A Land System representation for global assessments and land-use modeling

Current global scale land-change models used for integrated assessments and climate modeling are based on classifications of land cover. However, land-use management intensity and livestock keeping are also important aspects of land use, and are an integrated part of land systems. This article aims to classify, map, and to characterize Land Systems (LS) at a global scale and analyze the spatial determinants of these systems. Besides proposing such a classification, the article tests if global assessments can be based on globally uniform allocation rules. Land cover, livestock, and agricultural intensity data are used to map LS using a hierarchical classification method. Logistic regressions are used to analyze variation in spatial determinants of LS. The analysis of the spatial determinants of LS indicates strong associations between LS and a range of socioeconomic and biophysical indicators of human-environment interactions. The set of identified spatial determinants of a LS differs among regions and scales, especially for (mosaic) cropland systems, grassland systems with livestock, and settlements. (Semi-)Natural LS have more similar spatial determinants across regions and scales. Using LS in global models is expected to result in a more accurate representation of land use capturing important aspects of land systems and land architecture: the variation in land cover and the link between land-use intensity and landscape composition. Because the set of most important spatial determinants of LS varies among regions and scales, land-change models that include the human drivers of land change are best parameterized at sub-global level, where similar biophysical, socioeconomic and cultural conditions prevail in the specific regions. © 2012 Blackwell Publishing Ltd

Depositional development of the Muskeg Lake crevasse splay in the Cumberland Marshes (Canada)

Crevasse splays are common geomorphological features in alluvial and deltaic floodplains. Although crevasse splays can develop into full avulsions, thereby transforming large areas of floodbasins, little is known about their sedimentary and geomorphological development at the decadal scale and their avulsion potential. We used aerial photography and lithological cross-sections to reconstruct crevasse-splay formation in the largely unmanaged floodplain of the Saskatchewan River in the Cumberland Marshes (Saskatchewan, Canada). Based on surface geomorphology and subsurface deposits, various stages of crevasse-splay development were described which were linked to both external forcing and internal morphodynamics. Initial splay deposition, following a levee breach during a large flood, occurred as a broad but relatively thin sandy sheet in a down-basin direction in the receiving backswamp area. In a next phase, these primary crevasse-splay deposits blocked local down-basin flow, thereby forcing the crevasse-splay channel in a direction perpendicular to the parent channel and original floodbasin gradient. This created an asymmetrical splay sequence composition, which differs in appearance from more commonly observed dendritic crevasse splays. It is concluded that sedimentation patterns in the splay have been influenced by inherited effects of previously formed deposits. Feedbacks of the original floodbasin gradient and earlier stages of splay formation are suggested as prominent mechanisms in creating the current morphology, orientation, and architecture of its deposits

The relative contribution of peat compaction and oxidation to subsidence in built-up areas in the Rhine-Meuse delta, The Netherlands

An increasing number of people lives in coastal zones with a subsurface consisting of heterogenic soft-soil sequences. Many of these sequences contain substantial amounts of peat. While population growth and urbanization continues in coastal zones, they are threatened by global sea-level rise and land subsidence. Peat compaction and oxidation, caused by loading and drainage, are important contributors to land subsidence, and hence relative sea-level rise, in peat-rich coastal zones. Especially built-up areas, having densely-spaced urban assets, are heavily impacted by land subsidence, in terms of livelihoods and damage-related costs. Yet, built-up areas have been largely avoided in peat compaction and oxidation field studies. Consequently, essential information on the relative contributions of both processes to total subsidence and underlying mechanisms, which is required for developing effective land use planning strategies, is lacking. Therefore, we quantified subsidence due to peat compaction and oxidation in built-up areas in the Rhine-Meuse delta, The Netherlands, using lithological borehole data and measurements of dry bulk density, organic matter, and CO2 respiration. We reconstructed subsidence over the last 1000 years of up to ~4 m, and recent subsidence rates of up to ~140 mm·yr−1 averaged over an 11-year time span. The amount and rate of subsidence due to peat compaction and oxidation is variable in time and space, depending on the Holocene sequence composition, overburden thickness, loading time, organic-matter content, and groundwater-table depth. In our study area, the potential for future subsidence due to peat compaction and oxidation is substantial, especially where the peat layer occurs at shallow depth and is relatively uncompacted. We expect this is the case for many peat-rich coastal zones worldwide. We propose to use subsurface-based spatial planning, using specific subsurface information mentioned above, to inform land use planners about the most optimal building sites in organo-clastic coastal zones

Number of times underlying forces of wetland conversion are documented in the 105 analyzed case-studies.

<p>Number of times underlying forces of wetland conversion are documented in the 105 analyzed case-studies.</p

Number of times proximate causes of wetland conversion are documented in the 105 analyzed case-studies.

<p>Number of times proximate causes of wetland conversion are documented in the 105 analyzed case-studies.</p

Most frequent occurring combinations of proximate causes and underlying forces of wetland conversion.

<p>Agricultural development includes pasture expansion. For each proximate cause at least the two most important underlying forces are indicated, and for each underlying force at least two associated proximate causes indicated.</p

Sites of wetland conversion.

<p>In green wetland areas (including lakes and areas with partial wetland cover) from the Global Lakes and Wetland Database (from Lehner and Döll, [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081292#B27" target="_blank">27</a>]).</p