Cross-taxon congruence in tree, bird and bat species distributions at a moderate spatial scale across four tropical forest types in the Philippines

Abstract

Indicator species groups are often used as surrogates for overall biodiversity in conservation planning because inventories of multiple taxa are rare, especially in the tropics where most biodiversity is found. At coarse spatial scales most studies show congruence in the distribution of species richness and of endemic and threatened species of different species groups. At finer spatial scale levels however, cross-taxon congruence patterns are much more ambiguous. In this study we investigated cross-taxon patterns in the distribution of species richness of trees, birds and bats across four tropical forest types in a ca. 100 9 35 km area in the Northern Sierra Madre region of Luzon Island, Philippines. A non-parametric species richness estimator (Chao1) was used to compensate for differential sample sizes, sample strategies and completeness of species richness assessments. We found positive but weak congruence in the distribution of all and endemic tree and bird and tree and bat species richness across the four forest types; strong positive congruence in the distribution of all and endemic bat and bird species richness and low or negative congruence in the distribution of globally threatened species between trees, birds and bats. We also found weak cross-taxon congruence in the complementarity of pairs of forest types in species richness between trees and birds and birds and bats but strong congruence in complementarity of forest pairs between trees and bats. This study provides further evidence that congruence in the distribution of different species groups is often ambiguous at fine to moderate spatial scales. Low or ambiguous cross-taxon congruence complicates the use of indicator species and species groups as a surrogate for biodiversity in general for local systematic conservation planning.

Hotspot analysis of Taiwanese breeding birds to determine gaps in the protected area network

“…Most importantly, different hotspot criteria overlapped only partially and sometimes hardly at all in our analysis (see above), thereby confirming previous results of limited overlap or congruence (e.g., Prendergast et al 1993;Moritz et al 2001;Lund and Rahbek 2002;Moore et al 2003;Ho 2005;Orme et al 2005;Grenyer et al 2006;Franco et al 2009;van Weerd and de Haes 2010;but see Kerr 1997;Mac Nally et al 2002). This lack of congruence was especially evident at smaller spatial scales (Lund and Rahbek 2002;Grenyer et al 2006;Franco et al 2009;van Weerd and de Haes 2010). Since our results were based on a very fine scale of a 1 × 1-km grid size, they are supportive of this trend.…”

“…(2) Other taxa, such as mammals, insects, and plants, need to be incorporated in the analyses to make conclusions more relevant to all of Taiwan's biodiversity. As hotspots for different taxa frequently do not overlap (i.e., are not congruent, see Prendergast et al 1993;Moritz et al 2001;Lund and Rahbek 2002;Moore et al 2003;Ho 2005;Orme et al 2005;Grenyer et al 2006;Franco et al 2009;van Weerd and de Haes 2010), the more taxa that are included in the analyses, the more comprehensive the resulting recommendations will be. One obvious problem with including other taxa is that reliable distribution models need to be based on a minimum number of observation records (usually >20 to 30) which might not be available for many other taxa (e.g., cryptic mammals and undersampled beetles).…”

The amphibians and reptiles of Luzon Island, Philippines, VIII: the herpetofauna of Cagayan and Isabela Provinces, northern Sierra Madre Mountain Range

“…In contrast, forested areas that have been properly surveyed for herpetological diversity rank among the areas supporting the country’s most diverse herpetological communities (Brown et al 2000a, 2012; Siler et al 2011a). Before reasonably well-informed, biologically meaningful conservation measures are to be effective, a basic understanding of distribution patterns and cross-taxon congruence of Luzon’s vertebrate biodiversity will be necessary (Brown and Diesmos 2009; van Weerd and Udo de Haes 2010; Diesmos and Brown 2011). In the absence of actual, field-based, empirical, survey data, conservation status assessments (IUCN 2010) and priority setting exercises (Diesmos et al 2002; Diesmos and Brown 2011) will remain incomplete, uninformed, and overly reliant on secondary sources, extrapolation, and “expert” opinion (Diesmos et al 2004; Brown et al 2012).…”

Birds as surrogates for mammals and reptiles: Are patterns of cross-taxonomic associations stable over time in a human-modified landscape?

“…However, Grenyer et al (2006) and others (e.g. Weibull et al, 2003;van Weerd and de Haes, 2010) have noted that congruency between taxa tends to be highly scale dependent; levels of congruency may be particularly low if these patterns are measured at the fine spatial resolutions relevant to conservation. There is thus a need for more studies of cross-taxonomic surrogacy at these fine spatial scales which these surrogates are to be applied.…”