Abstract The role of resource availability in determining the incidence masting has been widely studied, but how floral transition and initiation are regulated by level is unclear. We tested hypothesis that stimulated high availabiltiy Fagus crenata based on a new technique, expression analyses flowering genes. isolated F. orthologues FLOWERING LOCUS T , LEAFY APETALA1 confirmed their functions using transgenic Arabidopsis thaliana . monitored gene levels for 5 years detected cycle off...

Abstract Synchronised and fluctuating reproduction by plant populations, called masting, is widespread in diverse taxonomic groups. Here, we propose a new method to explore the proximate mechanism of masting combining spatiotemporal flowering data, biochemical analysis resource allocation mathematical modelling. Flowering data 170 trees over 13 years showed emergence clustering with given cluster mutually synchronised reproduction, which was successfully explained budget models. Analysis...

Summary Two non‐mutually exclusive hypotheses have been proposed to explain the evolutionary advantages of mast seeding (the intermittent production large crops flowers or seeds by a population perennial plants). Mast could evolved as result increased pollination efficiency in mast‐flowering years and/or an anti‐predator adaptation that increases survival alternately starving seed predators non‐mast and satiating them years. We investigated annual test relative contributions pre‐dispersal...

To examine the proximate factors causing mast seeding in Fagus crenata Blume Hokkaido, northern Japan, we analyzed a 13-year time series of seed production relation to both previous reproduction and weather conditions. In an autocorrelation analysis observed significant negative correlation 1-year lags for log-transformed total crop. This indicates that internal resource dynamics are important seeding. A strong was between crop minimum temperature from late April mid-May year preceding...

To evaluate the effect of thinning on a mature coastal Pinus thunbergii Parlat. forest in Hokkaido, northern Japan, we established four study plots with different intensities (control and 20, 40, 60 % thinned at individual base; each 20 m × m) monitored them for 10 years. Radial growth trees plot was significantly greater than that other plots, whereas height lower plots. Applying contribution index, which represents trade-off between relative rate diameter rate, revealed control weakly (20...

The differential temperature (ΔT) model, based on the assumption that masting plants respond to difference in temperatures during growing seasons 1 and 2 years prior seed production, has recently been proposed explain proximate factor of masting. In this study, we used a 28-year series data pollen cone production Cryptomeria japonica D. Don Japan compared several models resources test whether ΔT acts as cue or is proxy for resource limitation. Of all tested, including ΔT, previous summer...

A previous study revealed low survival rates for Japanese larch (Larix kaempferi) summer-planted seedlings grown in Hiko-V-120 containers. This examines nursery practices that could potentially prevent deterioration of the seedling water balance after planting to improve rate this species, which has a drought tolerance. During summer planting, we tested (1) hardening or high-potassium fertilization two months before (2) antitranspirant topping treatment at and (3) use JFA-150 container with...

Robinia pseudoacacia L., one of the major invasive tree species in Japan, has been used for coppice wood production worldwide. However, we have little knowledge species' sprouting characteristics. Here, tested seasonality R. sprout development. We removed aboveground parts at different times throughout year (spring, summer, autumn, and winter) censused demographics three consecutive growing seasons thereafter. The most vigorous was observed among trees cut winter, while lowest those summer....

AbstractPrevention efforts to combat pine wilt disease must be instituted avoid destruction of coastal forests in Hokkaido, northern Japan. We examine an alternative method involving the conversion Pinus thunbergii native broadleaf species through advancing their growth, but we have little knowledge about response advanced growth overhead canopy release. To demonstrate demographic and height light change a forest, trees were removed sapling populations monitored for 6 years. Inhibition...

Abstract We grafted scions of Dahurian larch (Larix gmelinii var. japonica) onto Japanese (L. kaempferi) and F1 hybrid gmeli­nii japonica × L. rootstocks examined root­stock-scion compatibility by assessing the survival rate (SR) in two independent experiments. Scion overgrowth on root­stock was not observed. SR significantly different among due to large interquartile ranges (IQR) clones within a rootstock type. Results suggested that more dependent clonal characteristics scion than growth...

トドマツ人工林を多様な広葉樹を含む針広混交林へと誘導する施業法を検討するため,間伐後8∼11年経過した39年生の間伐林分と28年生の無間伐林分において下層植生を調べた。間伐は3段階の異なる強度の列状間伐(1伐4残,2伐3残,3伐2残)を行った。間伐後の林内の相対光合成有効光量子束密度は,間伐強度が強くなるにしたがって明るくなる傾向があった。高木性・亜高木性広葉樹の種の豊富さと個体数は,無間伐区に比べ間伐区で高かったが,間伐区間では間伐強度が強いほど,個体数が少なくなる傾向があった。低木類と草本類の最大植生高と植被率は,間伐強度が強くなるにしたがい増加していた。2伐3残区と3伐2残区では,ウド,アキタブキなどの大型草本の回復が著しく,多くの高木性・亜高木性広葉樹はこれらの草本類により覆われていた。しかし,2伐3残区と3伐2残区では,大型草本の被圧を抜け出した樹高1 m以上の広葉樹が11種あり,その個体数は1...

