Limits...
Assembly processes under severe abiotic filtering: adaptation mechanisms of weed vegetation to the gradient of soil constraints.

Nikolic N, Böcker R, Kostic-Kravljanac L, Nikolic M - PLoS ONE (2014)

Bottom Line: We analysed the multivariate response of cereal weed assemblages (including biomass and foliar analyses) to a strong man-made soil gradient (from highly calcareous to highly acidic, nutrient-poor soils) over short distances (field scale).The soil gradient favoured a substitution of calcicoles by calcifuges, and an increase in abundance of pseudometallophytes, with preferences for Atlantic climate, broad geographical distribution, hemicryptophytic life form, adapted to low-nutrient and acidic soils, with lower concentrations of Ca, and very narrow range of Cu concentrations in leaves.The trends of abundance of the different ecological groups of indicator species along the soil gradient were systematically reflected in the maintenance of leaf P concentrations, and strong homeostasis in biomass N:P ratio.

View Article: PubMed Central - PubMed

Affiliation: Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia.

ABSTRACT

Questions: Effects of soil on vegetation patterns are commonly obscured by other environmental factors; clear and general relationships are difficult to find. How would community assembly processes be affected by a substantial change in soil characteristics when all other relevant factors are held constant? In particular, can we identify some functional adaptations which would underpin such soil-induced vegetation response?

Location: Eastern Serbia: fields partially damaged by long-term and large-scale fluvial deposition of sulphidic waste from a Cu mine; subcontinental/submediterranean climate.

Methods: We analysed the multivariate response of cereal weed assemblages (including biomass and foliar analyses) to a strong man-made soil gradient (from highly calcareous to highly acidic, nutrient-poor soils) over short distances (field scale).

Results: The soil gradient favoured a substitution of calcicoles by calcifuges, and an increase in abundance of pseudometallophytes, with preferences for Atlantic climate, broad geographical distribution, hemicryptophytic life form, adapted to low-nutrient and acidic soils, with lower concentrations of Ca, and very narrow range of Cu concentrations in leaves. The trends of abundance of the different ecological groups of indicator species along the soil gradient were systematically reflected in the maintenance of leaf P concentrations, and strong homeostasis in biomass N:P ratio.

Conclusion: Using annual weed vegetation at the field scale as a fairly simple model, we demonstrated links between gradients in soil properties (pH, nutrient availability) and floristic composition that are normally encountered over large geographic distances. We showed that leaf nutrient status, in particular the maintenance of leaf P concentrations and strong homeostasis of biomass N:P ratio, underpinned a clear functional response of vegetation to mineral stress. These findings can help to understand assembly processes leading to unusual, novel combinations of species which are typically observed as a consequence of strong environmental filtering, as for instance on sites affected by industrial activities.

Show MeSH

Related in: MedlinePlus

Unconstrained ordination (NMS) of weed samples along the transects in cereal fields partially damaged by mine tailings.Data matrix: 84 species (see Table S4) in 100 samples, maximal species abundances (OTV) recorded during 2 months-survey. Unrelativized OTV (a); relativized OTV (b). The values in parentheses denote the proportion of variance represented by each axis. Superimposed soil variables correlated by more than 10% with weed samples ordination are shown. The angles and lengths of the radiating lines indicate the direction and strength of relationships of the soil variables with the ordination scores. Crosses denote group centroids.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4256224&req=5

pone-0114290-g004: Unconstrained ordination (NMS) of weed samples along the transects in cereal fields partially damaged by mine tailings.Data matrix: 84 species (see Table S4) in 100 samples, maximal species abundances (OTV) recorded during 2 months-survey. Unrelativized OTV (a); relativized OTV (b). The values in parentheses denote the proportion of variance represented by each axis. Superimposed soil variables correlated by more than 10% with weed samples ordination are shown. The angles and lengths of the radiating lines indicate the direction and strength of relationships of the soil variables with the ordination scores. Crosses denote group centroids.

Mentions: Though not a single weed species was found to be confined to one visual zone of crop growth disorders, 44 species very clearly indicate the turnover of vegetation along the soil gradient (Figure 2). Three major groups of weeds with similar response to the pollution-induced change of soil properties along the transects (Clusters A, B, and C; Figure 2) accounted for about 80% of variation in distances between weed species on the polluted fields. The succession of these three groups of weeds along the soil gradient was spatially explicit and visually very apparent over very short distances (Figure 3), commonly of less than 15 m. Accordingly, free ordination of the weed relevées showed a clear separation of vegetation along the NMS Axis 1, which corresponded to increasing pollution indicated by the increasing soil Stot concentrations (Figure 4). Fifteen soil chemical parameters, which considerably varied along the transects (plant-available concentrations of Ca, Mg, K, P, B, Fe, Zn, Mn, Al, Cu; Corg, Ntot, Stot, pH, CEC) were overlaid on the ordination of weed samples; nine of them were correlated by more than 10% with the ordination scores (Figure 4, Table 3; the remaining soil properties are shown in Table S3). Little systematic variations in weed vegetation coincided with a wide gradient of soil Cu concentrations (Table 3, Figure 4). There was a high degree of multicolinearity among the soil parameters that might influence plant growth in the concentration ranges measured (Table 3): Kendall’s correlation coefficients (tau) with the NMS Axis 1 for pH, Ca, P and Al were −0.72, −0.62, −0.61 and 0.63, respectively (for the unrelativized abundances, Figure 4a; and the values were even higher for the relativized data, Figure 4b).


