梅木 清

We monitored leaf biomass, seasonal changes in lea. all, and plot growth for 11 years post-thinning in a secondary deciduous hardwood stand dominated by Betula maximowicziana Regel in central Hokkaido, Japan. Annual leaf biomass was divided into two phenological amounts: leaves that fell from May to September (early foliage) and leaves that fell from October to November (late foliage). Annual leaf biomass and the ratio of late foliage to annual leaf biomass changed with stand development, thinning, and insect outbreaks. Multiple regression analysis revealed that the gross growth rate was positively dependent on both early and late foliage, whereas the effect of early foliage was stronger than that of late foliage. This result indicates that plot growth was determined by not only total leaf biomass, but also the phenological structure of the canopy. In assessing and controlling forest productivity, the phenological structure of the canopy should be considered.

this study, we conducted evaluation experiments by semantic differential method to examine the validity of utilizing three-dimensional (3D) computer graphic images made with virtual reality modeling language (VRML) as a stimulus for landscape assessment both in the laboratory and on the Internet. The results of the laboratory experiment and the Internet experiment were compared. In both experiments, we simulated a garden landscape at Chiba University by using VRML. With three media representing the landscape (Photographs, Static images of VRML and Walk-Through images by VRML), we recorded respondents' impressions of each scene. Their responses to the three stimuli were analyzed statistically with profile analysis, ANOVA and T-test. We also asked respondents which media best represented the actual landscape.The results of the profile analysis in the laboratory experiment were similar to those of the Internet experiment. The level of reality was the order of the Photographs, Walk-Through images and Static images in both experiments. The results showed that the VRML images could be used as an effective stimulus for landscape assessment both on the Internet and in the laboratory. The level of reality of Walk-Through images in the Internet experiment was almost the same as that of photographs. The results also indicated that respondents realized garden landscapes easily by Walk-Through simulation using VRML. (c) 2005 Elsevier B.V. All rights reserved.

To understand the development of crown structure in Betula platyphylla Sukatch., mortality patterns of long shoots were analyzed quantitatively. We selected 25 saplings growing under various light conditions and measured the relative photosynthetically active radiation (WAR) at, and the three-dimensional position of, first-order branches. A long shoot was assigned "no buds" (NB) status if it lacked buds at the end of the growing season, including at the tips of short shoots. A long shoot was classified as dead if it was NB and all the offspring long shoots issuing from it were NB. The probability that a leafy long shoot (a current-year long shoot with leaves or an older long shoot with short shoots with leaves) would become NB by the end of the season was positively dependent on shoot age and branch age, and negatively dependent on shoot length, centripetal shoot order, branch height and WAR at the branch. Randomization tests revealed that shoots became NB and dead in clusters of connected shoots. In particular, shoot clusters originating from 3-year-old shoots were more likely to die than expected if each shoot was assumed to become NB regardless of the connection. Stepwise logistic regression revealed that the maximum WAR within the crown of an individual tree had a significant effect on the mortality rate of 3-year-old shoot clusters, together with the WAR at the level of the branch and other structural entities. Correlative inhibition is an important mechanism for determining shoot mortality patterns.

In the process of landscape visualization by using computer graphics (CG), the formats of landscape description are different among the systems but there are many similarities in the contents of description of data. The purpose of this study is to show the availability of XML (Extensible Markup Language) for landscape description and visualization. In this study, we discussed the landscape elements for the description of landscape and defined the format of XML based on the description. The defined XML was applied to the simulation of a landscape by two visualization systems, i.e. AMAP (Atelier de Modelisation de Architecture de Plants) and VRML (Virtual Reality Modeling Language). The availability of the application of XML for landscape visualization was practically confirmed. We found there remained some problems on the present XML system and discussed the solution for the problems. We also discussed about application of standardized XML format for landscape visualization in geographic information systems.

