島野 光司

植生調査による各種の被度の情報から、河畔植生における在来種のコゴメヤナギから外来種であるニセアカシアが優占する群落への遷移過程を、TWINSPANを用いて明らかにすることを試みた。高木林を対象とした一般的な群落区分では、各種の上層(高木層、亜高木層)、低木層、草本層における被度の最も大きな値を用いて群落タイプごとの種組成を表すことが多いが、そのような方法では、高木層で優占しうる樹木種の高木層以外での分布関係が把握できない。そこで、各種の高木層、亜高木層、低木層、草本層のそれぞれの被度の値を用い、上層～下層における分布構造の情報を生かした手順で解析を行った。TWINSPANで階層ごとの被度データを活用して解析を行った結果、河畔で優占するコゴメヤナギ高木林の下層では外来種のニセアカシアが生育するが、ニセアカシア高木林の下層ではコゴメヤナギの実生や低木が生育しないことが明らかになった。この結果から、大規模な河川水による撹乱がなければ、在来種のコゴメヤナギから外来種のニセアカシアが優占する高木林に推移していくことが示唆された。本研究のような階層ごとの被度情報を活用した解析手順は、外来種が侵入した森林の更新や遷移過程を理解する上で、毎木調査による樹高や幹の直径などの情報が無いときでも有効であると考えられる。

Academia Journal of Agricultural Research

Vegetation Science

Vegetation Science

Vegetation Science

信州大学教育学部附属志賀自然教育研究施設研究業績

信州大学教育学部附属志賀自然教育研究施設研究業績

信州大学教育学部附属志賀自然教育研究施設研究業績

<p>1. 本研究は，長野県安曇野市光城山と長峰山で，草原，アカマツ植林，夏緑二次林で植生型や人為的な管理の違いがチョウやガの出現種にどのような影響を与えるかを調べ，チョウ・ガにとっての好ましい環境を明らかにすることを試みた．</p><p>2. 調査の結果，チョウ・ガの個体数と種数は，地表面が明るく，開花している植物の多い調査区で多かった．</p><p>3. こうした調査区は，低木を含む下草刈りや，間伐，除伐といった樹木の伐採が高い頻度で行われているところであった．</p><p>4. アカマツ植林や夏緑二次林といった森林の違いによって開花植物種数や被度は大きく変化しなかったのに対し，草原では開花植物種数や被度が高くなっていた．</p><p>5. 各調査区に出現していた植物種とその植物種を食草とするチョウの成虫が必ずしも同じ調査区で見られるとは限らなかった．このことは，成虫のチョウは幼虫時に食草として利用していた植物種の周りばかりで生活をするのではなく，成虫期には吸蜜できる開花植物を求めて移動していることを示唆した．</p>

植生学会誌

信州大学教育学部附属志賀自然教育研究施設研究業績

日本生態学会誌

Fixation of river flow passages and riverbed degradation may facilitate the development of higher floodplains with the establishment of exotic species such as black locust (Robinia pseudoacacia L.). We quantitatively evaluated the relationship between nitrogen (N) levels in black locust trees and in sediments under different flood disturbance regimes in a riparian area of the Chikuma River. In this study, allometric equations were developed for relating leaf N content to diameter at breast height of black locust. The amount of leaf N in black locust increased with distance from the river, reaching 159 kg N ha(-1) at 180 m from the river. There was a small difference in N content between green and fallen leaves (0.2%), and so the leaf N was almost equivalent to N input to riparian sediments. Fine sediments accumulated on the riparian area, where the amount of sediments N increased with distance from the river, ranging from 1091 +/- A 767 to 4953 +/- A 2953 kg N ha(-1). The N accumulation rates also increased with distance from the river, corresponding with the amount of leaf N in black locust per unit area, but the former exceeded the latter. The sediment N accumulation might be accelerated by sediment trapping effect due to riparian vegetation itself. A large input of N provided by invaded black locust might alter nutrient dynamics and native plant community structure in the riparian area.

