Reconstruction of local vegetation in ad 915 at an oligotrophic mire in northern Japan from pollen, present-day vegetation and tephra data

The use of data for present-day vegetation, modern and pretephra pollen have, together, allowed reconstruction of the spatial pattern of the vegetation of an oligotrophic mire, Shimo-kenashi Mire, in ad 915. The modern pollen data were compared with the surrounding vegetation, showing that pollen of Ericaceae, Rosaceae (excluding Sanguisorba), Sphagnum and Liliaceae, together with trees and shrubs, which form scrub or thicket, indicate the limits of the mires. Shimo-kenashi Mire was narrower in ad 915 and had more islands and peninsulas of scrub. Subsequently, the mire margin has advanced and the scrub islands and peninsulas have disappeared at some sites. The fact that the mire is spreading implies that conditions are wetter since ad 915, caused by changes in local hydrology. This history of vegetation at the site will contribute to the conservation and management of the mire as trends in vegetational change provide the basic information for conservation strategy.     

Recent changes in mire vegetation in Yawata,southwestern Japan

Recent changes of mire plant communities in the Yawata highland, southwestern Japan, are documented. The area and the boundary length of five important mires (range 1 to 6 ha) declined during past 24 years. Qualitative changes are primarily caused by human influences, e.g., accumulating debris from forest-harvest sites above the mires, from road construction, and increased drainage from man-made ditches. The Cirsieto-Molinietum japonicae, a characteristic mire community of temperate Japan climates, maintained its community structure and flora. However, 3 of 11 subordinate units of this community changed species composition and population structure, and 3 of them disappeared. The 28 mire plants classified as endangered in the 1950s were present in 1991.     

Effects of nutrient loadings from catchments on Asajino mire, a small coastal ombrotrophic mire in northernmost Japan

The relationship between water chemistry and vegetation was studied in a coastal ombrotrophic mire in northern Hokkaido, Japan. The distributions of Sphagnum and Phragmites communities were separated clearly by the pH and ion concentration of the peat surface-pore water. The drainage ditches along the road across the center of the mire had a high pH and ion concentration, as did the peat water in the western part of the mire. It was found that fields used for livestock farming on a hill to the west of the mire leached materials into the mire through drainage ditches, surface runoff, and probably also through ground water, and thus influenced the water chemistry of the mire. Management of the water, including that in the catchment of the mire, should be introduced before biological buffering capacity against excess nutrient loading caused by human activity is exceeded and the mire loses its ombrotrophic status.     

Gradients controlling vegetation in Alnus japonica forests in Kushiro mire, Hokkaido, Japan

This study examined factors controlling the vegetation in Kushiro mire, northern Japan, especially in the alder and reed communities. The alder community was classified into four types that were arranged by canonical correspondence analysis (CCA) as follows: Carex lasiocarpa type, Carex augustinowiczii type, Persicaria type, and Spiraea type. The four types exhibited differences in size (tree height) and in the ratio of sprouting stems. Although plants growing on the forest floor primarily determined the species composition of the community, shading by alder crowns had no marked effect on the community gradient. Therefore, hydrochemical variables could control the growth and occurrence of both the floor plants and alder tree size. The differences between reed community and the alder community sites were characterized as heavily eutrophic by the Kruskal–Wallis test. Overall, the chemical variables pH and P₂O₅ and the hydrochemical variables maximum and range of water level were positively correlated with the CCA axis, and effectively explained the community gradient in relation to alder growth. These variables could be controlled by the inflow of neutral and turbid water from river floods or run-off, which would increase pH by replacing the acidic mire water, ash content, and P₂O₅ by conveying suspended inorganic particles that adsorb phosphorus.     

