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.

scholarly journals Selection of a semivariogram model in the study of spatial distribution of soil moisture

2017 ◽  
Vol 35 (1) ◽  
pp. 161-166 ◽  
Author(s):  
Radomir Obroślak ◽  
Oleksandr Dorozhynskyy
Keyword(s):  
Spatial Distribution ◽  
Soil Moisture ◽  
Gaussian Model ◽  
Soil Surface ◽  
Exponential Model ◽  
Kriging Method ◽  
Semivariogram Model ◽  
The Individual ◽  
Nearest Points ◽  
Selection Of

AbstractThe paper presents a selection of a semivariogram model in the study of spatial variability of soil moisture in a loess agricultural catchment. Soil moisture tests were carried out in the Moszenki village, 15 km northwest of Lublin. Soil moisture measurements were performed at two dates at 104 points, located on a rectangular surface measuring 700 × 1200 m. These points were laid out in the corners of a grid of squares with sides 100 m. In addition, 6 measurements were made at a distance of less than 100 m from the nearest points. Soil moisture was measured in the soil surface (0–5 cm). ArcGis software with Geostatistical Analyst extension was used for modelling semivariograms. In both terms, five models of semivariograms were used: stable, circular, spherical, exponential and Gaussian. Kriging was used for the estimation of soil moisture values. Among the semivariogram models analyzed in this study, the largest errors in the determined values of soil moisture relative to the empirical data were observed for the exponential model, and the smallest for the Gaussian model. However, it should be emphasized that the values of the analysed errors for the individual semivariogram models were similar. Application of the ordinary kriging method for interpolation of spatial distribution of soil moisture yields good results, but it has to be kept in mind that the final shape of the spatial distribution is influenced by the choice of the semivariance function model.

scholarly journals Spatial Distribution Patterns Analysis of Hotspot in Central Kalimantan using FIMRS MODIS Data

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Adisty Pratamasari ◽  
Ni Ketut Feny Permatasari ◽  
Tia Pramudiyasari ◽  
Masita Dwi Mandini Manessa ◽  
Supriatna Supriatna
Keyword(s):  
Remote Sensing ◽  
Spatial Distribution ◽  
Correlation Analysis ◽  
Spatial Pattern ◽  
Forest Fires ◽  
Nearest Neighbor ◽  
Kernel Density ◽  
Distribution Patterns ◽  
Central Kalimantan ◽  
Noaa Avhrr

<p><em>One of the ways to observe the </em><em>hotspot created by </em><em>forest fires in Indonesia </em><em>is </em><em>through </em><em>Remote sensing imagery, such as MODIS, NOAA AVHRR, etc</em><em>. </em><em>Central Kalimantan is one of the areas in Indonesia with the highest hotspot data. In this research, MODIS FIRMS hotspot data in Central Kalimantan collected from 2017 – 2019, covering 13 districts: South Barito, East Barito, North Barito, Mount Mas, Kapuas, Katingan, Palangkaraya City, West Kotawaringin, East Kotawaringin, Lamandau, Murung Raya, Pulang Pisau, Seruyan, and Sukamara. That is four aspects that this research evaluated: 1) evaluating the spatial pattern using the Nearest Neighbor Analysis (NNA); 2) evaluate the hotspot density appearance using Kernel Density; and 3) correlation analysis between rainfall data and MODIS FIRMS. As a result, the hotspot in Central Kalimantan shows a clustered pattern. While the natural breaks KDE algorithm shows the most relevant result to represent the hotspot distribution. Finally, the hotspot is low correlated with rainfall; however, is see that most of the hotspot (~90%) appeared in low rainfall month (less than 3000 mm/month).</em></p><p><strong><em>Keywords</em></strong><em>: Forest fire, Hotspot, NNA, Kernel density, Central Kalimantan</em></p>

Small-scale resource heterogeneity in semi-arid landscapes

1994 ◽  
Vol 1 (3) ◽  
pp. 201 ◽  
Author(s):  
David J. Tongway ◽  
John A. Ludwig
Keyword(s):  
Grazing Pressure ◽  
Arid Ecosystems ◽  
Small Scale ◽  
Patchy Distribution ◽  
Landscape Degradation ◽  
Term Change ◽  
Regulation Mechanisms ◽  
Acacia Aneura ◽  
Semi Arid

Patchy distribution of plant populations is a hallmark of arid and semi-arid ecosystems. This has been attributed to the patchy distribution of scarce or limiting resources across the landscape and within the soil itself. Behind these descriptive properties are a range of processes which are the causal mechanisms of resource allocation, conservation and utilization within the landscape. Terrain-controlled mechanisms have been previously described in respect of groved mulga (Acacia aneura) communities. This paper describes a set of resource regulation mechanisms which are largely controlled by plants and plant communities and which are effective at fine scales. The actual mechanisms are inferred from field observations, and validated by looking for the net effects of defined processes acting over time. Plant-mediated resource control is inherently more sensitive to grazing pressure than terrain-controlled processes, because herbivores are able to quickly and drastically alter the density and basal cover of plants, and so change the effectiveness of the control processes. This may lead to a long-term change in system function. This paper examines the generality of these propositions in a series of contrasting landscape types, and proposes a framework by which landscape degradation can be assessed by examining the modes of basic resource regulation.