信州大学教育学部付属志賀自然教育研究施設研究業績

信州大学教育学部付属志賀自然教育研究施設研究業績

Cercidiphyllum japonicum and C. magnificum are deciduous tree species that produce large numbers of sprouts. They are found mainly in riparian and/or disturbed areas. C. japonicum is distributed in the montane zone in Japan, whereas C. magnificum is distributed mostly in the subalpine zone of central Japan. However, the two species sometimes coexist, e.g., on the talus slope at the valley head of the Chichibu Mountains. We investigated differences in sprouting traits in these two species by comparing class distributions of sprout diameter at breast height (DBH) and heights of individuals on the talus slope. Sprout DBH and individual height were smaller in C. magnificum as compared to C. japonicum. Moreover, the analysis of the DBH-class distribution of each species indicated that C. magnificum had numerous small sprouts and experienced high mortality, whereas C. japonicum had fewer small sprouts and low mortality. It is likely that the sprouting traits of C. magnificum make it more adapted to severe conditions in the subalpine zone than those of C. japonicum.

We determined the environmental requirements for Lepus brachyurus lyoni on Sado Island, Japan. during the winter when food resources are low Flare track survey sites were classified by vegetation type. The movement distances of hares, which indicated habitat preference, were evaluated as the relative length of tracks in a I-ha area In addition, we examined browse marks on plants and the protein content of plants to determine the preferred plant species. Movement distances of hares decreased significantly with increasing tree stand height, mean tree diameter. basal area of the tree stand, and forest canopy closure, but increased with branch-and-stem density. The percentage of browse marks Oil the branches of tree/shrub species decreased significantly with increasing branch-and-stem diameter The rate of feeding increased significantly with increased protein content in the branches These findings suggest that hares prefer shrub stands with high branch-and-stem density to mature forests. which have lower branch-and-stem densities Hares also prefer branches and stems containing large amounts of protein Young stands offering many shrub species as food resources and shelter constitute preferable environments for hares

乾性放棄水田の埋土種子による水辺植生再生の可能性をさぐり、埋土種子を用いた水辺植生の再生や保全する方法を検討するため、「放棄水田」、放棄水田から水田にした前後の「復田前」と「復田」、湿性放棄水田から開墾した「池」において植生調査を行った。また復田した場所で確認された種の由来を検討するため、「復田前」から採取した土壌の埋土種子調査を行った。乾性放棄水田から水田にした「復田」とその土壌を用いた埋土種子調査から、「復田前」には見られなかった絶滅危惧種II類のミズマツバが発生した。同時に、水辺植生の構成種であるアゼトウガラシやタマガヤツリなどがみられた。また、湿性放棄水田から「池」にした地点では、絶滅危惧種IA類であるアズミノヘラオモダカ、絶滅危惧種II類であるサンショウモ、絶滅危惧種I類であるイチョウウキゴケがみられた。こうした事から、放棄水田から耕作し、水を入れることによって、放棄された当時の水辺植生を埋土種子から再生し、保全できる可能性があることがわかった。また埋土種子調査では水位によって発生した種が異なったため、再生するには水位コントロールも重要な要素であると考えられる。放棄水田の埋土種子集団が、水辺植生再生のために貴重であると考えられる。

We investigated species composition and characteristics of plant communities in plots at seven site types within a ski resort: forests, an abandoned ski slope, an area under the gondola lines, forest waterfronts, open waterfronts, edges of ski slopes, and an active ski slope. On the abandoned ski slope, under the gondola lines, at the edges of ski slopes, and on the ski slope, canopy closure was low, tall herbs were present, and species diversity was high. Some wetland species were present at waterfront plots. Differential species composition was caused by vegetation cutting, which was necessary to manage the ski resort. We found various plants, including herbs, some rarely seen because their habitats have decreased. Despite their negative effects, such as surface-soil erosion and magnification of plant size due to the use of ammonium sulfate, ski resorts can be important plant habitats with highly diverse species composition.

