scholarly journals Linking the spatial patterns of organisms and abiotic factors to ecosystem function and management: insights from semi-arid environments

Web Ecology ◽  
2006 ◽  
Vol 6 (1) ◽  
pp. 75-87 ◽  
Author(s):  
F. T. Maestre
Keyword(s):  
Spatial Pattern ◽  
Empirical Evidence ◽  
Spatial Patterns ◽  
Ecosystem Functioning ◽  
Abiotic Factors ◽  
Small Scale ◽  
Ecosystem Structure ◽  
Arid Environments ◽  
Ecosystem Structure And Functioning ◽  
Semi Arid

Abstract. Numerous theoretical and modeling studies have demonstrated the ecological significance of the spatial patterning of organisms on ecosystem functioning and dynamics. However, there is a paucity of empirical evidence that quantitatively shows how changes in the spatial patterns of the organisms forming biotic communities are directly related to ecosystem structure and functioning. In this article, I review a series of experiments and observational studies conducted in semi-arid environments from Spain (degraded calcareous shrubland, steppes dominated by Stipa tenacissima, and gypsum shrublands) to: 1) evaluate whether the spatial patterns of the dominant biotic elements in the community are linked to ecosystem structure and functioning, and 2) test if these patterns, and those of abiotic factors, can be used to improve ecosystem restoration. In the semiarid steppes we found a significant positive relationship between the spatial pattern of the perennial plant community and: i) the water status of S. tenacissima and ii) perennial species richness and diversity. Experimental plantings conducted in these steppes showed that S. tenacissima facilitated the establishment of shrub seedlings, albeit the magnitude and direction of this effect was dependent on rainfall conditions during the first yr after planting. In the gypsum shrubland, a significant, direct relationship between the spatial pattern of the biological soil crusts and surrogates of ecosystem functioning (soil bulk density and respiration) was found. In a degraded shrubland with very low vegetation cover, the survival of an introduced population of the shrub Pistacia lentiscus showed marked spatial patterns, which were related to the spatial patterns of soil properties such as soil compaction and sand content. These results provide empirical evidence on the importance of spatial patterns for maintaining ecosystem structure and functioning in semi-arid ecosystems. Furthermore, they show how taking into consideration the small-scale spatial patterns of organisms and abiotic factors, their restoration can be improved.

scholarly journals Using a Groundwater Adjusted Water Balance Approach and Copulas to Evaluate Spatial Patterns and Dependence Structures in Remote Sensing Derived Evapotranspiration Products

2021 ◽  
Vol 13 (5) ◽  
pp. 853
Author(s):  
Mohsen Soltani ◽  
Julian Koch ◽  
Simon Stisen
Keyword(s):  
Remote Sensing ◽  
Water Balance ◽  
Spatial Pattern ◽  
Spatial Patterns ◽  
Principal Component ◽  
Small Scale ◽  
Dependence Structure ◽  
Test Case ◽  
Catchment Scale ◽  
Balance Approach

This study aims to improve the standard water balance evapotranspiration (WB ET) estimate, which is typically used as benchmark data for catchment-scale ET estimation, by accounting for net intercatchment groundwater flow in the ET calculation. Using the modified WB ET approach, we examine errors and shortcomings associated with the long-term annual mean (2002–2014) spatial patterns of three remote-sensing (RS) MODIS-based ET products from MODIS16, PML_V2, and TSEB algorithms at 1 km spatial resolution over Denmark, as a test case for small-scale, energy-limited regions. Our results indicate that the novel approach of adding groundwater net in water balance ET calculation results in a more trustworthy ET spatial pattern. This is especially relevant for smaller catchments where groundwater net can be a significant component of the catchment water balance. Nevertheless, large discrepancies are observed both amongst RS ET datasets and compared to modified water balance ET spatial pattern at the national scale; however, catchment-scale analysis highlights that difference in RS ET and WB ET decreases with increasing catchment size and that 90%, 87%, and 93% of all catchments have ∆ET < ±150 mm/year for MODIS16, PML_V2, and TSEB, respectively. In addition, Copula approach captures a nonlinear structure of the joint relationship with multiple densities amongst the RS/WB ET products, showing a complex dependence structure (correlation); however, among the three RS ET datasets, MODIS16 ET shows a closer spatial pattern to the modified WB ET, as identified by a principal component analysis also. This study will help improve the water balance approach by the addition of groundwater net in the ET estimation and contribute to better understand the true correlations amongst RS/WB ET products especially over energy-limited environments.

