Field planting experiments of mangrove on high-salinity beaches

【Objective】Growth adaptability of different mangrove species to the environmental influence on the high-salinity beach (higher than 30‰) was determined in order to provide reference and basis for mangrove afforestation on difficult sites. 【Method】Growth difference of mangrove species was analyzed through field planting experiments on high-salinity beaches in relation to different beach elevations, soil types and planting measures. 【Result and conclusion】 Beach elevation had significant effects on the growth and survival rate of mangrove species Rhizophora stylosa, Kandelia obovata, Laguncularia racemosa and Sonneratia apetala on high-salinity beaches. The growth and survival rate reached maximum at mean sea level beach elevation generally,while they showed a declining trend with the beach elevation above or below mean sea level. At the sandy beach with elevation at mean sea level, L. racemosa and S. apetala had a survival rate of over 80%, and the growth amount of L. racemosa was much larger than R. stylosa, K. obovata and S. apetala. At the muddy beach with elevation at 0.2 m above mean sea level, the survival rate of both R. stylosa and K. obovata was over 70% while the survival rate of both L. racemosa and S. apetala was lower than 20%. As for the growth amount, L. racemosa was close to S. apetala, a little larger than R. stylosa and K. obovata. Marine algae affected the growth of mangrove plants in winter and spring. Saplings could suffer heavily especially in the windward area, among which the survival rate of R. stylosa and L. racemosa in the windward area was only 40% of that in the leeward side. At sandy site the growth and survival rate of R. stylosa saplings originated from hypocotyl was much higher compared with those originated from seedlings, but at muddy sites, growth difference of R. stylosa saplings with different origins was relatively small. As for planting measure, planting depth of hypocotyl within a certain range did not influence the growth and survival of mangrove saplings.