Seed Vigor Dynamics Of Leaf Deciduous Broad - Leaved Forest And Changes Of Spatial Pattern Of Main Species In Malan Forest Region Of Loess Plateau

The self-recolonize and self-repair of forest is an important part of the forest community dynamics, and seed dispersal is one of the main methods for forest community regeneration. It determines seed spreading distance and the distribution patterns of species diversity in forest community. Based on the data of seeds rain and seedling regeneration from the long-term observation, this paper focused on the seeds and seedling dynamics in Quercus wutaishanica and Betula platyphylla mixed forest community on population and community scales, quantized the seed and seedling limitation, clarified effects of random process and deterministic process in community establishment, and analyzed seed dispersal strategies in forest regeneration process, which would supply the theoretical foundation and date support for the population and community structure dynamics.The main conclusions were as follows:(1) We analyzed the spatial patterns of the natural mixed forest of Quercus wutaishanica-Betula platyphylla. Betula platyphylla presented an random distribution in most scales, and only transformed into a aggregating type in the small scales, while Quercus wutaishanica presented a aggregating distribution on the scale of the 13m, and presented the random distribution in other scales. (2) From 2012 to 2013, we collected seed of ten families and thirteen species in total. And the number and variety of seeds in 2012 was significantly more than in 2013. And most of the seed dispersal can last a long time, for example, Betula platyphylla seeds can be collected four times. Different species had a different seed number of peaks. Quercus wutaishanica、Lespedeza bicolor and Swida walteri had the highest number of seeds in September, while Acer ginnala and Cotoneaster multiflorus were a little late. (3) Seed rain in collector level density and species richness were quite different in two fold, and a single seed trap could collect 6 species at most, and 70% of seed traps can receive more than thousand seeds. (4) Quercus wutaishanica as the most dominant species in this region, whose number changed a lot between the years and annual production was significant difference. The density of intact seeds was 130.24 / m2 in 2012, but 0.16/m2 in 2013. Because the observation only lasted two years, so we need further long-term research to get the cyclical change law. (5) In 2013, we collected ten families and eleven species in total, of which it was only twenty-one samples we observed the effective update. Seedlings were (Quercus wutaishanica and Spiraea pubescens) showed an obvious agminated phenomenon. (6) A linear model was established to assess correlation between seed and seedling based on relationship of seed density and seedling density. Quercus wutaishanica showed positive correlation between seed density and seedling density (P<0.05) and most other species showed none relevant. (7) There was a strong seed limitation and establishment limitation among the most species in mixed forest. Especially Betula platyphylla, because of the small size and large numbers, it can spread the whole forests. Each seed trap could collect its seed. But it could not regenerate effectively, indicating that Betula platyphylla had no seed limitation but a strong regeneration limitation. And Quercus wutaishanica、 Acer ginnala and Vitis piasezkii var. pagnucii were orderly. Betula platyphylla and Cotoneaster multiflorus had a strong regeneration limitation.