. Two perennial (Medicago sativa cv. CUF101 and Onobrychis viciijolia cv. Eski) and 3 annual legumes (Trifolium subterraneum ssp. brachycalycinum cv. Clare; M. truncatula cv. Sephi; Vicia villosa ssp. dasycarpa cv. Namoi) were sown each year from 1984 to 1986. Seedling establishment was measured 3-4 months after sowing, and where possible, the dry matter yields of the sown legume were also estimated. Seedling regeneration was measured in 1987 and the yield of legumes sown in 1985 was determined in 1986. All species failed to establish under the dry conditions experienced in 1984. In subsequent years seedling numbers of the annuals were higher than those of the perennials. Direct drilling increased establishment of all species compared with broadcasting. The provision of a large amount of cover by the resident native grasses (4.6-7 t/ha of dry matter, 0.6-0.7 In in height) also substantially increased seedling establishment in cvv. Clare, Sephi and CUFlO1. None of the treatments used were successful in establishing cv. Eski. Herbicide application prior to sowing did not significantly affect seedling numbers in the establishment year but resulted in higher numbers of seedlings regenerating in subsequent years, particularly in cv. Sephi. Seedling regeneration of the annuals was also increased (P<0.05) by direct drilling into moderate or high levels of vegetative cover. Dry matter yields of all sown species except cv. Namoi were low, and the environment was difficult for legume survival and production. This was attributed mainly to the variable rainfall that occurs at this low elevation, while for lucerne high summer temperatures probably affected its performance.
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Kupka, I. "Natural regeneration at different microclimatic sites in Zatec region". Journal of Forest Science 48, No. 10 (22 maggio 2019): 441–50. http://dx.doi.org/10.17221/11913-jfs.
Testo completoAbstract (sommario):
Natural regeneration is an important part of close-to-nature forestry. However, natural regeneration also has either natural or technological limits. Among the most important natural limits are a low sum of precipitation and site type. The study concentrates on Žatec region where the long term average sum of precipitation is only 440–450 mm per year. Dry periods during the vegetation time are quite frequent. The study was conducted on clear cut area, stand edge, shelterwood area and stand interior. The results showed the highest population densities in a shelterwood system, the lowest in the stand interior. On the other hand, the dry seedling biomass is lower for seedlings from shelterwood area than from clear cut area.
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McWilliams, William H., Susan L. Stout, Todd W. Bowersox e Larry H. McCormick. "Adequacy of Advance Tree-Seedling Regeneration in Pennsylvania's Forests". Northern Journal of Applied Forestry 12, n. 4 (1 dicembre 1995): 187–91. http://dx.doi.org/10.1093/njaf/12.4.187.
Testo completoAbstract (sommario):
Abstract Measurement of tree seedlings and herbaceous vegetation from 499 sample locations across Pennsylvania revealed that advance tree-seedling regeneration is inadequate for new stand establishment across most of the State. The samples were located in stands from 40% to 75% stocked to focus on stands with ample light and growing space for establishment of abundant advance regeneration. A range of regeneration adequacy criteria was applied to the measurements. Using the least stringent criterion, a low density of stems of any tree species, resulted in 40% of the sample locations being adequately stocked. Applying the most stringent criterion, a high density of stems of desirable species, resulted in only 4% of the sample locations being adequately stocked. With the exception of forest-type group, no significant relationship was found between the adequacy of regeneration and other variables tested at the broad level of geographic scale of this study. Levels of fern and grass sufficient to hamper tree-seedling development were found at 54% of the sample locations. Fern species that propagate primarily by spreading rhizomes accounted for 70% of the total fern sample. North. J. Appl. For. 12(4):187-191.