林火干扰对北方针叶林林下植被的影响

林下植被在北方针叶林植被群落中的物种多样性最高, 且具有较高的生物量周转率和地上部分净初级生产力, 对北方针叶林生态系统功能起着重要作用。火干扰是决定北方针叶林林下植被结构与功能的一个重要景观过程。该文综述了火干扰是如何通过与地形、火前林冠组成的交互作用而影响环境资源和林下植被的。最近的研究表明: 林下植被能够影响火后树木更新苗的定植、重建速率及森林演替轨迹; 林下植被还会通过影响元素的生物地球化学过程(凋落物降解和养分循环)影响林下环境资源的数量与异质性。因此, 研究火后初期北方针叶林林下植被的动态变化, 对于物种多样性保护和森林管理具有重要意义。     

Rapid understory plant recovery following forest floor protection on temporary drilling pads

Oil sands exploration fragments the boreal landscape by constructing numerous drilling pads to assess underground petroleum reserves. Reclamation of these pads is challenging and slow, particularly for forest understory species. We investigated the feasibility of accelerated forest understory restoration on these temporary pads by taking advantage of the propagule bank and clonal regeneration strategy of many boreal plants. We covered and protected the forest floor (FF) with subsoil during winter pad construction. This forest floor protection (FFP) method was then compared with the current practice of stripping off, stockpiling, and then replacing the FF during the reclamation phase (rollback, RB) and to conventional clearcut (CC) harvesting. In the first growing season, surface disturbance as well as richness and cover of plant regeneration was evaluated; vegetation assessment was repeated in the fifth growing season. Although there were some slight differences between the communities in the FFP and CC treatments, likely associated with varying levels of residual slash and subsoil material, there were striking differences between the communities in the RB and FFP treatments. In addition, while establishment of deciduous tree species was similar between the FFP and CC treatments, there were very few trees found in the RB treatment. The study indicates that protection and careful uncovering of the FF during temporary drilling pad construction should be a technique of choice for forest reclamation used in the boreal forest. However, as RB will still play a part in the reclamation of these sites, management intervention will be required to achieve reclamation goals.     

Major disturbances test resilience at a long‐term boreal forest monitoring site

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Midsummer spatial variation in methane efflux from stands of littoral vegetation in a boreal meso-eutrophic lake

1. Spatial variation of methane (CH₄) efflux from the littoral zone of a meso‐eutrophic boreal lake was studied with a closed‐chamber technique for three summer days in 22 vegetation stands, consisting of three emergent and three floating‐leaved species. 2. Between‐species differences in CH₄ emission were significant. The highest emissions were measured from the emergent Phragmites australis stands (0.5–1.7 mmol m^?2 h^?1), followed by Schoenoplectus lacustris > Equisetum fluviatile > Nuphar lutea > Sparganium gramineum > Potamogeton natans. Within‐species differences between stands were not significant. 3. In P. australis stands, the stand‐specific mean CH₄ emission was significantly correlated with solar radiation, probably indicating the role of effective pressurised ventilation on CH₄ fluxes. The proportion of net primary production emitted as CH₄ was significantly higher in P. australis stands (7.4%) than in stands of S. lacustris and E. fluviatile (both 0.5%). 4. In N. lutea stands, CH₄ efflux was negatively correlated with the mean fetch and positively with the percentage cover of leaves on the water surface. There were no differences in CH₄ efflux between intact N. lutea leaves and those grazed by coleopteran Galerucella nymphaeae. In S. graminaeum and P. natans stands, CH₄ effluxes were not related to any of the measured environmental variables. 5. For all vegetation stands, the biomass above water level explained about 60% of the observed spatial variation in CH₄ emission, indicating the important role of plants as gas conduits and producers of substrates for methanogens in the anoxic sediment.     

中国植被地理学:从传统植被地理学到功能植被地理学

本文回顾总结了我国植被地理学发展的历史,展望了其从传统植被地理学到功能地理学的未来研究趋势。作为研究植被地理分布规律的一门科学,植被地理学在我国经历了与社会经济发展密切相关的四个阶段：早期起步阶段,主要是新中国成立前(1920年代—1949)的植物地理学和植被地理学的零星工作;初期成长阶段,主要是新中国成立后至改革开放前(1949—1980)的传统植被地理学研究;中期迅速发展阶段,主要包括改革开放后至经济迅速发展时期(1980—2000),在全球气候变化国际研究背景下的植被地理学研究;近期转型与拓展阶段,主要是国民经济平稳发展及信息时代(2000—至今),面向全球环境变化的植被地理学研究的纵深发展。经过近百年的发展,在植被综合区划与生态功能区划、中国植被分类系统订正、中国植被图与植被志编纂、古植被地理学、植被地理模拟预测与情景分析、植物功能性状和生态化学计量学的功能植被地理学等6个方面取得了可喜成果。今后,需要在以下4个方面开展更广泛的精细与纵深研究：加强更多精细化的植被地理学研究,编纂新一代中国植被图与中国植被志;深入开展人类干扰的植被地理学研究;以植物性状研究为契机,拓展宏观功能植...     

