Currently in South China, large areas of plantations are still in pioneer stage with inadequate ecosystem services due to the absence of indigenous tree species. To improve understanding of whether and how direct seeding can lead to the establishment of indigenous tree species, Dr. WANG Jun of South China Botanical Garden, CAS, supervised by Prof. REN Hai carried out an experiment in four typical plantations (eucalyptus, mixed-native, mixed-legume, mixed-conifer) and a shrubland in South China.
In the study, they sowed seeds of three indigenous tree species (Castanopsis chinensis, Cryptocarya chinensis, and Psychotria rubra) under the four plantations and the shrubland, and also tested the effect of understory vegetation and litter removal on seedling establishment and growth. Seedling emergence, survival, and growth were recorded for 21 months.
They found that conditions that favored seedling emergence often differed from those that favored seedling survival. While the removal of understory vegetation and litter did not influence the final seedling establishments for all the three introduced species, growth of P. rubra was influenced at several sites. Seed mass was positively correlated with seedling emergence and subsequent growth. Seedlings of C. chinensis grew better in plant communities with high understory light penetration and high soil exchangeable potassium. Growth of P. rubra seedlings decreased significantly with soil hydrolyzed nitrogen.
In conclusion, direct seeding can be useful for the establishment of indigenous tree species into plantations and shrubland. Optimizing early seedling establishment and growth will require the selection of suitable native species for improving seedling establishment in different plantations.
The results are published on New Forests and online. (http://www.springerlink.com/content/j617805214426226/).
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