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1.
The last remains of native laurel forest in the Azores are highly threatened by the spread of invasive plants. Because landslides are very frequent in these islands, conservation of native laurel forest requires knowledge of the patterns of bird-dispersed seed rain into forest gaps. We monitored 78 seed traps over 1 year to investigate (1) the role of perches in attracting avian dispersers into gaps, (2) temporal patterns in the dispersal of exotic and native seeds, (3) how seed rain affects vegetation establishment in gaps at different distances from the native forest and (4) whether the caloric content of fruits could explain the number of seeds dispersed. Perches were highly effective in concentrating avian seed dispersal. While some native fruits are produced all year-round, most exotic plants set fruits during the main peak of the native fruit production (August–November). Most seeds recovered from the traps were native, and native seed rain inside the native forest was higher than in gaps. However, deposition of exotic seeds was not affected by distance from native forest. Seed dispersal frequencies monitored by seed traps and by faecal analysis were correlated with each other, but not with fruit caloric content, suggesting that other factors are more important that the nutritional value in predicting avian fruit choice. Forest restoration activities should take into consideration that seed dispersal decreases sharply beyond 100 m from native forest and the attractive potential of perches to direct natural seed dispersal into forest gaps.  相似文献   

2.
We evaluated the contribution of seed dispersal by birds to the colonization of fleshy-fruited plants beneath plants that bear fleshy fruits and were used as perches by birds. Specifically, we investigated the composition of seeds and saplings sampled beneath nine fleshy-fruited perch plant species in a Pinus thunbergii stand on a coastal sand dune in central Japan. Both the numbers and the species numbers of bird-dispersed (pulpless) seeds differed significantly among the perch plant species. Nevertheless, the quantitative compositions of bird-dispersed seeds were similar among the perch plant species because of the significant positive interspecific correlations of species rank order in numbers of bird-dispersed seeds per species. Similar relationships were also found for saplings. For each perch plant species, the numbers of fallen conspecific seeds were significantly higher than or not different from those of heterospecific seeds. Furthermore, the numbers of pulpy seeds that fell directly from the perch plant were significantly higher than those of bird-dispersed conspecific seeds for seven of nine perch plant species. However, the densities of conspecific saplings were significantly lower than those of heterospecific saplings. Most pulpy seeds, therefore, probably do not germinate beneath their mother plants, and conspecific seeds probably accumulate in seed banks or are consumed by herbivores.  相似文献   

3.
Fruiting phenology, assessed by seed fall, in five warm-and cool-temperate forests on Yakushima Island, southern Japan, was studied for two years in one 50 m × 50 m plot and for four years in four 100 m × 50 m plots. The elevation of the plots ranged between 170 and 1200 m a.s.l. Seed fall phenology showed annual periodicity in all five plots. This was clear when assessed by the number of species but became less clear when assessed by the biomass of seed litter. Community-level annual periodicity was based on the prevalence of population-level annual periodicity and interspecific synchronization of the fruiting peak from autumn to winter. Fleshy fruits had peaks of seed fall in a wider range of months than non-fleshy fruits, since it is sometimes beneficial to bear fruit outside the community-level fruiting peaks in order to avoid interspecific competition for animal seed dispersers. No consistent effect of climatic factors on seed fall phenology was detected.  相似文献   

4.
无量山自然保护区南段4种森林类型的林地土壤特性研究   总被引:2,自引:0,他引:2  
对设于云南省无量山自然保护区南段(景东段)常绿落叶阔叶混交林、中山湿性常绿阔叶林、山顶苔藓矮林、温凉性针叶林4种森林类型的10块监测样地的土壤进行了调查研究,结果表明:4种森林类型的林地土壤类型主要是黄棕壤、棕壤;其土壤的物理性状存在差异;10块样地土壤的有机质、有效氮、有效钾含量丰富,而全磷、有效磷的含量及盐基饱和度较低。在4种森林类型中,温凉性针叶林的林地土壤为砂壤,肥力较其它3种森林类型的林地土壤低。其他3种森林类型林地的土壤肥力没有较大的差异。  相似文献   