本研究では、屋外空間における温熱感指標と温熱感覚との関係について検討するため、千葉県松戸市を対象地とし、異なる特徴を持つ２つの屋外空間（駅広場・公園）で微気象観測とアンケートを行い、観測した気象要因（気温・風速）が人々の温熱感覚に及ぼす影響を調べ、その違いを比較した。また、観測データから求めた温熱感指標SET^*（Standard new Effective Temperature）をもって２つの屋外空間での温熱感覚の違いを分析した。その結果、駅広場と公園での温熱感はSET^*の快適域とほぼ一致していたことがわかった。また、公園での快適感はSET^*の快適域より広く、快適と感じる範囲が広いことも分かった。

メッシュ気候値の作成のためには、重回帰分析やニューラルネットワークが、測定地点間のデータを補間し推定を行う手法として用いられている。本研究では、Leave-one-out cross validation により、重回帰分析やニューラルネットワークの精度比較を行った。データすべてを使用して推定式の作成を行った場合、ニューラルネットでは、学習回数が多いほどRMSEの値が減り、重回帰分析よりも低い値を示している。一方Leave-one-out cross validation の効果では、RMSEは、ニューラルネットの場合より重回帰分析が低い値を示している。したがって、推定手法として、ニューラルネットに、重回帰分析以上の精度が期待できるとはいえないと考えられる。

The mean labor time of a leaf (hour/day(-1)) is defined as the ratio of mean daily photosynthetic rate of a leaf (D-a; mol m(-2) day(-1)) to the mean value of potential hourly photosynthetic rate (60 . 60A(max) mol m(-2) h(-1)) of the leaf. A model was proposed to estimate mean labor time of leaves. Mean labor time was obtained as the product of 24 (hours/day(-1)) and the four effects, each of which reduces production of a leaf: diel change in light (Diel Effect), reduction in light during cloudy and rainy days (Cloudy Effect), shading on the focal leaves (Shading Effect), and midday and afternoon depression in photosynthesis (Depression Effect). These four effects were estimated for open grown saplings of alder (Alnus sieboldiana), by measuring instantaneous photosynthetic rate and photon flux density above each leaf. The potential daily photosynthetic rate calculated from diel light condition in a clear day was 46.5% of hypothetical daily photosynthetic rate where maximum instantaneous photosynthetic rate was assumed to last throughout the life of the leaf (Diel Effect). The average of the daily photosynthetic rate considering clear, cloudy and rainy days was 79.7% of the clear day (Cloudy Effect). The photosynthetic rate estimated from light condition on the leaf was 85.6% of that in the open site (Shading Effect). Midday depression reduced the daily photosynthetic rate to 72.1% of the potential daily photosynthetic rate (Depression Effect). The product of the four effects multiplied by 24 h gave the estimate of mean labor time of leaves to be approximately 5.5 (h/day(-1)).

本研究では、緑被地と表面温度との関係を広範囲に渡り定量的に把握することを目的に、東京都23区内の約33.6km四方を対象地域とし、3時期の夏季のランドサットTMおよびETM＋データを、多変量解析手法を用いて解析した。緑地の表面温度と12種の緑地の特徴を表す量との関係を単回帰分析、主成分分析、重回帰分析といった多変量解析法を用いて解析し、12種の変数がどのように表面温度に影響を及ぼすかを把握した。その結果、12種の変数のうち、連続性の指標が表面温度を説明する上で有効であることや、設定した特徴量が表面温度の高低に影響を及ぼすことなどが明らかとなった。

The growth of first-order branches was measured in 25 saplings of Betula platyphylla Sukatchev var. japonica Hara growing under various light conditions in northern Hokkaido, northern Japan, and the effect of age, tip height, length, and angle of branches and light availability at the branch tips on branch growth were examined. Branch growth was evaluated as the total biomass growth of current-year long shoots within a first-order branch (TBG), the number of long shoots currently produced by the first-order branch (CSN), and the mean biomass of current-year long shoots within the first-order branch (MSG). In general, TBG, CSN, and MSG were negatively dependent on branch age and positively dependent on height, length, angle (from the horizontal), and light availability of the branch. The relationships between each of TBG, CSN, and MSG and the independent variables were individual specific. The dependency of TBG, CSN, and MSG on the light availability at the branch tips was affected by the maximum light availability at the individual level, suggesting that branch growth is affected not only by branch-level resources but also by conditions at the individual level. Based on these results, two concepts for understanding branch growth, branch autonomy and correlative inhibition, were discussed, and prediction models for TBG, CSN, and MSG were presented.

The mortality rates of five major tree species (Abies sachalinensis , Acer mono , Magnolia obovata , Quercus crispula , Tilia japonica ) on Hokkaido Island, northern Japan were modeled using logistic regressions based on the long-term observation of 8929 individuals in 65 permanent plots. Individual size, recent growth, one-sided and two-sided interactions with neighbors, climatic and topographic factors were used as independent variables in the logistic regressions, and relevant variables were selected using the stepwise method. For all species analyzed, the final models significantly explained tree mortality rates. The regression analyses indicated that individual size and/or recent growth had effects on tree mortality. A significant effect of one-sided interaction on tree mortality was detected for three species, and a significant effect of two-sided interaction was detected for two species. The interactions with neighbors were not necessarily competitive. For all species analyzed, climatic and topographic factors affected tree mortality. The mortality models obtained can be used for forest dynamics simulations. One ecological question was examined using these models. Species that can grow fast in forest stands with smaller basal areas tended to have high mortality rates in forest stands with larger basal areas. Some ecological characteristics of the analyzed species are described based on the results of the regressions.

