TY - JOUR
T1 - Assessing habitat quality when forest attributes have opposing effects on abundance and detectability
T2 - A case study on Darwin's frogs
AU - Valenzuela-Sánchez, Andrés
AU - Schmidt, Benedikt R.
AU - Pérez, Catalina
AU - Altamirano, Tania
AU - Toledo, Verónica
AU - Pérez, Ítalo
AU - Teillier, Sebastián
AU - Cunningham, Andrew A.
AU - Soto-Azat, Claudio
N1 - Funding Information:
This study was carried out in accordance with the Chilean law (Agriculture and Livestock Service permit No. 7489/2012). Thanks to Zoo Leipzig and European Association of Zoos and Aquaria for financial support. During data analyses and manuscript writing, AV-S was supported by FONDECYT de postdoctorado (grant no. 3180107).
Funding Information:
This study was carried out in accordance with the Chilean law (Agriculture and Livestock Service permit No. 7489/2012). Thanks to Zoo Leipzig and European Association of Zoos and Aquaria for financial support. During data analyses and manuscript writing, AV-S was supported by FONDECYT de postdoctorado (grant no. 3180107 ).
Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2019/1/15
Y1 - 2019/1/15
N2 - Forest management can be used to increase the local abundance of species of conservation concern. To achieve this goal, managers must be sure that the relationships between the targeted forest attributes and the focal species abundance are based on robust data and inference. This is a critical issue as the same forest attributes could have opposing effects on species abundance and the detectability of individuals, impairing our ability to detect useful habitat quality surrogates and to provide correct forest management recommendations. Using spatially stratified capture-recapture models (a.k.a. multinomial N-mixture models), we evaluated the effects of stand-level forest attributes on detection probability and local abundance for the endangered Southern Darwin's frog (Rhinoderma darwinii), a forest-specialist and fully terrestrial amphibian endemic to the South American temperate forest. Our results show that an increase of stand basal area and a decrease of daily microclimatic fluctuation (i.e. an increase in structural complexity) were positively associated with the local abundance of R. darwinii. These stand-level forest attributes also explained the among-population variation in detection probability, although the relationships were opposite to those for abundance. Consequently, an analysis of raw frog counts (i.e. not adjusted for imperfect detection) did not reveal all the factors associated with local abundance. Our results provide further support to previous claims that raw counts of individuals should not be used, generally, as a proxy of abundance in species inhabiting forest ecosystems and elsewhere. More importantly, the opposite effect of forest attributes on abundance and detectability observed in our study highlights the need to use methods that quantify species-habitat relationships in a robust way and which take habitat-specific imperfect detection into account.
AB - Forest management can be used to increase the local abundance of species of conservation concern. To achieve this goal, managers must be sure that the relationships between the targeted forest attributes and the focal species abundance are based on robust data and inference. This is a critical issue as the same forest attributes could have opposing effects on species abundance and the detectability of individuals, impairing our ability to detect useful habitat quality surrogates and to provide correct forest management recommendations. Using spatially stratified capture-recapture models (a.k.a. multinomial N-mixture models), we evaluated the effects of stand-level forest attributes on detection probability and local abundance for the endangered Southern Darwin's frog (Rhinoderma darwinii), a forest-specialist and fully terrestrial amphibian endemic to the South American temperate forest. Our results show that an increase of stand basal area and a decrease of daily microclimatic fluctuation (i.e. an increase in structural complexity) were positively associated with the local abundance of R. darwinii. These stand-level forest attributes also explained the among-population variation in detection probability, although the relationships were opposite to those for abundance. Consequently, an analysis of raw frog counts (i.e. not adjusted for imperfect detection) did not reveal all the factors associated with local abundance. Our results provide further support to previous claims that raw counts of individuals should not be used, generally, as a proxy of abundance in species inhabiting forest ecosystems and elsewhere. More importantly, the opposite effect of forest attributes on abundance and detectability observed in our study highlights the need to use methods that quantify species-habitat relationships in a robust way and which take habitat-specific imperfect detection into account.
KW - Amphibian
KW - Conservation
KW - Habitat degradation
KW - Multinomial N-mixture model
KW - Unmarked
UR - http://www.scopus.com/inward/record.url?scp=85055089586&partnerID=8YFLogxK
U2 - 10.1016/j.foreco.2018.10.022
DO - 10.1016/j.foreco.2018.10.022
M3 - Article
AN - SCOPUS:85055089586
SN - 0378-1127
VL - 432
SP - 942
EP - 948
JO - Forest Ecology and Management
JF - Forest Ecology and Management
ER -