11 results on '"Arid and semi-arid ecosystems"'
Search Results
2. Land surface phenology retrievals for arid and semi-arid ecosystems.
- Author
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Xie, Qiaoyun, Cleverly, Jamie, Moore, Caitlin E., Ding, Yanling, Hall, Christopher C., Ma, Xuanlong, Brown, Luke A., Wang, Cong, Beringer, Jason, Prober, Suzanne M., Macfarlane, Craig, Meyer, Wayne S., Yin, Gaofei, and Huete, Alfredo
- Subjects
- *
PLANT phenology , *ARID regions climate , *ECOSYSTEMS , *PHENOLOGY , *ARID regions , *ECOLOGICAL resilience , *GROWING season - Abstract
Land surface phenology (LSP) plays a critical role in the regulation of photosynthesis, evapotranspiration, and energy fluxes. Significant progress has been made in extracting LSP information over large areas using satellite data, yet LSP retrievals remain a challenge over vast arid and semi-arid ecosystems because of sparse greenness, high variability and the lack of distinct annual patterns; for example, the MODerate Imaging Spectrometer (MODIS) Land Cover Dynamics Product MCD12Q2 that provides LSP metrics globally often failed to provide LSP information in these ecosystems. In this study, we used a modified threshold algorithm to extract LSP timing metrics, including the start, peak, and end of growing seasons, using the 16-day composite Enhanced Vegetation Index (EVI) time series from MODIS data. We applied this regionally customized algorithm across all arid and semi-arid climate regions of Australia (75% of the continental land area) encompassing shrublands, grasslands, savannas, woodlands, and croplands, extracting LSP metrics annually from 2003 to 2018, with up to two (phenology) seasons accounted for in each year. Our algorithm yielded an average of 64.9% successful rate of retrieval (proportion of pixels with retrieved LSP metrics) across 16 years in Arid and Semi-arid AUStralia (AS-AUS), which was a significant increase compared to the 14.5% rate of retrieval yielded in our study area by the global product and the major cause of the different performances between these two approaches was the different EVI amplitude restrictions utilized to avoid spurious peaks (i.e. EVI amplitude ≥ 0.1 used by the global product and peak EVI ≥ time series average EVI used by our algorithm). Gross primary productivity (GPP) measurements at OzFlux eddy covariance (EC) tower sites were used to cross-compare with the presence/absence of growing seasons detected by our algorithm, and 97% of our retrieved seasons matched with those extracted using EC data. Preliminary tests at five OzFlux sites showed that our algorithm was robust to view angle-induced sensitivity of the input data and showed similar performance when using EVI data calculated using MODIS Nadir BRDF-Adjusted Reflectance product. Our retrieved LSP metrics revealed that vegetation growth in arid ecosystems is highly irregular and can occur at any time of the year, more than once in a year, or can skip a year. The proportion of pixels with two growing seasons was found to be correlated with the average annual precipitation of the study area (p < 0.01), providing an estimation approach of LSP via rainfall. Our study improves the detection and measurement of vegetation phenology in arid and semi-arid regions by improving the spatial extend of LSP retrievals, which contributes to studies on LSP variations and dryland ecosystem resilience to climate change. More evaluation is planned for future work to assess and further improve the accuracy of the retrieved LSP metrics. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
3. The Cacti Microbiome: Interplay between Habitat-Filtering and Host-Specificity
- Author
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Fonseca-García, Citlali, Coleman-Derr, Devin, Garrido, Etzel, Visel, Axel, Tringe, Susannah G, and Partida-Martínez, Laila P
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Microbiology ,Biological Sciences ,Ecology ,arid and semi-arid ecosystems ,Cactaceae ,CAM plants ,holobiont ,Illumina amplicon sequencing ,microbial diversity ,microbiomes ,plant-microbe interactions ,Environmental Science and Management ,Soil Sciences ,Medical microbiology - Abstract