Based on growth data obtained from 13 804 individual trees in 110 permanent plots, diameter at breast height (d.b.h.) growth was modeled for six major tree species growing in Hokkaido Island, northern Japan. For each species, d.b.h. growth was regressed on independent variables, indicating the effects of initial size, competition, climate and topography. In developing the d.b.h. growth models, independent variables were selected using the stepwise method. For all species analyzed, the final models accounted for significant amounts of the variation (r(2) = 5.65-20.99%; P < 5%) in d.b.h. growth. Significant (P < 5%) effects of competition, climate and topography on d.b.h. growth were detected. The model obtained can be used in simulations of forest dynamics. Some ecological questions were examined using the d.b.h. growth models obtained. For hardwoods, the d.b.h. growth rate did not correlate with the published grouping of species in terms of shade-tolerance; however, the plasticity in d.b.h. growth in the presence of competition seemed to be correlated with the shade-tolerance of species. The degree of a-symmetry in competition evaluated for each species was not correlated with the availability of underground resources, which was expressed by surrogate variables (mean values of climatic and topographic variables for species). The degree of asymmetry in competition was not different between conifers and hardwoods.

20年生時(1982)に様々な強度で間伐したヨーロッパトウヒ間伐試験地で，間伐が林分成長と個体の幹材積成長および形態に対して及ぼす効果を検討した。 間伐時に面積0.1haのプロット6つを設定し，それぞれ異なる本数間伐率4.0～78.0%で間伐した。間伐後の林分・個体の成長を調べるため，間伐直前(1982)・間伐4年後(1986)・11年後(1997)に，プロット内のすべての個体の胸高直径を測定した。また，1997年に，サンプル個体15本(3プロット×5本)について，樹幹解析を行い，枝の大きさ，枝のついている高さを測定した。 樹幹解析のデータから得られた胸高直径－個体材積の相対成長関係をプロット間で比較した。間伐直後(1982，1987)の相対成長関係にプロット間の差はなかったが，間伐10年後以降にはプロット間の差が生じており，強度に間伐したプロットで幹の細りが大きくなっていた。強度に間伐をしたプロット内の個体は弱い間伐をしたプロット内の個体に比べ，地上部現存量を枝・葉に対してより多く分配していた。 間伐直後の期間(1982～1986)に，間伐は個体の幹材積成長を顕著に増加させていた。しかし，その後の期間(1986～1997)，個体材積成長に対する間伐の促進効果は弱くなった。 極端に強い間伐を施したプロット(超強度間伐区:本数間伐率78.0%)以外のプロットの林分成長は無間伐プロットとほぼ同じであった。林分の胸高直径分布に対する間伐の影響は顕著で，強い間伐をしたプロットで大径個体が生産されていた。

Dendroecological techniques were used to study the dynamics and species recruitment patterns, spanning nearly four centuries, for a mesic, montane, old-growth forest in Hokkaido, northern Japan. The forest is dominated by Abies sachalinensis (Masters), Acer palmatum (Thunb.), Quercus mongolica var. grosseserrata (Rehd.), and Cercidiphyllum japonicum (Sieb.). From 1620 to 1750 and 1820 to 1840, Q. mongolica exhibited continuous recruitment into the overstory. A lack of recruitment for all tree species from 1750 to 1820 followed a 1739 volcanic eruption 200 km from the study area. Release events for individual trees occurred almost every decade of the stand history, indicating that frequent small-scale disturbances coupled with infrequent large-scale disturbances, impact tree growth and species recruitment. From 1870 to 1950, canopy recruitment of Abies and Acer dominated the forest, while recruitment of Quercus ceased. These later successional species appeared to be replacing Quercus, suggesting that the syndrome of declining oak dominance is an increasingly global phenomenon. However, successional patterns in the forest are difficult to predict because intensive deer browsing has recently prevented canopy recruitment of all tree species and the possibility of future large-scale disturbances, such as fire and volcanic eruption.

