Fast Spatial Species Accumulation Curves R package spacc version 0.8.3 High-performance spatial species accumulation curves using nearest-neighbor algorithms. Implements 'kNN' and 'kNCN' sampling methods with a 'C++' backend for speed. Supports Hill numbers (q=0,1,2), beta diversity partitioning (turnover/nestedness), coverage-based rarefaction and extrapolation, phylogenetic diversity (Faith's PD, mean pairwise distance, mean nearest taxon distance), functional diversity accumulation, diversity-area relationships (DAR), endemism-area curves, sampling-effort correction and fragmentation analysis, and species-area relationship (SAR) models based on extreme value theory (EVT). Multiple starting points (seeds) provide uncertainty quantification. Methods are described in 'Chao' et al. (2014) <doi:10.1890/13-0133.1>, 'Baselga' (2010) <doi:10.1111/j.1466-8238.2009.00490.x>, 'Chao' and 'Jost' (2012) <doi:10.1890/11-1952.1>, 'Faith' (1992) <doi:10.1016/0006-3207(92)91201-3>, 'Ma' (2018) <doi:10.1002/ece3.4526>, 'Borda-de-Agua' et al. (2025) <doi:10.1038/s41467-025-59239-7>, 'Hanski' et al. (2013) <doi:10.1073/pnas.1311190110>, and 'Jost' (2007) <doi:10.1890/06-1736.1>. Software Depends: R (>= 3.5) Imports: Rcpp, RcppParallel, stats, parallel LinkingTo: Rcpp, RcppParallel Suggests: testthat (>= 3.0.0), knitr, rmarkdown, svglite, ggplot2, cli, sf, areaOfEffect, ape, iNEXT, betapart, cluster Gilles Colling <gilles.colling051@gmail.com> Comprehensive R Archive Network (CRAN) Gilles Colling [aut, cre, cph] (ORCID: <https://orcid.org/0000-0003-3070-6066>) MIT + file LICENSE (https://CRAN.R-project.org/package=spacc/LICENSE) 2026-06-20 application/tgz https://CRAN.R-project.org/package=spacc doi:10.32614/CRAN.package.spacc en-US