Cactaceae represents one of the most species-rich families of succulent plants native to arid and semi-arid ecosystems, yet the associations Cacti establish with microorganisms and the rules governing microbial community assembly remain poorly understood. We analyzed the composition, diversity, and factors influencing above- and below-ground bacterial, archaeal, and fungal communities associated with two native and sympatric Cacti species: Myrtillocactus geometrizans and Opuntia robusta. Phylogenetic profiling showed that the composition and assembly of microbial communities associated with Cacti were primarily influenced by the plant compartment; plant species, site, and season played only a minor role. Remarkably, bacterial, and archaeal diversity was higher in the phyllosphere than in the rhizosphere of Cacti, while the opposite was true for fungi. Semi-arid soils exhibited the highest levels of microbial diversity whereas the stem endosphere the lowest. Despite their taxonomic distance, M. geometrizans and O. robusta shared most microbial taxa in all analyzed compartments. Influence of the plant host did only play a larger role in the fungal communities of the stem endosphere. These results suggest that fungi establish specific interactions with their host plant inside the stem, whereas microbial communities in the other plant compartments may play similar functional roles in these two species. Biochemical and molecular characterization of seed-borne bacteria of Cacti supports the idea that these microbial symbionts may be vertically inherited and could promote plant growth and drought tolerance for the fitness of the Cacti holobiont. We envision this knowledge will help improve and sustain agriculture in arid and semi-arid regions of the world.
- Published
- 2016
4. Wetting-warming climate increases ecosystem carbon use efficiency of Chinese arid and semi-arid ecosystem.
- Author
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Sun, Yihan, Zhao, Guang, Zheng, Zhoutao, Zhu, Yixuan, Zhu, Juntao, Di, Yangping, Gao, Jie, Cai, Mengke, and Zhang, Yangjian
- Subjects
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ECOSYSTEM management , *CARBON sequestration , *ALPINE regions , *MOUNTAIN plants , *ARID regions - Abstract
• A warming and wetting trend in Chinese drylands resulted in an increased CUEe. • The slight inhibiting effect of warming on CUEe is overridden by the strong promotion effect by increased precipitation. • The response pattern of CUEe to warming or wetting is nonlinear and unimodal. Co-limited by environmental constraints, ecosystems in arid and semi-arid regions (ASARs) are extremely sensitive to climate change. A warmer and wetter climate trend has been observed extensively in ASARs of China, but whether and how the changing climate has influenced ecosystem carbon allocation and balance remains largely unclear. To bridge this knowledge gap, we conducted a comprehensive study integrating manipulative experiments, flux observations, and model simulations and our research findings reveal that the changing climate exerts a significant influence on ecosystem carbon use efficiency (CUEe) in ASARs. Specifically, the effect of increased precipitation has outweighed the warming effect, resulting in a widespread rise in CUEe across most parts of ASARs. In regions with alpine vegetation, the stimulated effects of increased temperature and precipitation play a dominant role in shaping the pattern of CUEe changes. However, with intensified warming, its stimulated effect on CUEe gradually diminishes or even reverses in ASARs. These findings can improve our understanding of ecosystem carbon sequestration regarding the response of resource-constrained ecosystems to climate change, thereby guiding ecosystem management. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Temporal dynamics of ultraviolet radiation impacts on litter decomposition in a semi-arid ecosystem.
