70渡部俊太郎89Shuntaro WATANABE奄美大島における外来植物の分布拡大をもたらした個体群生態学的要因とその時間スケールの解明（2021採択）Exploring the ecological factor gave rise to rapid range expansion of invasive weed in Amami island(Project 2021)衰退以前と異なる植生への遷移を引き起こす可能性が示唆された．今後，長期的なデータを蓄積し，環境条件を変えた検証を進めることで，植生回復への技術的な応用が期待される．In this study, I analyzed the interaction between forest vegetation and soil to examine the mechanism of the soil legacy effect, in which vegetation decline caused by deer affects the growth of tree seedlings through modification of soil functions. The results showed that changes in soil nutrient dynamics associated with veg-etation decline alter soil microbial activities and functions, which have a historical effect on the growth of tree seedlings in the next generation. The response differed among functional groups of tree seedlings. This study suggests that forest vegetation decline may not only inhibit seedling regeneration through changes in soil microbial functions but may also cause a transition to vegetation that differs from before vegetation de-cline. Further validation under other environmental conditions, based on long-term data accumulation, is ex-pected to lead to technical applications for vegetation restoration.外来種は，元来その地域にない病気を持ち込むことや，生育地環境の競合により在来種を駆逐することなどを通じて経済活動や自然資源に大きな影響を与えることが知られている．しかし，すべての外来種が急速に数を増やして生態系に大きな影響を与えるわけではなく，外来種の定着の成否や密度は近縁な系統群の間でもしばしば異なる．本研究では，鹿児島県内に定着しているキク科センダングサ属の外来種3種に着目し，その分布パターン，鹿児島県への移入の過程，繁殖様式，種間相互作用の役割を比較し，定着過程に作用した生態学的要因の解明を目指した．調査の結果，3種の繁殖様式と分布には種間で違いがみられ，奄美群島で優占種となっているオオバナノセンダングサは自家不和合性である可能性が示唆された．また，オオバナノセンダングサは他の2種よりも遅れて本土に定着し，現在分布を拡大しつつある状況であることが示唆された．繁殖形質において不利な自家不和合性のオオバナノセンダングサが分布を拡大しつつある背景には種間相互作用が何らかの役割を果たしている可能性が考えられた．Invasive species have a significant impact on natural ecosystem trough to introduce diseases and displace na-tive species due to competition for habitat. However, not all invasive species have a significant impact on ecosystems, and the invasion success often varies among closely related taxa. In this study we focused on three Bidens (Asteraceae) species and compare the distribution, reproductive characteristics, interspecific in-teraction, to elucidate the ecological factors which affect species invasion success. The results of the study showed suggest that B. pilosa. var. radiata which is the dominant species in the Amami Islands, is self-incom-patible. Additionally, it was suggested that B. pilosa. var. radiata invaded the mainland later than the other two species and is currently in the process of expanding its distribution. Since self- incompatibility generally dis-advantage for range expansion, negative inter-specific interactions might involve the B. pilosa. var. radiata's range expansion in the mainland.
元のページ ../index.html#74