コンテナへ直接播種し育苗した1年生カラマツコンテナ苗が積雪期以外で通年植栽可能か明らかにするため,2014年5月から10月まで毎月植栽し,生存率,成長,生理生態特性を調べた。対象として5月には裸苗も植栽した。5月に植栽した未開葉のコンテナ苗は裸苗よりも植栽後の成長量が大きく,2成長期間で裸苗のサイズに追いついた。これは,コンテナ苗の方が植栽後の根の成長が旺盛で光合成速度や気孔コンダクタンスが高かったことが要因と考えられた。6~8月に植栽したコンテナ苗は,植栽時の細根の電解質漏出率,圧ポテンシャルを失うときの葉の水ポテンシャルおよび葉/根比が高いなど,個体全体の耐乾性が他の時期よりも低かった。さらに7月の極端に少ない降水量と土壌乾燥が重なり,6,7月植栽の当年秋の生存率はそれぞれ62, 22% と低かった。一方,8月植栽苗は植栽前後に十分な降水があり生存率が97% と高かった。9,10月植栽苗は耐乾性が高く,植栽翌年秋の生存率が高かった。現状では,カラマツ裸苗の秋の植栽は10月下旬から11月上旬までの短い期間に限定されているが,コンテナ苗の植栽により2カ月程早められると考えられた。

2004年台風18号により風倒被害を受けた, 北海道美唄市内の防風保安林の風倒要因を解析した。この台風による最大風速は21 m/sであった。調査を行った防風林はヨーロッパトウヒ, カラマツ, シラカンバ, ヤチダモ人工林である。防風林に21箇所の方形区を設定し, 各個体の胸高直径と「根返り」, 「幹折れ」, 「無被害」別の被害状況を記録した。また, 深さ別の土壌の硬さを簡易貫入試験機により測定した。さらに, 樹種別に風倒被害の異なる要因を知るために, 幹を側方に引き, 根返りを発生させる際の最大抵抗モーメントを測定した。数量化2類による解析の結果, カラマツが最も被害を受けやすく, 次いでヨーロッパトウヒ, ヤチダモの順に風倒被害を受けにくくなった。胸高直径は30 cmをピークに被害を受けやすかった。被害の種類については, カラマツとシラカンバは根返りしやすく, ヨーロッパトウヒは幹折れしやすかった。土壌の硬さは被害にあまり影響していなかった。根返り抵抗モーメントはヤチダモ>シラカンバ≒カラマツ≒ヨーロッパトウヒとなり, 樹高や葉量の違いとともに,...

To assess and improve methods for the development of coastal forests in Hokkaido, northern Japan, this study examined factors affecting mortality planted Pinus thunbergii Parlat. saplings a region with seasonal soil frost. The needles pine at site turn red late spring, suggesting xylem embolism, which can lead to death. Sapling was strongly correlated degree cold just after planting occurrence repeated severe winters. Volcanic ash had been supplied nutrients, volcanic always thawed later...

AbstractTo demonstrate the effect of excess soil moisture on decline a coastal Pinus thunbergii stand in Oshamanbe, southwestern Hokkaido, Japan, content was monitored for 4 years. The saturated hydraulic conductivities (KS) different types (coastal sand, supplied topsoil, and buried concreted andosol) distribution andosol layer were investigated. We also examined needle length to verify real-time response P. moisture. Soil at heavily damaged site more heterogeneous than that slightly site,...

ブナ種子の長期貯蔵条件を見出すため, ヨーロッパブナにおいて提唱された貯蔵条件が日本のブナにも適用できるかどうか検証した。種子の含水率を3段階 (弱乾燥, 11.3%; 中乾燥, 6.1%; 強乾燥, 4.0%) に調製して−20ºCで冷凍保存したところ, 弱乾燥処理は貯蔵4年目に発芽率が大きく低下し, 6年目に発芽能力を失った。強乾燥処理は貯蔵4年間で発芽率の低下はみられなかった。中乾燥処理で貯蔵5年まで高発芽率 (60%) が維持され, 貯蔵10年後にも発芽率は25%を示した。中乾燥処理の結果は追試験 (含水率6.6%, −20ºC) によっても支持され (貯蔵7年で発芽率60%程度を維持), 長期貯蔵のための最適含水率は6∼9%と考えられた。貯蔵8年間で種子含水率の増加は1%に留まった。貯蔵4年目から本葉展開に至った実生の8∼25%に形態異常がみられたが, その後苗畑での生育には支障なかった。今後は, 北海道で確認された貯蔵条件が国内の他地域でも適用できるかどうか検討する必要がある。