- Author
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Wang, Jing, Yang, Sen, Zhang, Beibei, Liu, Weixing, Deng, Meifeng, Chen, Shiping, and Liu, Lingli
- Subjects
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RADIATION , *FOREST litter , *FOREST soils , *HUMUS , *LEAF-mold - Abstract
Background and aims: The emerging consensus posits that ultraviolet (UV) radiation accelerates litter decomposition in xeric environments mainly by preconditioning litter for subsequent microbial decomposition. However, how UV radiation affects the interactions among litter chemistry, microbes, and eventually litter mass during different decomposition stages is still poorly understood. Methods: Here, we conducted a 29-month in situ decomposition experiment with litter exposed to ambient and reduced UV in a semi-arid grassland. Results: The decomposition rate for Cleistogenes squarrosa and Stipa krylovii under ambient UV was 82 and 111% greater than that under reduced UV, respectively. UV's positive effect showed three-stage temporal dynamics. During the early stage, UV had no impact on either litter chemistry or mass loss. During the intermediate stage, UV decreased litter carbon concentration and increased dissolved organic carbon concentration, but still had no effect on litter mass. During the late stage, UV exposure increased microbial population size in the surface soil and significantly increased litter mass loss. Conclusions: Overall, our study suggested that UV exposure accelerated litter decomposition first by improving litter biodegradability during the intermediate stage and then by enhancing microbial decomposition during the late stage. More long-term photodegradation experiments are needed to explore the biotic and abiotic interactions during different decomposition stages. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
6. The Cacti microbiome: interplay between habitat-filtering and host specificity
- Author
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Citlali eFonseca-Garcia, Devin eColeman-Derr, Etzel eGarrido, Axel eVisel, Susannah Green Tringe, and Laila Pamela Partida-Martinez
- Subjects
Microbial Diversity ,Plant-Microbe Interactions ,Arid and semi-arid ecosystems ,microbiomes ,holobiont ,Cacti ,Microbiology ,QR1-502 - Abstract
Cactaceae represents one of the most species-rich families of succulent plants native to arid and semi-arid ecosystems, yet the associations Cacti establish with microorganisms and the rules governing microbial community assembly remain poorly understood. We analyzed the composition, diversity and factors influencing above- and below-ground bacterial, archaeal and fungal communities associated with two native and sympatric Cacti species: Myrtillocactus geometrizans and Opuntia robusta. Phylogenetic profiling showed that the composition and assembly of microbial communities associated with Cacti were primarily influenced by the plant compartment; plant species, site and season played only a minor role. Remarkably, bacterial and archaeal diversity was higher in the phyllosphere than in the rhizosphere of Cacti, while the opposite was true for fungi. Semi-arid soils exhibited the highest levels of microbial diversity whereas the stem endosphere the lowest. Despite their taxonomic distance, M. geometrizans and O. robusta shared most microbial taxa in all analyzed compartments. Influence of the plant host did only play a larger role in the fungal communities of the stem endosphere. These results suggest that fungi establish specific interactions with their host plant inside the stem, whereas microbial communities in the other plant compartments may play similar functional roles in these two species.Biochemical and molecular characterization of seed-borne bacteria of Cacti supports the idea that these microbial symbionts may be vertically inherited and could promote plant growth and drought tolerance for the fitness of the Cacti holobiont. We envision this knowledge will help improve and sustain agriculture in arid and semi-arid regions of the world.