scholarly journals Altered phenology and temperature sensitivity of invasive annual grasses and forbs changes autotrophic and heterotrophic respiration rates in a semi-arid shrub community

2013 ◽  
Vol 10 (4) ◽  
pp. 6335-6375 ◽  
Author(s):  
M. Mauritz ◽  
D. L. Lipson
Keyword(s):  
Soil Respiration ◽  
High Temperatures ◽  
Temperature Sensitivity ◽  
Seasonal Pattern ◽  
Arid Ecosystems ◽  
Small Scale ◽  
C Storage ◽  
Annual Grasses ◽  
Semi Arid ◽  
Invasive Annuals

Abstract. Many invasions, like the wide-spread establishment of annual grasses and forbs in semi-arid shrublands, are associated with climate change. In order to predict ecosystem carbon (C) storage it is critical that we understand how invasion affects soil respiration (Rt). Because plants and microbes have different seasonal dynamics, determining the relative contribution of autotrophic (Ra) and heterotrophic (Rh) respiration provides critical insight into soil C processes. Using automated soil respiration measurements and root exclusion cores we evaluated the moisture and temperature sensitivity of Rt and Rh and calculated the contribution of Ra in native shrub and invaded areas. Invasion increased cumulative Rt by 40% from 695 (±51) g C m−2 under shrubs to 1050 g C m−2 (±44) in invaded areas. Cumulative Rh did not change but invasion altered the seasonal pattern of Rh. Throughout the season Rt and Rh responded positively to temperature increases when soils were wet and negatively when soils were dry. Invasion increased temperature sensitivity of Rt and Rh in wet soils and decreased temperature sensitivity in dry soils. The altered temperature sensitivity of invasives was attributed largely to differences in phenology. Early phenology of invasive grasses caused rapid Ra increases early in the season; late phenology of invasive forbs resulted in the surprising maintenance of diurnal Ra and Rh signals despite high temperatures and low soil moisture. Invasion extended the respiration season of the system. Ability of the invasive community to withstand high temperatures and drought could confer greater resilience if temperature and precipitation patterns in the region change. The high contribution of Ra by invasive annuals means ecosystem C storage will depend heavily on seasonal rainfall dynamics and productivity of invasive annuals. In semi-arid ecosystems even small scale changes in plant community composition alter Rt, Ra and Rh and should be considered when attempting to predict Rt.

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.

Impact of the Small-Scale Spatial Distribution of Dust Particles on the Chemical Evolution of the Diffuse Interstellar Medium

2020 ◽  
Vol 64 (8) ◽  
pp. 693-710
Author(s):  
V. A. Sokolova ◽  
A. I. Vasyunin ◽  
A. B. Ostrovskii ◽  
S. Yu. Parfenov
Keyword(s):  
Spatial Distribution ◽  
Interstellar Medium ◽  
Chemical Evolution ◽  
Dust Particles ◽  
Small Scale

Effects of defoliation timing on plant nutrient resorption and hay production in a semi-arid steppe

2020 ◽  
Author(s):  
Tongrui Zhang ◽  
Frank Yonghong Li ◽  
Hao Wang ◽  
Lin Wu ◽  
Chunjun Shi ◽  
...  
Keyword(s):  
Nutrient Cycling ◽  
Nutrient Resorption ◽  
Plant Production ◽  
Conservation Strategy ◽  
Plant Nutrient ◽  
Resorption Efficiency ◽  
Nutrient Return ◽  
Peak Biomass ◽  
Arid Steppe ◽  
Semi Arid

Abstract Aims Nutrient resorption is a key plant nutrient conservation strategy, and its response to environmental and management changes is linked to nutrient cycling and production of ecosystems. Defoliation is a major pathway of mowing affecting plant nutrient resorption and production in grasslands, while the effect of defoliation timing has not been unexplored. The aim of this study was to examine the effect of defoliation timing on plant nutrient resorption and production in a steppe ecosystem. Methods We conducted a field experiment in a semi-arid steppe of Inner Mongolia including four treatments: early defoliation, peak defoliation, late defoliation and non-defoliation. We measured plant nitrogen (N) and phosphorus (P) resorption at species and community levels, and quantified plant N and P fluxes in resorption, litter return and hay output. Plant production in the mowing system was assessed by hay production and quality. Important Findings Peak and late defoliation, but not early defoliation, reduced plant community N and P resorption proficiency (RP); and late defoliation reduced N resorption efficiency (RE) but not P resorption efficiency. Peak and late defoliation, but not early defoliation, reduced plant nutrient resorption flux and litter nutrient return flux. Defoliation timing did not alter root nutrient accumulation as nutrient uptake from soil likely compensated the deficit of nutrient resorption. Peak defoliation had the highest hay production and quality, while early defoliation had the lowest. Our results provide new insights into the nutrient cycling in mowing grassland, and imply that the mowing timing can be used as a tool to mediate the balance between conservation and production of steppes, and the early mowing before plant peak biomass period is recommended for conservation of the steppes while keeping sustainable pastoral production.

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