The influence of mistletoes on nitrogen cycling in a semi-arid savanna, south-west Zimbabwe

2013 ◽  
Vol 29 (2) ◽  
pp. 147-159 ◽  
Author(s):  
Hilton G. T. Ndagurwa ◽  
John S. Dube ◽  
Donald Mlambo
Keyword(s):  
Soil Nutrient ◽  
Nutrient Concentrations ◽  
Ecosystem Structure ◽  
Soil N ◽  
Mineral N ◽  
N Transformations ◽  
South West ◽  
Tree Canopies ◽  
Ecosystem Structure And Functioning ◽  
Semi Arid

Abstract:This study investigated the effects of mistletoe infection on N cycling in a semi–arid savanna, south-west Zimbabwe. We established five plots (10 × 10 m) which each included three large canopy-dominantAcacia karrootrees infected by one of three mistletoes (Erianthemum ngamicum,Plicosepalus kalachariensisandViscum verrucosum) and non-infectedA. karrootrees. In each plot, we measured litterfall, litter quality (N, phenolics, tannins and lignin), soil nutrient concentrations and N transformations beneath tree canopies. Soil N, P and Ca were greatest beneath trees infected byP.kalachariensisthan beneath non-infected trees. Litterfall and litter N returns were 1.5, 2 and 1.4 times more beneathA. karrootrees infected byE.ngamicum,P.kalachariensisandV. verrucosum, respectively. Mineral N increased with mistletoe infection but did not exceed 20%. Soil N transformations were greater beneath trees infected byE.ngamicum(> 40%), and lower beneath trees infected byP.kalachariensis(<50%) andV.verrucosum(<48%) than beneath non-infectedA. karrootrees. Soil N transformations were negatively correlated with condensed tannins, lignin and lignin : N. We conclude that the improved N concentration can increase resource heterogeneity, which may alter the ecosystem structure and functioning in the semi-arid savanna.

scholarly journals Sustainable Small-Scale Agriculture in Semi-Arid Environments

2011 ◽  
Vol 16 (1) ◽  
Author(s):  
Katherine A. Spielmann ◽  
Margaret Nelson ◽  
Scott Ingram ◽  
Matthew A. Peeples
Keyword(s):  
Small Scale ◽  
Arid Environments ◽  
Semi Arid

scholarly journals Adaptation to drought in arid and semi-arid environments: Case of the Zambezi Valley, Zimbabwe

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Emmanuel Mavhura ◽  
Desmond Manatsa ◽  
Terence Mushore
Keyword(s):  
Crop Production ◽  
Smallholder Farmers ◽  
Meteorological Data ◽  
Rainfall Variability ◽  
Small Scale ◽  
Arid Environments ◽  
Water Shortages ◽  
The Impact ◽  
Semi Arid ◽  
Zambezi Valley

Small-scale rain-fed agriculture is the main livelihood in arid to semi-arid regions of subSaharan Africa. The area is characterised by erratic rainfall and frequent droughts, making the capacity for coping with temporal water shortages essential for smallholder farmers. Focusing on the Zambezi Valley, Zimbabwe, this study investigates the impact of drought on food security and the strategies used by smallholder farmers to cope with drought. We used meteorological data and interviews to examine the rainfall variability in the study area and the drought-coping mechanisms employed by smallholder famers respectively. The results show that there are various strategies used by smallholder farmers to cope with the impact of drought. These strategies include drought-tolerant crop production, crop variety diversification, purchasing cereals through asset sales, non-governmental organisations’ food aid and gathering wild fruit. However, consecutive droughts have resulted in high food insecurity and depletion of household assets during droughts. Smallholder farmers in the valley have also resorted to a number of measures taken before, during and after the drought. Still, these strategies are not robust enough to cope with this uncertainty

Small-scale spatial patterns of two soil lichens in semi-arid Mediterranean steppe

2003 ◽  
Vol 35 (1) ◽  
pp. 71-81 ◽  
Author(s):  
Fernando T. Maestre
Keyword(s):  
Spatial Distribution ◽  
Correlation Analysis ◽  
Spatial Pattern ◽  
Soil Surface ◽  
Arid Ecosystems ◽  
Small Scale ◽  
Significant Relationships ◽  
Arid Steppe ◽  
The Individual ◽  
Semi Arid

AbstractBiological crusts are a common feature of the soil surface in arid and semi-arid ecosystems, where they play a major role in ecosystem functioning. In recent years, there has been an increasing interest in the ecophysiology, floristics, and dynamics of crust-forming lichens but little is known about the effect of vascular plants on their small-scale spatial distribution. To increase our understanding about the interactions between crust-forming lichens and vegetation in semi-arid areas, the spatial pattern and interaction of two soil lichens, Cladonia convoluta and Squamarina cartilaginea, at two microsites in semi-arid Stipa tenacissima steppe of south-eastern Spain are evaluated. The aim of this study was to determine if the microsite provided by Stipa tussocks promoted changes in the individual patterns and in the spatial covariation of these soil lichens. Spatial analysis by distance index (SADIE) coupled with correlation analysis was used to explore the individual patterns and the spatial relationships between the two species. SADIE detected a significant clumped pattern in the spatial distribution of both species, but Stipa tussocks promoted changes only in the spatial pattern of Cladonia. Correlation analysis revealed the presence of significant relationships between the two species, particularly close to Stipa tussocks. The results show that the microenvironment provided by Stipa is able to modify the small-scale spatial pattern of soil lichens in semi-arid steppe, and suggest the presence of facilitation between Stipa and Cladonia.

Small alteration – big impacts: effects of small-scale riparian forest management on host–parasite dynamics in streams

2017 ◽  
Vol 92 (1) ◽  
pp. 64-73 ◽  
Author(s):  
C. Lagrue ◽  
A.A. Besson ◽  
A. Lecerf
Keyword(s):  
Forest Management ◽  
Intermediate Host ◽  
Riparian Forest ◽  
Freshwater Ecosystems ◽  
Small Scale ◽  
Ecosystem Structure ◽  
Cascading Effects ◽  
Ecosystem Structure And Functioning ◽  
Riparian Forest Management ◽  
Parasite Dynamics

AbstractEnvironmental changes and ecological disturbances can have large and unpredictable effects on parasite dynamics. Increasing human impacts on freshwater ecosystems through land use may thus modify the distribution and abundance of parasites and have cascading effects on host populations. Here we tested the effects of small-scale riparian forest management on the nematode Cystidicoloides ephemeridarum and its insect intermediate host Ephemera danica in forested streams. We assessed the impacts of harvesting riparian trees on parasite prevalence and abundance concomitantly with host densities. We also looked at upstream and downstream reaches to document potential cascading effects on unaltered stream sections mediated by aerial dispersal of adult mayfly or downstream drift of E. danica larvae. We show that host densities and parasite levels (prevalence and abundance) increased significantly following riparian tree removal. Overall, parasite densities showed a 6- to 66-fold increase in harvested reaches compared to upstream, pristine reaches. Similar effects were also clear downstream of the disturbance. Thus, despite the small extent of riparian forest alteration along the study streams, both parasite and intermediate host were strongly affected. Small-scale riparian forest management may thus have large, unforeseen impacts on some aspects of freshwater ecosystem structure and functioning that are often ignored. Generally, understanding how human perturbations influence parasites is vital when trying to predict overall impacts on ecosystem structure and functioning, and how changes in infection dynamics may further affect host species.

scholarly journals An integrodifference model for vegetation patterns in semi-arid environments with seasonality

2020 ◽  
Vol 81 (3) ◽  
pp. 875-904
Author(s):  
Lukas Eigentler ◽  
Jonathan A. Sherratt
Keyword(s):  
Seed Dispersal ◽  
Spatial Patterns ◽  
Dry Season ◽  
Vegetation Patterns ◽  
Arid Environments ◽  
Wet Season ◽  
Temporal Separation ◽  
Pde Model ◽  
Dispersal Events ◽  
Semi Arid

