共查询到20条相似文献,搜索用时 31 毫秒
1.
Jorge De Las Heras Daniel Moya Francisco López-Serrano Sonia Condés 《Annals of Forest Science》2007,64(1):59-66
In Spain, wildfires have increased during the last decades with Pinus halepensis forests being the most affected. Cone differentiation and the early flowering of this species in comparison to other native Spanish species, are traits considered as adaptations to postfire regeneration. The high recurrence of fires promotes a high increase in young and immature pine stands with low capability of regeneration. In this study, silvicultural treatments such as thinning and pruning were carried out 5 years after fire in eleven years old P. halepensis stands located in dry and semi-arid sites in SE Spain. The formation of male and female strobili, production of serotinous grey, mature brown and new green cones were recorded six years after treatments. Seed production and germination percentage were also tested. Results showed acceleration in cone and viable seed production in thinned plots, with some differences between sites being recorded. Serotinous cone production also increased as a result of this treatment. 相似文献
2.
Rüdiger Otto Eduardo García-del-Rey Pascual Gil Muñoz José María Fernández-Palacios 《European Journal of Forest Research》2010,129(4):499-508
The Canarian pine (Pinus canariensis) exhibits a striking combination of high adult resistance to fire and intermediate serotiny. Hence, the study of its post-fire
regeneration can support valuable new insights about functional adaptations to fire. Here, we analyse the first-year seedling
establishment after fire in a P. canariensis forest on the northern slope of Tenerife, Canary Islands. The effects of fire severity and other explanatory variables on
the seedling density recorded 9 months after fire were examined. We detected a clear unimodal relationship between seedling
density and fire severity, with maximum regeneration associated with intermediate fire severity and no regeneration associated
with very high crown damage. The results suggested that high severity fires may have caused the partial destruction of the
aerial seed bank and/or the creation of unfavourable seedbed conditions for germination and seedling emergence. The density
of large pine trees, reflecting seed availability, was the second most important factor explaining the distribution of seedlings.
Cover of scorched needle litter on the ground correlated strongly and positively with pine seedling density and negatively
with fire severity. The complete lack of regeneration at sites most strongly affected by fire does not represent a major threat
for the stand recovery of the Canarian pine, due to the very high tree resistance to fire and the tremendous capacity of the
Canarian pine to resprout after fire. The observed very high seedling densities at sites with intermediate fire impacts can
probably be related to both the complete liberation of the seed bank (including seeds stored in serotinous cones) and favourable
micro-environmental conditions for seed germination and seedling establishment. 相似文献
3.
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. 相似文献
4.
Morphological and anatomical differences in Aleppo pine seeds from serotinous and non-serotinous cones 总被引:1,自引:1,他引:0
R. Salvatore D. Moya L. Pulido R. Lovreglio F. R. López-Serrano J. De las Heras V. Leone 《New Forests》2010,39(3):329-341
Mediterranean communities have been historically conditioned by fire and have therefore developed adaptive traits. Serotiny
is a strategy that increases fire resilience by storing seeds in the canopy, protecting them from heat and delaying their
dispersion. Aleppo pine is an important serotinous tree species in the low altitude, near-coastal Mediterranean Basin. Differences
in serotinous and non-serotinous cones have been detected previously but in order to resolve a gap in the knowledge on seed
adaptation to fire, we focused this study on two fire-prone habitats in southern Italy. Several cones were sampled and opened
in an oven at two different temperatures in order to group seeds according to provenance and cone type (serotinous or non-serotinous).
The sampled seeds were weighed and their coats were removed. Seed size, embryo diameter and nutritive tissue thickness were
recorded. We found that seeds with greater weight and size came from the more humid site and from non-serotinous cones. Also,
we observed wax and cutine cells formed a thicker seed coat in seeds from the more humid site using a scanning electron microscope.
The scanning electron microscopy/energy dispersive X-ray spectroscopy showed higher Si and Ca concentrations in the covers
of serotinous seeds. Seeds from different provenance and cone types have anatomic and morphological differences that confer
different properties against heating. This knowledge can improve post-fire management and promote restoration tools. 相似文献
5.