保全生態研究

We surveyed plant community development at the abandoned Ogushi sulfur mine. We found seven communities dominated by the following respective species: Deschampsia flexuosa, Miscanthus sinensis, shrub willow, Gaultheria miqueliana-Betula ermanii, Sasa senanensis-Betula ermanii, willow-Betula ermanii, and Sasa kurilensis-Abies veitchii. We examined the succession of these communities, in which younger communities of low height and ground cover contained seedlings of the successive communities that were taller and had higher ground cover. To understand the development of these different communities, we surveyed damage from mining pollution and effects of immature soils formed by landslides. The average pH (H(2)O) was 4.12, and aluminum concentrations were not sufficiently high to damage plant growth, except in areas where sulfur had been mined. The organic carbon and nitrogen content in soil samples were very low because of a delay in soil development caused by a large landslide in 1937. Hence, succession was positively correlated with the soil development stage. The delay in soil development after a large landslide influenced the seven successional steps of the plant communities, but mineral poisons at the abandoned Ogushi sulfur mine had no effect on succession.

The Japanese riparian forest in the Pacific region is dominated by three deciduous trees as Fraxinus platypoda, Pterocarya rhoifolia and Cercidiphyllum japonicum. These species would regenerate and coexist with regeneration strategies adaptive to the riparian disturbances respectively. Many researchers have revealed ecological traits about F. platypoda and/or P. rhoifolia, we, moreover, clarified ecological traits of C. japonicum. The riparian forest in this study, in central Japan, includes various topographies the sedimentation of mud stream, where is stable and gentle in slope, and V-shaped valley, where is unstable and steep slope. F. platypoda was distributed at all sites, especially in the stable area since due to their high shade tolerance, and, on the other hand, P. rhoifolia selected high growth than that of F. platypoda and established colonies of canopy tree immediately in the large disturbed area. We found C. japonicum make grand stands by numerous sproutings despite their fewer individuals in the riparian forest. Many C. japonicum canopy trees were distributed especially in the V-shaped valley but their juveniles were distributed under the P. rhoifolia canopy. C. japonicum germination site is the bare soil with steep slope, not the thick litter accumulation and/or gravel, because of their small seeds and seedlings. Their current-year seedlings were almost washed away by rain and/or running water, especially small seedlings in the dark light condition, since their germination site is difficult to survive. However, C. japonicum produced sequential sprouts as a result of endogenous factors such as aging, as it reached the canopy, and it produced many sprouts simultaneously as a result of external factors, such as gap formation and physical damage, in response to long-term environmental changes. There is a rare large disturbance to destroy the forest completely when various low-intensity, high-frequency disturbances occur in V-shaped valley, where C. japonicum could maintain themselves by sproutings for a long time, once regeneration occurs. Therefore, C. japonicum coexist with F. platypoda, most dominant tree with shade tolerance, and P. rhoifolia, secondarily dominant and pioneer tree, in the riparian forest. Three species, moreover, have habitat respectively in the community unit, and species composition indicates the comprehensive environment of their habitat.

信州大学教育学部付属志賀自然教育研究施設研究業績

信州大学教育学部付属志賀自然教育研究施設研究業績

景観生態学会

日本生態学会誌

Riparian plants can use nitrogen (N) from soil and river water, but the use of river water N might be limited in higher floodplain environments of the Chikuma River. The purpose of this study is to reveal the relationship between N uptake by riparian plants and the floodplain topography (relative height and distance from a river channel). We examined the hypothesis that surface sediment removal from the higher floodplain increases river water N uptake by riparian plants by using a stable isotope analysis. The delta(15)N value of river water samples (ca. 8 parts per thousand) were significantly higher than those of the soil extracts (ca. 3 parts per thousand) in the study area. The delta(15)N value of riparian plants increased from +3.0 parts per thousand (standard deviation, SD +/- 2.1 parts per thousand) before sediment removal to +9.6 parts per thousand (+/-2.1 parts per thousand) after sediment removal, although there was no significant change in the delta(15)N value in N sources of soil and river water. The sediment removal enhanced frequency of flood disturbance, relative ground water level, and river water N uptake by riparian plants on the floodplain.