The long-term growth dynamics of natural forest stands on the island of Hokkaido were described on the basis of an analysis of data from 38 permanent plots spanning 15 - 22 yr. Stand structure was characterized by basal area, stem density and tree size variability. To detect trends in stand structure, regression models for recruitment rate (per ha per yr). mortality rate and the rate of change in stem density and tree size variability were developed by a stepwise method using initial basal area, stem density, tree size variability, species composition summarized by LNMDS ordination, altitude, annual mean temperature, annual precipitation, type of understorey vegetation, topography and slope aspect as candidates for predictor variables. The same analyses were conducted for basal area increment (net growth) and its components: survivor growth = basal area gain by growth of surviving individuals and mortality = basal area loss by death of individuals. Stem density remained generally unchanged; recruitment was relatively low even in very sparse stands. Stand basal area generally increased as survivor growth was approximately double the mortality. Recruitment rate was strongly affected by the presence of dwarf bamboo (Sasa spp.) vegetation on the forest floor which inhibited tree regeneration Mortality rate was density-dependent; dense stands had higher mortality than sparse stands. Density change rate (recruitment rate - mortality rate) was, therefore, determined by both the type of understorey vegetation and stem density. Survivor growth was high in stands with high stem density and basal area. Mortality was dependent on basal area and altitude. Net basal area increment (net growth) was dependent only on stem density with other factors that influenced survivor growth and mortality omitted. Tree size variability decreased in stands with high tree size variability whereas it increased in stands with low size variability. Based on the obtained models for density change rate and net basal area increment, trajectories of stands were illustrated on a log-log diagram of stem density and basal area. The predicted differences in trajectories as affected by the understorey vegetation type indicated the importance of dwarf bamboo vegetation for forest dynamics on Hokkaido.

We developed a game-theoretic model for wind-dispersed seed production to examine the seed mass-dispersal ability relationship and the evolutionarily stable distance of seed dispersal in terms of exploitation of safe sites. We assumed trade-offs between masses of the embryo (including albumen) and the wind-dispersal structures per seed, and also between seed mass and number of seeds per parent. We showed that ESS wing-loading is independent of embryo mass; that is, heavy seeds are not poor dispersers if the cost of producing wind-dispersal structures per unit area is constant. The ESS embryo mass per seed depends only on the factors which determine the probability of a seedling being established from a seed. However, wing-loading was found to increase with embryo mass when the change in length was isometric and there was a negative correlation between seed mass and dispersal ability. Thus, the area-mass relationship in wind-dispersal structures may have large effects on the ESS production of wind-dispersed seeds. On the other hand, given that only a limited number of adults can be established at a safe site, the ESS seed dispersal distance depends on the relative degree of sib to non-sib competition. A parent disperses its seeds over a wide area to exploit many safe sites if sib competition is strong. However, it disperses its seeds within a narrow area if the mean number of parents per unit area is large, or if non-sib competition is strong. Thus, in addition to an upper limit on the number of adults per safe site, the degree of sib and non-sib competition may be important for the ESS dispersal distance in wind-dispersed seeds.

The effect of crown asymmetry on the size-structure dynamics of populations was evaluated using a spatial competition model incorporating crown asymmetry. Computer simulations were carried out with various combinations of density levels, spatial patterns, and degrees of asymmetry in competition to assess how they modify the effect of crown asymmetry on size-structure dynamics. In the model, crown asymmetry is expressed by the crown-vector, or the vector linking the stem base and the centre of the projected area of the crown on the horizontal plane. Crown-vectors are assumed to develop in the manner by which crowns repel each other. As crown-vectors develop, the positions of the crown-centres move. Competition between individuals is expressed by a neighbourhood model, in which individual growth is determined by the distance from, and size of, the neighbours' crown-centres. Generally, populations of individuals which developed asymmetric crowns had larger survivorship, larger mean size, smaller coefficients of variation and skewness, and a more regular spatial pattern than populations of individuals which developed symmetric crowns. The effect of crown Symmetry is generally stronger in populations with high density and a clumped spatial pattern. The effect of mortality caused by one-sided competition on size-structure dynamics was similar to that of crown asymmetry; mortality increased mean size, reduced size hierarchy, and made the spatial pattern more regular. Because mortality was heavier in populations without crown asymmetry, its effect on size-structure dynamics cancelled out, or overwhelmed, the effect of crown asymmetry in later growth stages. If crown asymmetry is associated with a reduction in growth, the effect of crown asymmetry is reduced. Nevertheless, the resultant population structure is different from that of populations without crown asymmetry. (C) 1997 Annals of Botany Company.

