Allelopathy on Bark of Downed Logs of Chamaecyparis Obtusa sieb. and Zucc. var. formosana (Hayata) Rehder

Abstract

Chamaecyparis obtusa Sieb. and Zucc. var. formosana (Hayata) Rehder is the dominant species in the temperate forest of Yuanyang Lake Nature Reserve (YYL), Taiwan. Although downed logs of C. obstusa var. formosana occupy only a small percentage of the forest floor area in YYL, they are important regeneration substrates. Seedlings of this species often grow without competition on the new downed logs, and a few broadleaf trees grow with them. We hypothesized that the bark of the newly fallen logs possesses allelopathic potential that provides a habitat especially suitable for seedling establishment. Eight different seeds including those from Lactuca sativa L. (lettuce), Bidens pilosa (an invasive weed), and six species in YYL were planted on the bark of the downed logs in an incubator for germination tests. Two dominant species in the forest of YYL, C. obtusa var. formosana and Rhododendron formosanum, were able to grow normally, but the others, Pieris taiwanensis, Barthea formosana, Chamaecyparis formosensis, Miscanthus transmorrisonensis, lettuce, and B. pilosa were growth inhibited. A bioactivity-guided isolation was designed to isolate allelochemicals from the bark. Salicylic acid, one of the inhibiting substances, was isolated and identified by gas chromatography/mass spectroscopy (GC/MS), proton nuclear magnetic resonance ((1)H NMR), and infrared (IR). Bioassay of salicylic acid confirmed a phytotoxic effect. The results suggest that the dominance of C. obtusa var. formosana seedlings on bark could be partly due to allelopathy.

Pine stumps act as hotspots for seedling regeneration after pine dieback in a mixed natural forest dominated by Chamaecyparis obtusa

“…The observed regeneration of C. obtusa and coexisting Rhododendron spp. on deadwood supports the findings of previous studies (Yamamoto 1993;Liao et al 2003;Tseng et al 2007). Both C. obtusa and Rhododendron spp.…”

Weed Control and Organic Mulches Affect Physiology and Growth of Landscape Shrubs

“…For example, Duryea et al (1999) observed allelopathic effects of several fresh mulches in bioassays on germination of lettuce seeds. Salicylic acid from bark of Chamaecyparis obtusa induced allelopathic effects on seeds of plants native to the species' range in Taiwan as well as on seeds of exotic plants (Tseng et al, 2007). Allelopathic effects on newly planted or existing woody landscape plants, however, have not been documented.…”

Characteristics of proanthocyanidins in leaves of Chamaecyparis obtusa var. formosana as strong α‐glucosidase inhibitors

“…formosana (Hayata) Rehder (Cupressaceae) is a coniferous and native tree that grows at elevations of 1800–2600 m and is indigenous to Taiwan. It has been used as a medicinal plant in Taiwan and has various biological activities such as antitermitic activity, allopathic activity, cytotoxicity against carcinoma cell lines, antioxidant activity and delayed aging effects . Moreover, the hot water extract (HWE) from C. obtusa var.…”