Disturbances that create gaps can shape the structure and function of forests. However, such disturbance regimes in Asian tropical montane rainforests remain largely unquantified. Least studied are typhoon disturbance...Disturbances that create gaps can shape the structure and function of forests. However, such disturbance regimes in Asian tropical montane rainforests remain largely unquantified. Least studied are typhoon disturbances that are attributable to climate change. We investigated gap characteristics in terms of size, age, and gap-maker to quantify the gap disturbance regimes in an intact old-growth tropical montane rainforest on Hainan Island, China. The intensity of typhoons has increased since 1949, and typhoon winds blow mostly (45.5%) from the northeast corner of Hainan Island, resulting in a higher frequency of gaps in the northeast. A total of 221 gap-makers (trees that fell to create canopy gaps) and 53 gaps were observed in a 3.16 ha old-growth rainforest. Most canopy gaps (85%) were < 200 m(2). The average size of canopy gaps was smaller in the rainforest than in other tropical forests, while the average size of expanded gaps was similar to those in other tropical forests. The maximum age of gaps was 23.5 years indicating that gaps had more rapid turnover than other parts of tropical forests. The frequency distribution of gap-makers followed a lognormal distribution with a distinctive peak at three gap-makers, which was different from the inverse J-shaped curve typical of other tropical forests. Gaps were recorded mainly on slopes between 20A degrees and 35A degrees and wood density of gap-makers was between 0.6 and 0.7 g cm(-3). Our results suggest that small-scale disturbance was the dominant agent of gap formation in this old-growth rainforest that is subject to increasing typhoon disturbances.展开更多
目的:通过对神经侧支发芽过程中外源性神经生长因子对生长相关蛋白-43(gr owt h associ at ed pr ot ei n-43,GAP-43)的调控,探讨神经侧支发芽再生的机制。方法:SD大鼠共40只,建立胫腓神经端侧吻合模型,随机分为神经生长因子(nervegr ow...目的:通过对神经侧支发芽过程中外源性神经生长因子对生长相关蛋白-43(gr owt h associ at ed pr ot ei n-43,GAP-43)的调控,探讨神经侧支发芽再生的机制。方法:SD大鼠共40只,建立胫腓神经端侧吻合模型,随机分为神经生长因子(nervegr owt h f act or,NGF)组和生理盐水(SAL)组,各组又分为1周、2周、4周和8周组。切取吻合近端和远端神经纵切片标本,进行GAP-43的免疫组织化学反应,并结合计算机图像分析进行反应强度的半定量分析。结果:NGF组GAP-43表达显著增高。结论:应用NGF可以促进端侧吻合后神经侧支发芽。展开更多
基金supported by the Ministry of Science and Technology(2012BAD22B01 and 2006BAD03A04)special funds of Research Institute of Tropical Forestry,Chinese Academy of Forestry(RITFYWZX2012-02CAFYBB2014QA010)
文摘Disturbances that create gaps can shape the structure and function of forests. However, such disturbance regimes in Asian tropical montane rainforests remain largely unquantified. Least studied are typhoon disturbances that are attributable to climate change. We investigated gap characteristics in terms of size, age, and gap-maker to quantify the gap disturbance regimes in an intact old-growth tropical montane rainforest on Hainan Island, China. The intensity of typhoons has increased since 1949, and typhoon winds blow mostly (45.5%) from the northeast corner of Hainan Island, resulting in a higher frequency of gaps in the northeast. A total of 221 gap-makers (trees that fell to create canopy gaps) and 53 gaps were observed in a 3.16 ha old-growth rainforest. Most canopy gaps (85%) were < 200 m(2). The average size of canopy gaps was smaller in the rainforest than in other tropical forests, while the average size of expanded gaps was similar to those in other tropical forests. The maximum age of gaps was 23.5 years indicating that gaps had more rapid turnover than other parts of tropical forests. The frequency distribution of gap-makers followed a lognormal distribution with a distinctive peak at three gap-makers, which was different from the inverse J-shaped curve typical of other tropical forests. Gaps were recorded mainly on slopes between 20A degrees and 35A degrees and wood density of gap-makers was between 0.6 and 0.7 g cm(-3). Our results suggest that small-scale disturbance was the dominant agent of gap formation in this old-growth rainforest that is subject to increasing typhoon disturbances.
文摘目的:通过对神经侧支发芽过程中外源性神经生长因子对生长相关蛋白-43(gr owt h associ at ed pr ot ei n-43,GAP-43)的调控,探讨神经侧支发芽再生的机制。方法:SD大鼠共40只,建立胫腓神经端侧吻合模型,随机分为神经生长因子(nervegr owt h f act or,NGF)组和生理盐水(SAL)组,各组又分为1周、2周、4周和8周组。切取吻合近端和远端神经纵切片标本,进行GAP-43的免疫组织化学反应,并结合计算机图像分析进行反应强度的半定量分析。结果:NGF组GAP-43表达显著增高。结论:应用NGF可以促进端侧吻合后神经侧支发芽。
