We investigated microbial abundance, diversity and activity in soils under Pinus nigra Arn. and under Robinia pseudoacacia L.cultivation. Trees were planted in the 1970’s on lapillus from the last Vesuvius eruption in 1944. Black locust soil was richer in organic matter and nutrients than pine soil. In contrast, microbial biomass, basal respiration and catabolic diversity were higher in pine soil. As compared to pine litter: 1) lignin concentration was higher in black locust litter in the late stage of decomposition, 2) the percentage of aromatic substances (110 – 165 ppm) in 13C CPMAS NMR spectra was higher both in fresh and in decomposed black locust litter. Living tissues of black locust are known to have allelopathic effects. Using the hypothesis that black locust allelochemicals occur in tree litter and may inhibit soil biological activity, we performed laboratory and field trials. In laboratory experiments, we added water extracts of fresh and of decomposed litter to pine and black locust soils. Microbial activity in pine soil amended with aqueous extracts of fresh litter was significantly (P<0.05) lower than in control soil, whereas no effect was observed in black locust soil, likely because in this soil microbial populations were adapted to the presence of allelochemicals. 1H NMR spectra of litter water exctracts showed in the decomposed litter extract more abundant sugars; in the fresh litter extract more abundant aromatic or unsaturated compounds. In particular, 4 – hydroxyacetophenone was isolated and identified from the fresh litter extract. In field experiments, we incorporated a known amount of fresh and decomposed black locust litter on pine soil, after removing needle litter, and we found a lower microbial and fungal biomass in the soil under fresh black locust litter. Moreover the pine soils amended with fresh black locust litter showed a lower basal respiration and catabolic diversity than those of the control soils.

Allelopathic effects of black locust (Robinia pseudoacacia L.) litter on soil microbial activity.

DE MARCO, ANNA;ZARRELLI, ARMANDO;
2008

Abstract

We investigated microbial abundance, diversity and activity in soils under Pinus nigra Arn. and under Robinia pseudoacacia L.cultivation. Trees were planted in the 1970’s on lapillus from the last Vesuvius eruption in 1944. Black locust soil was richer in organic matter and nutrients than pine soil. In contrast, microbial biomass, basal respiration and catabolic diversity were higher in pine soil. As compared to pine litter: 1) lignin concentration was higher in black locust litter in the late stage of decomposition, 2) the percentage of aromatic substances (110 – 165 ppm) in 13C CPMAS NMR spectra was higher both in fresh and in decomposed black locust litter. Living tissues of black locust are known to have allelopathic effects. Using the hypothesis that black locust allelochemicals occur in tree litter and may inhibit soil biological activity, we performed laboratory and field trials. In laboratory experiments, we added water extracts of fresh and of decomposed litter to pine and black locust soils. Microbial activity in pine soil amended with aqueous extracts of fresh litter was significantly (P<0.05) lower than in control soil, whereas no effect was observed in black locust soil, likely because in this soil microbial populations were adapted to the presence of allelochemicals. 1H NMR spectra of litter water exctracts showed in the decomposed litter extract more abundant sugars; in the fresh litter extract more abundant aromatic or unsaturated compounds. In particular, 4 – hydroxyacetophenone was isolated and identified from the fresh litter extract. In field experiments, we incorporated a known amount of fresh and decomposed black locust litter on pine soil, after removing needle litter, and we found a lower microbial and fungal biomass in the soil under fresh black locust litter. Moreover the pine soils amended with fresh black locust litter showed a lower basal respiration and catabolic diversity than those of the control soils.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/343595
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact