Mediterranean desertification and land degradation

Hill, Joachim; Stellmes, Marion; Udelhoven, T.; Röder, Achim; Sommer, Stefan

doi:10.1016/j.gloplacha.2008.10.005

Cited by 245 publications

(57 citation statements)

References 76 publications

(86 reference statements)

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“…For example, Kurc (2008) pointed out that some critical threshold must have been crossed in desertification process, while Vogt et al (2011) only stressed that desertification is the most extreme case of land degradation. This inkling involved what should be preferentially consisted of indicator systems in MAD, fast variables or slow variables (Reynolds et al 2007), as well as desertification reversibility (Archer 1989;Friedel 1991;Laycock 1991;Hill et al 2008), and what can really characterize land degradation instead of just fluctuation with disturbances from climate variation or human activities. Land degradation is generally reversible unless damage is very severe or soils are shallow (Dregne 1995).…”

Section: Uncertainties In Madmentioning

confidence: 99%

Several challenges in monitoring and assessing desertification

et al. 2014

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Desertification is one of the most serious environmental and socioeconomic problems in the world. Desertification has got ever-increasing attention from scientists to policy makers worldwide. Monitoring and assessing desertification (MAD) has been a key and extreme important work, for combating desertification in threatened areas. Tremendous progress has been made in MAD during the last several decades, including multi-level indicator system, various kinds of extracting and assessing method of desertification information, etc. In particularly, Remote Sensing has become an important data source and technology in MAD due to its strength of macroscopic, synthesis, abundant information, quickly updated data, but it focused primarily on biophysical symptoms and involved some uncertainties challenging MAD. In this paper, several key challenges in MAD were reviewed and discussed. Some findings were given, mainly including: (1) the reference frame or baseline of desertification usually lacking of enough scientific support from environmental background reconstruction and ecosystem dynamics, (2) effective and readily accessible monitoring indicators of desertification usually lacking of reliability and scientific basis derived from bio-physics mechanism of desertification process, (3) underemphasized temporal and spatial scales of desertification and the scale effect, as well as (4) those extracting and assessing methods of real desertification information in need of improvement. Finally, some suggestions were put forward for advancing desertification research and providing authentic desertification information, including more distinct desertification connotation, addressing desertification research at multiple temporal and spatial scales, integrated application of multisource remote sensing data, closely combining MAD with field research work about desertification processes, establishing and protecting natural ecosystems' reserves with different climate types and vegetation types for desertification baselines, etc.

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Section: Uncertainties In Madmentioning

confidence: 99%

Several challenges in monitoring and assessing desertification

et al. 2014

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“…Remote sensing data, along with geocomputation techniques, have substantially contributed to correcting various 'myths' surrounding the desertification process and have provided tangible items, such as soil and vegetation properties (Hill et al, 2008). Nevertheless, there is no indicator of degradation that is directly inferable from satellite-based data.…”

Section: Introductionmentioning

confidence: 99%

Bush encroachment monitoring using multi-temporal Landsat data and random forests

Symeonakis

Higginbottom

2014

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:It is widely accepted that land degradation and desertification (LDD) are serious global threats to humans and the environment. Around a third of savannahs in Africa are affected by LDD processes that may lead to substantial declines in ecosystem functioning and services. Indirectly, LDD can be monitored using relevant indicators. The encroachment of woody plants into grasslands, and the subsequent conversion of savannahs and open woodlands into shrublands, has attracted a lot of attention over the last decades and has been identified as a potential indicator of LDD. Mapping bush encroachment over large areas can only effectively be done using Earth Observation (EO) data and techniques. However, the accurate assessment of large-scale savannah degradation through bush encroachment with satellite imagery remains a formidable task due to the fact that on the satellite data vegetation variability in response to highly variable rainfall patterns might obscure the underlying degradation processes.Here, we present a methodological framework for the monitoring of bush encroachment-related land degradation in a savannah environment in the Northwest Province of South Africa. We utilise multi-temporal Landsat TM and ETM+ (SLC-on) data from 1989 until 2009, mostly from the dry-season, and ancillary data in a GIS environment. We then use the machine learning classification approach of random forests to identify the extent of encroachment over the 20-year period. The results show that in the area of study, bush encroachment is as alarming as permanent vegetation loss. The classification of the year 2009 is validated yielding low commission and omission errors and high k-statistic values for the grasses and woody vegetation classes. Our approach is a step towards a rigorous and effective savannah degradation assessment.

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“…In the last decades, several studies reported the increase of land degradation and desertification in Mediterranean ecosystems (Hill et al 2008, Moreira et al 2011, Schulz et al 2010. Mediterranean plants are well adapted to summer drought, though such adaptation may not be sufficient to ensure plant regeneration under extreme land degradation scenarios (e.g., wildfires -Pausas et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Differential adaptations in nursery seedlings from diverse Chilean provenances of Peumus boldus Mol.

Diaz¹,

Espinoza²,

Garrido³

et al. 2016

iForest

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Seed germination, seedling growth and biomass allocation of the endemic species Peumus boldus Mol. (Boldo) were studied in four provenances (two northern and two southern provenances) from central Chile. Seeds collected from five different mother plants for each provenance were sowed in plastic pots and placed in an ambient nursery. Germinated seeds were transplanted to 130-mL containers and cultivated under nursery conditions during one growing season. Germination capacity, seed weight, morphological traits of seedlings (root collar diameter, height, number of leaves, foliar area, root length), their biomass allocation pattern (dry mass of leaves, shoots and roots) and survival were analyzed. Results showed significant differences among provenances and mother plants for most traits. Northern provenances showed slower germination, smaller size, higher root biomass, lesser leaf area, and higher survival, while seedlings from southern provenances were taller, with more body mass, larger leaf area and lower root biomass. We concluded that northern provenances of Peamus boldus are more tolerant to drought and therefore are suitable for ecological restoration of drought-prone Mediterranean sites, while the use of southern provenances must be restricted to restoration of more humid environments.

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Mediterranean desertification and land degradation

Cited by 245 publications

References 76 publications

Several challenges in monitoring and assessing desertification

Several challenges in monitoring and assessing desertification

Bush encroachment monitoring using multi-temporal Landsat data and random forests

Differential adaptations in nursery seedlings from diverse Chilean provenances of Peumus boldus Mol.

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