5.
动物取食和扩散森林植物种实研究进展   总被引:1,自引:0,他引:1  
动物取食扩散森林植物种实作为森林生态系统中植物和动物联系的-个重要方面, 不仅是联系母株与其子代幼苗的重要桥梁, 也是植物生活史中的-个重要阶段。文中综述了近年来关于动物取食森林植物种实及其与这些植物种子散布、萌发、幼苗生长和种群扩展等方面关系的研究成果。动物在取食和破坏森林植物种实的同时也将这些植物的种子扩散到-个新的生境斑块, 其消化道机械的或化学的作用提高了这些森林植物的种子萌发率和萌发进程, 促进了其早期定居和种群扩大。动物对森林植物的这种作用具有长期性, 形成特定动植物间或多物种间的协同进化。近年来, 森林生态系统受到了严重的干扰和破坏, 可能会因为干扰了森林植物种实的动物散布者而影响森林植物种群的扩展。  相似文献   

6.
This article reports the regeneration dynamics of a temperate Abies–Tsuga forest in Kirishima Yaku National Park, southwestern Japan, and examines the influence of species coexistence mediated by gap disturbances on biomass production. All trees taller than 2 m in a 1-ha plot were monitored over four growing seasons. Three growth-form groups occupied different vertical layers. Evergreen conifers and deciduous broad-leaved trees tended to be spatially segregated from evergreen broad-leaved trees, which formed thickets in the understorey. The regeneration of understorey evergreen broad-leaved trees was affected by canopy gaps. The recruitment of conifers and deciduous broad-leaved species was not observed during the four growing seasons. This suggests that regeneration is sporadic and the present environmental conditions are not favorable for these canopy species. The mortality and unsuccessful recruitment of conifers and deciduous trees appeared to cause fluctuations in the productivity of the stand. However, an abundance of canopy gaps accelerates the regrowth of shorter species, and the fluctuation of productivity resulting from the population dynamics of canopy species would be partly mitigated by the regeneration of evergreen understorey species. The horizontal and vertical heterogeneity of the temperate mixed forest was a result of the patch structures of the three growth-form groups. The different regeneration patterns among the three groups, which were driven by interactions of species-specific regeneration niches and disturbance regimes, might be an important factor in maintaining the aboveground productivity in a transitional mixed forest between warm-temperate and cool-temperate zones.  相似文献   

7.
We explored the temporal effects of fruit consumption on the subsequent seed germination pattern of a fleshy-fruited tree, the Chinese hackberry (Celtis sinensis). Via nursery-based sowing experiments, we investigated (1) how pulp removal affected seed germination patterns at the different stages of fruit maturation, and (2) how the timing of seed dispersal (August, October, and December) affected the germination patterns of seeds from ripe fruits after the removal of pulp. We found that the removal of pulp from around the seeds of ripe fruit had no effect on the percentage and timing of germination. In contrast, the removal of pulp from seeds of unripe fruits largely reduced the germination percentage. The time of sowing did not affect the germination percentage, whereas the timing of germination was delayed for seeds that were sown later or under shaded environments.  相似文献   

8.
We demonstrate a method for evaluating the appropriate number of samples required to estimate plant species richness in different forest types within a forested landscape. In each of 36 plots (0.1 ha each) from 5 forest types (deciduous broad-leaved secondary forest and 4 categories of coniferous plantation classified according to stand age) in central Japan, 40 quadrats of 1 × 1 m were set in a regular pattern; the total number of quadrats in each forest type ranged from 200 to 400. In each plot, the number of observed species in 40 quadrats ranged from 60 to 80% of the number of species estimated by the rarefaction method for each forest type. Sampling 30 quadrats detected approximately 90% of the observed species in each plot that were detected using 40 quadrats. In specific functional groups (i.e., tall trees and weed species), the ratios of both tall trees and weed species to all species were at equilibrium for 30 or more quadrats. For fewer than 30 quadrats these ratios were highly variable. No significant differences were found among forest types in the ratio of the observed number of species in each plot to the estimated number of species calculated using the rarefaction method, and in sampling efficiency estimated by use of non-parametric estimators. We concluded that the number of samples does not need to be changed according to forest type or plantation stand age in the studied landscape, and that the method used to evaluate the number of samples could be useful.  相似文献   