Changes in vegetation after 22 years' natural restoration in the Karst disturbed area in northwestern Guangxi, China

Variations of plant vegetation and spatial distribution were investigated in the areas of 4 types of typical disturbance, which had been under natural restoration for 22 years in the Karst area in northwestern Guangxi while the climax plant community was utilized as control. The slope scale and disturbance theory were used to study the plant diversity in the whole area and selected plots. It is clear that the disturbance had resulted in severe loss of plant species, and only 241 species of vascular plants that belong to 91 families and 206 genera survived in disturbed areas, accounting only for 26.6% of those in the natural reserve area. The consequent succession of 6 types of plant vegetation was sparse grass of rocky desertification, grass, shrub, liana-shrub, deciduous broad-leaved forest and mixed segment of evergreen and deciduous broad-leaved forest. The height, coverage, biomass and species diversity of plants decreased sharply with slope elevating, and the plant density appeared with normal distribution. Compared with the natural reserve area, all indices of plant vegetation in disturbed areas were much worse. Furthermore, different types of disturbance showed various affections on natural vegetative restoration, among which tilling after the whole slope was set on fire caused the worst impact and rocky desertification was the consequence, followed by depasturing after the whole slope was set on fire. Cutting was selective disturbance, and the vegetative restoration in the area with combination of cutting, grazing and setting on fire on the upper slope was relatively fast; however, it was even better in the area with combination of cutting and setting the upper slope on fire. In our studies, 4 strategies for vegetative recovery, using both natural and artificial approaches, were established, which were suitable for the Karst area in northwestern Guangxi.     

桂西北喀斯特人为干扰区植被自然恢复22年后群落特征

采用全面调查和样方调查的方法,以坡面为尺度,以顶极群落为对照,运用干扰理论和多样性分析方法,研究了桂西北喀斯特4类典型干扰区自然恢复22a之后植被特征及空间分布的变化。结果表明,干扰区的物种多样性丧失严重,共出现维管束植物91科206属241种,仅有自然保护区的26．6％,6种植被类型的顺向演替系列为石漠化稀疏草丛→草丛→灌丛→藤刺灌丛→落叶阔叶林→常绿落叶阔叶混交林片段。随着坡位的上升,群落的高度、盖度、生物量和物种多样性急剧下降。密度则呈少、多、次少的单峰分布状态,各项指标均远低于自然保护区。不同干扰方式对植被自然恢复的影响不同,其中整坡火烧＋垦殖的破坏性最大,呈现了石漠化景观,整坡火烧＋放牧次之,采樵属选择性干扰,采樵＋放牧＋坡脚火烧的恢复相对较快,没有放牧干扰的采樵＋坡脚火烧恢复更好。此外还针对性地提出了桂西北喀斯特干扰区在不同立地类型上人工与自然相结合的4条植被恢复途径。对因各种人为干扰导致的桂西北喀斯特生态系统处于极度退化状态下的植被恢复建设和生态重建具有重要的理论价值和实际意义。     

Temporal variation in the drift of plant litter and propagules in a small boreal river

SUMMARY 1. Rivers are linear ecosystems across landscapes with an effective transport of organisms, sediment and organic matter. Dispersal is studied mostly during single events and for single species, and there is little knowledge on how the drift of plant litter and propagules varies within and between years for entire communities.
2. We used floating traps for collecting waterborne plant litter and propagules in a small boreal river over 2 years. We installed the traps at four different locations along the river, and emptied them at least once a week during the ice-free season. We analysed propagule content by sorting and identifying species and through germination tests on bare soil.
3. In total, we recorded at least 54 taxa in the samples, and the highest density recorded in one sample was 5000 propagules per 100 g litter (dry weight). Large temporal variations in litter and propagule transport were revealed, both within and between years.
4. The longitudinal pattern was consistent between years, with an increasing mass of litter and number of propagule taxa downstream. The results highlight the importance of the temporal and longitudinal dimensions in river management.     

