| Cones and seeds are the most important part of propagation system for conifers, and have great ecological adaptation under strong selection pressure. They can also form the basis for distinction and comparison between conifer species because they are mostly determined by genetic control. Abies fargesii is a common species currently under no conservation threats, while Abies chensiensis is an endangered species. The distribution area of A. fargesii is larger and encompasses the distribution of the less widespread A. chensiensis. Mature cones of the two firs were collected at the south slope of Qinling Mountain and the north slope of Shennongjia Mountain. The fruiting characteristics of cones and seeds were measured and comparatively analyzed. Accelerated seed aging processes and seed germination were studied under different experimental conditions. The spatial and temporal pattern of seed rain in Shennongjia was monitored through the setting of seed collectors in selected plots of A. fargesii communities, and was compared to that of A. chensiensis. Field experiments were conducted to determine seedling adaptations of A. chensiensis to different environmental conditions. Similarities and differences in fruiting characteristics and regeneration dynamics for these 2 firs with different population status were found for the first time based on above research. This provides the scientific basis to understand the regeneration strategies, wisely choose parent trees and allocate seeds and seedlings for A. fargesii. It also provides further understanding on the endangering causes for A. chensiensis and aids in the development of suitable restoration approaches. The major results are as follows.1. One-way ANOVA analysis showed fruiting characteristics had significant differences among populations and parent trees for both species. The number of cones per tree was 110.1 for A. chensiensis, which significantly lower than that of A. fargesii(201.6). For A. chensiensis in Qinling Mountain, the number of seeds per cone and the seed size were greater than that of most other specimens studies, but fewer seeds were fully developed per cone and showed very high abortion rates. With the increase of elevation, the ratio of fruiting trees to adult trees and the number of cones per tree were reduced, which indicated better reproduction for A. chensiensis at low elevations. Significant differences in cone size, the number of seeds per cones, and seed quality were found among differing elevations for A. fargesii, indicating better reproduction capabilities for A. fargesi at low elevations.2. The variance component analysis indicated the presence of significant differences of morphological traits of cones and seeds among populations, parent trees and cones for both fir species. For A. chensiensis, approximately 85% of the variation was attributable to differences between individual trees and within tree variation, providing strong evidence of substantial genetic control over traits. The mean values of traits for cones and seeds showed that plants distributed at low elevations were better than plants distributed at higher elevations, the core region was higher than the border area, the planted forest greater than the natural forest, showing that overall A. chensiensis reproduced better in the core region. For A. fargesii, the mean values of traits for cones and seeds changed along a vertical gradient, which showed that the high elevation was better than the low elevation. The different cone and seed traits between A. chensiensis populations was greater than those found between A. fargesii populations. The percentage of fully developed seeds in total seeds was 25.7% for A. chensiensis and 57.9% for A. fargesii.3. The seed rain of two firs showed different patterns that were affected by wind and seed weight. This dispersal pattern determines the seed germination, seedling regeneration and future distribution pattern of the populations. For A. chensiensis, the seed rain depended mainly on weight due to its comparatively larger size, and seed rain was concentrated in the distance of 6m far from the parent tree. 88% of the seed rain of A. fargesii populations was concentrated in the distance of 12m far from the parent tree. The seed rain pattern changed from a clump distribution pattern at the beginning of seed dispersal to a random pattern at the end of the dispersal period.4. The seed germination rates were significantly different between the 2 firs. The germination rate of A. fargesii (80 %) was 3 times that of A. chensiensis (28 %) under the same conditions. This suggests that seed viability may be an important causal factor in determining the abundance and consequently the conservation status differences between the two species.5. The seeds of A. chensiensis were found to undergo light dormancy. Some physical and chemical treatments were helpful to break dormancy of A. chensiensis besides cold stratification. Cold stratification under 1-5℃was the most successful method to increase germination rates and speed, after the seeds were soaked in water for 3-5 days and mixed with wet sand at a ratio of 1:3. Germination rates of seeds from the core region (38.1%) were significantly better than those from the border area (13.8 %) , which indicated that A. chensiensis in the core region had superior reproductive traits.6. High relative humidity and high temperature not only changed the moisture content of the seeds but also led to seed deterioration. The seeds of A. fargesii lost their vigor after storage at 40℃and 100% relative humidity for a period of 6 days.7. Seedling adaptation of A. chensiensis was revealed by field experiments under different conditions. The mean seedling emergence in field was only 16.9% and no morn than the half of that in lab. After one year, the seedling mortality was 57.6%. Seed germination and seedling survival and growth of A. chensiensis were affected by elevation, light conditions, seedbed material, sowing depth and seed provinces in differing degrees.
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