9.
In early spring, snow-buried mammal feces simultaneously emerge on the ground with the melting of the snow across regions with heavy snowfall. Here, we evaluated the ecological implications of this phenomenon for the cool-temperate forest ecosystem in terms of the resource use of dung beetles (Coleoptera: Scarabaeidae), which play key roles in secondary seed dispersal and nutrient cycling. During May 2012 and 2013, we conducted cafeteria experiments in heavy snowfall regions with different types of forest cover in northern Japan by using pitfall traps baited with the snow-buried feces of Japanese macaques (Macaca fuscata), Japanese serows (Capricornis crispus), and Japanese hares (Lepus brachyurus angustidens). From the experiments, we identified 12 dung beetle species, indicating that the snow-buried feces could act as a valuable resource for vernal beetles. Most of the beetles had obvious fecal preferences. The snow-buried feces of serows were widely available resources for most vernal species, including dwellers and tunnelers, contributing to the biomass of those species. Although dung beetles using snow-buried feces in young broadleaf forests with rich feces supplies did not always exhibit the highest species richness, tunnelers frequently emerged in those forests, and Phelotrupes preferred macaque feces. This finding could have important implications for plant regeneration, as it relates to time-lagged mammal–beetle interactions. Endozoochorous seeds dispersed by macaques in the autumn have insufficient opportunities for secondary seed dispersal by beetles as the beetles are inactive in autumn, but those seeds are protected against predation by snow during winter and are safely preserved under soil by vernal tunnelers.  相似文献   

10.
In several areas in Northeast Thailand, evergreen and deciduous forests coexist under uniform terrain and climatic conditions. We compared depth and physical properties of soils between evergreen and deciduous forests in the Sakaerat Environmental Research Station to clarify what factor determines their distribution. The averaged soil depths were 79 ± 27 cm and 135 ± 58 cm in the deciduous and evergreen forests, respectively. The soils in the deciduous forests were relatively coarser in soil texture than those in the evergreen forests, particularly in the surface layers. The average available water capacity of the solum was lower in the deciduous forest soils (78 mm) than in the evergreen forest soils (123 mm). Compared with the evapotranspiration from the evergreen forest in the study area, the available water capacity of the evergreen forest soil was almost the same as the water deficit during the dry season (November–February), while that of the deciduous forest soil was lower and insufficient to maintain the evapotranspiration. These results suggest that the distribution of deciduous and evergreen forests in the study area was associated with soil water availability, which mainly depends on soil depth.  相似文献   

11.
Seed predation and dispersal are key processes in the survival and distribution of plant species. Many animals cache seeds for later consumption, and, failing to recover some of these seeds, act as seed dispersers, influencing post-dispersal seed and seedling survival. Both animal and plant benefit from scatterhoarding and natural selection of seed characteristics and adaptations of seed predators (and dispersers) is one of the most important examples of co-evolution and mutualism. We studied the producer–consumer Arolla pine (Pinus cembra)–red squirrel (Sciurus vulgaris) system in a subalpine forest in the Italian Alps. Arolla pine produced large seed-crops (masting) at irregular intervals, followed by years with poor or moderate seed production. Squirrel density fluctuated in synchrony with the food resource, eliminating the time-lag normally present when resources are produced in pulses. In all years except 2009 (a mast-crop year), all Arolla pine cones were harvested (their seeds consumed and/or cached) by September to late October by different species. Both squirrels and nutcrackers (Nucifraga caryocatactes) fed on seeds, and their relative pre-dispersal predation rates (on cones in the canopy) differed between years. Overall, nutcrackers consumed more seeds between July and October than squirrels, but in 1 year squirrels took the largest number of seeds. Pre-dispersal seed predation by squirrels tended to be lower in years with large seed-crop size and there was a positive correlation, over the entire study period, between density of recovered hoards and Arolla pine seed density of the previous year. We conclude that (i) squirrels and nutcrackers are important pre-dispersal seed predators and seeds dispersers; (ii) squirrels are also post-dispersal seed predators, and (iii) the proportion of cached seeds consumed by squirrels increased with the size of the Arolla pine seed-crop, suggesting that red squirrel is a conditional mutualistic scatterhoarder of Arolla pine seeds.  相似文献   