植被、海拔、人为干扰对大中型野生动物分布的影响——以九寨沟自然保护区为例

利用九寨沟自然保护区内8条动物监测样线在2003—2010年的生态监测数据,分析了植被、海拔、人为干扰对大中型野生动物分布的影响,结果显示:1)本监测共记录到保护区内大中型野生动物26种,其中兽类18种,鸟类8种,属于我国Ⅰ级、Ⅱ级保护动物的分别有5种和11种。2)针阔混交林和针叶林是大中型野生动物种类最丰富的两种植被类型(分别有26种和17种),阔叶林和灌丛次之(分别为10种和12种),草地最少(2种)。3)海拔2400 m以下的地方,大中型野生动物种类稀少,为10种,2400—2599 m海拔段物种数增加至20种,之后随海拔上升物种丰富度下降。4)人为干扰显著影响大中型野生动物的空间分布:历史上的人类活动将原生森林植被转化为次生的落叶阔叶林、灌丛和草地,使树正、亚纳和尖盘等地下坡位(相对海拔0—199 m)的大中型野生动物的物种丰富度降低(分别为4、2、2种)。包括旅游活动和交通在内的人为干扰,可能导致附近50m海拔范围内保护动物的缺失,并使下坡位的某些物种向高海拔处移动。生境破碎化则使野生动物的种类组成发生改变,使原有森林内部优势种,如羚牛(Budorcas taxicolor),逐渐被适应能力强的物种,如豹猫(Prionailurus bengalensis)、雉鸡(Phasianuscolchicus)和野猪(Sus scrofa)等所取代,并将长期影响野生动物种群的存活。当前九寨沟自然保护区大中型野生动物的分布是植被、海拔与人为干扰综合作用的结果。     

Vegetation patterns and their dependency on site conditions in the pre-industrial landscape of north-eastern Japan

We reconstructed the vegetational landscape of the pre-industrial era (the beginning of the twentieth century) in north-eastern Japan, and estimated the distribution patterns of traditional land-uses, as suggested from the vegetation. We found significant correspondence between the spatial patterns of vegetational landscape and site attributes, and hypothesized the underlying mechanisms. The study area was classified into three vegetation types: grasslands, secondary forests and old-growth forests. It was determined that the grasslands were formed and maintained by burning; secondary forests were derived from either charcoal woods or forests recovered on abandoned grasslands; and old-growth forests had suffered the least anthropogenic disturbance. Each past vegetation type showed significant dependency on site attributes such as altitude, slope angle, slope aspect, hydrological topography and distance from the nearest human habitation. The relative importance of these site attributes varied depending on the vegetation type. Grasslands and old-growth forests, which were the most and the least disturbed sites in the study area, respectively, showed clear contrasts in their dependencies especially on the slope aspect and on elevation. These site attributes were thought to have had influences on each vegetation type by determining the inflammability of the site. Satellite photographs indicated that north-facing valleys had been relatively wet throughout the fire-prone spring season. Hence, these areas would have been free from frequent fire, and more likely to preserve old-growth forests. Ground wetness in spring was thought to be the underlying factor determining the contrasts in past vegetation and land-use patterns in the area.An erratum to this article can be found at     

Sugar maple (Acer saccharum Marsh.) establishment in boreal forest: results of a transplantation experiment

Aim To evaluate whether seedlings of sugar maple (Acer saccharum Marsh.) can establish beyond the species northern range limit in adjacent boreal forest. Location The hardwood–boreal forest transition zone on the north‐east shore of Lake Superior, Ontario, Canada. Methods Seed fall of sugar maple was monitored for 5 years in a stand of this species at its northern range limit, and seed from this stand was transplanted to five micro‐habitat types in an adjacent boreal forest. The establishment and survival of sugar maple seedlings there, and in the seed‐source stand, was monitored for the following 7–11 years. Soil‐surface light levels were measured in both forest types. Results Most seed fell in the final year of monitoring, when c. 250 seeds m^?2 were recorded. First‐year seedling establishment rates in the maple stand, deriving from this mast seed year, was approximately double that deriving from seed transplanted to the boreal forest sites; this is tentatively attributed to seed predator satiation in the maple stand. However, subsequent seedling survivorship in the boreal forest was greater than that in the maple stand, resulting in comparable seedling densities by the end of 6 years. This difference is tentatively attributed to better illumination in the boreal forest sites, and canopy‐opening disturbances appear to be especially facilitative of seedling survival. Main conclusions There is no fundamental impediment to sugar maple seedlings establishing in boreal forest communities if climate warming occurs and seed is available. If management intervention is needed to accelerate seed availability in a rapidly warming boreal forest, then diffuse seed application to disturbed boreal forest sites during mast years of local boreal tree species is recommended as the most effective way of avoiding seed predation and increasing seedling survival.     

