Determining method of light compensation utilization of phalaris arundinacea in reed and phalaris arundinacea community

[0019] Example 1:

[0020] On May 5, 2015, in fine weather, select Phragmites australis community, the plot area is 1m×1m, the height of the reed is about 2.0m, and the density is 25 plants/m. 2 , The height of Phalaris is about 1.5m. Follow the steps below to determine the method of light compensation and utilization of Phalaris arundinacea in Phragmites australis community.

[0021] (1) Using the LI-6400 portable photosynthetic instrument produced by LI-COR, USA, measure the middle of the third unfolded leaf below the top. Using the artificial light source configured by the instrument, the time is 8:00, 10:00, 12:00, 14:00, 16:00, and the light intensity gradient is 0, 20, 50, 100, 150, 200, 400, 600, 800 , 1000, 1200, 1500, 1800, 2000, 2200, 2500μmolm -2 s -1 , The system automatically records the net photosynthetic rate corresponding to different light intensities every 3 minutes to fit the light response curve. According to the coefficient of determination R 2 It can be seen that the fitting effect of the quadratic curve equation is better. Therefore, under artificial light sources, it is more appropriate to fit the light response curve of Phalaris arundinacea surface leaves with a quadratic curve equation. The corresponding light response curves of Phalaris arundinacea surface leaves at 8:00, 10:00, 12:00, 14:00, and 16:00 are y=-5×10 -6 x 2 +0.0150x+1.5636( figure 1 ), y=-4×10 -6 x 2 +0.0147x+1.3829( figure 2 ), y=-4×10 -6 x 2 +0.0136x+1.2515( image 3 ), y=-4×10 -6 x 2 +0.0124x+1.2094( Figure 4 ), y=-6×10 -6 x 2 +0.0176x+1.2854( Figure 5 ).

[0022] (2) Measure the light intensity of the surface leaves of Phalaris arundinacea and the surrounding unobstructed environment at 8:00, 10:00, 12:00, 14:00, and 16:00 under natural light with dual radiometers. The results are shown in Table 1.

[0023] Table 1 The light intensity of Phalaris arundinacea surface leaves and surrounding unobstructed environment at different time periods under natural light

[0024]

[0025] (3) According to the light response curve of Phalaris arundinacea leaves fitted in step (1), calculate the light intensity of the surface leaves of Phalaris arundinacea and the surrounding unobstructed environment under natural light in step (2) on the light response curve. The corresponding net photosynthetic rate. The results are shown in Table 2.

[0026] Table 2 The net photosynthetic rate corresponding to the light response curve of the surface leaf of Phalaris arundinacea and the surrounding unobstructed environment under natural light at different times

[0027]

[0028] (4) Calculate the ratio of the net photosynthetic rate corresponding to the light response curve of the light intensity of the surface leaves of Phalaris arundinacea under natural light and the surrounding unobstructed environment in each time period in step (3). The results were 71.61%, 73.41%, 76.29%, 78.31%, 77.43%.

[0029] Example 2:

[0030] On May 5, 2015, in fine weather, select Phragmites australis community, the plot area is 1m×1m, the height of reed is about 2.0m, and the density is 45 plants/m. 2 , Pheasant grass height is about 1.5m. Follow the steps below to determine the method of light compensation and utilization of Phalaris arundinacea in Phragmites australis community.

[0031] (1) Using the LI-6400 portable photosynthetic instrument produced by LI-COR, USA, measure the middle of the third unfolded leaf below the top. Using the artificial light source configured by the instrument, the time is 8:00, 10:00, 12:00, 14:00, 16:00, and the light intensity gradient is 0, 20, 50, 100, 150, 200, 400, 600, 800 , 1000, 1200, 1500, 1800, 2000, 2200, 2500μmolm -2 s -1 , The system automatically records the net photosynthetic rate corresponding to different light intensities every 3 minutes to fit the light response curve. According to the coefficient of determination R 2 It can be seen that the fitting effect of the quadratic curve equation is better. Therefore, under artificial light sources, it is more appropriate to fit the light response curve of Phalaris arundinacea surface leaves with a quadratic curve equation. The corresponding light response curves of Phalaris arundinacea surface leaves at 8:00, 10:00, 12:00, 14:00, and 16:00 are y=-5×10 -6 x 2 +0.0150x+1.5636( figure 1 ), y=-4×10 -6 x 2 +0.0147x+1.3829( figure 2 ), y=-4×10 -6 x 2 +0.0136x+1.2515( image 3 ), y=-4×10 -6 x 2 +0.0124x+1.2094( Figure 4 ), y=-6×10 -6 x 2 +0.0176x+1.2854( Figure 5 ).

[0032] (2) Measure the light intensity of the surface leaves of Phalaris arundinacea and the surrounding unobstructed environment at 8:00, 10:00, 12:00, 14:00, and 16:00 under natural light with dual radiometers. The results are shown in Table 3.

[0033] Table 3 The light intensity of Phalaris arundinacea surface leaves and surrounding unobstructed environment at different time periods under natural light

[0034]

[0035] (3) According to the light response curve of Phalaris arundinacea leaves fitted in step (1), calculate the light intensity of the surface leaves of Phalaris arundinacea and the surrounding unobstructed environment under natural light in step (2) on the light response curve. The corresponding net photosynthetic rate. The results are shown in Table 4.

[0036] Table 4 The net photosynthetic rate corresponding to the light response curve of the surface leaf of Phalaris arundinacea and the surrounding unobstructed environment under natural light at different time periods

[0037] (4) In the calculation step (3), the light on the surface leaves of Phalaris arundinacea and the surrounding unobstructed environment at each time period under natural light

[0038]

[0039] The ratio of the light intensity to the net photosynthetic rate corresponding to the light response curve. The results were 35.81%, 36.05%, 39.98%, 35.79%, 33.26%.

[0040] Implementation Effect

[0041] Calculated from Table 2, when the reed density is 25 plants/m 2 The average compensation utilization rate of the net photosynthetic rate of Phalaris arundinacea leaves was 75.44%, and Table 4 shows that when the density is 45 plants/m 2 At time, the average compensation utilization rate of the net photosynthetic rate of Phalaris arundinacea leaves was 36.18%. It can be seen that the density is 25 plants/m 2 The canopy of the reed has little effect on the net photosynthetic rate of Phalaris arundinacea. Light can maintain the normal growth of Phalaris arundinacea, and the density is 45 plants/m. 2 The canopy of the reed has a great influence on the net photosynthetic rate of Phalaris arundinacea, and light cannot satisfy the normal growth of Phalaris arundinacea, which is consistent with the growth of Phalaris arundinacea in the field. In addition, the growth dynamics of Phragmites communis and Phragmites communis ( Image 6 During the coexistence of the two species, Phalaris arundinacea was significantly lower than that of Phragmites australis in a relatively short period of time, and Phalaris arundinacea was in the seed filling and post-maturation stage. For Phalaris arundinacea, a clonal plant whose roots and stems are the main propagation, the photosynthetic rate in the later period is certain The degree of decline must have less impact on its life history. Therefore, when the reed density is 25 plants/m 2 When left and right or further improved, the light compensation utilization of Phalaris arundinacea can still ensure a relatively stable coexistence pattern of the two species to a certain extent. Therefore, this technical method can realize the light compensation and utilization of Phragmites arundinacea by controlling the density of reeds in the constructed wetland, so as to realize the stable coexistence of the two. It is not only important for revealing the maintenance mechanism of Phragmites arundinacea-Phragmites communis metapopulation coexistence in wetland, but also It is also of great significance to determine the light compensation utilization of plants under the canopy of other communities with vertical distribution characteristics.