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KERRY D. WOODS 《Journal of Ecology》2004,92(3):464-476
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银杉(Cathaya argyrophylla)林林窗更新的研究 总被引:17,自引:1,他引:16
银杉(Cathaya argyrophylla)在林窗内和非林窗群落内均占有最大的重要值,说明银杉是典型的林窗更新方式.银杉个体在林窗内呈集群分布,林窗边缘往往集中了较多的银杉植株。林窗内银杉直径分布中,出现胸径〉8cm 及胸径〈3cm的高峰和3~7cm的低谷。对最近10a银杉幼树每年高生长量的研究发现,林窗内和荫蔽要完下的结果差异显著,林窗内的幼树高生长快于荫蔽林冠下。 相似文献
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西天目山黄山松阔叶林的冠层干扰与动态推测 总被引:7,自引:2,他引:5
根据年龄结构和直径生长图分析研究了浙江省西天目山黄山松阔叶混交林的冠层干扰年表和发展动态。结果表明黄山松在该林地的定居发生在1861-1880年之间,黄山松定居30-40年后,其他阔叶树开妈在林下萌发生长,形成目前的黄山阔叶混交林,该林浆被阔叶叶树取代。 相似文献
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Differential predation on mangrove propagules in open and closed canopy forest habitats 总被引:2,自引:0,他引:2
Amounts of seed predation by grapsid crabs (Brachyura: Grapsidae) on two species of mangroves (Aegiceras corniculatum and Avicennia marina) were compared among different habitats in an Australian mangrove forest. For Avicennia, comparisons were between canopy gaps and the adjacent forest understory for six, mid intertidal, gaps of different sizes. For Aegiceras the comparisons were among canopy gaps in the high intertidal; open, accreting mud/sand banks where mangroves were colonizing in the low intertidal; and in the forest understory in both the high and low intertidal zones. These were repeated in the high salinity (35\%) downstream portion and the low salinity (0–5\%) upstream portion of a tidal river.Predation on Avicennia was significantly higher in the understory than in adjacent canopy gaps. Within a canopy opening, predation was greatest in the smallest gaps and lowest in the largest gaps. Predation on Aegiceras was greater in the high intertidal compared to the low intertidal, but no differences were found between river mouth and upstream locations. In the high intertidal zone of the forest, there were no differences in predation between canopy gap or forest understory sites for Aegiceras. In the low intertidal zone, however, significant differences in amount of predation were found between habitats. More Aegiceras propagules were consumed in the understory than on adjacent accreting sandbanks.Frequency of tidal inundation, which in turn affects the amount of time available to forage, is hypothesized to account for differences in predation between low and high intertidal forests and between small and large canopy gaps. Our results also suggest that shade intolerance in these two species may actually reflect an escape from predators, successful when the seeds are dispersed into open areas such as canopy gaps or mud banks. 相似文献
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亚高山云冷杉混交林树木生长释放与干扰分析 总被引:9,自引:2,他引:9
对云南碧塔海亚高山云冷杉林内4个样地冠层树木的生长压制和释放的历史,用树木年轮分析方法进行了重建,然后根据生长释放频率推测林冠干扰强度(每10年冠层树木的死亡百分率)。4个林分(1个中龄林,3个成过熟林)生长释放的平均百分率为48%~92%。中龄林内,平均生长释放频率为71%/10a,成过熟林则为74%~95%/10a,在油麦吊云杉〔Piceabrachytylavar.complanata(Mast.)ChengexRehd.〕占优势的林分和大果红杉(Larixpotaninivar.macrocarpaLaw)油麦吊云杉混交林分内,估测的林冠干扰强度分别为48%/10a和59%/10a。 相似文献
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Soil-plant interactions in a neotropical mangrove forest: iron, phosphorus and sulfur dynamics 总被引:5,自引:0,他引:5
We examined soil porewater concentrations of sulfate, alkalinity, phosphorus, nitrogen, and dissolved organic carbon and
solid phase concentrations of pyrite in relation to mangrove species distributions along a 3.1-km-long transect that traversed
a 47.1-km2 mangrove forest in the Dominican Republic. Iron, phosphorus, and sulfur dynamics are closely coupled to the activity of sulfate-reducing
bacteria, the primary decomposers in anoxic soils of mangrove ecosystems. Patterns in the chemistry data suggested that sulfate
reduction rates and storage of reduced sulfur were greater in the inland basin forest dominated by Laguncularia racemosa than the Rhizophora mangle dominated forest of the lower tidal region. The distribution of Laguncularia was significantly correlated with concentrations of total phosphorus (r= 0.99) and dissolved organic carbon (r= 0.86), alkalinity (r= 0.60), and the extent of sulfate depletion (r= 0.77) in the soil porewater and soil pyrite concentrations (r= 0.72) across the tidal gradient. Leaf tissue chemistry of Laguncularia was characterized by lower C:N and C:P ratios that could fuel the higher rates of decomposition in the Laguncularia-dominated forest. We suggest that a plant-soil-microbial feedback contributes to the spatial patterning of vegetation and
soil variables across the intertidal zone of many mangrove forest communities.
