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1.
Oak (Quercus spp.) regeneration is an important forest management goal in the central hardwood forest region of the United States. Silvicultural methods that target oak regeneration, such as the creation of canopy openings and removal of shade-tolerant midstory trees, are complicated by the impact of pre- and post-dispersal predators of oak acorns like acorn weevils (Curculio spp.) and granivorous small mammals. Understanding the effects of forest disturbance created by silviculture on these predators is important to promote successful oak regeneration. We conducted a 6-year study of acorn production, weevil infestation, and acorn removal at 113 black (Q. velutina) and white oak (Q. alba) trees impacted by three types of silvicultural treatments: adjacent to harvest openings, midstory removal (first-stage shelterwood harvest), and control (no harvest) in south-central Indiana, USA. We observed highly variable acorn production across years, but minimal impact of silvicultural treatments. Levels of weevil infestation and acorn removal by small mammal seed predators also varied greatly, and predation pressure was highest in years when acorns were scarce. Weevil infestation was reduced following midstory removal in shelterwood harvests, but probability of acorn removal by small mammals was unchanged following harvest. Damaged, germinated, and weevil-infested acorns were less likely to be removed by seed predators, suggesting additive effects of pre- and post-dispersal predators. This study emphasizes the importance of considering acorn predators in oak regeneration silviculture, and timing harvests to follow large acorn crops in order to reduce predation pressure and generate a high number of seedlings. 相似文献
2.
We studied population changes of the field mouse,Apodemus speciosus Temminck, by live trapping in a mixed stand of cypress and broad-leaved trees at Tama Forest Science Garden during the period
from October 1991 to March 1994. We also used radiotelemetry to investigate acorn hoarding. The number of mice captured in
1992 was three to ten times higher than that in either 1991 or 1993. The home ranges of resident mice overlapped greatly,
but a path and differences in the vegetation structure may have affected the home range of individuals. From June 1992 to
April 1993, mice actively transported and hoarded acrons. Individuals hoarded 70% of the acorns in their home ranges within
one day after release. This species was a typical scatter-hoarder and hoarded a single acorn at each cache site. Mice buried
acrons in the soil at the first hoarding, but recovered and carried them into their nests later. Although more than 50% of
the acorns were buried 0–5 cm deep, where the condition for germination seemed to be good, mice recovered and ate all cached
acorns. Mice relocated acorns farther from the original food station as they repeated hoarding. Mice transported acorns an
average of about 15–18 m (range: 2.2–49.8 m) before they ate them. From May 1993 to March 1994, the hoarding behavior of mice
was not active. Most acorns were left at food stations or cache sites for more than three months. Acorn hoarding byA. speciosus probably contributes little to the dispersal and regeneration of acorn-producing trees in years with a high rodent density. 相似文献
3.
The management of burnt wood after a fire may affect seed predation by vertebrates due to the change produced in habitat structure. We analyze the effect of burnt wood management on post-dispersal seed predation in the Holm oak. Three plots were established in a burnt forest, with three treatments per plot: (1) non-intervention (NI, all trees left standing), (2) “partial cut plus lopping” (PCL, felling 90% of trees, cutting their main branches, leaving all the biomass in situ), and (3) “salvage logging” (SL, felling the logs for their removal and masticating the woody debris). Acorns were buried to mimic dispersal by jays or rodents two and three years after fire, with two trials per year (7200 monitored acorns), and the predation rate was evaluated until the time of seedling emergence. The spatial patterns of acorn predation were assessed by computing a transformed-Ripley's K function and Moran's I correlograms. There was a large spatial and temporal variability in acorn predation, with differences among trials, plots, and replicates within treatments and plots. Overall, PCL showed the lowest predation values (83.0% versus 87.4 in NI and 88.0 in SL). Predator species (mice versus wild boar) also differed among treatments, wild boar having a negligible effect in PCL, presumably due to the physical barrier of felled logs and branches. The results support that: (1) salvage logging offers no advantage against predators and (2) that post-fire burnt wood management alters the guild of acorn predators and may reshape the pattern of seedling establishment. 相似文献
4.