Evangelia N. Daskalakou Kosmas Albanis Asimina Skouteri Costas A. Thanos 《New Forests》2014,45(1):53-70
A regeneration predictor (RP) has been elaborated to forecast the minimal inter-fire period, required for full recovery (assumed at 1,000 mature stems ha?1, a typical value for a dense pine forest) of an even-aged, postfire regenerating Pinus halepensis population after a subsequent wildfire, in the future. The study has been conducted in three Aleppo pine forests of northern Euboea Island, Greece. Postfire field surveys of sapling growth, sapling density and reproductive dynamics (cone-bearing population fraction, annual cone and seed production per sapling, canopy seed bank build-up) were carried out for three, consecutive growing seasons (years). Additional postfire parameters, with values estimated from literature data, have been also included in order to devise the RP. In the cases of the three populations studied, the application of this RP provides time-windows for full recovery after a recurrent fire, as short as 10–15, 8–11 and 7–11 years, respectively (values corresponding to best and worst scenarios). It is suggested that in even-aged, postfire regenerating Aleppo pine populations, the minimal inter-fire period required for full recovery can be predicted by monitoring a few selected variables, namely (a) sapling density, (b) vegetative to reproductive shift dynamics, and (c) cones/sapling and germinable seeds/cone, for at least 2 years (either consecutive or 2–3 years apart) at a postfire age of 7–12 years. 相似文献
6.
Daniel Moya Jorge De las Heras Rossella Salvatore Edelmira Valero Vittorio Leone 《Annals of Forest Science》2013,70(1):49-59
? Context
The Mediterranean Basin is a fire-prone area. Pinus halepensis Mill. is a naturally growing conifer which is frequently used for reforestation and restoration as it displays some degree of adaption to fire. One of the traits conferring tolerance to fire is the frequent presence of serotinous cones that are thought to protect seeds from fire damage.? Aim
We checked for the physiological responses of seeds to different intensities of fire and related them to the degree of serotiny of the cones.? Methods
Germination percentage, mean germination rate and enzymatic activity (??-amylase and protease) were recorded for seeds burned either free or enclosed in cones. We included as experimental factors the following: fire intensity, serotiny and time during which seeds were stored in cones after harvesting and germination stage.? Results
Burned seeds (released and enclosed) developed in serotinous cones exhibited higher heat insulation. In released seeds, germination was decreasing according to increasing fire intensity, although we found differences depending on site, serotiny and time stored after harvesting. The enzymatic activity was also found to be related to serotiny and fire intensity.? Conclusion
Serotiny is an adaptive trait increasing the tolerance to fire which should be promoted in natural and restored populations. 相似文献7.
Leonor Calvo Celia García-Domínguez Agustín Naranjo José R. Arévalo 《European Journal of Forest Research》2013,132(5-6):909-917
Knowledge of the germination characteristics of Pinus species can help in the understanding, prediction and management of the regeneration of pine forests. In the Canary Islands, several exotic pines (Pinus halepensis L. and Pinus pinea L.) were planted with Pinus canariensis Chr. Sm. Ex DC, the only native pine species, and there is now an interest in controlling these exotic species to restore the original forest. The main objective of the present study is to determine the germination response of P. canariensis, P. halepensis and P. pinea to different light regimes (darkness and light/darkness), thermal shocks and the presence of inhibitory substances from the leaves and litter of P. canariensis. P. halepensis seeds showed the highest viability and germination rate. Darkness accelerated P. halepensis germination, while exudates accelerated P. canariensis germination. Only treatments of 200 °C for 5 min and 300 °C for 5 min significantly decreased the germination of all three pine species. In the absence of strong differences in germination among species after treatments, the key for fire management or prescribed burning in this case may be the sprouting ability of P. canariensis. A possible management strategy to control the two obligate seeder exotic species could be to use one intense prescribed fire followed by a low-intensity prescribed fire after seed bank germination in the field, so in this way, only P. canariensis could resprout after fire and it would eliminate only the exotic pines in a mixed stand. 相似文献
8.
The aim of the study was to investigate dynamics and pattern of natural regeneration and the influence of seedbed and light
on germination and initial seedling survival of Scots pine (Pinus sylvestris L.) during three growing seasons. Four 5-m2 plots in a natural Scots pine forest in central Spain were randomly established at the beginning of the regeneration process.
Germination and seedling survival were recorded in 100 regeneration sampling subplots (0.25 m2) per plot, while seedbed type and the relative light intensity reaching the forest floor was characterised in 1-m2 subplots. The spatial correlations between survival, light conditions and organic matter depth were analysed through cross-variograms.
Germination and survival were highly variable both within and between plots (ranging from 0 to 89%) and affected by high summer
temperatures (33–35°C) in 2003. The spatial pattern characterisation of survival by Ripley’s K function showed a dominant cluster distribution. Occurrence tended to be clumped when abundance was greater than 15 seedlings,
whereas for lower densities, seedlings were randomly distributed. Seedlings and herbs occupied the same sites where environmental
conditions were appropriate for them to live. Spatial association occurred frequently for light and organic matter depth.
Results suggested that the Scots pine seedlings in our study in central Spain preferred moderate light conditions (Global
Site Factor <0.40). Thus, if this forest is to be naturally regenerated with Scots pine, the shelterwood system (whereby some
mother trees are left to provide shelter for at least 5 years), along with mechanical disturbance of the seedbeds, would promote
seed germination, as long as a seed source is present. However, regeneration success is affected by year-to-year conditions. 相似文献
9.
《Forest Ecology and Management》1998,111(1):23-33
In 1988, fires killed extensive lodgepole pine (Pinus contorta Dougl. ex. Loud) in Yellowstone National Park. This species bears both serotinous and non-serotinous cones, with the former most common in fire-origin stands of an even-aged character. Reconnaissance of burned stands indicated that former even-aged communities regenerated effectively. Others did not. The larger and more uniformly-sized seedling under formerly even-aged communities suggests primarily a single wave of regeneration there. Seedlings appeared to initiate to some degree over multiple years under other stands, but not sufficiently to make them well stocked. Four different regeneration pathways seem to characterize the natural reforestation of lodgepole pine following the 1988 fires. These include: (1) a dense, uniformly distributed cohort that will develop as a single-storied stand; (2) lodgepole pine islands that form over long periods around isolated seedlings; (3) a moderate to low density cohort that will gradually fill with multiple age classes over a protracted period; and (4) a cohort of only widely scattered single seedlings that initially form as small nearby tree islands, and may eventually converge into a more continuous stand with multiple age classes. 相似文献
10.
11.
《Forest Ecology and Management》2001,140(1):29-37
Remnant tree stands left intact following a disturbance constitute the sole seed banks available for regeneration of coniferous species that neither bear serotinous cones nor reproduce vegetatively. The success of regeneration of tree species on these disturbed sites is, therefore, dependent on the distance from potential seed sources. The regeneration of balsam fir (Abies balsamea (L.) Mill.), white spruce (Picea glauca (Moench) Voss) and white cedar (Thuja occidentalis L.) was studied at two sites in Québec’s southwestern boreal forest in order to quantify the influence of remnant stands on spatial distribution of regeneration. The first site is located in an area that burned in 1944 while the second site is located in an area that was clear-cut in the mid-1980s. Canonical correspondence analyses were used to determine the respective contributions of environmental data and spatial variables to the pattern of spatial distribution of regeneration. The results reveal that distance from a remnant stand is the most important variable in explaining spatial distribution of regeneration when compared to environmental variables such as soil type, drainage, slope and altitude. The plots of regeneration density against distance from a remnant stand for both the burned site and logged site show that regeneration density decreases abruptly with distance from a remnant stand. Furthermore, spatial autocorrelation analyses (Moran’s I) indicate that even small remnant zones can significantly influence the pattern of spatial distribution of regeneration for the three species studied. The results presented here suggest that where preestablished regeneration is not abundant enough, alternative silvicultural systems such as strip clear-cutting or seed-tree systems could be used instead of cuts with protection of regeneration and soils (CPRS). 相似文献
12.
《Forest Ecology and Management》1988,25(1):17-29
The effects of reproductive phenology, date of cone harvest, cone storage and seed pretreatment on yield and germination of seeds from a Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seed orchard were studied. Flowering phenology (early, intermediate or late) had no discernible effect on seed maturation. Higher germination and yields of filled seeds were obtained from cones collected in mid-August, approximately 2 weeks prior to cone opening, than from cones collected just as they began to open. Seeds extracted immediately following harvest germinated better than those from cones stored for 2 months. Seeds from all treatments were dormant and responded to prechilling by exhibiting increased germination rates. The implications of these findings for cone-crop management are discussed. 相似文献
13.
Context
Excessive recruitment in post-fire regeneration of Pinus halepensis can require pre-commercial thinning. The 1994 Moratalla fire (Spain) and the thinning applied there since 2004 provided good conditions for testing pre-commercial thinning effectiveness.Aims
To analyse pre-commercial thinning effects on tree size, reproductive potential, stem biomass and annual growth in 15-year-old saplings.Methods
Twenty nine circular plots (5 m radius) were established based on (1) years since thinning and (2) aspect. Non-thinned plots were included as controls. Sapling variables were measured and pine cones were counted and classified according to maturity. Three saplings per plot were felled, five sample disks were extracted from each and tree rings were analysed with Windendro® software.Results
Sapling size, annual growth and stem biomass were higher in thinned plots than in control plots 2–4 years after thinning. Annual growth declined five years after thinning. Cone counts were higher 2–5 years after thinning, depending on the cone type. Aspect influenced some variables.Conclusion
Thinning accelerated stand maturity but positive effects were indiscernible until 2–5 years later. Serotinous cones, which are fundamental to regeneration after fire, increased in number after 5 years. The effects of aspect were inconclusive due to interactions with years since thinning. 相似文献14.
