Guo-Liang Xu

Seasonal Exposure to Drought and Air Warming Affects Soil Collembola and Mites

Global environmental changes affect not only the aboveground but also the belowground components of ecosystems. The effects of seasonal drought and air warming on the genus level richness of Collembola, and on the abundance and biomass of the community of Collembola and mites were studied in an acidic and a calcareous forest soil in a model oak-ecosystem experiment (the Querco experiment) at the Swiss Federal Research Institute WSL in Birmensdorf. The experiment included four climate treatments: control, drought with a 60% reduction in rainfall, air warming with a seasonal temperature increase of 1.4°C, and air warming + drought. Soil water content was greatly reduced by drought. Soil surface temperature was slightly increased by both the air warming and the drought treatment. Soil mesofauna samples were taken at the end of the first experimental year. Drought was found to increase the abundance of the microarthropod fauna, but reduce the biomass of the community. The percentage of small mites (body length 0.20 mm) increased, but the percentage of large mites (body length >0.40 mm) decreased under drought. Air warming had only minor effects on the fauna. All climate treatments significantly reduced the richness of Collembola and the biomass of Collembola and mites in acidic soil, but not in calcareous soil. Drought appeared to have a negative impact on soil microarthropod fauna, but the effects of climate change on soil fauna may vary with the soil type.

Responses of soil Collembola to long-term atmospheric CO2 enrichment in a mature temperate forest.

Responses of Collembola to 7 years of CO(2) enrichment (550 ppm) in a Swiss free-air CO(2) enrichment (FACE) experiment in a forest with 80- to 120-year-old trees were investigated in this study. Contrary to our expectations, increased CO(2) caused a significant decrease in Collembola numbers, including a significant decrease in euedaphic Collembola. Increased CO(2), however, did not affect community group richness. Collembola biomass was not significantly changed by CO(2) enrichment, regardless of whether it was considered in terms of the total community, life-strategy groups, or individual species (with an exception of Mesaphorura krausbaueri). The reason for this is that CO(2) enrichment caused a general increase in individual body size, which compensated for reduced abundances. The results are consistent with the idea that the rhizosphere is important for soil fauna, and the combination of reduced fine root growth and increased soil moisture might trigger a reduction in Collembola abundance.

Two new species of Coecobrya (Collembola: Entomobryidae: Entomobryinae) from China, with a key to the Chinese species of the genus

Two new species of the genus Coecobrya are described. Both species, belonging to tenebricosa-group, present smooth chaetae on manubrium and base of dens, three sutural cephalic chaetae, labial formula MREL1L2, spiny microchaetae X and X4 posterior to labium, large outer tooth on unguiculus, 3 inner ungual teeth, S-chaetotaxy formula 32/222–3, and 4+4 central macrochaetae on Abd. IV. C. brevis sp. nov. is similar to C. tibiotarsalis, and differs from the latter by Abd. IV chaetotaxy and ventral tube. C. pani sp. nov. is similar to C. borerae but can be separated by the latter in chaetotaxy of Abd. III and IV. A key to the Chinese Coecobrya species is provided.

Effect of Collembola on mineralization of litter and soil organic matter

Although soil Collembola are known to contribute to soil carbon (C) cycling, their contribution to the mineralization of C sources that differ in bioavailability, such as soil organic C (SOC) and leaf litter, is unknown. Stable C isotopes are often used to quantify the effects of both soil C and litter C on C mineralization. Here, 13C-labeled litter was used to investigate the effects of Collembola (Folsomia candida) on the mineralization of both SOC and litter C in laboratory microcosms. The three microcosm treatments were soil alone (S); soil treated with δ13C-labeled litter (SL); and soil treated with δ13C-labeled litter and Collembola (SLC). The presence of Collembola did not significantly affect soil microbial biomass or litter mass loss and only had a small effect on CO2 release during the first week of the experiment, when most of the CO2 was derived from litter rather than from SOC. Later, during the experiment (days 21 and 63), when litter-derived labile C had been depleted and when numbers of Collembola had greatly increased, Collembola substantially increased the emission of SOC-derived CO2. These results suggest that the effect of Collembola on soil organic C mineralization is negatively related to C availability.

Two new species of Coecobrya (Collembola, Entomobryidae) from China, with an updated key to the Chinese species of the genus.

Abstract Two new Coecobrya species, which were newly collected in 2014, are described from China. Coecobrya sanmingensis sp. n. from southeast China (Fujian) is the fourth 1+1 eyed species in the genus; it can be distinguished from other three species by the ciliate chaetae X and X2-4 on the ventral side of head, the abundant chaetae on the trochanteral organ, a large outer tooth on the unguiculus, the absence of smooth manubrial chaetae, and the dorsal chaetotaxy. Coecobrya qinae sp. n. from southwest China (Yunnan) is characterized by paddle-like S-chaetae of Ant. III organ, ciliate chaetae X, X2 and X4 posterior to labium, medial macrochaetae on the mesothorax, and 5+5 central and 2+2 lateral macrochaetae on the fourth abdominal segment. An updated key to the Chinese species of Coecobrya is given.

A new species of Dicranocentrus (Collembola, Entomobryidae) from China with comments on the systematic position of the genus

Abstract Dicranocentrus liuae sp. n. is described from the northern subtropical region of China. The new species is most similar to D. wangi Ma & Chen, 2007, but differs from it in the relatively shorter Ant. V, the 1+1 central macrochaetae on Abd. III, the number of chaetae on tenaculum, and the absence of dental spines. The systematic position of Dicranocentrus is also discussed. Present evidence, particularly S-chaetotaxy, indicates that the genus is closer to Heteromurus than to the unscaled species of Orchesella and Orchesellides.

First record of Acrocyrtus Yosii, 1959 (Collemobla, Entomobryidae) from Chinese mainland

Abstract The genus Acrocrytus is reported from Chinese mainland for the first time, with description of two new species Acrocyrtus zhujiensis sp. n. and Acrocyrtus finis sp. n. from Zhejiang Province, East China. They can be separated from other species of this genus by colour pattern, unscaled appendages (antennae, legs and ventral tube), interocular chaetae, labial basal chaetae, bothriotrichal complex chaetae on Abd. II–IV, microchaeta a2 on Abd. II, im on Abd. III and C1p on Abd. IV. Illustrations and a table showing main differences with closest Acrocyrtus species are provided.

Two new species of Sinella from Guangdong Province, China (Collembola: Entomobryidae)

Abstract Two new blind species of Sinella are described from Guangdong Province, China. Sinella colubra sp. n. possesses minute smooth postlabial chaetae, long mucronal spine, and 4+4(5) lateral mac on Abd. IV, and can be distinguished from two closely related species by the postlabial chaetae and the dorsal macrochaetotaxy. Sinella zhangi sp. n. is also described and can be diagnosed by having minute labial chaeta r and postlabial chaetae X and X4, 5+5 mac on Abd. I, 4+4 central mac on Abd. II, and 4+4 central and 5+5 lateral mac on Abd. IV.