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Earthworm Populations (earthworm + population)
Selected AbstractsThe apparent electrical conductivity as a surrogate variable for predicting earthworm abundances in tilled soilsJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 4 2010Monika Joschko Abstract Noninvasive geophysical methods have a great potential for improving soil-biological studies at field or regional scales: they enable the rapid acquisition of soil information which may help to identify potential habitats for soil biota. A precondition for this application is the existence of close relationships between geophysical measurements and the soil organism of interest. This study was conducted to determine whether field measurements of apparent electrical conductivity (ECa) are related to abundances of earthworms in tilled soils. Relationships between ECa and earthworm populations were investigated along transects at 42 plots under reduced and conventional tillage at a 74 ha field on sandy-loam soil in NE Germany. Relations were analyzed with linear-regression and spatial analysis. The apparent electrical conductivity (ECa) was quantitatively related to earthworm abundances sampled 5 months after the geophysical measurements. No relationship was found, however, in plots under conventional tillage when analyzed separately. If earthworm abundances were known at every other location along the transects and if the state-space approach was used for analysis, the analysis of ECa measurements and earthworm abundances indicated that 50% of the earthworm samples could have been substituted by ECa measurements. Further research is needed to fully evaluate the potential of ECa measurements for predicting earthworm habitats in tilled soil. [source] The development of sustainable earthworm populations at Calvert landfill site, UKLAND DEGRADATION AND DEVELOPMENT, Issue 1 2004K. R. Butt Abstract Earthworms Allolobophora chlorotica and Aporrectodea longa were inoculated into Calvert landfill site in spring 1992, in conjunction with the planting of two tree species Alnus glutinosa and Acer pseudoplatanus. Monitoring has taken place over a period of 11 years. Sampling in 2003 revealed that earthworm distribution no longer equated to the inoculation treatments; the worms had spread extensively. The presence of A. glutinosa had a significant effect (p<0,01) on earthworm number (mean density 198,m,2) and biomass (34,g,m,2) compared to plots where A. pseudoplatanus had been planted and subsequently died (mean density 118,m,2; biomass 21,g,m,2). Results suggest that tree presence may be critical to earthworm community development. In 2002, the spread of A. chlorotica from the original points of inoculation had reached 60,m with the highest recorded population density at 108,m,2 with a mass of 18,6,g,m,2. A. longa was recorded at a distance of 132,m from the nearest point of inoculation with the highest recorded population density at 70,m,2 with a mass of 49,3,g,m,2, 10,m from the original inoculation grid. Other species recorded (and % of total) were Aporrectodea rosea (0,9) Lumbricus castaneus (7,4), Eiseniella tetraedra (21,5) and Lumbricus rubellus (4,5). The two inoculated species, A. chlorotica (40,4) and A. longa (25,3), accounted for two thirds of the earthworms found on site. The highest earthworm community density was 213,m,2 with a mass of 73,9,g,m,2 at 10,m from original point of inoculation. In 1999, treatments of surface organic matter (OM), in the form of composted green waste, and rotavation were applied to non-replicated plots of 50,m2 with the effects on earthworm distribution and abundance recorded in 2002. Addition of OM alone led to an increase in number and mass (331,m,2; 95,g,m,2) compared to the control (233,m,2; 51,g,m,2), while rotavation alone (111,m,2; 36,g,m,2) had a detrimental effect over the given time period. This long-term monitoring programme has demonstrated the development of sustainable earthworm communities on a landfill site. Natural nutrient accumulation and addition of OM on or into the soil-forming material appeared to assist this process. This work may help to inform post-capping treatment at similar landfill sites Copyright © 2004 John Wiley & Sons, Ltd. [source] Appraisal of the electrical octet method for estimating earthworm populations in arable landANNALS OF APPLIED BIOLOGY, Issue 2 2001O SCHMIDT Summary Quantitative methods are needed for the assessment of the size and composition of earthworm communities. A poorly documented electrical sampling method, Thielemann's octet method, was compared with two long-established methods, formalin extraction and soil hand sorting, in conventional and direct-drilled wheat cropping systems at two sites with medium to heavy textured soils in Ireland. Under all agronomic conditions tested, the electrical method extracted significantly higher earthworm numbers than formalin, but earthworm biomasses were not significantly different. When used routinely over two years during periods of high earthworm activity, the electrical method yielded community estimates that were comparable in both size and species composition to those obtained by soil hand sorting (25 cm depth), except in recently ploughed land. However, Murchieona minuscule, a minute endogeic species, was underestimated by electrical extraction. It is concluded that the electrical octet method can be a reliable and useful alternative to other dynamic methods for estimating earthworm populations, especially in situations where minimum soil disturbance is desirable. [source] | ||||||||||