Environmental Factors Influencing The Success Of Coastal Forest Shelterbelt Establishment In Jinjiang City, Fuijan Province, China

In this article, we set up a automatic meteorological station, took soil samples at regular intervals to monitor the environmental factors influencing the success of coastal forest shelterbelt establishment in Shenhu Bay of Jinjiang City, Fuijan Province, China. Relationship between growth of Casuarina equisetifolia plantation shelterbelt and environmental factors were investigated, and the main reasons influencing effects of C. equisetifolia plantation shelterbelt afforestation. The main results were as follows:(1) At height 3 m, in Shenhu Bay, during January to September in 2015, mean air temperature was 20.76℃, monthly mean air temperature was highest in July (26.50 ℃), lowest in January (13.08℃); extreme highest air temperature (35.78℃) appeared in July, extreme lowest air temperature (4.73℃) appeared in January.(2) Mean air relative humidity during January to September in 2015 was 82.34%, highest monthly mean air relative humidity was highest (85.08%) in August and lowest in January (76.06%). Mean air relative humidity was second lowest (79.82%) in April, and the values of the rest 7 months were all over 80%.(3) Precipitation during January to September in 2015 was 1091.6 mm, it was lowest in February (17.1 mm), second lowest in January (29.5 mm), highest in August (270.2 mm), second highest in September (236.3 mm).(4) During January to September in 2015, average wind velocity was 3.12 m·s-1, maximum monthly wind velocity was in January (13.7 m-s"1). We divided the wind directions into 16 numbers. There were 16 wind directions appeared during January to September in 2015, but their wind velocity and frequency were different. During 9 months frequency of NE and NNE direction were 17.04% and 16.77%, respectively, and they were highest and second highest frequency among 9 months. The sum of the frequencies of the 2 highest- frequency wind direction was 33.81%, and their wind velocities were 4.54 m·s-1 and 4.46 m·s-1, respectively, and their value were highest and the second highest, respectively. During 9 months, WNW wind direction was the lowest frequency (1.73%), and W wind direction had the lowest wind velocity (0.69 m·s-1).(5) There were different wind velocities in different months. January had the highest wind velocity (4.35 m·s-1), its wind direction frequency was highest in NNE (35.70%), and wind velocity was also highest (5.63 m·s-1) in this direction. In February, mean wind velocity (3.37 m·s-1) was the third highest monthly values, NE wind direction frequency (27.80%) was the highest among all directions, its wind velocity (4.53 m·s-1) was the second highest among all directions; NNE wind direction frequency (23.83%) was the second highest among all directions, its wind velocity (4.59 m·s-1) was the highest among all directions. In March, mean wind velocity (3.55 m·s-1) was the second highest monthly values, NE wind direction frequency (24.42%) was the highest among all directions, its wind velocity (5.05 m·s-1) was the second highest among all directions; NNE wind direction frequency (23.37%) was the second highest among all directions, its wind velocity (5.20 m·s-1) was the highest among all directions. In June, mean wind velocity (2.58 m·s-1) was the lowest monthly values, SSW wind direction frequency (23.89%) was the highest among all directions, its wind velocity was 2.73 m·s-1, SW wind direction frequency (19.47%) was the second highest among all directions, its wind velocity was 2.69 m·s-1, NE wind direction frequency (6.43%) was medium, but its wind velocity (3.26 m·s-1) was the highest among all directions. In May, mean wind velocity (2.60 m·s-1) was the second lowest monthly values, NE wind direction frequency (14.49%) was the highest among all directions, its wind velocity (3.44 m·s-1) was the highest among all directions t, too.(6) Strong NE-direction wind, low precipitation, dry soil and low air relative humidity leading to high spike top and even death rate, was the main reason of afforestation failure of C. equisetifolia plantation shelterbelt. Wind velocities in different locations of C. equisetifolia plantation shelterbelt were different. Tress of C. equisetifolia grew well and had high survival rate near stone windbreak or over 50 m far away from sea shore where the wind velocity were low. Tress of C. equisetifolia grew poorly and had low survival rate far from stone windbreak and near sea shore (shorter than 50 m).(7) Salt-water intrusion and salt mist in front of the coastal C. equisetifolia plantation, with soil salinity over 1% plus strong wind were main reasons leading to excess mortality rate of C. equisetifolia young tress in special location.(8) Results of the five C. equisetifolia clones afforestation trial showed that survival rate of Clone Huian-1 (85.64%) was the highest, while the Clone Pingtan-2 (69.72%) was the lowest, but their difference were not significant (P>0.05).(9) In the open field of strong wind, wind speed increased with the high increased. Protection effect of stone windbreak decreased with the distance from windbreak increased.(10) In conclusion, strong NE wind in Autumn and Winter, soil drought and soil salinization caused by salt-water intrusion were main reasons leading to afforestation failure of coastal C. equisetifolia plantation shelterbelt.