果园转型生态公益林防控薇甘菊的生态改造

【背景】深圳大面积果园已转型为生态公益林,但果树被入侵的薇甘菊攀爬覆盖,严重地段已导致群落退行性演替,问题亟待解决。【方法】选取有多种生境的转型果园,分片区开展以植树为核心的生态改造试验,树种以种植后不进行人工除草抚育的血桐、幌伞枫、阴香为主,辅以提高物种多样性为目标的演替中后期树种,均采用袋装大苗于2011年5月种植。【结果】在树冠连续、郁闭的果林片区,所植苗木死亡,林下草本稀少,始终无薇甘菊。在其他非郁闭片区,血桐与幌伞枫生长良好且从未被覆盖;阴香虽于秋冬季被全覆盖但不死亡,次年春新枝穿透覆盖层正常生长;其余种苗木对薇甘菊处于劣势。【结论与意义】郁闭度高的果林片区林下光照弱,能阻止薇甘菊定居,无需人工干预;血桐和幌伞枫分别具抗/耐受薇甘菊覆盖的特性,种后均无需抚育;其余树种则需抚育。因此,掌握各个树种的特性,适地种植、按需精准定株抚育是转型果园低成本、技术简单、一劳永逸地防控薇甘菊生态改造的精髓。在应对有害藤本危害时,勿忽略筛选出不惧该藤本的植物种的可能,在不使用农药、无有效动物或微生物天敌的情况下,它们有可能成为生态安全的防控改造树种。

Ecological restoration to control Mikania micrantha in an orchard farm transformed into an ecological non-commercial forest

Background] A large area of orchard farm in Shenzhen, China, was transformed into an ecological non-commercial forest. However, many trees became densely covered with an invasive herbaceous vine Mikania micrantha and eventually died. A solution to counter this recessive succession was needed.Method] An orchard farm having various habitats, divided into corresponding sections, was used for an ecological restoration experiment by planting big tree saplings (height > 1 m) originally grown in nutritious container in May 2011. Most saplings were those of Macaranga tanarius, Heteropanax fragrans and Cinnamomum burmannii, which tolerate/resist covering.Result] In the section where orchard''s crown was continuous, no saplings survived and Mikania micrantha was not able to get established. In the other sections, Macaranga tanarius and H. fragrans grew well and were never covered by Mikania micrantha. C. burmannii was fully covered by Mikania micrantha in autumn and winter but none died, and in the following spring new shoots penetrated the dense coverage of Mikania micrantha and grew normally. The rest of the saplings were inferior to Mikania micrantha and most died.Conclusion and significance] No manual interference was needed at closed orchard since its shading totally prevented Mikania micrantha to establish. Macaranga. tanarius and H. fragrans were able to grow normally without treatments as they were either resistant or tolerant to Mikania micrantha. All saplings of the other species needed tending. Thus to select tree species based on good understanding of their properties, to plant in proper habitat, and to target tending individually based on species were the core of simple and low cost restoration practice to control Mikania micrantha. Further, the results suggest that susceptible plant species can be selected if the vine is controlled, and screened plants that tolerate/resist harmful vine coverage might be used as control agents without herbicide application while natural animals or pathogen enemies are yet to be introduced.