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<front>
<journal-meta>
<journal-id journal-id-type="publisher">EGUsphere</journal-id>
<journal-title-group>
<journal-title>EGUsphere</journal-title>
<abbrev-journal-title abbrev-type="publisher">EGUsphere</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">EGUsphere</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub"></issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/egusphere-2026-3020</article-id>
<title-group>
<article-title>A perturbation robustness audit of global landscape-entropy regime classification across grain, subset, bootstrap, threshold, spatial structure, and external ground-truth</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Dai</surname>
<given-names>Rongzhen</given-names>
<ext-link>https://orcid.org/0009-0005-7165-0080</ext-link>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Feng</surname>
<given-names>Wei</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Independent Researcher, Yangzhou, China</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Sinopec Yangzhou Branch, Yangzhou, China</addr-line>
</aff>
<pub-date pub-type="epub">
<day>06</day>
<month>07</month>
<year>2026</year>
</pub-date>
<volume>2026</volume>
<fpage>1</fpage>
<lpage>22</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Rongzhen Dai</copyright-statement>
<copyright-year>2026</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3020/">This article is available from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3020/</self-uri>
<self-uri xlink:href="https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3020/egusphere-2026-3020.pdf">The full text article is available as a PDF file from https://egusphere.copernicus.org/preprints/2026/egusphere-2026-3020/egusphere-2026-3020.pdf</self-uri>
<abstract>
<p>Global-scale claims about landscape-entropy regimes are highly perturbation-sensitive at the individual-tile level but surprisingly stable at the aggregate-envelope level. We demonstrate this on the Dai (2026, submitted) baseline, which partitions 209 ten-degree tiles at 0.5&amp;deg; resolution into three threshold-defined attribution bands &amp;mdash; land-cover-dominant, mixed, and climate-elevated &amp;mdash; based on the ratio of unique partial R&amp;sup2; of land-cover and climate blocks in a per-tile nested OLS. We do not defend any specific numerical partition. Instead we report a &lt;em&gt;perturbation envelope&lt;/em&gt; across seven non-overlapping perturbations: cell grain (MAUP coarsening from 0.5&amp;deg; to 1&amp;deg;, plus a 5&amp;deg; check), a stratified sensitivity on the high-entropy cell subset, per-tile bootstrap over 500 cell-level resampling iterations, a classification-threshold scan, a spatial-null toroidal-shift test, Hansen Global Forest Change partial corroboration at post-2000 frontier cells, and FAOSTAT national agricultural change at country level.&lt;/p&gt;
&lt;p&gt;Across all seven perturbations the information band ranges between 43 and 92 per cent, the mixed band between 0 and 55 per cent, and the climate-elevated band between 1 and 10 per cent. Within &amp;plusmn;50 per cent of the reference thresholds the climate-elevated band narrows to 5&amp;ndash;7 per cent. The narrowest envelope therefore attaches to the band that audit-na&amp;iuml;ve readers might expect to be the most contested &amp;mdash; climate-elevated. Two independent observations explain the apparent paradox. Bootstrap resampling preserves the modal classification in 100 per cent of land-cover-dominant tiles, 89 per cent of mixed tiles, and only 73 per cent of climate-elevated tiles (four of fifteen flip to mixed). Under the spatial-null toroidal shift the median class survival is 12 per cent for information tiles, 32 per cent for mixed tiles, and 54 per cent for climate-elevated tiles. Climate-elevated &lt;em&gt;individual-tile labels&lt;/em&gt; are highly sensitive to OLS sampling and substantially classifications are therefore numerically stable in aggregate proportion but the reproducible by random spatial shifts alone &amp;mdash; diagnostic of a ratio-instability pathology in which the climate / land-cover R&amp;sup2;-ratio diverges when the land-cover denominator approaches zero in low-LULC-variance cells. Hansen GFC corroborates only a small subset of post-2000 frontier cells (one of fifty exceeds 5 per cent within-decade pixel-level forest loss); the remainder fall in countries with documented FAOSTAT national agricultural area change between 2000 and 2018. We offer the seven-perturbation audit package as a recommended baseline for future global LULC entropy classification studies.</p>
</abstract>
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