Vegetation and climate controls on potential CO2, DOC and DON production in northern latitude soils

Climatic change may influence decomposition dynamics in arctic and boreal ecosystems, affecting both atmospheric CO₂ levels, and the flux of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) to aquatic systems. In this study, we investigated landscape‐scale controls on potential production of these compounds using a one‐year laboratory incubation at two temperatures (10° and 30 °C). We measured the release of CO₂, DOC and DON from tundra soils collected from a variety of vegetation types and climatic regimes: tussock tundra at four sites along a latitudinal gradient from the interior to the north slope of Alaska, and soils from additional vegetation types at two of those sites (upland spruce at Fairbanks, and wet sedge and shrub tundra at Toolik Lake in northern Alaska). Vegetation type strongly influenced carbon fluxes. The highest CO₂ and DOC release at the high incubation temperature occurred in the soils of shrub tundra communities. Tussock tundra soils exhibited the next highest DOC fluxes followed by spruce and wet sedge tundra soils, respectively. Of the fluxes, CO₂ showed the greatest sensitivity to incubation temperatures and vegetation type, followed by DOC. DON fluxes were less variable. Total CO₂ and total DOC release were positively correlated, with DOC fluxes approximately 10% of total CO₂ fluxes. The ratio of CO₂ production to DOC release varied significantly across vegetation types with Tussock soils producing an average of four times as much CO₂ per unit DOC released compared to Spruce soils from the Fairbanks site. Sites in this study released 80–370 mg CO₂‐C g soil C^?1 and 5–46 mg DOC g soil C^?1 at high temperatures. The magnitude of these fluxes indicates that arctic carbon pools contain a large proportion of labile carbon that could be easily decomposed given optimal conditions. The size of this labile pool ranged between 9 and 41% of soil carbon on a g soil C basis, with most variation related to vegetation type rather than climate.     

持久土壤种子库研究综述

土壤种子库是指存在于土壤上层凋落物和土壤中全部存活种子,简单地可分为短暂土壤种子库和持久土壤种子库。即使给予理想的萌发条件如季节、温度、湿度等,土壤种子库中也仍有部分种子保持休眠状态,休眠的种子组成了持久土壤种子库。持久土壤种子库具有在承受了空间或时间上不可预测的干扰的植被中发挥繁殖能力的潜势,因此,其在植被承受干扰后的恢复、管理和重建中常常起关键作用。研究持久土壤种子库能丰富生物多样性的内容,同时,可以为深入了解植被更新提供更多的信息。本文从持久土壤种子库的研究方法、分类方法、指示因子、生态意义,以及持久土壤种子库研究中存在的问题和今后的工作进行综述,试图为将来的工作奠定基础。     

Effects of fire on regional evapotranspiration in the central Canadian boreal forest

Changes in fire regimes are driving the carbon balance of much of the North American boreal forest, but few studies have examined fire‐driven changes in evapotranspiration (ET) at a regional scale. This study used a version of the Biome‐BGC process model with dynamic and competing vegetation types, and explicit spatial representation of a large (10⁶ km²) region, to simulate the effects of wildfire on ET and its components from 1948 to 2005 by comparing the fire dynamics of the 1948–1967 period with those of 1968–2005. Simulated ET averaged, over the entire temporal and spatial modeling domain, 323 mm yr⁻¹; simulation results indicated that changes in fire in recent decades decreased regional ET by 1.4% over the entire simulation, and by 3.9% in the last 10 years (1996–2005). Conifers dominated the transpiration (E_C) flux (120 mm yr⁻¹) but decreased by 18% relative to deciduous broadleaf trees in the last part of the 20th century, when increased fire resulted in increased soil evaporation, lower canopy evaporation, lower E_C, and a younger and more deciduous forest. Well‐ and poorly drained areas had similar rates of evaporation from the canopy and soil, but E_C was twice as high in the well‐drained areas. Mosses comprised a significant part of the evaporative flux to the atmosphere (22 mm yr⁻¹). Modeled annual ET was correlated with net primary production, but not with temperature or precipitation; ET and its components were consistent with previous field and modeling studies. Wildfire is driving significant changes in hydrological processes by affecting mean stand age, forest species, and energy balance. These changes, particularly in poorly drained areas, may control the future carbon balance of the boreal forest.