12.
Ecological investigation of the distribution and composition of dung beetle species utilizing feces of wild mammals has rarely been attempted, especially in cool-temperate forests. In this study we recorded and evaluated the community structure of dung beetle species utilizing feces of Japanese monkeys (Macaca fuscata) by conducting a macro-scale inventory survey in the northeastern Shirakami Mountains, located in the northernmost part of mainland Japan. Moreover, to assess the effect of human-induced forest disturbance on species assemblages in this cool-temperate area, we also carried out field sampling using pitfall traps baited with monkey feces in primary forests, secondary forests, and coniferous plantations, during every season except winter. Our findings were: (1) 14 dung beetle species comprising eight dwellers and six tunnelers utilized monkey feces; (2) Aphodius eccoptus was the core species in dung beetle assemblages attracted to the feces during spring and summer; (3) the frequency of occurrence of every species was extremely high in spring; and (4) human-induced forest disturbance did not increase species richness or biomass in cool-temperate forests.  相似文献   

13.
长沙市绿地植物群落结构特征与优化构建   总被引:1,自引:0,他引:1  
对长沙市典型植物群落进行取样调查,分析群落类型、群落密度、冠幅等对群落景观的影响,结果表明,长沙市的绿地植物群落类型以落叶阔叶林为主,常绿阔叶林次之;部分群落结构简单,植物群落种植密度过高;群落物种中外来植物的比例较大,但绿地植物与植物区系特征基本一致.提出了优化绿地植物群落结构、构建高物种多样性植物群落的措施.  相似文献   

14.
We estimated the potential of plantation forests for the restoration of the original plant community. We compared the understory vegetation in hinoki (Chamaecyparis obtusa [Sieb. et Zucc.] Endlicher) plantations at the understory re-initiation stage and in adjacent natural forests. To estimate the effect of the original natural forests on the understory species composition of plantation forests, we established study sites in five types of natural forests (mature evergreen broadleaf, mature deciduous broadleaf, mature evergreen coniferous, immature deciduous broadleaf warm-temperate, and immature deciduous broadleaf cool-temperate) and nearby plantation forests. The understory vegetation of the plantation forests had a higher species richness, a higher proportion of early-seral species, and a higher proportion of herb or fern species than the natural forests. The differences between natural and plantation forests varied according to the species composition of the natural forests. The composition of the understory vegetation of the plantations at the understory re-initiation stage was similar to that of the immature deciduous forests. The characteristics of immature, disturbed forests remained in the understory vegetation of the hinoki forests. No great loss of species was observed. Our findings suggest that most of the original forest species still survive in the understory of the plantation forests. These forests have the potential to follow the successional pathway to broadleaf or mixed forests via thinning or clear-cutting without planting.  相似文献   

