DISPERSAL PATTERN OF JUVENILES OF EMERGENT, CANOPY AND SHADE-TOLERANT TREE SPECIES ON FLOOD-PLANE FOREST AREA AT BERAU, EAST KALIMANTAN

Pola penyebaran anakan jenis pohon emergent (Shorea sp.), kanopi (Maduca malaccensis) dan toleran naungan (Aglaia tomentosa) telah diamati pada hutan dataran rendah luapan banjir di Berau, Kalimantan Timur. Hasil penelitian menunjukkan bahwa, penyebaran anakan ketiga jenis pohon tersebut sangat dipengaruhi oleh agen dispersal buah. Anakan Shorea sp., yang mana memiliki buah tipe samara, sebagian besar tersebar pada bagian Utara-Barat pohon induknya, mengikuti arah angin yang menerbangkan buahnya. Anakan dua jenis lainnya, yang mana buahnya yang bertipe berry sangat disukai oleh binatang mamalia, menyebar secara lebih merata. Struktur populasi anakan ketiga jenis tersebut menunjukkan kecenderungan yang berbeda. Shorea sp. menunjukkan struktur populasi berbentuk huruf J terbalik yang sangat tajam, sedangkan struktur populasi anakan dua jenis lainnya cenderung berbentuk garis horizontal. Perbedaan struktur populasi tersebut terkait dengan toleransi jenis-jenis tersebut terhadap naungan. Buah Shorea sp. yang jumlahnya melimpah segera berkecambah setelah jatuh, namun pertumbuhan anakan selanjutnya tertahan oleh naungan kanopy hutan yang sangat rapat. Key words : Dispersal, Juvenil, Emergent, Canopy, Shade-tolerant

Dispersal of Pissodes strobi in putatively resistant white spruce in Vernon, BC

White pine weevil Pissodes strobi behaviour was observed in a five-year-old plantation of white spruce in Vernon, British Columbia. Seasonal weevil-host interactions were monitored in four susceptible and four putatively resistant reciprocal cross family pairs in three of five replicates. Classification of susceptibility to weevil attack was based on previous weevil attack history. Performance of eight reciprocal cross pairs was ranked as a function of visitation, oviposition and brood establishment resulting in top-kill. The four putatively resistant family crosses ranked 1 to 4 for resistance to weevil attack, while the four susceptible crosses were ranked 5 to 8 and were consistently attacked. Seasonal and diurnal weevil movement was monitored using mark-recapture techniques. Diurnally, weevils moved within the tree. Feeding occurred at dawn in the leader and upper laterals after which weevils moved down the tree into the forest floor during the high mid-summer temperatures. Later in the season weevils fed in mid-morning on the leader and on the under-sides of lateral branches. A dispersal index was developed to describe seasonal movement. Weevils did not move far throughout the season. Overall dispersal index for both males and females was less than 0.24 m, suggesting that on average, weevils do not move further than the adjacent tree throughout the season after mating and oviposition. Key words: Dispersal, pest management, Pissodes strobi, resistance, silviculture, white spruce

Seed germination ecology of poison hemlock, Conium maculatum

In north-central Kentucky, United States, seeds of Conium maculatum are dispersed from mid-September to mid to late February, with up to 95% of them being dispersed by late December. Depending on the year, 40–85% of the freshly matured seeds had morphological dormancy (MD) and thus needed only a moist substrate, 10–15 14-h photoperiod days and 12-h alternating thermoperiods of 30:15 °C for embryo growth and germination. The other seeds had morphophysiological dormancy (MPD), and embryo dormancy had to be broken before embryo growth and germination could occur. MPD was broken in some of the undispersed seeds during summer, and by September 50–85% (depending on the year) germinated at 25:15 °C in light. During late autumn and winter, 35–95% (depending on the year) of the undispersed seeds in MD in autumn entered MPD. Cold stratification at 5 °C induced about half the seeds with MD into MPD. Seeds in MD germinated to higher percentages on soil than on sand, and in light than in darkness. Most of the seeds sown on soil in a nonheated greenhouse in July, August, and September germinated in September. Seeds sown in October and November germinated in autumn, late winter, and the following autumn, and those sown in late winter germinated in spring and autumn. The later seeds were sown, the higher germination percentages were the following autumn. Key words: dispersal, dormancy, germination, morphological dormancy, poison hemlock, Conium maculatum, monocarpic perennial.