We compared patterns of acorn dispersal and predation by wood mice among four tree species (Quercus serrata, Quercus crispula, Castanea crenata, and Juglans mandshurica var. sieboldiana) that are abundant in cool temperate woodlands. We devised an acorn dispersal experiment using 400 magnet-inserted acorns and a magnetic locator in a 1.8-ha study plot, which spanned a cut-over area and an adjacent deciduous forest. Ten wire mesh baskets, each containing 40 acorns (10 acorns per species), were placed on the border between these two habitat types. About 13.0% (n = 52) of the total acorns remained in the baskets, while 77.3% (n = 309) were dispersed throughout the study plot and subsequently retrieved using the magnetic locator. Microhabitat, distance, and burial depth of transported acorns were significantly different among species. In the cut-over area, J. mandshurica var. sieboldiana acorns were dispersed under fallen trees or branches and near stumps, and were buried deeply in the soil. Dispersal distances of J. mandshurica var. sieboldiana acorns were significantly greater than those of Q. serrata acorns. The number and microhabitat of transported acorns significantly differed between habitat types. J. mandshurica var. sieboldiana acorns were dispersed in the cut-over area rather than in the forest. For all four species, the numbers of acorns delivered to fallen trees or branches, stumps, and crumbled soil with overhang under any vegetation type were greater in the cut-over area than in the forest. 相似文献
5.
Vegetation structure of forest edges and type of adjacent field can affect seed and seedling survival patterns of tree species.
We investigated acorn removal and seedling survival of Quercus germana and Q. xalapensis in relation to woody plant density across old field-forest gradients with soft and abrupt edges. Experiments were established
along four parallel bands located at 40–50 m in the forest, forest and field edges (0–10 m to each side of the border), and
20–30 m in the old field. Within each band, woody plant and acorn density was measured, and four points for acorn and seedling
removal experiments were randomly positioned. In each position, 20 acorns or four seedlings were placed. Survival was monitored
during one month. In abrupt edges, acorn density was higher along edges than in forest interior. Also, higher acorn removal
and seedling mortality were observed in the adjacent old-field whereas acorn and seedling survival was the highest at the
edges. Acorn and seedling survival was positively correlated to woody vegetation density. As the vegetation density of field
and forest edges grows, abrupt edges develop into soft edges, and they become more hospitable to oak recruitment and then
to forest cover expansion. 相似文献
6.
《Forest Ecology and Management》2007,238(1-3):302-308
Acorn predation by insects and its effects on seedling establishment were investigated among three co-occurring oak species (Quercus variabilis, Q. serrata and Cyclobalanopsis glauca) in a subtropical evergreen broadleaved forest, Southwest China. All oak species had high tannin concentration (over 10%) but differed in acorn mass and germination schedule. We hypothesized that the defensive traits in acorns (e.g. seed mass, tannins and germination schedule) act together to reduce damage from insect seed predators. Q. variabilis had significantly lower predation (51.2%) than either Q. serrata (71.4%) or C. glauca (73.8%). Seedling establishment decreased with increasing injury for all oak species studied. As much as 43% of insect infested acorns germinated and established as viable seedlings despite extensive acorn mortality due to insect seed predators. The larger seed mass of Q. variabilis appears to tolerate insect infestation and retain enough stored reserves for seed germination and early growth of seedlings. Autumn germination also benefited Q. variabilis and Q. serrata, allowing escape from both direct and ancillary effects of insect feeding by fast reserve shifting to immediate germination of mature acorns. Our results indicate that large seed mass, tannin and autumn germination act together to ameliorate effects of insect seed predation, and the joint evolution of resistance and tolerance (as well as escape through autumn germination) in acorns may be the selective consequences driven in part by interactions with insect seed predators. 相似文献
7.
Tree Seed Production and Food Conditions for Rodents in an Oak Wood in Southern England 总被引：5，自引：0，他引：5
Seed production and seed losses were monitored in an oak (Quercusrobur) wood in southern England between 1975 and 1988. In additionto acorns, seeds from several large beech (Fagus sylvatica)and sweet chestnut (Castanea sativa) trees which occurred withinthe wood, and from the understorey of hazel (Corylus avellana)trees, were also monitored. The seeds from these four tree speciesare all subject to heavy predation by rodents, as well as otherseed-eaters such as birds and insects. Seed fall tended to be irregular and three years, 1976, 1985and 1987 were considered oak mast years. There were too fewyears with large acorn crops to examine whether resource depletionin these years resulted in poor crops in subsequent years. Therewas no correlation in seed production between the four treespecies which does not agree with one of the predictions ofthe predator satiation theory of masting behaviour. The effectsof weather on seed production were investigated but few significantcorrelations were found. In general the results tended to supportprevious findings. Between 1980 and 1982 a serious outbreakof Tortrix moth caterpillars occurred within the wood and mayhave affected acorn production. A negative relationship wasfound between oak defoliation and acorn production in the subsequentyear. The loss of seeds from the forest floor was initially rapidand in 9 years no seeds survived into the following year andfood conditions were poor for granivores. In 3 of the remaining4 years acorns survived well into spring and early summer providinggood food conditions for forest rodents through to the timeswhen alternative food supplies became available. Although oaktrees contributed most seed energy in good years, the othertree species, especially beech, became important when acornproduction was poor. Predispersal losses due to predators werefrequently high and averaged 80 per cent, 40 per cent, 38 percent and 33 per cent in hazel, sweet chestnut, oak and beechrespectively. On average, hazel nuts tended to fall first, some6 weeks before acorns which tended to be the last seeds to fallof the four tree species. Knopper galls and weeviled acornsfell earlier than sound acorns. A key-factor analysis indicatedthat a failure to mature, predispersal predation and insectinfestation from weevils and Knopper galls contributed equallyto changes in numbers of acorns among years. 相似文献
8.