- Published
- 2016
- Full Text
- View/download PDF
7. Local-scale disturbance by Siberian marmots has little influence on regional plant richness in a Mongolian grassland.
- Author
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Sasaki, Takehiro and Yoshihara, Yu
- Subjects
MARMOTS ,GRASSLANDS ,PLANT communities ,GRASSLAND plants ,BIOTIC communities - Abstract
Our objective was to examine the relative importance of local-scale disturbance by Siberian marmots in increasing regional (landscape-wide) plant richness. We used an additive diversity partitioning framework and quantified species richness patterns of grassland plant communities affected by marmot disturbance across different spatial scales: within and among on- and off-marmot-mound subsites, among sites, and among landscape units (corresponding to α and three levels of β richness). Values of β richness among subsites and β richness among landscape units were similar to those expected by chance. This suggests that plant species are randomly distributed among subsites and among landscape units, despite the prediction based on previous studies that local-scale disturbance by Siberian marmots and its interactive effects with landscape contexts disproportionately influence spatial patterns of plant species. Of the spatial components of regional richness, only the β richness among sites was significantly different from the expected value, probably reflecting the differential spatial pattern of disturbance by marmots at a site scale. The β richness among landscape units contributed the most to regional richness, whereas β richness among subsites and among sites contributed less. Thus, our results suggest that local-scale disturbance by Siberian marmots has little influence on regional plant richness in a Mongolian grassland. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
8. The Cocoon System : ecotechnology for ecological restoration and rainfed agriculture in the mediterranean basin
- Author
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Vicenç Carabassa, Ander Achotegui-Castells, Josep M. Alcañiz, and Xavier Domene
- Subjects
Mediterranean climate ,Irrigation ,business.industry ,Agroforestry ,media_common.quotation_subject ,Seedling ,Ecotechnology ,Climate change adaptation ,Arid and semi-arid ecosystems ,Desertification ,Agriculture ,Afforestation ,Summer drought ,Establishment ,Environmental science ,Rainfed agriculture ,business ,Restoration ecology ,media_common - Abstract
Ecological restoration projects of degraded natural areas or rainfed agriculture in the Mediterranean region, especially when they include the plantation of woody species, generally shown to be very expensive and inefficient, mainly due to the large number of leaks during the first summer drought. Even in cases where support irrigation is carried out, medium-term mortality rates remain high, as root systems developed under irrigation conditions present superficial growth being more vulnerable to drought episodes. One of the current initiatives to address this problem is the so-called "Cocoon". It is a 100% biodegradable device, built with recycled plant fibers. It is designed to reduce water stress for the planted seedlings during the first drought season, while also encouraging the development of a deep root system. This device has been successfully implemented in various countries around the world and in a wide range of different environmental conditions and objectives, from the restoration of areas affected by desertification to the recovery of agricultural uses in abandoned lands. Results after first summer drought demonstrate that Cocoon ecotechnology is working well, improving survival ratios and physiological state of the seedlings, despite its efficacy depends on the species and the environmental conditions of the site. Moreover, Cocoon is acting as refuge for some insects and could favor the growing of some commercially interesting fungi. In general, the perception of the agricultural and forestry owners, and the administrations involved, is very positive.
- Published
- 2019
9. LIFE The Green Link: restoring degraded areas with the cocoon ecotechnology
- Author
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Campo, Julián [0000-0003-0009-138X], Andreu Pérez, V. [0000-0003-2170-1394], Carabassa, V., Díaz, Elisa, Franco, K., Kallen, S., Campo, Julián, Andreu Pérez, V., Gimeno-García, Eugenia, González, F., Viera, G., Crescenzo, V., Bertaina, F., Castro, A. J., Gutiérrez, Inés, Kourkoumpas, Dimitrios, Grammelis, Panagiotis, Alcañiz, Josep M., Campo, Julián [0000-0003-0009-138X], Andreu Pérez, V. [0000-0003-2170-1394], Carabassa, V., Díaz, Elisa, Franco, K., Kallen, S., Campo, Julián, Andreu Pérez, V., Gimeno-García, Eugenia, González, F., Viera, G., Crescenzo, V., Bertaina, F., Castro, A. J., Gutiérrez, Inés, Kourkoumpas, Dimitrios, Grammelis, Panagiotis, and Alcañiz, Josep M.
