Agricultural intensification and urbanization negatively impact soil nematode richness and abundance: a meta-analysis

Abstract

Human activity has extensively transformed the land surface by agricultural intensification and urbanization. In soil, nematodes are the most abundant invertebrates. The effect of human interventions was assessed on overall richness, overall abundance, richness and abundance of nematodes of each trophic group and colonizerpersister (c-p) guild by comparing urban, agriculture and disturbed grassland (DGL) with natural grassland (NGL) and forest ecosystems. Meta-analyses were conducted to generate quantitative summaries from 111 published articles that met the inclusion criteria, 91 expressed data in grams and 20 expressed data in cm 3. Results from data expressed per 100 g of soil indicated that overall richness was higher in forest than in NGL, DGL, urban, and agriculture ecosystems. The richness of all c-p guilds and of all trophic groups except herbivores was highest in forest ecosystems. In contrast, overall abundance was highest in DGL, agriculture and forest ecosystems. The abundance of c-p 1, c-p 2 and c-p 3 guilds and bacterivores, fungivores and herbivores was highest in disturbed ecosystems, while the abundance of c-p 4 and c-p 5 guilds and predators and omnivores was highest in relatively undisturbed ecosystems. Results from data expressed as nematodes per 100 cm 3 of soil indicated that abundance followed a similar pattern, but richness often differed between the two methodologies. These meta-analyses strengthen the concept that human interventions adversely impact both richness and abundance using nematodes as soil health bioindicators.

Distinct community structures of soil nematodes from three ecologically different sites revealed by high-throughput amplicon sequencing of four 18S ribosomal RNA gene regions

“…There have been several reports of taxonomic analyses of nematodes in forest [ 33 , 58 , 60 – 71 ] and agricultural field [ 11 , 13 , 15 – 17 , 19 – 22 , 30 , 72 ] soils. Studies on forest soils have shown that bacteria, plant, and fungus feeders occupy significant fractions of the nematode communities despite varied proportions by the sampling sites, periods, and environmental status of forests [ 33 , 62 , 68 , 70 ].…”

“…Nematode communities in agricultural fields have also been reported to contain mainly bacteria, fungus, and plant feeders, with minor groups of omnivores and predators [ 11 , 13 , 15 – 17 , 19 – 22 , 30 , 72 ]. However, the proportions of feeding groups in agricultural soils can be modified by tillage [ 15 , 20 , 21 ], fertilizers and compost treatments [ 13 , 15 – 17 , 19 , 20 , 22 ], or crop cultivation [ 16 , 17 ].…”

Taxonomic profiling of individual nematodes isolated from copse soils using deep amplicon sequencing of four distinct regions of the 18S ribosomal RNA gene

“…These observations clearly indicate different environmental and biological conditions of copse soils from those of the field and flower bed soils. Pothula and colleagues have examined the impact of agricultural intensification and urbanization on soil nematode communities using 111 published articles and examined the richness and abundance of 5 trophic groups in 5 different environmental soils including forest [ 50 ], indicating that the order of abundance was herbivores (plant feeders) > bacterivores > fungivores and omnivores > predators despite high variation. So far, several taxonomic studies on soil nematode communities in forest soils have been known and were performed using morphogenic and sequence-based approaches over the world (Brazil [ 51 ], Canada [ 52 ], China [ 53 – 56 ], Germany [ 57 ], Japan [ 58 , 59 ], Slovakia [ 60 ], Sweden [ 61 ], USA [ 62 ]).…”

The fate of biological soil quality : Functional diversity and realised niche width

“…Although there is variability in the results regarding specific indicators of biological soil quality, recent meta-analyses have observed overall negative effects of agricultural management on the nematode community (Pothula et al 2019;Liu et al 2016) in line with the decrease in the nematode Structure index and the increase in the nematode I CS , reported in Chapter 4. The examples of literature presented above are a great start in understanding the effects of specific management decisions on biological soil quality, but it is necessary that these changes are adopted by farmers, which touches upon subjects discussed before and in the discussion of Chapter 5: providing incentives that make the adoption of sustainable practices less risky to farmers as well as tools that provide insight into management decisions not just to maximise primary productivity, but to do so sustainably.…”

“…The multi-criteria decision models used to assess primary productivity (PP), nutrient cycling (NC) and biodiversity and habitat provision (B-HP) each had a different requirement in terms of input variables. If we assumed al sites to have the same value, we have underlined it.Soil biota are indispensable for the delivery of soil functions, but agricultural management has been shown to cause harm to soil biodiversity(de Graaff et al 2019;Emmerson et al 2016;Geiger et al 2010;Pothula et al 2019). This has been highlighted…”