Assembly processes under severe abiotic filtering: adaptation mechanisms of weed vegetation to the gradient of soil constraints.

Nikolic N, Böcker R, Kostic-Kravljanac L, Nikolic M - PLoS ONE (2014)

Unconstrained ordination (NMS) of weed samples along the transects in cereal fields partially damaged by mine tailings.Data matrix: 84 species (see Table S4) in 100 samples, maximal species abundances (OTV) recorded during 2 months-survey. Unrelativized OTV (a); relativized OTV (b). The values in parentheses denote the proportion of variance represented by each axis. Superimposed soil variables correlated by more than 10% with weed samples ordination are shown. The angles and lengths of the radiating lines indicate the direction and strength of relationships of the soil variables with the ordination scores. Crosses denote group centroids.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4256224&req=5

pone-0114290-g004: Unconstrained ordination (NMS) of weed samples along the transects in cereal fields partially damaged by mine tailings.Data matrix: 84 species (see Table S4) in 100 samples, maximal species abundances (OTV) recorded during 2 months-survey. Unrelativized OTV (a); relativized OTV (b). The values in parentheses denote the proportion of variance represented by each axis. Superimposed soil variables correlated by more than 10% with weed samples ordination are shown. The angles and lengths of the radiating lines indicate the direction and strength of relationships of the soil variables with the ordination scores. Crosses denote group centroids.
Mentions: Though not a single weed species was found to be confined to one visual zone of crop growth disorders, 44 species very clearly indicate the turnover of vegetation along the soil gradient (Figure 2). Three major groups of weeds with similar response to the pollution-induced change of soil properties along the transects (Clusters A, B, and C; Figure 2) accounted for about 80% of variation in distances between weed species on the polluted fields. The succession of these three groups of weeds along the soil gradient was spatially explicit and visually very apparent over very short distances (Figure 3), commonly of less than 15 m. Accordingly, free ordination of the weed relevées showed a clear separation of vegetation along the NMS Axis 1, which corresponded to increasing pollution indicated by the increasing soil Stot concentrations (Figure 4). Fifteen soil chemical parameters, which considerably varied along the transects (plant-available concentrations of Ca, Mg, K, P, B, Fe, Zn, Mn, Al, Cu; Corg, Ntot, Stot, pH, CEC) were overlaid on the ordination of weed samples; nine of them were correlated by more than 10% with the ordination scores (Figure 4, Table 3; the remaining soil properties are shown in Table S3). Little systematic variations in weed vegetation coincided with a wide gradient of soil Cu concentrations (Table 3, Figure 4). There was a high degree of multicolinearity among the soil parameters that might influence plant growth in the concentration ranges measured (Table 3): Kendall’s correlation coefficients (tau) with the NMS Axis 1 for pH, Ca, P and Al were −0.72, −0.62, −0.61 and 0.63, respectively (for the unrelativized abundances, Figure 4a; and the values were even higher for the relativized data, Figure 4b).

Bottom Line: We analysed the multivariate response of cereal weed assemblages (including biomass and foliar analyses) to a strong man-made soil gradient (from highly calcareous to highly acidic, nutrient-poor soils) over short distances (field scale).The soil gradient favoured a substitution of calcicoles by calcifuges, and an increase in abundance of pseudometallophytes, with preferences for Atlantic climate, broad geographical distribution, hemicryptophytic life form, adapted to low-nutrient and acidic soils, with lower concentrations of Ca, and very narrow range of Cu concentrations in leaves.The trends of abundance of the different ecological groups of indicator species along the soil gradient were systematically reflected in the maintenance of leaf P concentrations, and strong homeostasis in biomass N:P ratio.

View Article: PubMed Central - PubMed

Affiliation: Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia.

ABSTRACT

Questions: Effects of soil on vegetation patterns are commonly obscured by other environmental factors; clear and general relationships are difficult to find. How would community assembly processes be affected by a substantial change in soil characteristics when all other relevant factors are held constant? In particular, can we identify some functional adaptations which would underpin such soil-induced vegetation response?

Location: Eastern Serbia: fields partially damaged by long-term and large-scale fluvial deposition of sulphidic waste from a Cu mine; subcontinental/submediterranean climate.

Methods: We analysed the multivariate response of cereal weed assemblages (including biomass and foliar analyses) to a strong man-made soil gradient (from highly calcareous to highly acidic, nutrient-poor soils) over short distances (field scale).

Results: The soil gradient favoured a substitution of calcicoles by calcifuges, and an increase in abundance of pseudometallophytes, with preferences for Atlantic climate, broad geographical distribution, hemicryptophytic life form, adapted to low-nutrient and acidic soils, with lower concentrations of Ca, and very narrow range of Cu concentrations in leaves. The trends of abundance of the different ecological groups of indicator species along the soil gradient were systematically reflected in the maintenance of leaf P concentrations, and strong homeostasis in biomass N:P ratio.

Conclusion: Using annual weed vegetation at the field scale as a fairly simple model, we demonstrated links between gradients in soil properties (pH, nutrient availability) and floristic composition that are normally encountered over large geographic distances. We showed that leaf nutrient status, in particular the maintenance of leaf P concentrations and strong homeostasis of biomass N:P ratio, underpinned a clear functional response of vegetation to mineral stress. These findings can help to understand assembly processes leading to unusual, novel combinations of species which are typically observed as a consequence of strong environmental filtering, as for instance on sites affected by industrial activities.

Show MeSH
Related in: MedlinePlus