Forest vegetation in the upper basin was strongly dependent upon the topography. More specifically, landforms vary in the riparian zone, and the valley floors are mosaics that include active channels, abandoned channels, floodplains, terraces, and alluvial fans Gregory et al. 1991 Sakio 1997. These complex mosaic structures of landforms result from various disturbance regimes in the riparian zone, and the high diversity of microsites and disturbance regimes may promote the coexistence of canopy trees in riparian zones. © 2008 Springer Japan.

日本生態学会誌

日本林学会誌

植生情報

本研究では, 千曲川河畔域の比高の異なる氾濫原環境に分布する植物が, 河川水との関わりを有しているのかどうかを窒素動態に着目し, 安定同位体比を用いて解析した. 氾濫原の低位面の植物のδ¹⁵Nは, 河川表流水のδ¹⁵Nと同様に流程に沿って上昇しており, 植物が河川水由来の窒素を利用していたことを示唆した. 一方で, 河岸から離れるほど, 植物のδ¹⁵Nは低下しており, 種を問わず, 高位面の植物が依存している窒素源が河川水とは異なることが明らかになった. 高位面では, ハリエンジュが樹林化しており, ハリエンジュが無いところと比べて有意に比高が高かった. 高位面の土壌は, 低位面に比べて42倍もの硝酸態窒素が存在しており, ハリエンジュによる土壌への窒素負荷が起きている可能性がある. 高位面は, 堆積や水理などの物理環境だけでなく, 植物の窒素利用においても, 低位面とは異なっており, 窒素動態という観点からも特異な系を構成していることが明らかになった. 洪水によって特徴付けられる河川生態系において, 河道内で長期に渡って安定的に存在しているハリエンジュ林は極めて異質な存在である. 河川環境のあり方に未だ定見はないが, ハリエンジュ林拡大の要因となっている, 河道掘削や河床低下に伴う流路の固定化など, 河川管理について, 河川環境の多様性の維持, 物質循環の観点からも検討していく必要があるだろう.

We aimed to clarify the factors that affect Japanese hare (Lepus brachyurus) densities and habitat availability in certain vegetation types. Using fecal pellet counts, we found that hare densities and habitat availability were higher in open-tree-canopy habitats with a dense ground cover of herbs and grasses, such as cleared areas in artificial forests. However, when we examined the relationships between fecal pellets as an indicator of hare density and various attributes of forest floor vegetation, no vegetation parameters had a significant correlation with fecal pellets among different plant communities. Thus, it is difficult to predict hare density based on forest floor vegetation, in general. However, in seven Japanese cedar (Cryptomeria japonica) plantation sites, high herb volume index and a low degree of canopy closure, calculated from fisheye-lens photographs, had a significant correlation with fecal pellet density (P = 0.029 and 0.006, respectively). Based on the relationships between fecal pellets and certain forest attributes (e.g., stand height and diameter at breast height of trees), we determined that fecal pellet density was higher in young stands in these plantations. This is likely because young stands have a larger volume of herbaceous species that provide food and shelter for hares, owing to the bright ground conditions resulting from the relatively open canopy. Appropriate plantation control such as cutting and planting trees is important for habitat conservation of L. brachyurus, because planted C. japonica forest occupies more than half of artificial forests in Japan.