Production and oxidation of methane in a boreal mire after a decade of increased temperature and nitrogen and sulfur deposition

Natural wetlands are the single largest source of atmospheric methane (CH₄). Both a changed climate and deposition of anthropogenic nitrogen and sulfur can alter the production and oxidation of CH₄ respectively and thereby also CH₄ exchange. We used a long‐term (12 years) factorial field experiment in a boreal oligotrophic mire to evaluate the effects of greenhouse cover and addition of ammonium nitrate and sodium sulfate on the production and oxidation of CH₄ by applying laboratory incubations of samples from five depths in the mire. The rates of CH₄ production were measured without amendments and after the addition of either glucose or sulfate. Twelve years of increased nitrogen deposition has changed the mire from a Sphagnum‐dominated plant community to one dominated by sedges and dwarf shrubs. The deposition of nitrogen to the field plots caused increased production of CH₄ in incubations without amendments (34%), and also after amendments with glucose (40%) or sulfate (42%). This indicates increased substrate availability (without amendments) but also a greater abundance of methanogens (glucose amendment). The greenhouse cover caused a decrease in CH₄ production in incubations without amendments (34%), after glucose amendment (20%) and after sulfate amendment (31%). These responses indicate decreased substrate availability (without amendment) accompanied by the reduced abundance of methanogens (glucose amendment). The field application of sulfur had no effect on CH₄ production at the depth where maximal CH₄ production occurred. Closer to the mire surface, however, the rate of CH₄ production was significantly reduced by 32–45%. These results suggest that the deposition of sulfate has altered the vertical distribution of methanogens and sulfate‐reducing bacteria. The oxidation of CH₄ was not significantly affected by any of the long‐term field treatments.     

Effects of scale-dependent factors on herbaceous vegetation patterns in a wetland,northern Japan

Herbaceous vegetation was examined in an Otanoshike wetland in northern Japan to clarify the relationships between vegetation patterns and environmental factors with different scales. Alders (Alnus japonica) have recently invaded and might modify the herbaceous vegetation. In total, 150 50×50cm plots were established on the transitional areas between alder thickets and grassy marshland. Cover was measured for the vascular plant taxa, and canopy area, number of stumps, number of mounds, water depth, elevation difference, litter thickness, soil organic matter, and soil pH were measured in each plot. TWINSPAN cluster analysis classified four vegetation groups: (i), grasslands represented by Phragmites australis, Trientalis europaea, Lythrum salicaria, and Hosta rectifolia; (ii), Calamagrostis langsdorfii, and Polygonum thunbergii grasslands with Spiraea salicifolia; (iii), reed swamp dominated by Phragmites australis, and (iv), marshland dominated by Carex lyngbyei. Canonical correspondence analysis indicated that water depth primarily divided vegetation groups 1–2 and 3–4. Alder established in drier sites mostly by re-sprouting, and the canopy affected light and soil conditions on the ground surface. The second axis of canonical correspondence analysis was related to the canopy area and soil pH, and explained the vegetation differentiation between groups 1 and 2, and groups 3 and 4. In conclusion therefore, scale-dependent or hierarchical variables affected the vegetation patterns in different ways, that is, the herbaceous vegetation was first differentiated by water depth that was corresponding to alder establishment on a large scale, and subsequent light and soil conditions were second determinants on a small scale.     

The pH dependence of photosynthesis and elongation of Sphagnum squarrosum and S. girgensohnii in the Picea glehnii mire forest in Cape Ochiishi, north-eastern Japan

We investigated the pH dependence of the elongation of and photosynthesis by Sphagnum squarrosum and S. girgensohnii in a coastal Picea glehnii peat mire in Cape Ochiishi, north-eastern Japan. S. squarrosum grew in the acidic centre of the P. glehnii forest and showed the highest photosynthetic rate at pH = 3.8. S. girgensohnii grew at the margin of the P. glehnii forest and showed the maximum photosynthetic rate at pH = 7.2. Both species showed maximum growth at pH = 3.8. S. squarrosum elongated even at pH = 8.8, whereas S. girgensohnii stopped elongation at pH = 7.2. Although the pH dependence of photosynthesis by the Sphagnum species corresponded well to their distribution along the pH gradient from the centre to the margin of the P. glehnii forest, their short-term photosynthetic activity did not predict their long-term growth.     

