Natural seedling regeneration and tree establishment are affected by various environmental factors.In this study,we established eight,eight,six,and four independent forest stands(each stand was further divided into fi...Natural seedling regeneration and tree establishment are affected by various environmental factors.In this study,we established eight,eight,six,and four independent forest stands(each stand was further divided into five subplots) respectively based on the altitudinal gradient,stand density,slope location,and slope aspect to investigate the effects of environmental factors on tree seedling regeneration in a pine-oak mixed forest.The results indicated that the seedling density was significantly higher at altitudes of 1,283 m to 1,665 m,whereas the sapling density did not differ with altitudes.The seedling and sapling density decreased significantly at 1,835 m.The seedling densities on the upper slopes were much higher than those on the middle and lower slopes,whereas the sapling density had no difference.The sapling density decreased gradually from the southwest(20°-75°) whereas it increased on the shady slopes to the northeast(40°).The seedling density increased from southwest(20°) to northeast(40°).The seedling and sapling densities increased with the stand density(850 trees ha-1to 1,525 trees ha-1) whereas the sapling density was significantly lower in stands(1,900 trees ha-1).Principal components analysis showed that the slope aspect and stand density had more important roles in tree regeneration in this study region compared with the other two factors.Therefore,our findings suggest that it will be beneficial to keep stands at a moderate density on shady slopes.Appropriate thinning of higher density stands is also expected to promote the natural regeneration of pine-oak mixed forest.展开更多
Background:Seed dispersal by scatter-hoarding animals can affect the developmental dynamics of plant communities.However,how animals might participate in plant inter-community competition has rarely been investigated....Background:Seed dispersal by scatter-hoarding animals can affect the developmental dynamics of plant communities.However,how animals might participate in plant inter-community competition has rarely been investigated.Forest community junction is an area where the competition between plant communities is most prominent and animal activity is more frequent.At present,little is known about how scatter-hoarding animals might assist competitions by adjacent plant communities.Thus,for 3 years(2015–2017),we tracked the fate of 2880 tagged seeds(Quercus aliena var.acuteserrata,Pinus tabuliformis,and P.armandii seed)placed near an edge where the forest composition changes from a pine forest to an oak forest in northwestern China.Results:We found that the seed fates differed when Quercus and Pinus seeds entered adjacent stands.In contrast to Pinus seeds,acorns that entered pine forests were characterized by higher caching rates and longer dispersal distances.Pinus seeds had the highest probability of being predated(85%)by rodents,and eleven Q.aliena var.acuteserrata seedlings were established in pine forests,although none survived in the later stages.In addition,rodents exhibited obvious selectivity in terms of the microhabitats for the seed caching sites.Conclusions:Seed fates differed when Quercus and Pinus seeds entered adjacent stands.The predation pressure by rodents on the seeds of Pinus species limited the germination of seeds and seedling establishment in oak forests.The different seed fates after their bidirectional dispersal could affect the differences in natural regeneration between pine and oak forests,and they might increase the recruitment rates for oak at the edge of an adjacent community.Rodent-mediated seed dispersal could potential unintentionally affect the competition between plant communities.展开更多
基金funded by the Special Research Program for Public-Welfare Forestry of State Forestry Administration of China (Grant No. 20100400206)National Natural Science Funds of China (Grant No. 31070570)CFERN & GENE Award Funds on Ecological Paper
文摘Natural seedling regeneration and tree establishment are affected by various environmental factors.In this study,we established eight,eight,six,and four independent forest stands(each stand was further divided into five subplots) respectively based on the altitudinal gradient,stand density,slope location,and slope aspect to investigate the effects of environmental factors on tree seedling regeneration in a pine-oak mixed forest.The results indicated that the seedling density was significantly higher at altitudes of 1,283 m to 1,665 m,whereas the sapling density did not differ with altitudes.The seedling and sapling density decreased significantly at 1,835 m.The seedling densities on the upper slopes were much higher than those on the middle and lower slopes,whereas the sapling density had no difference.The sapling density decreased gradually from the southwest(20°-75°) whereas it increased on the shady slopes to the northeast(40°).The seedling density increased from southwest(20°) to northeast(40°).The seedling and sapling densities increased with the stand density(850 trees ha-1to 1,525 trees ha-1) whereas the sapling density was significantly lower in stands(1,900 trees ha-1).Principal components analysis showed that the slope aspect and stand density had more important roles in tree regeneration in this study region compared with the other two factors.Therefore,our findings suggest that it will be beneficial to keep stands at a moderate density on shady slopes.Appropriate thinning of higher density stands is also expected to promote the natural regeneration of pine-oak mixed forest.
基金the National Natural Science Foundation of China(No.31470644).
文摘Background:Seed dispersal by scatter-hoarding animals can affect the developmental dynamics of plant communities.However,how animals might participate in plant inter-community competition has rarely been investigated.Forest community junction is an area where the competition between plant communities is most prominent and animal activity is more frequent.At present,little is known about how scatter-hoarding animals might assist competitions by adjacent plant communities.Thus,for 3 years(2015–2017),we tracked the fate of 2880 tagged seeds(Quercus aliena var.acuteserrata,Pinus tabuliformis,and P.armandii seed)placed near an edge where the forest composition changes from a pine forest to an oak forest in northwestern China.Results:We found that the seed fates differed when Quercus and Pinus seeds entered adjacent stands.In contrast to Pinus seeds,acorns that entered pine forests were characterized by higher caching rates and longer dispersal distances.Pinus seeds had the highest probability of being predated(85%)by rodents,and eleven Q.aliena var.acuteserrata seedlings were established in pine forests,although none survived in the later stages.In addition,rodents exhibited obvious selectivity in terms of the microhabitats for the seed caching sites.Conclusions:Seed fates differed when Quercus and Pinus seeds entered adjacent stands.The predation pressure by rodents on the seeds of Pinus species limited the germination of seeds and seedling establishment in oak forests.The different seed fates after their bidirectional dispersal could affect the differences in natural regeneration between pine and oak forests,and they might increase the recruitment rates for oak at the edge of an adjacent community.Rodent-mediated seed dispersal could potential unintentionally affect the competition between plant communities.