Received: 28 May 1997 / Accepted: 23 January 1998 相似文献
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Turnover within both mangrove and terrestrial forests is driven by standdevelopment in conjunction with factors influencing tree death andreplacement at various temporal and spatial scales. Development interrestrial forests appears comparable with that in mangroves but turnoverseems to differ considerably between these broad forest types. The mostimportant difference is in the character of small forest gaps. Gaps arecommon in terrestrial forests but those in mangroves rarely involve falls oflarge older trees in the first instance. Instead, mangrove trees usually diestanding in small clusters of mixed age cohorts. Identifying a common causefor gap creation in mangroves might be important towards understandingwhat drives forest turnover but there is a greater need to quantify thisprocess. Small-scale disturbance in mangrove forests is poorly quantified butpreliminary evidence implies that its' importance may have been greatlyunder-estimated. Based on available observations, a conceptual model ofmangrove forest development and gap regeneration is proposed. The modelhelps explain the peculiar characteristics and structure of mangrove forestsand how these forests might respond to changing environmental conditionsand disturbance at various landscape scales. 相似文献
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Hurricane disturbance in a temperate deciduous forest: patch dynamics, tree mortality, and coarse woody detritus 总被引:1,自引:0,他引:1
Patch dynamics, tree injury and mortality, and coarse woody detritus were quantified to examine the ecological impacts of
Hurricane Fran on an oak-hickory-pine forest near Chapel Hill, NC. Data from long-term vegetation plots (1990–1997) and aerial
photographs (1998) indicated that this 1996 storm caused patchy disturbance of intermediate severity (10–50% tree mortality;
Woods, J Ecol 92:464–476, 2004). The area in large disturbance patches (>0.1 ha) increased from <1% to approximately 4% of
the forested landscape. Of the forty-two 0.1-ha plots that were studied, 23 were damaged by the storm and lost 1–66% of their
original live basal area. Although the remaining 19 plots gained basal area (1–15% increase), across all 42 stands basal area
decreased by 17% because of storm impacts. Overall mortality of trees >10 cm dbh was 18%. The basal area of standing dead
trees after the storm was 0.9 m2/ha, which was not substantially different from the original value of 0.7 m2/ha. In contrast, the volume and mass of fallen dead trees after the storm (129 m3/ha; 55 Mg/ha) were 6.1 and 7.9 times greater than the original levels (21 m3/ha; 7 Mg/ha), respectively. Uprooting was the most frequent type of damage, and it increased with tree size. However, two
other forms of injury, severe canopy breakage and toppling by other trees, decreased with increasing tree size. Two dominant
oak species of intermediate shade-tolerance suffered the largest losses in basal area (30–41% lost). Before the storm they
comprised almost half of the total basal area in a forest of 13% shade-tolerant, 69% intermediate, and 18% shade-intolerant
trees. Recovery is expected to differ with respect to vegetation (e.g., species composition and diversity) and ecosystem properties
(e.g., biomass, detritus mass, and carbon balance). Vegetation may not revert to its former composition; however, reversion
of biomass, detritus mass, and carbon balance to pre-storm conditions is projected to occur within a few decades. For example,
the net change in ecosystem carbon balance may initially be negative from losses to decomposition, but it is expected to be
positive within a decade after the storm. Repeated intermediate-disturbance events of this nature would likely have cumulative