Key variables controlling the vegetation of a cool-temperate mire in northern Japan

Abstract. In the cool-temperate Bibi Mire, Hokkaido, Japan, valley fens and flood-plain fens have quite different vegetation. The main variables controlling the vegetation were all hydrological: mean water level, water level fluctuation and surface water flow. Chemical factors such as electrical conductivity, dissolved oxygen and related peat decomposition were less important. The pH was about neutral and has little effect. The flood-plain fen developed under fluctuating water table conditions. The dominant species are Calamagrostis langsdotffii and Carex pseudocuraica. When temporal inundation occurs in the rainy or typhoon seasons, the submergence stimulates bud germination of the stoloniferous C. pseudocuraica, which can rapidly elongate its stolons upward. Some large floating peat mats occurred in the flood-plain fen zone. On these mats some Alnus japonica saplings establish and patches of alder forest can arise. Here the water level was higher than in the peripheral alder forest zone. The valley fen is dominated by Carex lasiocarpa var. occultans and/or C. limosa. It is formed under stable water table conditions in the inundated parts of the mire -where the non-inundated wet areas are dominated by alder trees. In the area where the surface water is flowing, these two fen sedges grow in deeper water since the high oxygen content is considered to compensate the flooding stress.     

Topographical pattern of the forest vegetation on a river basin in a warm-temperate hilly region,central Japan

The relationship between tree distribution and topography was examined in a small river basin (3.4 ha) comprising a complex mosaic of topographical units at 10² to 10³ m² order, each of which had a shallow valley bordered by small ridges or breaks of slopes. Twenty-five major woody species were divided into two groups (groups A and B) based on a cluster analysis using the distribution data in the basin. Group A, which mainly consisted of early-successional species, was distributed around the valley sites of the topographical units, while group B, which mainly consisted of late-successional species, was distributed around the ridge sites of the topographical units. This vegetation pattern coincided with erosional condition in the basin. That is, the valley sites were eroded more actively than the ridge sites, as soil depth tended to be thin in the valley sites and thick in the ridge sites, and because large (canopy) trees were restricted in the ridge sites. There was no tendency that group B was replacing group A, and hence it was suggested that repeated disturbance by slope failures or small-scale shallow landslides have prevented compositional change from the early-successional (group A) to the late-successional (group B) species by preventing the invasion of the latter into valley sites.     

Effects of herbivory and the season of disturbance on algal succession in a tropical intertidal shore,Phuket, Thailand

The effects of herbivory and the season of disturbance on species composition and algal succession were experimentally tested at a tropical intertidal shore, Phuket Island, Thailand. Dead coral patches were cleared of all organisms during both the dry and rainy seasons in order to study the effects of season on algal succession and cages were set up to exclude fish herbivory. Algal succession in this intertidal habitat showed a simple pattern and took a year from the early Ulva paradoxa C. Agardh stage to the late Polysiphonia sphaerocarpa Børgesen stage. The abundance of algae during succession was under the influence of seasonal change. U. paradoxa reproduced and recruited throughout the year. Caging effects did not apparently influence algal abundance, perhaps because resident herbivorous damselfishes excluded other herbivores from their territories and maintained their algal “farms”. Unexpectedly, the percent cover of Ulva in the caged plots was lower than in uncaged plots. This pattern may indicate that caging excluded damselfishes only, but allowed small herbivores that consumed substantial amounts of soft filamentous algae in the cages.     

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。     

Effects of five years of grazing on a salt-marsh vegetation

Plant Ecology - In a salt-marsh, which was ungrazed from 1958 to 1971, grazing was reintroduced in 24 out of 32 ha from 1972 onwards. Vegetation changes under these conditions were investigated....     

