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Elisa Brewster-Salmones;Juan Manuel Díaz-García;Fabiola López-Barrera; 《Restoration Ecology》2024,32(5):e14146
Direct sowing of acorns is a technique for oak forest restoration, however, high seed predation by mammals can occur and cost-effective alternatives to protect acorns are therefore required. The present study evaluated the protection provided by chili peppers (Capsicum annuum and Capsicum pubescens) to acorns of Quercus germana, an endangered endemic oak tree of the cloud forests. Greenhouse and field experiments were established to evaluate the effect of chili peppers on acorn removal, germination, and seedling emergence. These processes were related to the prevalent microhabitat characteristics where the acorns were introduced, and the fauna that consumed chili peppers and acorns was identified using camera traps. In the greenhouse trial, more seedlings emerged from acorns covered by fruits of C. pubescens (65.71 ± 8.14) and C. annuum (57.14 ± 8.49%) compared to unprotected acorns (31.43 ± 7.96%). Contrary to expectation, acorn removal in the field was greater using C. pubescens than the unprotected acorns, particularly in microsites with lower tree cover and higher grass dominance. Acorn removal was similar among chili pepper treatments. These results are explained by the camera trap records, which showed bird species consuming Capsicum fruits, thus exposing the acorns to subsequent removal and/or consumption by rodents. The studied Capsicum fruits had no negative effect on acorn germination and seedling emergence under greenhouse conditions, and future practices could, therefore, involve the use of different techniques to prevent the discovery of chili peppers by birds; for example, using green chili peppers for camouflage, or hiding them under litter or herbaceous vegetation. 相似文献
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Question: Hurricanes and cyclones cause a wide range of damage to coastal forests worldwide. Most of these storms are not catastrophic in ecological terms, but forest responses to storms of moderate intensities are poorly understood. In regions with a high frequency of moderate hurricanes, how does variation in disturbance intensity affect the magnitude of ecological responses? Location: Naushon Island, Massachusetts, USA. Methods: We use historical records and dendroecological methods to characterize establishment and growth of Fagus grandifolia, Quercus alba, and Quercus velutina in response to seven non‐catastrophic hurricanes of varying intensity, and a major logging event, relative to baseline conditions, over the past 150 years. Our aim was to document variation in the magnitude of responses to known disturbance events of varying intensity, and to determine whether tree growth after moderate hurricanes differs from growth during periods of no disturbance. Results: Forest harvesting in 1824‐1827 had a strong impact on forest composition and growth. Since then, the study region has been characterized by little harvesting but frequent hurricanes. However, only one of the seven storms examined caused substantial increases in growth and new establishment for the dominant species; most moderate disturbances had minimal impact on growth and regeneration dynamics. We also