effects, particularly on vegetation properties. 相似文献
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米槠-木荷林优势种群的年龄结构及其更新策略 总被引:1,自引:0,他引:1
通过年轮分析,构建了浙江天童米槠-木荷林优势种木荷、米槠、石栎的年龄结构,分析了高生长和径向生长及萌枝策略随年龄的变化规律,探讨了干扰对群落动态的影响。研究结果表明:(1)3个物种的胸径、高度与年龄的关系均可用logistic曲线和线性模型拟合,但随年龄增加胸径、高度与年龄的关系显著下降。(2)随年龄增加3树种的DBH/H逐渐增加,米槠、石栎幼龄个体(1-20a)的有萌个体率和有萌个体萌枝数逐渐下降;米槠和石栎幼苗的主干较木荷细长、多萌枝,木荷和石栎成树主干较米槠细长;体现了米槠的更新策略具开拓性,木荷的具保守性,石栎在幼龄期具开拓性,成年期转为保守性。(3)米槠和石栎的年龄结构呈逆J型,幼龄个体充足,但中龄段(21-40a)存在更新断层,这与其高消耗的开拓性策略有关;木荷的年龄结构呈间歇型,各龄级均存有个体,这与其保守性策略有关;(4)3物种在大龄级上(52-60a)均存在更新高峰,与该地区的择伐干扰时间一致,高强度的干扰促生了次生演替,形成了以木荷为第一优势种的群落。(5)米槠、木荷、石栎的年龄结构是更新策略和干扰的综合表现,它不仅与径级结构一样可展现种群更新特征、预测种群发展动态,更能精确地反映群落动态事件的发生频次和发生时间。 相似文献
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NEAZ AHMAD SIDDIQI 《Austral ecology》1995,20(2):340-343
Abstract A study in the Bangladesh Sundarbans forest observed the impact of crabs on mangrove regeneration. Crabs were not found to cause any damage to the seedlings of experimental plots. In addition, no morphological damage attributable to crabs was observed in Rhizophora propagules collected from the forest floor. Further studies covering other areas of the forests have been suggested. 相似文献
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Shin-Ichi Yamamoto 《Ecological Research》1993,8(3):277-285
Gap characteristics and gap regeneration were studied in three mature stands belonging to different community types in a subalpine
coniferous forest on Mt Ontake, central Honshu, Japan. Gap disturbance regimes were remarkably similar among stands studied;
percentage gap area to surveyed area, gap density and mean gap size were 7.3–8.5%, 17.8–20.0 ha−1 and 40.8–42.5 m2, respectively. The gap size class distributions were also similar and showed a strong positive skewness with a few large
and many small gaps; gaps <40m2 were most frequent and gaps >200m2 were rare. Forty-five to 66% of gaps were due to the death of single canopy trees. Canopy trees more often died leaving standing
dead wood (40–5.7%) or broken trunks (43–49%). Shade tolerantAbies mariesii andAbies veitchii, frequently, andTsuga diversifolia, less frequently, regenerated in gaps, from advance regenerations recruited before gap formation.Picea jezoensis var.hondoensis may regenerate in gaps, from new individuals recruited after gap formation. The breakage of denseSasa coverage and the mineral soils exposed by the uprooted plants that form gaps might provide regeneration opportunities for
shade intolerantBetula. Of the important species limited to the ridge site,Chamaecyparis obtusa, frequently, andThuja standishii, infrequently, regenerated from plants alreadyin situ. Regeneration ofPinus parviflora was not seen. Based on the gap characteristics and gap regeneration behaviour of each species described, stand dynamics in
each stand are discussed. 相似文献
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Decomposition of Avicennia marina (Forsk.) Vierh. leaf and woody litter (twigs) was studied using litter bag experiments in a subtropical mangrove forest at two tidal levels (high and low) with different inundation regimes and during two seasons (summer and winter). Losses in dry weight were best described by a single exponential model which showed loss rates of both leaves and twigs were significantly higher low down on the shoreline (greater inundation) and in summer. The time (days) required for the loss of half of the initial dry weight (t
50) was summer: high 59, low 44; winter: high 98, low 78. For twigs the values (days) were summer: high 383, low 179; winter; high 1327, low 1207. There is an exponential relationship between leaf litter t
50's and latitude which indicates the importance of temperature and therefore season, to the dynamics of organic cycling and export in mangrove systems. 相似文献
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