海南昌江石碌铁矿尾矿库区植被调查

实验开展了3个不同年代的海南石碌铁尾矿库区植被调查研究,根据记录数据计算了各样地物种的重要值、物种多样性指数和均匀度等。结果表明,铁尾矿库区内植物种类总体上来看较为稀少,不同尾矿库区内植物群落组成成分差异比较大。已经停止使用20a的尾矿区（样地1）内,自然定居的植物仅有44种,其中禾本科植物种类较多,其次为豆科植物和莎草科植物,表明这3个科的植物种类较其它科植物更容易适应这种环境,特别是禾本科的水竹（Phragmites karka）、雀稗（Paspalum commersonii）和豆科的田菁（Sesbaniacannabina）表现出较强的适应能力;刚停止使用2a的尾矿库区（样地2）内,自然定居的植物有21种,其中硬骨草（Panicum repens）、斑茅（Saccharum arundinaceum）和芒（Miscanthussinensis）等禾本科植物为该样地的优势种群;正在使用的尾矿库区（样地3）内物种单一,只有水竹（Pyllosacys karka）、芒（Miscanthus sinensis）和田菁（Sesbaniacannabina）三种植物能在该恶劣的生境中顽强地生长和发育,表现出极强的适应能力。结果还表明了3个不同年代库区的植物群落的组成与结构存在明显的演替顺序差异,样地3单种优势明显,从样地3到样地1,这种优势依次减弱,物种多样性指数也依次增加,这表现出由较少先锋物种种类组成的简单群落向稳定复杂群落方向演替的趋势,反映了植物群落结构随演替时间的延长越来越趋向复杂化。在同一个尾矿库区内土壤的不同水分含量和理化性质会对植物的定居与群落的组成关系密切。     

广西马山岩溶植被年龄序列的群落特征

石漠化地区是我国西南植被恢复和生态重建的重点和难点地区。通过对马山县岩溶植被年龄序列(石漠、草丛、灌丛、小乔林和成熟林)5个演替阶段15个样地(20 m×50 m)的系统取样调查,研究了停止人为干扰后岩溶植被的更新、演替及群落特征的变化。结果表明:沿石漠、草丛、灌丛、小乔林、成熟林的顺向演替发展,群落各层次的覆盖度存在显著差异(P<0.05),乔木层覆盖度以成熟林最大,灌木层覆盖度以小乔林最高,而草本层覆盖度以灌丛最高;重要值≥10.00的科、属、种最大值出现在小乔林;不同演替阶段群落不同层次的结构明显不同,乔木层的植物密度存在显著差异(P<0.05),以小乔林最高;成熟林灌木层的植物密度显著低于小乔林和草丛(P<0.05),与石漠和灌丛差异不显著(P>0.05);森林阶段草本层的植物密度显著低于灌丛、草丛和石漠(P<0.05);群落的物种丰富度随着顺向演替发展而增加,但不同演替阶段不同层次的丰富度变化不同,草本层的物种丰富度以草丛阶段最大,成熟林最小;灌木层的丰富度以小乔林阶段最大,石漠阶段最小;乔木层的丰富度以小乔林最大,成熟林有所下降;不同演替阶段群落草本层的生态优势度无显著差异(P>0.05),而灌木层和乔木层均存在显著差异(P<0.05)。岩溶植被恢复可分为恶劣物理环境阈值和顶极种缺乏的阈值两个阶段,每一个阶段内由不同功能特征的驱动种和关键种决定着群落的演替方向和速度,越接近演替后期,顶极种越丰富,群落驱动种和关键种向高级、大型和长寿植物发展的趋势越明显。     

Distribution of plants in relation to microsites on recent volcanic substrates on Mount Koma,Hokkaido, Japan

On Mount Komas volcanically devastated summit six common plant species colonized 12 microsite types differentially. Flat sites covered 65%, rills and gullies 16% and biotic sites 13% of the study area. Most species preferred sites near rocks and avoided flat and biotic microsites. Polygonum and Salix preferred gully bottoms and edges. Polygonum and Salix seedlings avoided flat areas and Polygonum seedlings strongly colonized gullies. Carex oxyandra seedlings preferred Salix patches. The distributions of seedlings and adult plants were correlated. Biotic microsites supported the largest Carex individuals, rills supported the largest Agrostis individuals and the largest Salix individuals were in gully bottoms and flats.     

Effects of climatic change on chemistry and vegetation of peatlands,with special reference to interaction with atmospheric deposition

This paper summarizes expected changes in hydrology, chemistry and biota of Dutch peatlands (bogs, fens and moorland pools) caused by climatic changes resulting from the Greenhouse Effect. Special attention is paid to the interaction with atmospheric acid deposition. In both bogs and moorland pools prolonged drought periods may cause deleterious effects on biota because of the release of atmospherically-derived reduced sulphur compounds. In fenlands negative changes will be caused by eutrophication due to increased supply of allochtonous water. Long-term water and nutrient budgets are needed, along with better predictions of expected climate changes, to develop models of changes in hydrology, chemistry and biota of peatlands.     

