Ehsan Sayad; Shaieste Gholami; Mohammad Reza Askarpour
Abstract
Introduction: Sustainability and maintenance of riparian vegetation or restoring of degraded sites is critical to sustain inherent ecosystem function and values. Description of patterns in species assemblages and diversity is an essential step before generating hypotheses in functional ecology. If we ...
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Introduction: Sustainability and maintenance of riparian vegetation or restoring of degraded sites is critical to sustain inherent ecosystem function and values. Description of patterns in species assemblages and diversity is an essential step before generating hypotheses in functional ecology. If we want to have information about ecosystem function, soil biodiversity is best considered by focusing on the groups of soil organisms that play major roles in ecosystem functioning when exploring links with provision of ecosystem services. Information about the spatial pattern of soil biodiversity at the regional scale is limited though required, e.g. for understanding regional scale effects of biodiversity on ecosystem processes. The practical consequences of these findings are useful for sustainable management of soils and in monitoring soil quality. Soil macrofauna play significant, but largely ignored roles in the delivery of ecosystem services by soils at plot and landscape scales. One main reason responsible for the absence of information about biodiversity at regional scale is the lack of adequate methods for sampling and analyzing data at this dimension. An adequate approach for the analysis of spatial patterns is a transect study in which samples are taken in a certain order and with a certain distance between samples. Geostatistics provide descriptive tools such as variogram to characterize the spatial pattern of continuous and categorical soil attributes. This method allows assessment of consistency of spatial patterns as well as the scale at which they are expressed. This study was conducted to analyze spatial patterns of soil macrofauna in relation to tree canopy in the riparian forest landscape of Maroon.
Materilas and Methods: The study was carried out in the Maroon riparian forest of the southeasternIran (30o 38/- 30 o 39/ N and 50 o 9/- 50 o 10/ E). The climate of the study area is semi-arid. Average yearly rainfall is about 350.04 mm with a mean temperature of 24.5oc. Plant cover, mainly comprises Populus euphratica Olivie and Tamarix arceuthoides Bge and Lycium shawii Roemer & Schultes. Soil macrofauna were sampled using 175 sampling point along parallel transects (perpendicular to the river). The distance between transects was 100m. We considered distance between samples as 50 m. tree canopy were measured in 5* 5 plots. soil macrofauna were extracted from 50 cm×50 cm×10 cm soil monolith by hand-sorting procedure. All soil macrofauna were identified to family level. Evenness (Sheldon index), richness (Menhinich index) and diversity (Shannon H’ index) by using PAST version 1.39, were determined in each sample. Classical statistical parameters, i.e. mean, standard deviation, coefficient of variation, minimum and maximum, were calculated using SPSS17 software. For analysis of the relationship between Soil macrofauna diversity indices and tree canopy (Total canopy, Populous canopy, Tamarix canopy and Serim canopy) we calculated the correlation among soil properties and macrofauna using the Pearson correlation coefficient. Next, to determining the spatial structure, we calculated the semivariances. Semivariance quantifies the spatial dependence of spatially ordered variable values. In order to gather information about the spatial connection between any two variables, and to compare the similarity of their spatial structure patterns, cross-variograms were constructed. Cross-variograms are plots of cross-semivariance against the lag distance.
Results and Discussion: Soil macrofauna communities were dominated by earthworm, diplopods, coleoptera, gastropoda, araneae, and insect larvae. Correlation analysis of soil macrofauna and tree canopy indicated weak relationships between them. Weak, but significant relationships were found between macrofauna diversity, evenness, richness and total canopy, Populous canopy and Tamarix canopy (positive). Macrofauna indices and tree canopy(excepted Tamarix canopy) were spatially structured; the variograms revealed the presence of spatial autocorrelation. The variograms of variables especially tree canopy, were characterized by relatively large nugget values, which can be explained by sampling error, short range variability, random and inherent variability.Soil macrofauna diversity indices and tree canopy were moderately spatially dependent. Spatial similarity between variables, indicating potential relationships between macrofauna and tree canopy, was evaluated by cross-variograms for pairs of macrofauna indices and measured tree canopy. According to the cross-variograms, using RSS as criterion for model performance, macrofauna diversity were spatially closely related to total tree canopy, Populus canopy. Spatial distribution of soil macrofauna may be influenced by factors like gradients in soil properties and vegetation cover structure. These factors together with intrinsic population processes constitute proximate controlling factors of population structure.
