| Rattan,as the main associated species,is the precious non-woody forest product of tropical forest with significant ecological and economic value.The excessive cutting and utilization of rattan,the habitat of rattan was destroyed,the ecological stability of the forest was reduced.It was decreased of the supply capacity of rattan resources,which had restricted the development of rattan industry.To improve the ecological stability and supply capacity of rattan resources has become an urgent scientific problem.Nitrogen and phosphorus are essential nutrients for plant growth,and reasonable fertilization is an important way to improve the growth of rattan and the associated stands.In this paper,the natural distribution of Daemonorops jenkinsiana,Calamus tetradactylus and the associated stands were taken as the research object in Ganzhaling of Hainan Province.The effects of crown,ground nitrogen and ground nitrogen and phosphorus on the growth of two kinds of rattan and their associated stands were systematically studied by using the randomized block experiment design.The response law of rattan to the nitrogen addition mode and the nitrogen and phosphorus addition quantity was proposed to reveal its response to the brown forest.The results of this study provide an important support for the efficient cultivation of rattan.The main results are as follows:1.The effects of different nitrogen addition methods on the growth of rattan and its associated forest were different.Compared with the crown nitrogen,the ground nitrogen had more direct and effective effects on the growth,rhizosphere soil nutrients and litter of rattan.Under TN50,the biomass,projected area and specific leaf area of Daemonorops jenkinsiana were 48.66%,44.14%and 13.03%lower than that of the ground nitrogen,and 40.19%,31.62%and 17.54%lower than that of Calamus tetradactylus.Under TN100,the contents of ammonium,nitrate and organic carbon in the rhizosphere soil of Daemonorops jenkinsiana were 29.88%,31.23%and 15.86%lower than that in the ground,and the contents of ammonium and organic carbon in the rhizosphere soil of Calamus tetradactylus were 29.36%and 20.92%lower than that in the ground.The amount of nitrogen added to the canopy and the ground also had different effects on the productivity of rattan associated forest.The order of productivity of rattan associated stand under different nitrogen addition methods was:TN50>GN100>GN50>TN100.The way of TN50 and TN100 to the canopy increased the productivity of rattan associated forest,while TN100 decreased the productivity of the forest.2.Appropriate amount of nitrogen and phosphorus added to the ground significantly promoted the growth of rattan regeneration seedlings and their associated forests,but with the increase of the amount of nutrients added,the promotion effect decreased.(1)The ground nitrogen and phosphorus addition significantly promoted the productivity of Daemonorops jenkinsiana and Calamus tetradactylus.associated stands,and the most significant effect was the joint nitrogen and phosphorus addition.Under GN50+P50,the productivity of the arbor layer and the whole forest were the highest,which were 26.113 t/ha/a and 29.05 t/ha/a respectively,228.59%and 235.06%higher than the control.The productivity of herbaceous layer is the most sensitive to N and P addition,which can significantly improve the growth ability of the sprouting plants in the short term.Under the treatment of GN50+P50,the highest growth and biomass of the sprouting plants were 56.2 cm/a and 24.21 g/m~2/a,which were143.29%and 157.28%higher than the control.(2)The nitrogen and phosphorus on the ground promoted the nutrient cycle and turnover speed of the stand,and changed the nutrient content and the lowest value of litter.The improvement of soil physical and chemical properties was more significant when N and P were added together than single element was added.When nitrogen and phosphorus were added together,the litter volume of the stand was larger than that of the control in the growth season(April to August),and the time of the lowest value(April)was two months earlier than that of the control(June).Under GN50+P50,the contents of ammonium nitrogen,nitrate nitrogen and available phosphorus were the highest,which were 44.35%,72.33%and 39.02%higher than that of the control,the surface soil moisture content,bulk density and soil aeration were significantly higher than the control 55.17%,20.47%and 50.51%.(3)The combination of nitrogen and phosphorus on the ground significantly promoted the ground diameter,plant height,leaf number,and increased the biomass and survival rate of seedlings.The order of productivity of Daemonorops jenkinsiana seedlings in different nitrogen and phosphorus treatments was:GN50+P50>GP50>GN50>GN100>GN100+P100>GP100.Under GN50+P50,the annual growth of the ground diameter,plant height and leaf number of Daemonorops jenkinsiana were 1.935 mm/a,3.728 cm/a and 1.24 leaf/a,the survival rate was 92%.The order of productivity of Calamus tetradactylus seedlings in different nitrogen and phosphorus treatments was:GN100+P100>GN50+P50>GP50>GN50>GN100>GP100.Under GN100+P100,the annual growth of ground diameter and plant height of Calamus tetradactylus was 1.516 mm/a and 2.277 cm/a respectively.3.To some extent,the addition of nitrogen and phosphorus affected the environmental factors of the forest,there was strong correlation between the seedlings growth characters of rattan and the environmental factors.The main influencing factors of the height of Daemonorops jenkinsiana seedlings were the germination height of herbaceous layer plants and the minimum water holding capacity of soil,the main influencing factors of ground diameter were soil nitrate nitrogen content and herbaceous layer biomass,the main influencing factors of survival rate were soil capillary water holding capacity and minimum water holding capacity.The plant height of Calamus tetradactylus seedlings was mainly affected by soil p H value and herb layer plant germination height,the ground diameter was mainly affected by soil nitrate nitrogen content and herbaceous biomass,and the survival rate was mainly affected by soil available potassium content and organic matter content.In conclusion,it has an obvious effect on the productivity of the nitrogen and phosphorus addition of rattan and associated forest in Ganzhaling area of Hainan Province.To a certain extent,the atmospheric nitrogen deposition can improve the productivity of forest.Therefore,in the process of cultivation of rattan associated forest,we can take measures such as increasing the application of nitrogen and phosphorus fertilizer and removing impurities artificially,to improve the soil properties,increase the nutrient absorption capacity,adjust the density and height of the budding plants under the forest,and promote the growth of rattan and improve the quality of the forest land. |
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