《Forest Ecology and Management》2005,217(1):67-79
The purpose of this study was to examine the effect of habitat edges on the probability of acorn germination of three oak species (Quercus crassifolia Humb. and Bonpl., Quercus rugosa Née and Quercus laurina Humb. and Bonpl.). The effects of edge type (hard and soft), habitat type (grassland, edges and forest) and leaf litter cover (covered or uncovered acorns) on acorn germination was evaluated by the experimental establishment of acorns along transects crossing habitat edges. More acorns developed into seedlings in grasslands (38%) than in the forest edge (18%) or the forest interior (15%). In sites with soft edges, a higher number of seedlings emerged from acorns covered by litter compared with acorns sowed in the adjacent forest edge and forest interior (P < 0.05). In sites with hard edges, fewer seedlings emerged in the edge (14%) compared with the adjacent grassland (38%), and the adjacent forest (20%) presented intermediate values. However, in sites with soft edges significant differences in seedling emergence were recorded between the grassland (38%) and the forest (10%), whereas the edge presented intermediate values (23%). The effect of leaf litter cover on acorn germination was only significant in grasslands in sites with soft edges (P < 0.05). Acorns in grasslands received relatively little insect damage (10%) compared with the edge (19%) and the forest (30%, P < 0.05), emphasising the importance of acorn dispersal for successful oak establishment. The implications for regeneration of these oak species and the dynamics of montane oak forests in Mexico are discussed. 相似文献
9.
Koichi Sone Keita Oishi Tatsuya Shibato Kunihiko Hata 《Journal of Forest Research》2016,21(4):185-192
We conducted field studies to evaluate the impact that curculio weevil attacks on Pasania edulis (Fagacea) acorns have on the regeneration of this tree. The germination ratio of weevil-attacked acorns was significantly lower than that of sound acorns. The number and position of the attacks on acorns affected the germination ratio. The seedlings from weevil-attacked acorns were shorter and had a smaller leaf area than those from sound acorns. The negative effects on seedling height lasted for at least three years after germination. We also studied the handling of the two types of acorns by granivorous Apodemus mice in a broad-leaved forest dominated by P. edulis. The mice picked up, transported, hoarded, and recovered sound and weevil-attacked acorns similarly. In the study site, the seedlings from weevil-attacked acorns were estimated to account for 1.5–20.4 % of the total seedlings for cohorts of mast years and 0–3.7 % for those of poor or medium acorn production. From these results, we conclude that acorns with the lower part of their cotyledons slightly damaged by weevil larvae might still be able to contribute to the regeneration of P. edulis in the field but that their contribution would be negligible or small even in mast years in this study site. 相似文献
10.
Carlos Renato Ramos-Palacios Ernesto I. Badano Joel Flores Jorge A. Flores-Cano José L. Flores-Flores 《European Journal of Forest Research》2014,133(3):391-404
Forest fragmentation affects seed production, but little is known about how seeds are distributed in fragmented forests after primary dispersion and how this affects their interactions with other organisms. This study addressed these issues in a fragmented oak forest of Quercus laeta where four habitat types were recognized: interior and edge of patches, deforested matrix around patches, and an abandoned field. Areas and distances to the abandoned field were measured for 40 patches, and acorns were sampled in all habitats. Only samples from the interior and edge of patches had acorns, which were classified as aborted, viable, and parasitized by insects or fungi. Acorns in all these classes were regressed against patch area and distance to the abandoned field. Field experiments were also conducted to determine whether acorn removal rates varied across habitats. Aborted acorns within patches were not related to area or distance, but they decreased with increasing values of both variables at patch edges. Within patches, viable acorns were positively related to increases in area and distance, while the converse occurred for insect-damaged acorns; fungal-infested acorns were not related to patch variables in this habitat. Complex interactions between area and distance explained how acorns in these classes were distributed across patch edges. Acorn removal was higher within patches and their edges when compared to human-disturbed habitats; both mice and birds were identified as potential acorn dispersers. These results suggest that forest fragmentation affects acorn-mediated processes and that this may influence the recovery of patch connectivity in the landscape. 相似文献
11.