Abstract Vegetation patterns are a characteristic feature of semi-deserts occurring on all continents except Antarctica. In some semi-arid regions, the climate is characterised by seasonality, which yields a synchronisation of seed dispersal with the dry season or the beginning of the wet season. We reformulate the Klausmeier model, a reaction–advection–diffusion system that describes the plant–water dynamics in semi-arid environments, as an integrodifference model to account for the temporal separation of plant growth processes during the wet season and seed dispersal processes during the dry season. The model further accounts for nonlocal processes involved in the dispersal of seeds. Our analysis focusses on the onset of spatial patterns. The Klausmeier partial differential equations (PDE) model is linked to the integrodifference model in an appropriate limit, which yields a control parameter for the temporal separation of seed dispersal events. We find that the conditions for pattern onset in the integrodifference model are equivalent to those for the continuous PDE model and hence independent of the time between seed dispersal events. We thus conclude that in the context of seed dispersal, a PDE model provides a sufficiently accurate description, even if the environment is seasonal. This emphasises the validity of results that have previously been obtained for the PDE model. Further, we numerically investigate the effects of changes to seed dispersal behaviour on the onset of patterns. We find that long-range seed dispersal inhibits the formation of spatial patterns and that the seed dispersal kernel’s decay at infinity is a significant regulator of patterning.

MEASUREMENT OF SELF-ORGANIZATION IN ARID ECOSYSTEMS

2010 ◽  
Vol 18 (02) ◽  
pp. 495-508 ◽  
Author(s):  
GUI-QUAN SUN ◽  
ZHEN JIN ◽  
QIULIN TAN
Keyword(s):  
Spatial Patterns ◽  
Arid Ecosystems ◽  
Self Organization ◽  
Central Feature ◽  
Arid Environments ◽  
Arid Areas ◽  
Plant Mortality ◽  
Vegetation Model ◽  
Self Organized ◽  
Semi Arid

In semi-arid environments, vegetation is not homogeneous, but rather self-organized into spatial patterns. And spatial patterns of vegetation are a central feature of these semi-arid areas. Thus, in this paper, we give detailed analysis of a vegetation model in arid ecosystems. According to the dispersion relation formula, we discuss the changes of the wavelength, with respect to the rainfall and plant mortality rate. The obtained results show that, as rainfall being decreased, spotted, striped and "black-eye" patterns emerge successively.

scholarly journals Small-Scale Abiotic Factors Influencing the Spatial Distribution of Phytophthora cinnamomi under Declining Quercus ilex Trees

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 375
Author(s):  
Rafael Sánchez-Cuesta ◽  
Rafael M. Navarro-Cerrillo ◽  
José L. Quero ◽  
Francisco J. Ruiz-Gómez
Keyword(s):  
Spatial Analysis ◽  
Spatial Patterns ◽  
Quercus Ilex ◽  
Phytophthora Cinnamomi ◽  
Abiotic Factors ◽  
Canopy Cover ◽  
Holm Oak ◽  
Small Scale ◽  
Aggregation Index ◽  
Phytophthora Root Rot

Phytophthora root rot is considered one of the main factors associated with holm oak (Quercus ilex L.) mortality. The effectiveness and accuracy of soilborne pathogen and management could be influenced by soil spatial heterogeneity. This factor is of special relevance in many afforestation of southwestern Spain, which were carried out without phytosanitary control of the nursery seedlings. We selected a study area located in a 15 year-old afforestation of Q. ilex, known to be infested by Phytophthora cinnamomi Rands. Soil samples (ntotal = 132) were taken systematically from a grid under 4 trees, and analysed to quantify 12 variables, the colony forming units (cfu) of P. cinnamomi plus 11 physical and chemical soil properties. The combined analysis of all variables was performed with linear mixed models (GLMM), and the spatial patterns of cfu were characterised using an aggregation index (Ia) and a clustering index (ν) by SADIE. Cfu values ranged from 0 to 211 cfu g−1, and the GLMM built with the variables silt, P, K and soil moisture explained the cfu distribution to the greatest extent. The spatial analysis showed that 9 of the 12 variables presented spatial aggregation (Ia > 1), and the clustering of local patches (νi ≥ 1.5) for organic matter, silt, and Ca. The spatial patterns of the P. cinnamomi cfu under planted holm oak trees are related to edaphic variables and canopy cover. Small-scale spatial analysis of microsite variability can predict which areas surrounding trees can influence lower oomycetes cfu availability.

Sign in / Sign up

Export Citation Format

Share Document