Conclusion: The relationship between macrofauna indices and tree canopy was further explored by means of spatial analyses. Macrofauna indices and tree canopy (excepted Tamarix canopy) were spatially structured. Tree canopy distribution is important for the spatial variability and structure of Soil macrofauna diversity.
Sh. Gholami; S.M. Hosseini; J. Mohammadi; A. Salman Mahiny
Abstract
Abstract
Soil invertebrate and their spatial pattern are affected strongly by environmental factors. Spatial variability of soil properties is one of the most important reasons of the macrofauna variability. This study was conducted to investigate the spatial variability of soil properties and soil ...
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Abstract
Soil invertebrate and their spatial pattern are affected strongly by environmental factors. Spatial variability of soil properties is one of the most important reasons of the macrofauna variability. This study was conducted to investigate the spatial variability of soil properties and soil macrofauna biomass in the riparian forest landscape of Karkhe River. Soil macro fauna were sampled using 200 sampling point along parallel transects (perpendicular to the river). The sampling procedure was hierarchically, maximum distance between samples was 0.5 km, but the samples were taken at shorter distance at different location of sampling. Soil macro fauna were extracted from 50 cm×50 cm×25 cm soil monolith by hand-sorting procedure. At each transect point, approximately 1m distance from the macro fauna sample location, three 50 cm×50 cm×25 cm samples were taken from 0-25 depth of soil. Soil macro fauna biomass, pH, EC and soil texture were measured. Then the spatial continuity, using geostatistics (variogram) were described. The maps obtained by block kriging. The variograms of variable revealed the presence of spatial autocorrelation. The range of influence was 1728 m for macro fauna biomass, 1800 m for pH, 1536 m for EC, 2964 for sand (%), 2100 for silt (%) and 3264 for clay (%).The kriging maps showed that the soil macro fauna biomass and soil properties have spatial variability. In this research, the spatial pattern of soil macro fauna biomass is similar with the spatial pattern of silt and soil pH, that was shown in correlation.
Keywords: Spatial pattern, Soil macrofauna biomass, Soil properties, Variogram, Block kriging
Sh. Gholami; S.M. Hosseini; J. Mohammadi; A.R. Salman Mahiny
Abstract
Abstract
Information about the spatial patterns of soil biodiversity is limited though required, e.g. for understanding effects of biodiversity on ecosystem processes. This study was conducted to determine whether soil macrofauna biodiversity parameters display spatial patterns in the riparian forest ...
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Abstract
Information about the spatial patterns of soil biodiversity is limited though required, e.g. for understanding effects of biodiversity on ecosystem processes. This study was conducted to determine whether soil macrofauna biodiversity parameters display spatial patterns in the riparian forest landscape of Karkhe. Soil macrofauna were sampled using 200 sampling point along parallel transects (perpendicular to the river). The sampling procedure was hierarchically, maximum distance between samples was 0.5 km, but the samples were taken at shorter distance at different location of sampling. Soil macrofauna were extracted from 50 cm×50 cm×25 cm soil monolith by hand-sorting procedure. Abundance (Number of animals), diversity (Shannon H’ index), richness (Menhinick index) and evenness (Sheldon index) were analyzed using geostatistics (variogram) in order to describe and quantify the spatial continuity. The variograms of indices were spherical and revealed the presence of spatial autocorrelation. The range of influence was 1724 m for abundance, 1326 m for diversity, 1825 m for richness and 1450 for evenness. The variograms featured high ratio of nugget variance to sill (abundance (52%), diversity (55%), richness (53%) and evenness (35%)). This showed that there was the small-scale variability and proportion of unexplained variance. The kriging maps showed that the soil macrofauna have spatial variability.
Key words: Spatial pattern, Soil macrofauna, Geostatistics, Variogram, Kriging