15.
We examine whether different guilds of foragers remove seeds differentially according to seed quality (seed size and insect infestation) and seed location (habitat and microhabitat) in a mixed oak-beech forest. Video recordings indicated that the wood mouse (Apodemus sylvaticus) was first to encounter seeds. Foragers preferred acorns to beechnuts, large to small size and sound to infested. Nevertheless, infested seeds were removed by rodents even when sound seeds were present. Seeds that were not preferred by scatter-hoarding rodents remained longer on the ground and were more vulnerable to predation and desiccation (4% moisture loss per day). However, seeds that were removed by scatter-hoarders were moved away from their mother trees (96%) and cached individually (32%), increasing their moisture content (3% per day). Buried seeds, simulating scatter-hoarding behavior, experienced only a 17% removal after 4 months. Seed removal differences among habitats were not due to habitat attributes but to the spatial distribution of rodent-preferred microhabitats. Thus, a significant lower seed removal was observed under the tree canopy with no shrubs. However, seed removal in forest gaps with deadwood cover was not significantly different from the preferred microhabitat (under shrub cover). In pure beech forests, seed removal by rodents only occurred under Ilex aquifolium (the only perennial cover) and under woody debris. This study concludes that seed quality and seed location determine the contribution of different removers (predators vs. dispersers), their seed selection and their removal speed, leading to different seed fates which will eventually affect tree regeneration.  相似文献   

16.
The abandonment of sites after clearcutting plantations is increasing rapidly in Japan. Although a few stand-level studies have been conducted, a broad-scale study is needed to understand the general tendency of vegetation recovery and to obtain information for the management of such extensively distributed abandoned clearcut sites. This study is a province-level study that aims to interpret the patterns and factors in early-stage vegetation recovery at abandoned plantation clearcut sites. We also discuss the potential indicators that may determine whether a certain site recovers towards evergreen broad-leaved forest consisting of Castanopsis cuspidata and Quercus glauca or towards deciduous broad-leaved forest comprising Q. serrata and Q. acutissima. A cluster analysis revealed that five types of vegetation (evergreen trees, evergreen trees–deciduous pioneer shrubs, pioneer species, deciduous trees, and deciduous shrubs) were observed from an early stage of succession. The first two vegetation types were considered to recover successfully to the target vegetation of evergreen broad-leaved forest, but the remaining three vegetation types did not show any tendency to recover to the target vegetations. According to the results of the detrended correspondence analysis, a smaller size of the abandoned site with adjacent evergreen broad-leaved forest and a longer time after clearcutting were identified as factors that enhance the invasion of evergreen tree species; these factors are also useful to predict the future successional tendency. In conjunction with these factors, the existence of regeneration sources (i.e., stumps) that allow sprouting appeared to be an important indicator for predicting the early-stage vegetation recovery.  相似文献   

17.
大熊猫主食竹种及其生物多样性   总被引:3,自引:1,他引:2  
现代大熊猫分布在四川西部37个县市区、陕西南部5个县和甘肃南部1个县,栖息地面积约200,000 km2,竹林面积约600,000 hm2,竹子蓄积量约18,000,000 t。分布范围在λ(E)102°00′~108°11,′ψ(N)27°53′~33°55,′常年活动在海拔(1 200)2 000 m~3 000(3 600)m之间。从南到北长度直线距离约750 km,东西宽约50 km~180km,处于我国地形第一级阶梯青藏高原向第二级阶梯高原山地盆地过渡地带上,呈狭长状弧形分布外貌,但并不连续而是作岛状的间断分布。大熊猫主食竹种在其分布范围内,分隶于竹亚科仅有的箣竹超族和北美箭竹超族2个超族中,前者含5属19种,后者含6属45种,一共采食11属64种竹子。其中除箣竹属的孝顺竹、硬头黄竹,慈竹属的慈竹及苦竹属的斑苦竹为栽培外,其余8属51种均为野生竹种,并有大面积的天然竹林。慈竹属、刚竹属、筇竹属、巴山木竹属和箬竹属等5属为我国特产,占大熊猫主食竹属的45%。筇竹属、镰序竹属、方竹属、箭竹属、玉山竹属和巴山木竹属等90%以上的种类产于我国西南部山区,而且大熊猫分布区也是该6属的分化中心和现代分布中心之一。大熊猫分布区的植物区系起源古老,成分复杂。在大熊猫天然采食的64种竹种中,除峨眉箬竹分布区域小和数量零星,不足以形成独立的群系外,其余63种竹子均可在竹林植被型中形成独立的群系。中国大熊猫栖息地主要是针叶林和阔叶林两个植被型组,有时偶见活动于灌丛植被型组区域。在针叶林植被型组共有5个植被型中的寒温性针叶林、温凉性针叶林、温凉性针阔叶混交林和暖性针叶林等4个植被型及以竹子为次优势层片的59个以上植物群丛组,阔叶林植被型组的落叶阔叶林、常绿落叶阔叶混交林和常绿阔叶林等3个植被型及以竹子为次优势层片的56个以上植物群丛组,总计针、阔叶林有7个植被型及115个以上植物群丛组是大熊猫的栖息地。其中温凉性针阔叶混交林又是大熊猫的最主要栖息地,周年四季都有活动足迹和采食其林下竹种。大熊猫栖息在有竹子为次优势层片的森林植物群落中,不但有食物的保障,而且有复杂的森林生态系统和良好的生活环境,使大熊猫得以长期延续生存繁衍和不断发展。  相似文献   