- Abstract
The impacts of climate change in the Mediterranean area are becoming increasingly perceptible. Many semi-arid regions are suffering significant declines in water availability. This led to faster desertification and to increase forest fires occurrence. Therefore, implementing adaptation and mitigation measures is needed to reduce the vulnerability of these Mediterranean ecosystems and strengthening their resilience. The Green Link is a collaborative LIFE project (LIFE15 CCA/ES/000125) that aims to demonstrate the environmental and economic benefits of an innovative tree growing method. This consists of replacing traditional planting techniques with the ¿Cocoon¿, a low-cost and biodegradable device that improves water supply to seedlings during the first months. To prove the viability of the Cocoon technology and demonstrate its potential, the project has planted a variety of woody species on different soil types located in areas on a climate gradient from semi-dry to extremely dry across the Mediterranean basin and the Canary Islands. As a whole, 7 experimental areas located in Italy, Greece and Spain, covering more than 70 ha and 30 plant species (4 subspecies). The main expected results of the project are: 1. Demonstrate that the Cocoon technology allows planting woody species in dry climates and poor soils to combat desertification phenomena. 2. Offer a competitive market solution to plant trees without the need of irrigation, using the Cocoon device. 3. Improve long-term soil quality through microorganisms and mycorrhiza facilitation that will enhance the association among roots and soil. 4. Improve ecosystem services, mainly by increasing biodiversity and soil carbon stock over time. First characterization of the seedlings, planted autumn-winter 2016-17, was conducted in May-June 2017, according to a monitoring protocol. Despite the measurements were previous to the summer drought, important survival differences were detected between controls and Cocoon treatmen
- Published
- 2018
10. LIFE The Green Link: restoring degraded areas with the cocoon ecotechnology
- Author
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Carabassa, V., Díaz, Elisa, Franco, K., Kallen, S., Campo, Julián, Andreu Pérez, V., Gimeno-García, Eugenia, González, F., Viera, G., Crescenzo, V., Bertaina, F., Castro, A.J., Gutiérrez, Inés, Kourkoumpas, Dimitrios, Grammelis, Panagiotis, Alcañiz, Josep M., Campo, Julián, Andreu Pérez, V., Campo, Julián [0000-0003-0009-138X], and Andreu Pérez, V. [0000-0003-2170-1394]
- Subjects
Cocoon ecotechnology ,Climate change adaptation ,Ecosystem services ,Land degradation ,Arid and semi-arid ecosystems ,Ecological restoration - Abstract
Trabajo presentado en TERRAenVISION Environmental Issues Today: Scientific Solutions for Societal Issues, celebrado en Barcelona (España) del 27 de enero al 2 de febrero de 2018, The impacts of climate change in the Mediterranean area are becoming increasingly perceptible. Many semi-arid regions are suffering significant declines in water availability. This led to faster desertification and to increase forest fires occurrence. Therefore, implementing adaptation and mitigation measures is needed to reduce the vulnerability of these Mediterranean ecosystems and strengthening their resilience. The Green Link is a collaborative LIFE project (LIFE15 CCA/ES/000125) that aims to demonstrate the environmental and economic benefits of an innovative tree growing method. This consists of replacing traditional planting techniques with the ¿Cocoon¿, a low-cost and biodegradable device that improves water supply to seedlings during the first months. To prove the viability of the Cocoon technology and demonstrate its potential, the project has planted a variety of woody species on different soil types located in areas on a climate gradient from semi-dry to extremely dry across the Mediterranean basin and the Canary Islands. As a whole, 7 experimental areas located in Italy, Greece and Spain, covering more than 70 ha and 30 plant species (4 subspecies). The main expected results of the project are: 1. Demonstrate that the Cocoon technology allows planting woody species in dry climates and poor soils to combat desertification phenomena. 2. Offer a competitive market solution to plant trees without the need of irrigation, using the Cocoon device. 3. Improve long-term soil quality through microorganisms and mycorrhiza facilitation that will enhance the association among roots and soil. 4. Improve ecosystem services, mainly by increasing biodiversity and soil carbon stock over time. First characterization of the seedlings, planted autumn-winter 2016-17, was conducted in May-June 2017, according to a monitoring protocol. Despite the measurements were previous to the summer drought, important survival differences were detected between controls and Cocoon treatments. Globally, 9% of the seedlings were classified as dead trees, but referring to the controls this percentage increased to 30% while in Cocoons group the mortality ratio was only 3%.
- Published
- 2018
11. Risk of fire occurrence in arid and semi-arid ecosystems of Iran: an investigation using Bayesian belief networks
- Author
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Bashari, Hossein, Naghipour, Ali Asghar, Khajeddin, Seyed Jamaleddin, Sangoony, Hamed, and Tahmasebi, Pejman
- Published
- 2016
- Full Text
- View/download PDF
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