Study on the Nitrogen Source and Invertebrate Community in the Substrate of Bird's Nest Fern (Asplenium nidus L.)
Date Issued
2007
Date
2007
Author(s)
Yen, Mu-Hsin
DOI
zh-TW
Abstract
Thirteen bird's nest ferns (Asplenium nidus L.) were collected from Fushan experimental forest. First, we separated the invertebrates from substrate, then measured the dry weight of the bird’s nest ferns and invertebrates to investigate the relationship between invertebrates and nest fern sizes. This investigation employed δ13C and δ15N analysis of sampled bird's nest ferns and invertebrate, to determine whether epiphytes derived nitrogen from animal sources with increased plant size. Trophic level was also analysied from stable isotope data of invertebrates. The nest fern total biomass and substrate biomass exponentially increased with mean leaf length and the biomass (or substrate) largely accumulated in "large ferns" (mean leaf length > 60 cm). Invertebrates total biomass logarithmically increased with nest fern total biomass and linearly increased with nest fern total biomass using logarithmic transformation (R2 = 0.7, P < 0.01). It is concluded that the biomass accumulation of nest fern was different from invertebrates increasing with increased plant size. In "medium ferns" (mean leaf length 40-60 cm) had higher invertebrate biomass (substrate-1) (0.3-2.2%), while both in "small" (< 30 cm) and "large" (> 60 cm) ferns had lower invertebrate biomass (substrate-1). Contrary to soil-plant systems, we found 4 nest ferns' δ15Nfern leaf higher than δ15Nhumus (fern leaf -6.5--3.5‰, humus -7--3‰), potentially besides the available N from animals sources (enriched-15N) absorbed by plants, the influence of a large amount of decomposed imported litter (depleted-15N) diluted the δ15N of humus also existed. Though the "enriched" sources may be the main effect in "medium ferns" and in the "large ferns", the "depleted" litter input may be the main factor because of the dilution of large amount imported litter received. ∆δ13C and ∆δ15N revealed trophic levels of invertebrates in 13 nest ferns. ∆δ15N of invertebrates distinguished into predators (Araneae and Chilopoda; 5.5-10‰) and primary consumers (herbivores, detritivores and fungivores; 1-7‰). ∆δ13C could further distinguish primary consumers into herbivores (Lepidoptera larvae; 1-3.5‰), fungivores (Ptiliidae; 3.52 ± 0.19‰) and detritivores (Isopoda, Oligochaeta and Diplopoda; 4.25-7.5‰) whereas the high value of detritivores’ ∆δ13C indicate they may have food sources from C4 and Crassulacean acid metabolism (CAM) plants in canopy. The trophic level analysis of omnivores (Myrmicinae, Formicinae and Gryllidae (Duolandrevus sp.)) by ∆δ15N revealed that Formicinae significantly aligned with primary consumers (unpaired t-test P > 0.01 with primary consumers; δ15N -2.355 ± 1.58‰，∆δ15N 3.725 ± 1.32‰), Myrmicinae aligned between predators and primary consumers (unpaired t-test P > 0.01 with 4 functional groups; δ15N -0.099 ± 1.36‰，∆δ15N 5.757 ± 1.28‰) and ∆δ15N of Strumigenys formosensis, one of the predators in Myrmicinae, was low (4.94‰), and Gryllidae (Duolandrevus sp.) also significantly aligned with primary consumers (unpaired t-test P > 0.01 with primary consumers; δ15N -2.414 ± 1.07‰，∆δ15N 3.000 ± 1.03‰). Our results confirm the use of 15N natural abundance in animal-diet studies of omnivorous species and exemplify the importance of trophic level study in epiphytes by stable isotope analysis.
Subjects
Asplenium nidus
穩定同位素分析
天然含量
食性功能群
stable isotope analysis
natural abundance
trophic functional groups
SDGs
Type
thesis
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