The Spatial Distribution of Nematode Trophic Groups Across a Cultivated Ecosystem

Robertson, G. Philip; Freckman, Diana W.

doi:10.2307/1938145

Cited by 144 publications

(70 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The degree of spatial dependence (Robertson & Freckmann 1995) was high and varied between 82 and 100%, indicating that most of the total variance could be explained by the variogram models. Fig.…”

Section: Resultsmentioning

confidence: 99%

Small-scale non-linear geostatistical analysis of Liocarcinus depurator (Crustacea: Brachyura) abundance and size structure in a western Mediterranean population

Rufino

Maynou²,

Abelló³

et al. 2004

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

The small-scale spatial distribution of density and biomass of the crab Liocarcinus depurator off the Ebro delta was analysed using universal kriging (non-linear geostatistics), considering depth as an external trend. In order to understand the spatial distribution of crab size, a third variable was created from the residuals of the non-linear regression between biomass and density. Variogram analysis of crab density and residuals of the biomass/density relationship presented a quadratic relationship with depth, while biomass showed a linear relationship with depth. All experimental variograms were fitted to spherical models. The patch size (range) found was 10.64 km for density, 14.53 km for biomass and 20.49 km for the residual variables. The spatial distribution of 8 sediment variables (temperature, redox potential at 1 and 6 cm depth [R1 and R6], carbonate content [CO 3 ], median grain size [ϕ], sediment sorting [IGSD: inclusive graphic standard deviation] and organic matter content [OM]) was studied. The maps obtained were compared with those calculated for the biological variables of L. depurator using Mantel and partial Mantel tests. Distribution characteristics of this species were significantly affected by most sediment variables considered, particularly by temperature, organic matter content and redox potential, although overall the correlation level was low, coinciding with the generalist ecological role and opportunistic behaviour of the species. Density and biomass, as well as residuals, presented a negative correlation with the sorting coefficient (IGSD) and with carbonates. In relation to IGSD, high densities of L. depurator were found in homogeneous sediments. Residuals (size structure of the population) were significantly correlated with grain size (ϕ), with larger individuals occurring in finer sediments, while juveniles were preferably found in areas with very fine sand sediments. Both density and biomass presented significant positive correlations with the redox potential, indicating that the species favoured well-oxygenated sediments with a low organic content.

show abstract

Section: Resultsmentioning

confidence: 99%

Small-scale non-linear geostatistical analysis of Liocarcinus depurator (Crustacea: Brachyura) abundance and size structure in a western Mediterranean population

Rufino

Maynou²,

Abelló³

et al. 2004

Mar. Ecol. Prog. Ser.

View full text Add to dashboard Cite

show abstract

“…Natural and disturbed soils are inherently variable both spatially and temporally (Robertson et al 1988;Robertson and Freckman 1995;Gorres et al 1998). Patchiness in soil properties, such as organic matter leads to "hot spots" of microbial and fauna!…”

Section: Discussionmentioning

confidence: 99%

The Effects of Disturbance Events on Labile Phosphorus Fractions and Total Organic Phosphorus in the Southern Appalachians

Wright

Coleman

1999

Soil Science

View full text Add to dashboard Cite

Changes in labile soil phosphorus pools, together with changes in organic matter and total organic soil phosphorus levels, were measured following rhododendron harvest and hurricane windthrow events at the Coweeta Long Term Ecological Research (LTER) site. Seasonal soil samples were 1 taken every 3 months from June 1996 to September 1997. Soil cores were taken along four transects within each study area at distances approximately 1, 5, and 15 m upslope from the stream channel. Levels of resin P were low for all sites and sampling dates (<5 [jug PO 4 -P g soil" 1 ). Levels of bicarbonate inorganic P were <8 (jig PO 4 -P g soil" 1 for all sites and sampling dates, whereas bicarbonate organic P levels were somewhat higher and ranged from 6.5 to 26.6 jjig PO 4 -P g soil" 1. Microbial P levels were the most variable and ranged from 4.5 to 25.8 |xg PO 4 -P g soil" 1. In contrast, total organic P levels were high, 149 to 348 (jug PO 4 -P g soil" 1. For the 3 years after the disturbance events, there were no significant changes in labile phosphorus pools or in total organic phosphorus levels in the soil. This lack of significant differences is likely attributable to the low phosphorus, high P-sorbing status of the soils at Coweeta and the lack of erosion that followed these disturbance events. (Soil Science 1999;164:391-402)

show abstract

“…Another subsample was removed for determination of the population size of culturable bacteria using serial dilutions on a soilextract agar. A third subsample was removed for nematode trophic-group analysis (Robertson and Freckman 1995).…”

Section: Analysesmentioning

confidence: 99%

Soil Resources, Microbial Activity, and Primary Production Across an Agricultural Ecosystem

Robertson

Klingensmith

Klug

et al. 1997

Ecological Applications

Self Cite

View full text Add to dashboard Cite

Abstract. The degree to which soil resource availability is linked to patterns of microbial activity and plant productivity within ecosystems has important consequences for our understanding of how ecosystems are structured and for the management of systems for agricultural production. We studied this linkage in a 48-ha site in southwest Michigan, USA, that had been cultivated and planted to row crops for decades. Prior to seeding the site to genetically identical soybean plants (Glycine max) in early spring, we removed soil samples from ഠ600 locations; plant biomass was harvested from these same locations later in the season. Soil samples were analyzed for physical properties (texture, bulk density), chemical properties (moisture, pH, total C, total N, inorganic N), and biological attributes (microbial biomass, microbial population size, respiration potential, and nitrification and N-mineralization potentials). Plant analyses included biomass and C and N contents. Soil resource variability across this long-cultivated site was remarkably high, as was variability in microbial activity and primary productivity. In almost all cases variability exhibited a strong spatially explicit structure: for most properties and processes Ͼ50% of sample variance was spatially dependent at a scale of 5-60 m. Exceptions included microtopography, soil pH, and inorganic P, which were spatially dependent across the entire 1-1200 m range of separation distances examined in this study, and the culturable-bacteria population, which was not spatially autocorrelated at any scale examined. Both topographic relief and soil pH exhibited strongly nested structures, with autocorrelation occurring within two (topography) or more (pH) distinct ranges. Multiple regression analysis showed surprisingly little correlation between biological processes (soybean productivity, soil N turnover, soil respiration), and static soil properties. The best predictor of soybean biomass at late reproductive stages (r 2 ϭ 0.42) was a combination of nitrate N, bulk density, inorganic P, N-mineralization rates, and pH. Overall, results suggest a remarkable degree of spatial variability for a pedogenically homogeneous site that has been plowed and cropped mostly as a single field for Ͼ100 yr. Such variability is likely to be generic to most ecosystems and should be carefully evaluated when making inferences about ecological relationships in these systems and when considering alternative sampling and management strategies.

show abstract

The Spatial Distribution of Nematode Trophic Groups Across a Cultivated Ecosystem

Cited by 144 publications

References 28 publications

Small-scale non-linear geostatistical analysis of Liocarcinus depurator (Crustacea: Brachyura) abundance and size structure in a western Mediterranean population

Small-scale non-linear geostatistical analysis of Liocarcinus depurator (Crustacea: Brachyura) abundance and size structure in a western Mediterranean population

The Effects of Disturbance Events on Labile Phosphorus Fractions and Total Organic Phosphorus in the Southern Appalachians

Soil Resources, Microbial Activity, and Primary Production Across an Agricultural Ecosystem

Contact Info

Product

Resources

About