document highly variable responses among species to individual storms, including substantial growth decreases that may not be detected by standard analytical approaches. Conclusions: Our results caution against the use of simple metrics such as wind speed to predict forest response to specific hurricanes, and highlight the importance of individual disturbance events in controlling long‐term forest dynamics, even in regions characterized by high disturbance frequency. In addition, we show that standard approaches to reconstructing disturbance history based on increases in radial growth and pulses of tree establishment are likely to underestimate the frequency of moderate disturbances. 相似文献
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KERRY D. WOODS 《Journal of Ecology》2004,92(3):464-476
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Toshihiko Sato 《Ecological Research》2000,15(3):335-344
Emergence, survival and mortality patterns of current-year oak (Quercus crispula Blume) seedlings were investigated for 4 consecutive years in a secondary oak forest in Hokkaido, northern Japan. Despite the emergence of a considerable number of oak seedlings in the years following masting, few current-year seedlings survived until the end of the growing season. Almost all of the seedlings died from damage to their stems caused by the gnawing of rodents. Rodent gnawing on transplanted oak seedlings was also observed in the year following masting but not in the year following a bad crop year. Cuttings of dwarf bamboo, Sasa, did not reduce the seedling mortality caused by gnawing. However, transplanted oak seedlings were gnawed more quickly when they were placed on the forest floor with a thicker Sasa covering. All rodents trapped in the vicinity of the study area were Apodemus speciosus Temminck. These results suggest that rodents strongly influence the recruitment of oak trees not only through the predation and dispersal of acorns but also through gnawing seedlings. 相似文献
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在宁夏六盘山区龙潭林区华北落叶松(Larix principis-rupprechtii )人工林的不同样带, 按6个密度梯度(3.24、2.56、1.96、1.44、1.00和0.64株·m-2)移栽萌发生根的辽东栎(Quercus wutaishanica)幼苗, 研究了啮齿动物对幼苗子叶取食的密度效应及其对幼苗存活与生长的影响。结果表明, 辽东栎幼苗的子叶留存率随着幼苗密度的增大而减小。2个高密度处理(3.24和2.56株·m-2)的幼苗子叶留存率分别在移栽6周和5周后稳定在最低水平, 分别为8.64%和7.81%; 而2个较低密度处理(1.44和0.64株·m-2)的幼苗在最后一次观测时子叶留存率仍很高, 分别为44.44%和31.25%, 且二者均显著高于其他密度处理(p < 0.05)。受啮齿动物取食的影响, 在从高到低的不同密度处理下, 幼苗的主根留存率分别为64.16%、80.46%、87.23%、80.25%、69.84%和69.84%; 在1.44株·m-2处理下, 顶芽留存率最高(25.23%), 显著大于3.24株·m-2处理(4.19%) (p < 0.05), 其他密度处理的顶芽留存率均不足20%。子叶被动物取食的幼苗和子叶完整幼苗的最终留存率基本一致, 仅在个别密度处理的某一观测时期差异显著; 顶芽被动物取食的幼苗留存率略低于顶芽完整幼苗的留存率, 但个别密度处理完全相反; 不同类型幼苗的留存率随时间推移而上下波动, 可能与幼苗顶芽被动物取食后萌生形成新芽有关。幼苗的株高、基径、叶片数和单株叶面积均随密度的减小而略有增大, 但除株高外, 其他3个生长参数均在1.44株·m-2处理时最大, 与子叶是否被动物取食有一定的对应关系, 即高密度下更多的幼苗丢失了供应其生长所需营养物质的子叶, 从而影响了幼苗的早期生长。研究结果不仅丰富了“负密度效应”理论和种群更新的“增补限制”理论, 也可为六盘山区退化辽东栎灌丛和辽东栎次生林的恢复及生态系统管理提供 参考。 相似文献