We have experimentally investigated the impact of biotic factors, acting at the seed and seedling stages, on a Quercus pyrenaica forest in the Sierra Nevada mountains (SE Spain). We monitored the natural establishment of the oak for 3 years in two forest plots and two shrubland plots, by counting seedlings and juveniles. In addition, we established several experiments in these plots to examine acorn and seedling survival, while also considering the microhabitat effect on survival probability. Dispersed acorns were quickly consumed by several species of predators, particularly wild boar (Sus scrofa) and woodmouse (Apodemus sylvaticus). Less than 4% of the experimental acorns survived to produce seedlings, even when they were buried 4 cm in soil, simulating caches. No effect of microhabitat was found on predation, and thus no safe site appears to exist for Q. pyrenaica acorns in the study area. Some 98% of the 1000 experimental seedlings were killed by herbivores, notably woodmice, wild boar, and domestic and wild ungulates. Seedling survival varied spatially, being significantly higher under shrubs (4%) than in any other microhabitat (less than 0.5%). Both acorn and seedling survival were much lower in the shrublands than in the forests. In shrubland plots, the main agent of seedling mortality was trampling by domestic ungulates foraging in herds. This study suggests that the regeneration of Q. pyrenaica forests in Mediterranean mountains can be limited by herbivores acting at several life-history stages. 相似文献
12.
《Forest Ecology and Management》1988,25(1):9-16
Acorn transporting and hoarding, distribution, and utilization by mice of hoarded acorns were studied. Apodemus speciosus and A. argentus were observed to transport acorns. An individual A. speciosus observed scatterhoarded at least 49% of acorns transported. The rate of acorn utilization was higher in locations where two or more acorns were buried than where a single acorn was buried. Forty-seven percent of scatterhoarded acorns disappeared before snow cover and 99% before the next spring. Based on the extent of home ranges for mice, dispersal distance is presumed to be from 30 to 40 m. 相似文献
13.
To clarify the effects of asynchronous seed production among tree species on the population of seed predators, we investigated
the relationship between the annual variation in production of mature acorns and the insect damage in those acorns of two
sympatric oak species, Quercus variabilis Blume and Quercus serrata Thunb. ex Murray, over 4 years at two study sites. The annual variation in acorn production was noticeable, with a coefficient
of variation (CV) at the two sites of 1.05 and 0.80 for Q. variabilis and 0.87 and 0.73 for Q. serrata. Annual fluctuation in acorn production by Q. serrata was synchronized between the two sites. Since annual fluctuation in acorn production was not synchronized between the two
species, the CVs for the total acorn production by both oak species (0.83 and 0.62 at the two sites) were lower than those
for Q. variabilis and Q. serrata alone. The rate of predation by the specialist predators (Curculio weevils) on the acorns of both species was not related to the annual acorn crop size. Prolonged diapause of Curculio weevils might stabilize their populations. The rate of acorn predation by the generalist predators (tortricid moths) was
also not related to the annual crop size. Asynchronous acorn production by the two oak species would help to stabilize the
population. 相似文献
14.
《Forest Ecology and Management》1988,25(1):1-8
Effects of two sets of factors on the disappearance of acorns of Q. mongolica var. grosserrata were investigated. Acorns were distributed on (a) the floor of a forest with its canopy intact, (b) the floor of a forest clearing, (c) the vegetated sloping bank of a forest road, and (d) a bare forest road. They disappeared fastest from the forest with intact canopy and slowest from the bare road, an effect thought to be directly related to amounts of cover.When the acorns were covered with frames having netting with different-sized apertures, a mesh of 3.0×4.0 cm did not appreciably alter the rate of acorn disappearance compared with the uncovered controls: a mesh of 0.5×0.5 cm totally inhibited the disappearance of acorns.Five species of small mammal were live-trapped. Of these, Clethrionomys rufocanus, Apodemus argentinus and A. speciosus are thought to be implicated in the disappearance of acorns. The rate of acorn disappearance seems to be directly related to total numbers of small mammals.Acorns disappeared more rapidly when distributed on the ground than when buried. 相似文献
15.