18.
In beech (Fagus crenata Blume) forests on the Pacific Ocean side in Central Japan, snowpack depth is little and xeric conditions may prevail in winter, in contrast to heavy snow in beech forests on the Japan Sea side. The effects of such conditions during winter on the viability of beech seeds were studied at a beech forest on the Pacific Ocean side. Thickness and weight ratio of pericarp of beech seeds were significantly greater in populations on the Pacific Ocean side compared to the Japan Sea side, this apparently being related to snowpack depth in winter. During the initial stage of seed drying, the drying rate of seeds from the Fuji population (the Pacific Ocean side) was less than that from the Sumon population (the Japan Sea side), possibly due to the thicker pericarp. Germination percentage of seeds which dried to a water content as low as 7% d.w. did not decrease for either population, indicating desiccation tolerance of beech seeds. In the beech forest (University Forest at Yamanaka) on the Pacific Ocean side, water content of seeds sown below litter from both populations remained sufficient for viability during winter. Germinating seeds from the populations on the Japan Sea side were more desiccation-sensitive in early spring, compared to those from the Fuji population, partially due possibly to differences in pericarp thickness.  相似文献   

19.
We examined the year-round viable seed dispersal by European bison (Bison bonasus L.) subject to three population management systems (captive, semi-wild, wild) in Bia?owie?a Primeval Forest. The forest is inhabited by the world's largest free-roaming population of European bison (>450 head). Dung samples were collected approximately fortnightly from September 2005 to September 2006 in each of the management systems. Emergent seedlings were counted for 24 months in greenhouse conditions. A total of 10,807 seedlings, which included 178 plant taxa, emerged from 74 bison dung samples. Species richness and seedling abundance/sample were greatest during August and September, the months of the highest fructification season, and were lowest in May. Twenty-two percent of recorded species were forest plants. The captive bison population had the greatest mean seedling abundance (236 ± 61/sample), the greatest species diversity (144), and the highest percentage of synanthropic species (29.2%). The gradient of these characteristics decreased with a decrease in management intensity of the bison populations. The results of the regression analysis indicated that in the semi-wild managed system, the number of plant species found in dung samples collected during winter was significantly negatively correlated with snow depth. Number of seedlings and number of plant species dispersed depended on plant phenology and intensity of supplementary feeding. The mean number of seeds/sample dispersed by European bison was 5–15 times lower, and the mean number of species/sample was 2–3 times lower than those published for cattle or horses. In contrast, the total number of plant species dispersed by bison was approximately 2–3 times higher than for wild or domestic large ungulates. These results indicate that European bison are an important dispersal agent of seeds in forest ecosystems. The high percentage of synanthropic species dispersed by bison demonstrated that seeds in the fodder help maintain native and non-native plant diversity of ecosystems. Managers of animal populations must pay proper attention to fodder origin and quality.  相似文献   

20.
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   

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