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We evaluated leaf characteristics and herbivory intensities for saplings of fifteen tropical tree species differing in their successional position. Eight leaf traits were selected, related to the costs of leaf display (specific leaf area [SLA], water content), photosynthesis (N and P concentration per unit mass), and herbivory defence (lignin concentration, C:N ratio). We hypothesised that species traits are shaped by variation in abiotic and biotic (herbivory) selection pressures along the successional gradient. All leaf traits varied with the successional position of the species. The SLA, water content and nutrient concentration decreased, and lignin concentration increased with the successional position. Herbivory damage (defined as the percentage of damage found at one moment in time) varied from 0.9-8.5% among the species, but was not related to their successional position. Herbivory damage appeared to be a poor estimator of the herbivory rate experienced by species, due to the confounding effect of leaf lifespan. Herbivory rate (defined as percentage leaf area removal per unit time) declined with the successional position of the species. Herbivory rate was only positively correlated to water content, and negatively correlated to lignin concentration, suggesting that herbivores select leaves based upon their digestibility rather than upon their nutritive value. Surprisingly, most species traits change linearly with succession, while resource availability (light, nutrients) declines exponentially with succession. 相似文献
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该研究运用方差比率法、χ~2检验、Pearson相关检验和Spearman轶相关检验,对广西雅长兰科植物国家级自然保护区南盘江流域的细叶云南松(Pinus yunnanensis Franch.var.tenuifolia Cheng et Law)次生林14个大树树种(DBH≥10cm)、15个小树树种(5cm≤DBH10cm)和19个幼树树种(1cm≤DBH5cm)进行定量分析,以揭示南盘江流域细叶云南松次生林群落中木本种群的关联性及其更新演替规律,为桂西北细叶云南松林管理保护、干热河谷地区植被恢复和生态重建提供参考依据。结果表明:(1)研究区内细叶云南松林大树和小树的总体关联性表现为不显著负关联,幼树及群落总体表现为不显著正关联;χ~2检验显示,大树和小树负关联种对占多数(分别为48.35%和46.67%),幼树的正关联或负关联种对占比基本持平(分别为40.35%和39.18%),群落整体无关联种对占比较大(41.13%)。(2)Pearson相关系数和Spearman秩相关系数检验显示,细叶云南松林的大树、小树、幼树和群落总体均表现为负关联种对较多,正关联次之。(3)群落大树和小树物种在资源竞争上较激烈,结构不稳定;群落幼树物种适应了林下荫蔽环境,对光照要求较低,种间关系已具有较低的稳定性,个别物种表现出独立性。研究认为,南盘江流域细叶云南松次生林群落物种间存在一定的关联性,但未能形成稳定的配置关系,群落结构尚不稳定,仍处于演替早期阶段。 相似文献
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山杏（Prunus armeniaca)是广布于北京山区阳坡的矮林或灌丛,易生存在土壤贫脊、干旱、或严重退化的山坡、裸地,对于保护生态环境,减少水土流失及促进山区经济发展均具有重要作用。有关鼠类在山杏更新中作用的研究较少,本研究主要是确定影响山杏更新的鼠类种类、鼠类对山杏种子的取食压力、人工埋藏种子及植被因素对种子存活和萌发的影响。于1997年10月3－4日,采用夹捕法同时调查取食花生和山杏种子的鼠类种类及种群密度。于1997年9月24－25日,通过在地表放置山桔种子,调查在鼠类取食下,地表种子消失的速度。于1997年10月20日,作种子埋藏实验,调查种子存活及萌发情况。于1997年10月26日,进行扣网实验,研究网内、外山杏种子存活及萌发情况。结果表明：大林姬鼠（Apodemus speciosus)、社鼠（Rattus confucianus),黑线姬鼠（Apodemus agrarius)为取食山杏种子的主要鼠种种类;与取食花生相比,社鼠更偏爱山杏种子,大林姬鼠对山杏种子喜食性略低,黑线姬鼠对二者喜食程度相近;山杏种子放置地表后1、10、20、30d的消失率分别为13.06%,64.46%,90.70%,96.69%;扣网实验说明,山杏在地表的萌发率极低,生长也慢;而埋入土层内可明显提高萌发率和生长率（若除去鼠类的取食,萌发率还要高）;人工埋藏实验表明,将山杏种子埋入土层5cm后,能够有效地减少鼠类对种子的取食;通过分析山杏种子萌发与植被的关系,发现山杏易在开阔、阳光充分的草丛中存活和生长,而不易在阴闭的灌丛下存活和生长。 相似文献
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IGNACIO M. PÉREZ-RAMOS TEODORO MARAÑÓN JORGE M. LOBO JOSÉ R. VERDÚ 《Ecological Entomology》2007,32(4):349-356
Abstract. 1. Plant–animal interactions, and in particular the processes of seed predation and dispersal, are crucial for tree regeneration and forest dynamics. A novel and striking case of interaction between a dung beetle ( Thorectes lusitanicus ) and two Quercus species ( Q. suber and Q. canariensis ) in forests of southern Spain is presented here.
2. During the autumn, T. lusitanicus beetles (endemic to the southern Iberian Peninsula) bury and feed on single-seeded fruits (acorns) of Quercus , with important ecological implications.
3. Field experiments found differences in the removal rate of acorns by T. lusitanicus , depending on the type of microsite within the forest, the species of oak, the exclosure of large herbivores, and the forest site.
4. Acorn consumption by T. lusitanicus was studied under laboratory conditions, confirming for the first time that this dung beetle is a legitimate seed predator.
5. In addition, some buried acorns can be abandoned partially predated or even intact, and emerge as seedlings; thus, T. lusitanicus also has a potential role as secondary seed disperser. 相似文献
2. During the autumn, T. lusitanicus beetles (endemic to the southern Iberian Peninsula) bury and feed on single-seeded fruits (acorns) of Quercus , with important ecological implications.
3. Field experiments found differences in the removal rate of acorns by T. lusitanicus , depending on the type of microsite within the forest, the species of oak, the exclosure of large herbivores, and the forest site.
4. Acorn consumption by T. lusitanicus was studied under laboratory conditions, confirming for the first time that this dung beetle is a legitimate seed predator.
5. In addition, some buried acorns can be abandoned partially predated or even intact, and emerge as seedlings; thus, T. lusitanicus also has a potential role as secondary seed disperser. 相似文献
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Forest succession on degraded tropical lands often is slowed by impoverished seed banks and low rates of seed dispersal. Within degraded landscapes, remnant forests are potential seed sources that could enhance nearby forest succession. The spatial extent that forest can influence succession, however, remains largely unstudied. In abandoned agricultural lands in Kibale National Park, Uganda, recurrent fires have helped perpetuate the dominance of tall (2–3 m) grasses. We examined the effects of distance from forest and grassland vegetation structure on succession in a grassland having several years of fire exclusion. At 10 and 25 m from forest edge, we quantified vegetation patterns, seed predation, and survival of planted tree seedlings. Natural vegetation was similar at both distances, as was seed (eight species) and seedling (six species) survival; however, distance may be important at spatial or temporal scales not examined in this study. Our results offer insight into forest succession on degraded tropical grasslands following fire exclusion. Naturally recruited trees and tree seedlings were scarce, and seed survival was low (20% after 7 mo). While seedling survival was high (95% after 6 to 8 mo), seedling shoot growth was very slow (x?= 0.5 cm/100 d), suggesting that survivorship eventually may decline. Recurrent fires often impede forest succession in degraded tropical grasslands; however, even with fire exclusion, our study suggests that forest succession can be very slow, even in close proximity to forest. 相似文献
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Xuezhao Wang Yunyun He Brian E. Sedio Lu Jin Xuejun Ge Suphanee Glomglieng Min Cao Jianhong Yang Nathan G. Swenson Jie Yang 《Ecology letters》2023,26(11):1898-1910
Metabolomics provides an unprecedented window into diverse plant secondary metabolites that represent a potentially critical niche dimension in tropical forests underlying species coexistence. Here, we used untargeted metabolomics to evaluate chemical composition of 358 tree species and its relationship with phylogeny and variation in light environment, soil nutrients, and insect herbivore leaf damage in a tropical rainforest plot. We report no phylogenetic signal in most compound classes, indicating rapid diversification in tree metabolomes. We found that locally co-occurring species were more chemically dissimilar than random and that local chemical dispersion and metabolite diversity were associated with lower herbivory, especially that of specialist insect herbivores. Our results highlight the role of secondary metabolites in mediating plant–herbivore interactions and their potential to facilitate niche differentiation in a manner that contributes to species coexistence. Furthermore, our findings suggest that specialist herbivore pressure is an important mechanism promoting phytochemical diversity in tropical forests. 相似文献
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Geoffery M. Wahungu Lucy K. Mureu Yussuf A. Wato Sarah N. Mureithi Geoffery G. Karanja 《African Journal of Ecology》2010,48(3):783-790