Raquel Alfaro-Sánchez Francisco R. López-Serrano Eva Rubio Daniel Moya Raúl Sánchez-Salguero Jorge De Las Heras 《European Journal of Forest Research》2014,133(5):793-807
Despite the low timber productivity of Mediterranean Pinus halepensis Mill. forests in south-eastern Spain, they are a valuable carbon sequestration source which could be extended if young stands and understories were considered. We monitored changes in biomass storage of young Aleppo pine stands naturally regenerated after wildfires, with a diachronic approach from 5 to 16 years old, including pine and understory strata, at two different quality sites (dry and semiarid climates). At each site, we set 21 permanent plots and carried out different thinning intensities at two ages, 5 and 10 years after fires. We found similar post-fire regeneration capacity at both sites in terms of total above-ground biomass storage ~6 Mg ha?1 (3 Mg ha?1 of the above-ground pine biomass plus 3 Mg ha?1 of the above-ground understory biomass), but with a contrasting pine layer structure. Generally, across the diachronic study, the earlier thinning reduced biomass stocks at both sites, except for the best quality site (the dry site), where the earliest thinning (applied at post-fire year 5) enlarged carbon storage by 11 % as compared to non-thinned plots. We found root:shoot ratios of an average 0.37 for the pine layer and 0.45 for the understory layer. These results provided new information which not only furthers our understanding of carbon sequestration in low timber productivity Mediterranean forests, but will also help to develop new guidelines for sustainable management adapted to the high-risk terrestrial carbon losses of fire-prone areas. 相似文献
15.
16.
The major insects that destroy cones and seeds of eastern white pine, Pinus strobus L., were controlled with soil applications of the systematic insecticide carbofuran in orchards at Murphy and Morganton, NC, U.S.A. Carbofuran applied once a year at rates of 4.5, 9.0 or 13.5 g AI (active ingredient) per cm of diameter at breast height protected trees from the white pine cone beetle, Conophthorus coniperda (Schwarz), the leaffooted pine seed bug, Leptoglossus corculus (Say), the shieldbacked pine seed bug, Tetyra bipunctata (Herrich-Schäffer), and the white pine cone borer, Eucosma tocullionana Heinrich. Control was reflected by increased cone survival and increased yields of filled seeds per cone. Increasing the rate of application from 4.5 to 9.0 or 13.5 g generally improved control, but the improvement was not of statistical or practical significance. Carbofuran was ineffective against a seed chalcid, Megastigmus atedius (Walker). White pine clones varied in inherent susceptibility to insect attacks. 相似文献
17.
Throughout the southeastern United States, Rhus and Rubus species are common associates of the southern pines on a wide array of upland site and stand conditions. Because of their ability to overrun disturbed sites, these species are categorized as competitors to pine during stand regeneration. Since prescribed burning is often used for site preparation in advance of pine regeneration, this study investigated the effect of fire on the germination of seeds from three pine competitors (Rubus argutus Link, Rhus copallina L. and Rhus glabra L.). During dormant-season burns, sumac seeds were located 45 cm above litter, within the F layer of a reconstructed forest floor, and at the interface of the forest floor and mineral soil. During growing-season burns, fresh blackberry fruits were placed at heights of 0, 15, 30, and 45 cm above the surface litter of a reconstructed forest floor. In subsequent germination tests, sumac seeds from within the F layer of burned litter had significantly higher germination rates for smooth sumac (31%) and shining sumac (42%) as compared to unburned control seeds (1–5%). In general, germination rates for sumac seeds placed in the air or on mineral soil during burning were no better than control seeds. Seeds from blackberry fruits that were located at heights of 15, 30, and 45 cm had germination rates that were comparable to unburned control seeds (18%), but seeds from fruits placed on the litter during burning had <1% germination. Results suggest that sumac seed germination may be enhanced by the heat from prescribed burning, whereas blackberry seeds showed more germination response to multiple germination cycles which indicated a potential for long-term storage in the soil seed bank. 相似文献
18.
19.
优良红松坚果型优树的选择方法(英文) 总被引:3,自引:0,他引:3
于1988-1998 年对长白山、小兴安岭和完达山地区天然红松林以及黑龙江省鹤岗地区人工红松林结实量进行了实地调查和测定。根据调查和测定数据,对红松结实特征,包括结实量、球果长度、球果数量、出种率,种子千粒重、种子产量、种子大小、种子空实率、球果虫害率、结实指数等,进行分析方差分析、多重比较和逐步回归,得出各项结实因子对结实量的贡献率,将球果长度、千粒重和出种率确定为优树选择的重要指标,然后采用加权系数法确定红松坚果型优树,并制订出天然红松林坚果型优树标准和红松人工林坚果优树标准。本项研究为建立红松坚果园选择优树提供了方法和标准。 相似文献