《Scandinavian Journal of Forest Research》2012,27(6):540-549
Abstract Natural regeneration differences between oak and pine are common in the Qinling Mountains of central China. Thus, we examined whether this difference could be explained by seed dispersal. We investigated the seed dispersal of Quercus aliena var. acuteserrata Maxim. and Pinus tabulaeformis Carr. and the regeneration characteristics of both species were investigated in the pine-oak forest belt (oak stands, pine-oak stands, and pine stands) of Huoditang Forest in the Qinling Mountains in central China. We found that Q. aliena var. acuteserrata acorns were usually scatterhoarded, while seeds of P. tabulaeformis were generally consumed immediately. We found that 55% of the released acorns were transferred to the P. tabulaeformis stands. Moreover, Q. aliena var. acuteserrata regenerated successfully and was recruited in the three forest stands. However, the natural regeneration of P. tabulaeformis was very low in all stands because of high predation by small rodents. We propose, therefore, that the seed dispersal advantage of Q. aliena var. acuteserrata compared with P. tabulaeformis contributed greatly to the regeneration difference between these two species in the pine-oak forest belt of the Qinling Mountains in China. 相似文献
16.
Effects of flood duration and season on germination of black,cherrybark, northern red,and water oak acorns 总被引：1，自引：0，他引：1
Effects of flood duration (0, 10, 20, and 30 days) and season (winter and spring) on acorn germination were tested for two upland oaks [black and northern red oak (Quercus velutina Lam. and Q. rubra L.)] and two bottomland oaks [cherrybark and water oak (Q. pagoda Raf. and Q. nigra L.)]. Acorns were stratified for 30 days before flooding at a depth of 15 cm along the edge of a small pond. After flooding, acorns were sowed in sand-filled plastic cups and germinated for 40 days. Flood duration and season strongly affected radicle and epicotyl emergence of the upland oaks, but effects were generally limited to spring flooding. Embryo axes of the upland oak acorns were severely damaged with as little as 10 days of spring flooding. Almost no epicotyls developed, but radicles developed from the connective tissues between embryo axes and the cotyledons of many acorns. Spring flooding also significantly increased the percentage of decayed acorns for the upland oaks. In contrast, germination of the bottomland oaks was slightly improved by flooding during both seasons. Results demonstrated that the effects of flooding on the distribution of species within bottomlands can begin with seed storage and germination. 相似文献
17.
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19.
The effect of orientation, location, year, and pruning treatment on mean acorn mass in two open woodland experimental locations (Huelva, South-Western Spain) of Holm Oak (Quercus ilex L. subsp. ballota [Desf.] Samp.) was analyzed during 2001–2006. Data were analyzed by using a mixed linear model, where the covariates were tree size parameters (circumference at 80 cm height, crown size), topographic position (wet index and flow length), intraspecific competition, total acorn crops per tree (weight and number), and climatic parameters. Average estimated acorn mass was 3.17 g acorn?1 in the Calañas location and 4.12 g acorn?1 in the San Bartolomé location, with significant differences between locations, among individual trees and across years. Acorns from the south sides of trees were significantly heavier than those at other positions. The effect of pruning treatment and the interactions location × treatment and treatment × year were not significant. Our study provides no evidence that pruning affects acorn mass. None of the analyzed covariates related to tree size, topographic position and intraspecific competition explained the difference among trees, suggesting that heritable factors play an important role. Specific climatic parameters during September, the most important month for acorn growth, may explain the effects of year and location × year on acorn mass. In addition, there appeared to be a “trade-off” between acorn mass and number of acorns. 相似文献
20.
A field experiment was established in the autumn of 1992 in order to study predation of acorns, germination and early growth of oak seedlings. The experiment was established on a clearcut and an adjacent oak shelterwood in southern Sweden. In the experiment, a total of 6 840 acorns were sown. The sowing was carried out with different vegetation control and soil preparation treatments and with different planting depths.The germination percentage was highest for acorns sown at five cm depth and lowest for acorns sown on top of the soil, and lower for acorns sown in areas where the humus layer had been removed than in areas where the humus layer was retained. There was no difference in the percentage germination after two growing seasons between acorns sown inside the shelterwood and acorns sown on the clearcut. The height of the seedlings was lowest when the humus was removed while the number of leaves per seedling was lowest for seedlings in untreated areas after two growing seasons. Furthermore, seedlings in untreated areas showed the lowest relative height growth rate during the second growing season. In spite of higher biomass of ground vegetation in undisturbed areas compared to treated areas, no effect of the soil and vegetation control treatments could be found on soil water potentials. The soil temperature and photosynthetic active radiation at seedling level were higher in areas where soil preparation and vegetation control had been performed. However, it was concluded that neither low soil water availability nor low light levels could be the only cause of lower relative height growth rate during the second growing season for seedlings in undisturbed areas. 相似文献