The spatial patterns of seedling distribution in Manilkara butugi were studied between December 2004 and April 2005 at Kakamega forest, Kenya. Our objectives were to determine the spatial variation in seedling density in relation to distance from the parent tree and the survivorship patterns of M. butugi seedlings. We hypothesized that seedling density and mortality would be highest beneath the parent tree and would reduce with increasing distance from the parent tree. Line transects, radiating along the four compass directions from mature female M. butugi trees were established, and quadrats marked out at intervals of 5 m in which seedlings were counted. To determine establishment and survivorship, belt transects 5 m × 40 m running along the northerly compass direction were laid and data collected on seedling variables. Seedling density reduced with increasing distance from the parent plant (F = 25.72, df = 3; P < 0.001). Whereas seedling height (F = 14.806, df = 1; P < 0.05) and the number of leaves (F = 12.45, df = 1; P < 0.05) increased with increasing distance from the parent tree, damage to seedlings reduced with increasing distance (F = 27.59, P < 0.05). Our results were consistent with the Janzen–Cornell escape hypothesis and have implications for natural regeneration of M. butugi and to maintenance of species diversity. 相似文献
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Robert W. Johnson William J. McDonald Roderick J. Fensham Clive A. McAlpine Michael J. Lawes 《Austral ecology》2016,41(6):644-656
Plant succession theory underpins the development of strategies for the conservation and regeneration of native communities. Current theory has been based largely on space‐for‐time rather than long‐term monitoring data, which have known limitations. There is general consensus that more site‐specific studies are needed to corroborate existing hypotheses. The target vegetation is a brigalow (Acacia harpophylla, Mimosaceae) forest in one of Australia's most endangered ecosystems, which was cleared and burnt in 1963. Forty quadrats were placed systematically within each of six 20 m × 20 m permanent plots. Presence, density and per cent canopy cover data were recorded for each species at 18 times over 46 years. Brigalow dominated the original vegetation, assumed dominance soon after clearing through massive root suckering and remained dominant throughout the study. It achieved maximum density within two years when severe intraspecific competition led to self‐thinning. After approximately 30 years, vacant niches appeared. Woody understorey species were slow to recolonise. Species richness and other diversity indices increased rapidly to a maximum after 2–4 years, declined until the 30th year when they again increased. This was the pattern of the species‐rich herbaceous layer; woody species showed a steady monotonic increase. The ‘hump‐shaped’ relationship between cover (biomass) and species richness was confirmed. This example fits the inhibition model for which few examples have been described. While the long‐term successional pattern is slightly confounded by climatic variability preceding sample surveys, this space‐for‐time study not only supports a bimodal pattern of diversity over time but also indicates that the relative species richness of the herbaceous and woody layers may explain the extreme variability reported in the literature. 相似文献
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A sowing experiment was carried out using three endemic secondary successional species that commonly co‐occur with Pinus halepensis in afforestations in southeast Spain. The experiment simulated the natural arrangement of needle litter over soil to test the litter's effect on seedling emergence and early growth of dwarf‐shrubs and annual species, the main components of some European Habitats of Community Interest in Spain. Three sowing treatments were compared in a growth chamber: (1) soil without litter taken from clearings in a pine plantation (BARE); (2) intact soil and litter forming two distinct layers as in the field (PINE); and (3) soil and pine litter mixed in the laboratory (PINEMX). Seedling emergence of Diplotaxis harra and Thymus zygis were seven and two times higher, respectively, on BARE than on the pine litter treatments. Pine litter significantly decreased seedling biomass, length, and number of leaves of D. harra and T. zygis. Thymus capitatum was weakly affected by the presence of pine litter. We suggest that plant recruitment in the understory of P. halepensis is partially controlled by interference of pine litter, which might affect dynamics of the studied species. We propose that management practices counteract this negative effect by manipulating the pine litter layer to achieve successful ecological restoration and conservation of endemic‐rich secondary communities in Natura 2000 sites in semiarid western Mediterranean areas. 相似文献