@article{PAR00008545,
  title = {{S}ubsampling herbarium collections to assess geographic diversity gradients : a case study with endemic {O}rchidaceae and {R}ubiaceae in {C}ameroon},
  author = {{D}roissart, {V}incent and {H}ardy, {O}.{J}. and {S}onk{\'e}, {B}. and {D}ahdouh-{G}uebas, {F}. and {S}tevart, {T}.},
  editor = {},
  language = {{ENG}},
  abstract = {{W}e compiled herbarium specimen data to provide an improved characterization of geographic patterns of diversity using indices of species diversity and floristic similarity based on rarefaction principles. {A} dataset of 3650 georeferenced plant specimens belonging to {O}rchidaceae and {R}ubiaceae endemic to {A}tlantic {C}entral {A}frica was assembled to assess species composition per half-degree or one-degree grid cells. {L}ocal diversity was measured by the expected number of species ({S}(k)) per grid cell found in subsamples of increasing size and compared with raw species richness ({S}({R})). {A} nearly unbiased estimator of the effective number of species per grid cell was also used, allowing quantification of ratios of true diversity between grid cells. {S}pecies turnover was measured using a presence/absence-based similarity index ({S} phi rensen) and an abundance-based index that corrects for sampling bias ({NNESS}). {O}ur results confirm that the coastal region of {C}ameroon is more diverse in endemic species than those more inland. {T}he southern part of this coastal forest is, however, as diverse as the more intensively inventoried northern part, and should also be recognized as an important center of endemism. {A} strong congruence between {S} phi rensen and {NNESS} similarity matrices lead to similar delimitations of floristic units. {H}ence, heterogeneous sampling seems to confer more bias when measuring patterns of local diversity using raw species richness than species turnover using {S} phi rensen index. {O}verall, we argue that subsampling methods represent a useful way to assess diversity gradients using herbarium specimens while correcting for heterogeneous sampling effort.},
  keywords = {{B}iodiv{R} ; central {A}frica ; diversity patterns ; effective number of species ; herbarium collections ; rarefaction principles ; similarity index ; subsampling procedure ; {CAMEROUN}},
  booktitle = {},
  journal = {{B}iotropica},
  volume = {44},
  numero = {1},
  pages = {44--52},
  ISSN = {0006-3606},
  year = {2012},
  DOI = {10.1111/j.1744-7429.2011.00777.x},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00008545},
}