Differences in beech (Fagus crenata) regeneration were quantitatively investigated using power function analysis for the size-class (diameter at breast height, DBH) distribution and juvenile-to-canopy tree (J/C) ratio along a snow gradient throughout Japan. In snowy areas, all species combined, as well as F. crenata alone, showed constant regeneration, with parameter b approximate to-1.6 for the power function y=ax(b) (x=DBH, y=density), which is related to the DBH-class distribution. The good fit of the data to the function suggests that beech regenerates constantly with self-thinning patch dynamics. Parameter a, which indicates the abundance of small trunks, was high. Furthermore, the mean J/C ratio was approximate to 8, i.e., each parent beech tree produced eight juveniles. These results suggest that beech regenerates constantly with gap dynamics in snowy beech forests on the Japan Sea side of Japan (snowy). However, the fit of F. crenata was lower and nonsignificant in some forests in less snowy areas, despite the high fit of all species combined. In these areas, the mean of a was low, and b was often near zero for F. crenata regressions. These results suggest that the abundance of beech was low, and self-thinning was not evident because of the initial low abundance. Moreover, the mean J/C ratio was &lt; 1.0, suggesting that juvenile density was lower than that of canopy trees. Thus, the regeneration of F. crenata on the Pacific Ocean side of Japan (less snowy) is rather sporadic. Less snowy conditions may promote seed desiccation, predation of beechnuts and seedlings, and water stress. Lower F. crenata density may also reduce predator satiation and wind pollination.

Vegetation Science

We investigated the factors that encourage sprouting by Cercidiphyllum japonicum, as well as its ability to sprout after cutting, by analyzing the age structure, distribution, and growth of sprouts in one stool of this species. C japonicum produced numerous sprouts in various age classes, ranging from 7 to 92 years old; the main stein was 226 years old. Sprouts that were relatively close in age (e.g., 30 or 80 years old) tended to form clusters. Based on an increase in the width of annual growth rings, we estimated that gap formation occurred about 30 years ago. This encouraged existing Sprouts to grow more, and many sprouts were produced on the periphery of the stand to take advantage of the improved light conditions. After cutting, larger stems produced more simultaneous sprouts; therefore, sprout occurrence probably depends on the biomass of parent stems, although smaller stems were also able to produce some simultaneous sprouts. In the absence of physical damage, C japonicum produced more sprouts as a function of increased age as a means of self-maintenance. C. japonicum sprouted simultaneously in response to external disturbances, such as gap formation and cutting, and it sprouted sequentially with increasing age. Therefore, although C japonicum seedlings are rarely found in forests, C japonicum can maintain its populations over long periods by sprouting, which compensates for sparse seedling regeneration. (c) 2005 Elsevier B.V. All rights reserved.

信州大学教育学部附属志賀自然教育研究施設研究業績

Folia Geobotanica

DNA多型

Plant Species Biology

電力中央研究所報告

哺乳類科学

森林野生動物研究会誌

This paper reviews the differences in the distribution and regeneration of Fagus crenata between two types of Japanese beech forests, the Japan Sea (JS)-type and the Pacific Ocean (PO)-type, and discusses the causal factors and characteristics of these forests, particularly the PO-type. F. crenata in PO-type forests regenerates sporadically rather than constantly, whereas regeneration in the JS-type forests is relatively constant with gap dynamics. F. crenata has dominated in snowy areas both in the past, after the last glacial age, when there was less human disturbance, and in the present. Snow accumulation facilitaties beech regeneration in snowy JS-type forests, but not in the less snowy PO-type. Snow protects beechnuts from damage caused by rodents, desiccation, and freezing. In addition, snow suppresses dwarfbamboo in the spring, thus increasing the amount of sunlight available for beech seedlings on the forest floor. Snow also supplies melt water during the growing season and limits the distribution of herbivores. Moreover, snow reduces the number of forest fires during the dry winter and early spring seasons. The low densities of F. crenata impede its regeneration, because disturbed wind pollination lowers seed fertility and predators are less effectively satiated. In snowy JS-type beech forests, F. crenata dominates both at the adult and the juvenile stages because it regenerates well, while other species are eliminated by heavy snow pressure. On the less snowy PO-side, deciduous broad-leaved forests with various species are a primary feature, although F. crenata dominates because of its large size and long lifespan.