Effects of moist chilling and solid matrix priming on germination of loblolly pine (Pinus taeda L.) seeds

Loblolly pine (Pinus taeda L.) seeds from sources with a mild climate under maritime influence (North Carolina) required shorter moist chilling to achieve maximum germination vigor than seeds from sources with a harsher continental climate (Oklahoma). Solid matrix priming (SMP) for 6 d achieved as much as 60 d of moist chilling to improve rapidity, synchrony and completeness of germination for three of the four families studied. SMP after moist chilling increased the rapidity, synchrony and completeness of germination. The benefit of SMP was greatest for non-stratified seeds and the benefit decreased with length of moist chilling. In general, delaying planting for one week after SMP had minor effects on germination when seeds were kept in the SMP matrix at 4°C. Delayed planting after SMP can increase germination rapidity and synchrony of seeds that have received long moist chilling and reduce the benefit of SMP in non-moist-chilled seeds.     

Effects of drought stresses induced by polyethylene glycol on germination of Pinus sylvestris var. mongolica seeds from natural and plantation forests on sandy land

Effects of drought stresses induced by polyethylene glycol (PEG) (0.0%, 10%, 15%, 20%, 25%, and 30%, with four replicates) on germination of Mongolian pine (Pinus sylvestris var. mongolica) seeds produced in plantations (southern Keerqin sandy land) and natural forests (Hulunbeier sandy plain) were observed. The results indicated that the seeds from both provenances did not germinate when PEG concentration was more than 25%. The time of initial germination and that of its completion of stressed seeds from both provenances were delayed when compared with the unstressed seeds. The germination capacity and germination rate of natural seeds were significantly higher than those of plantation seeds for all treatment levels (P < 0.05). The mean growth rates of radicle and hypocotyl from natural seeds were significantly higher than those from plantation seeds at all treatment levels below 20% PEG treatment (P < 0.05). The ratios of radicle to hypocotyl of 20% PEG treatment were significant higher than those of the corresponding controls for both provenances (P < 0.05). These results suggested that Mongolian pine seeds/seedlings had stronger resistance to PEG drought stresses; 10% PGE stress did not significantly influence germination. Natural seeds exhibited more resistance to PEG stress than plantation seeds. It was concluded that drought stress on seed germination might be one cause of obstructed natural regeneration of Mongolian pine plantations on sandy land. It is recommended that natural seeds be used for afforestation, and light drought stress (e.g., 10% PEG stress) may be useful in improving seed germination and the growth of radicles and hypocotyls.     

山核桃天然群体家系种实和幼苗性状变异分析

基于岛石天然林山核桃自由授粉产生的44个单株果实与种子的表型及由种子实生繁殖1年生幼苗生长性状11个指标的数据,分别计算了各指标的特征值,并进行了方差分析,研究其自然变异.结果表明,果实和种子各表型变异程度不一,其中以果实质量的变异系数最大,为11.22％;其次是种子质量和出籽率,分别为8.64％和7.66％;种实各指标在采样单株间的差异均极显著.除果实质量与果形指数和种形指数之间无显著相关外,其余各指标两两间相关均极显著.1年生苗木苗高和地径变异系数分别达13.99％、10.28％,且各家系间差异极显著;苗高与地径的Pearson相关系数为0.552,相关性极显著.2个苗木生长指标与9个种实表型指标间相关性不显著.     

Legacies from natural forest dynamics: Different effects of forest management on wood-inhabiting fungi in pine and spruce forests

The species composition of wood-inhabiting fungi (polypores and corticoids) was investigated on 1138 spruce logs and 992 pine logs in 90 managed and 34 natural or near-natural spruce and pine forests in SE Norway.Altogether, the study included 290 species of wood-inhabiting fungi. Comparisons of logs with similar properties (standardized tree species, decay class, dimension class) in natural and managed forests showed a significant reduction in species number per log in managed spruce forests, but not in managed pine forests. The species number per log in managed spruce forests was 10-55% lower than on logs from natural spruce forests. The reduction was strongest on logs of large dimensions. A comparison of 200-400 spruce logs from natural and managed forests showed a 25% reduction in species richness corresponding to a conservative loss of ca. 40 species on a regional scale.A closer inspection revealed that species confined to medium and very decayed spruce logs were disfavored in managed forests, whereas species on early decay classes and decay generalists were unaffected. Similarly, species preferring large spruce logs were disfavored in managed forests. Forest management had strongest impact on low-frequent species in the spruce forests (more than 50% reduction), whereas common species were modestly affected. Corticoid fungi were more adversely affected than polypore fungi.These results indicate that wood-decaying fungi in pine forests are more adapted to forest disturbances than spruce-associated species. Management measures securing a continuous supply of dead wood are more important in spruce forests than in pine forests.