1. We test an expectation regarding the phenology of leafing in sapling trees: that the inclination of the terminal shoot from the vertical in species with a flushing type leaf emergence will be greater than that of species with successive leafing. 2. A large inclination of the terminal shoot will minimize self-shading among leaves that emerge simultaneously; this may be an advantage in maximizing carbon gain. A small inclination leads to more self-shading but allows a sapling to attain a greater height within a shorter period; this may be an advantage in situations where shading by adjacent plants is a greater potential problem than self-shading. 3. We observed that the shoot inclination in Tilia japonica and Quercus crispula, which have a flushing type leaf emergence, was more than 30 degrees in open, sunlit habitat. In contrast, the shoot inclinations of Betula platyphilla var japonica and Alnus hirsuta, which have successive type leaf emergence, were less than 10 degrees. These observations suggest a functional linkage between leaf-emergence pattern and shoot inclination that can be considered adaptive if selection is maximizing carbon gain by the whole shoot over the growing season.

The canopy structure in terms of the vertical distribution of leaf mass and the degree of asymmetry of competition between individual trees was studied in two types of forest stand in Hokkaido, northern Japan: a naturally regenerated stand of Betula spp. and an artificial plantation of Picea abies. The canopy structure in the Betula stand was more hierarchical larger individuals were not heavily shaded even in the lowest part of their crowns and smaller individuals were heavily shaded by their larger neighbours. The canopy structure in the Picea stand was less hierarchical even larger individuals were shaded in the lowest part of their crowns and smaller individuals were not heavily shaded by their neighbours. Application of the general formula of size-dependent mean growth tale revealed thai competition in the Betula stand was more one-sided than that in the Picea stand. This result was consistent with the trends in the change over time in size equality in both stands. Even if competition is mediated by light, which often makes competition one-sided, the degree of one- sidedness in competition can be variable depending on canopy structure.

Morphological plasticity in terms of asymmetric display of crowns was compared between Picea abies (L.) Karst. and Betula maximowicziana Regel. To evaluate crown asymmetry in relation to local environment, a model that predicts crown asymmetry from topography and configuration of neighbors was applied to data derived from a mixed forest in Hokkaido, northern Japan. Betula maximowicziana had greater crown asymmetry than P. abies in absolute value. However, observed crown asymmetry of both species was determined by local environment to similar degrees. Some other differences were found between the two species. Crowns of P. abies were more influenced by neighbors than topography, while crowns of B. maximowicziana were more influenced by topography than neighbors. Crowns of P. abies were influenced mainly by larger neighbors, while crowns of B. maximowicziana were influenced by large and by relatively small neighbors.

The asymmetry in crown display was modeled with respect to neighbors and microtopography. The direction and magnitude of the asymmetry were expressed by the 'crown-vector', the horizontal two-dimensional vector that joins the stem base position of a focal tree with the centroid of its projected crown area. In the model, the crown-vector of a focal tree was a function of the position and size of its neighbors and the direction and inclination of the slope on which it occurred. Using the model, the effect of repelling behavior of crowns on the spatial pattern of crowns was quantified; spatial patterns of crowns were more regular than those of stem bases. The effects of parameters in the model on the spatial pattern of population were also quantified. The model was applied to the data derived from two study plots: one in cool temperate deciduous broad-leaved forest in northern Japan and the other in warm temperate evergreen broad-leaved forest in central Japan. The least-squares fit of the model accounted for 56% and 73% of the total variance in crown-vector for the two study plots, respectively.

Interactions between individuals in terms of asymmetrical display of crowns and reduction of growth were followed in an experimental population of Xanthium canadense. Competitive interaction was analysed using a neighbourhood interference model. For the analysis of morphological interaction, crown-vector, a two-dimensional vector that joins the stem base position of a plant with the centroid of its projected crown area, was used to express the direction and magnitude of the asymmetry in crown display. A model was developed in which the change in crown-vector during a growth period was expressed as a function of both the size of the focal plant and the size and location of its neighbours. There was strong morphological interaction between crowns; they repelled each other. The competitive interaction was detectable by the competition model with crown-centres used as plant locations, but not detectable with stem bases used as plant locations. It was concluded that the positions of neighbours' crowns were important in determining the growth and crown asymmetry, which in turn determine the crown location; and morphological plasticity in crown shape works to reduce interference between individuals.