Land use data generalization indices considering scale and land use pattern effects

Land use generalization indices are critical for producing normative multi-scale land use databases and maps,but there is still not a national criterion for these indices in China.Previous studies on land use data generalization indices often neglect macroindices such as area proportion of land use types and map load,and also ignore landscape effects on land use generalization indices.Here we constructed an index system of land use data generalization from macro-and micro-perspectives,and examined scale and landscape effects on land use data generalization indices based on the countrywide multi-scale land use data samples.We formulated relationships between land use data generalization indices and both scale and land use pattern metrics.We defined thresholds of land use data generalization indices on scales of 1:50000,1:100000,1:250000,and 1:500000.We verified our methodology and index thresholds through generalizing a county land use database.

Land tenure and landscape change:a comparison of public-private lands in the southern High Plains

Introduction:Long-term drought in the southern Great Plains increases the vulnerability of coupled human-environment systems at a variety of scales.Developing better understandings of the dynamics at regional scales will become increasingly important as long-established land-use regimes break down in the face of climate change,resource depletion,and evolving governance.To demonstrate differential vulnerability during drought periods,this study hypothesized that observed increases in woody vegetation in grasslands would vary across land-tenure regimes.We argue that differences in State Trust Land governance,in part,lead to differential land management practices that contribute to landscape change.Methods:The study area encompasses adjacent counties,Cimarron County in Oklahoma and Union County in New Mexico,with similar climate variability and agricultural economies.We analyzed National Land Cover Database(NLCD)land-cover maps from 1992 and 2011 to assess changes in landscape composition and structure between 1992 and 2011.Results:During both years under consideration,each county in the study region,across various land-tenure regimes,was dominated by herbaceous vegetation.However,there were changes in both composition and structure across the whole study area,in particular losses of herbaceous vegetation and increases in woody vegetation.The greatest gains in woody vegetation occurred in State Trust Lands of Cimarron County.Overall,the data suggest a fragmentation of herbaceous vegetation and a coalescing of shrubland patches.Conclusions:Research about the influence of land tenure on land management decisions,specifically the role of State Trust Land leases in overgrazing,informs the broader context of drought management in the southern Great Plains.Recommendations include continued research to highlight the specific mechanisms of land-tenure governance that drive landscape change.