Nitrogen dynamics in the hyporheic zone of a forested stream during a small storm, Hokkaido, Japan

Water and dissolved nitrogen flows through the hyporheic zone of a 3rd-order mountain stream in Hokkaido, northern Japan were measured during a small storm in August 1997. A network of wells was established to measure water table elevations and to collect water samples to analyze dissolved nitrogen concentrations. Hydraulic conductivity and the depth to bedrock were surveyed. We parameterized the groundwater flow model, MODFLOW, to quantify subsurface flows of both stream water and soil water through the hyporheic zone. MODFLOW simulations suggest that soil water inflow from the adjacent hill slope increased by 1.7-fold during a small storm. Dissolved organic nitrogen (DON) and ammonium (NH ₄ ⁺ ) in soil water from the hill slope were the dominant nitrogen inputs to the riparian zone. DON was consumed via mineralization to NH ₄ ⁺ in the hyporheic zone. NH ₄ ⁺ was the dominant nitrogen species in the subsurface, and showed a net release during both base and storm flow. Nitrate appeared to be lost to denitrification or immobilized by microorganisms and/or vegetation in the riparian zone. Our results indicated that the riparian and hyporheic system was a net source of NH ₄ ⁺ to the stream.     

Spontaneous and assisted restoration of vegetation on the bottom of a former water reservoir,the Elwha River,Olympic National Park,WA, U.S.A.

Early seral vegetation was studied on a former lake bottom after the removal of the 64‐m‐tall Glines Canyon Dam on the Elwha River. In 2015, vegetation cover of all vascular plant species was determined in 63 plots located on sites that emerged in 2011–2012. The sites had been planted and/or seeded, or were permitted to revegetate spontaneously. The plots were further classified by substrate texture: coarse sediments on the valley bottom and fine ones on the valley slopes. Plots were located randomly along random transects perpendicular to the former lake shore that extended into coarse sediment terraces perched above the floodplain. Additionally, 32 plots were sampled in surrounding native forests near these transects. Data were analyzed by detrended correspondence analysis and by canonical correspondence analysis. Substrate texture, that is whether fine or coarse, appeared to explain most of the variability in vegetation. The distance to forest and successional age, that is time since the site had been drained, were also significant explanatory variables, while assisted restoration by planting and seeding appeared to be insignificant to date. Spontaneous succession on fine sediments led to a species composition approaching that of adjacent natural forests. Invasive species were much less abundant than expected. Spontaneous restoration of vegetation on fine sediments in drained lake bottoms can rapidly produce a desirable vegetation composition and structure. On coarse sediments, active restoration may be useful to accelerate the development of native vegetation communities.     

Influence of a non-native invasive tree on primary succession at Mt. Koma, Hokkaido, Japan

The slopes of Mt. Koma in Japan are undergoing primary succession as a result of a 1929 eruption. Understory vegetation below a non-native invasive tree species, Larix kaempferi, a native tree, Betula ermanii, and in the open were compared to determine if the non-native tree species was influencing species composition. Larix canopies are significantly larger than Betula canopies. Vegetation under Larix canopies had significantly greater richness and diversity than vegetation in the open, vegetation under Betula was intermediate but was significantly greater than the open in diversity. Vegetation cover was highest under Betula and significantly lower in the open. Larix canopy size was positively correlated with size and number of Salix reinii shrubs. Betula canopy size was positively correlated with size but not with number of Salix reinii shrubs. Species assemblages in the three sites are slightly different as shown by DCA. Due to the limited species pool on Mt. Koma the greatest possible extent of differences between the three microsites is not large. At this point Larix certainly appears to be accelerating succession for the non-tree species. If Larix persists on the slopes then succession would be permanently deflected towards a Larix forest. This would be a case of succession being deflected towards dominance by the introduced species. This revised version was published online in June 2006 with corrections to the Cover Date.