Dataset Information

Earthworm distributions are not driven by measurable soil properties. Do they really indicate soil quality?

ABSTRACT: Abundance and distribution of earthworms in agricultural fields is frequently proposed as a measure of soil quality assuming that observed patterns of abundance are in response to improved or degraded environmental conditions. However, it is not clear that earthworm abundances can be directly related to their edaphic environment, as noted in Darwin's final publication, perhaps limiting or restricting their value as indicators of ecological quality in any given field. We present results from a spatially explicit intensive survey of pastures within United Kingdom farms, looking for the main drivers of earthworm density at a range of scales. When describing spatial variability of both total and ecotype-specific earthworm abundance within any given field, the best predictor was earthworm abundance itself within 20-30 m of the sampling point; there were no consistent environmental correlates with earthworm numbers, suggesting that biological factors (e.g. colonisation rate, competition, predation, parasitism) drive or at least significantly modify earthworm distributions at this spatial level. However, at the national scale, earthworm abundance is well predicted by soil nitrate levels, density, temperature and moisture content, albeit not in a simple linear fashion. This suggests that although land can be managed at the farm scale to promote earthworm abundance and the resulting soil processes that deliver ecosystem services, within a field, earthworm distributions will remain patchy. The use of earthworms as soil quality indicators must therefore be carried out with care, ensuring that sufficient samples are taken within field to take account of variability in earthworm populations that is unrelated to soil chemical and physical properties.

SUBMITTER: Hodson ME

PROVIDER: S-EPMC8404981 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:BACKGROUND:Earthworm communities are generally very sensitive to physico-chemical properties of the soil in different agro-ecosystem i.e. cultivated or non-cultivated which directly or indirectly influence the earthworm survival. The difference in physico-chemical properties of soil at different sites contributed to the formation of population patches for earthworm species. Understanding the physico-chemical properties of soil at a particular site could facilitate the prediction of earthworm species at that site. The objective of the present study was to investigate the diversity, abundance, and distribution of earthworms in cultivated and non-cultivated agroecosystems and their physico-chemical properties affecting the earthworm diversity and abundance. RESULTS:Total 10 species of earthworms i.e. Amynthas alexandri, Amynthas morrisi, Eutyphoeus incommodus, Eutyphoeus waltoni, Metaphire birmanica, Metaphire houlleti, Metaphire posthuma, Octochaetona beatrix, Perionyx excavatus, and Polypheretima elongata, were reported. Out of all the reported species, Metaphire posthuma was found to be the most abundant earthworm species in both cultivated and non-cultivated agroecosystems with the occurrence at 56.81% sites. The Shannon-Wiener index (H), Margalef species richness index (DMg) and Pielou species evenness (E) was ranged from 0 to 0.86, 0 to 0.64 and 0.78 to 1 respectively. The principal component analysis resulted in four principal components i.e. PC1, PC2, PC3 and PC4 which contributing variance (%) of 22.96, 19.37, 14.23 and 10.10 respectively. The principal component analysis also showed that physico-chemical parameters of soil such as EC, pH, TDS, texture, OC, moisture, etc. play a critical role in earthworm distribution. CONCLUSION:The conventional farming system has a negative effect on the earthworm diversity in the soil while the physico-chemical properties of soil also have a determinant effect on the same. Earthworms abundance in the present study have significant direct relation with soil properties at a particular site and vice versa. The diversity indices also change due to the conventional farming system which directly affects the earthworm abundance.

Project description:Recent studies have shown that invasive earthworms can dramatically reduce native biodiversity, both above and below the ground. However, we still lack a synthetic understanding of the underlying mechanisms behind these changes, such as whether earthworm effects on soil chemical properties drive such relationships. Here, we investigated the effects of invasive earthworms on soil chemical properties (pH, water content, and the stocks and fluxes of carbon, nitrogen, and phosphorus) by conducting a meta-analysis. Invasive earthworms generally increased soil pH, indicating that the removal of organic layers and the upward transport of more base-rich mineral soil caused a shift in soil pH. Moreover, earthworms significantly decreased soil water content, suggesting that the burrowing activities of earthworms may have increased water infiltration of and/or increased evapotranspiration from soil. Notably, invasive earthworms had opposing effects on organic and mineral soil for carbon and nitrogen stocks, with decreases in organic, and increases in mineral soil. Nitrogen fluxes were higher in mineral soil, whereas fluxes in organic soil were not significantly affected by the presence of invasive earthworms, indicating that earthworms mobilize and redistribute nutrients among soil layers and increase overall nitrogen loss from the soil. Invasive earthworm effects on element stocks increased with ecological group richness only in organic soil. Earthworms further decreased ammonium stocks with negligible effects on nitrate stocks in organic soil, whereas they increased nitrate stocks but not ammonium stocks in mineral soil. Notably, all of these results were consistent across forest and grassland ecosystems underlining the generality of our findings. However, we found some significant differences between studies that were conducted in the field (observational and experimental settings) and in the lab, such as that the effects on soil pH decreased from field to lab settings, calling for a careful interpretation of lab findings. Our meta-analysis provides strong empirical evidence that earthworm invasion may lead to substantial changes in soil chemical properties and element cycling in soil. Furthermore, our results can help explain the dramatic effects of invasive earthworms on native biodiversity, for example, shifts towards the dominance of grass species over herbaceous ones, as shown by recent meta-analyses.

Project description:1. Human activities have been a significant driver of environmental changes with tremendous consequences for carbon dynamics. Peatlands are critical ecosystems because they store ~30% of the global soil organic carbon pool and are particularly vulnerable to anthropogenic changes. The Zoige peatland on the eastern Tibet Plateau, as the largest alpine peatland in the world, accounts for 1‰ of global peat soil organic carbon storage. However, this peatland has experienced dramatic climate change including increased temperature and reduced precipitation in the past decades, which likely is responsible for a decline of the water table and facilitated earthworm invasion, two major factors reducing soil organic carbon (SOC) storage of peatlands. 2. Because earthworms are often more active in low- than in high- moisture peatlands, we hypothesized that the simultaneous occurrence of water table decline and earthworm invasion would synergistically accelerate the release of SOC from peatland soil. We conducted a field experiment with a paired split-plot design, i.e. presence vs. absence of the invasive earthworms (Pheretima aspergillum) nested in drained vs. undrained plots, respectively, for three years within the homogenous Zoige peatland. 3. Water table decline significantly decreased soil water content and bulk density, resulting in a marked reduction of SOC storage. Moreover, consistent with our hypothesis, earthworm presence dramatically reduced SOC in the drained but not in the undrained peatland through the formation of deep burrows and decreasing bulk density of the lower soil layer over three years. The variation in SOC likely was due to changes in aboveground plant biomass, root growth, and earthworm behavior induced by the experimental treatments. 4. Synthesis and applications. We suggest that incentive measures should be taken to prevent further water table decline and earthworm invasion for maintaining the soil C pool in Zoige peatland. Artificial filling of drainage canals should be implemented to increase the water table level, facilitating the recovery of drained peatlands. Moreover, the dispersal of earthworms and their cocoons attached to the roots of crop plants and tree saplings from low-lying areas to the Zoige region should be controlled and restricted.

Dataset Information

Earthworm distributions are not driven by measurable soil properties. Do they really indicate soil quality?

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets