Báldi A.: Habitat heterogeneity overrides the species-area relationship

Báldi A.
2008
Habitat heterogeneity overrides the species–area relationship
Journal of Biogeography 35: pp. 675-681
Csatolt dokumentum: 
Összefoglaló: 

Aim The most obvious, although not exclusive, explanation for the increase of
species richness with increasing sample area (the species–area relationship) is that
species richness is ultimately linked to area-based increases in habitat
heterogeneity. The aim of this paper is to examine the relative importance of
area and habitat heterogeneity in determining species richness in nature reserves.
Specifically, the work tests the hypothesis that species–area relationships are not
positive if habitat heterogeneity does not increase with area.
Location Sixteen nature reserves (area range 89–11,030 ha) in central Hungary.
Methods Four-year faunistic inventories were conducted in the reserves
involving c. 70 fieldworkers and 65 taxonomists. CORINE 50,000 land-cover
maps were used for calculating the heterogeneity of the reserve landscape
(number of habitat types, number of habitat patches and total length of edges).
Results Large reserves were less heterogeneous than small reserves, probably
because large reserves were established in large blocks of unproductive land
whereas small reserves tended to be in more fertile land. In total, 3975 arthropod
species were included in the analysis. The slope of the species–area relationship
was positive only for Neuroptera and Trichoptera. There was no significant
relationship in the other nine taxa examined (Collembola, Acari, Orthoptera,
Thysanoptera, Coleoptera, Araneae, Diplopoda, Chilopoda, Diptera). The density
(number of species ha)1) of all species, however, showed a positive correlation
with heterogeneity.
Main conclusions The general lack of fit of species–area relationships in this
study is inconsistent with most previous published studies. Importantly, and
unlike many other studies, habitat heterogeneity was not correlated with reserve
area in the studied system. In the absence of this source of covariation, stronger
relationships were identified that suggested a fundamental link between species
richness and habitat heterogeneity. The results indicate that habitat heterogeneity
rather than area per se is the most important predictor of species richness in the
studied system.
Keywords
Arthropods, central Hungary, community ecology, faunal survey, island ecology,
land cover, species–area relationship.

Angol nyelvű összefoglaló: 

Aim The most obvious, although not exclusive, explanation for the increase of
species richness with increasing sample area (the species–area relationship) is that
species richness is ultimately linked to area-based increases in habitat
heterogeneity. The aim of this paper is to examine the relative importance of
area and habitat heterogeneity in determining species richness in nature reserves.
Specifically, the work tests the hypothesis that species–area relationships are not
positive if habitat heterogeneity does not increase with area.
Location Sixteen nature reserves (area range 89–11,030 ha) in central Hungary.
Methods Four-year faunistic inventories were conducted in the reserves
involving c. 70 fieldworkers and 65 taxonomists. CORINE 50,000 land-cover
maps were used for calculating the heterogeneity of the reserve landscape
(number of habitat types, number of habitat patches and total length of edges).
Results Large reserves were less heterogeneous than small reserves, probably
because large reserves were established in large blocks of unproductive land
whereas small reserves tended to be in more fertile land. In total, 3975 arthropod
species were included in the analysis. The slope of the species–area relationship
was positive only for Neuroptera and Trichoptera. There was no significant
relationship in the other nine taxa examined (Collembola, Acari, Orthoptera,
Thysanoptera, Coleoptera, Araneae, Diplopoda, Chilopoda, Diptera). The density
(number of species ha)1) of all species, however, showed a positive correlation
with heterogeneity.
Main conclusions The general lack of fit of species–area relationships in this
study is inconsistent with most previous published studies. Importantly, and
unlike many other studies, habitat heterogeneity was not correlated with reserve
area in the studied system. In the absence of this source of covariation, stronger
relationships were identified that suggested a fundamental link between species
richness and habitat heterogeneity. The results indicate that habitat heterogeneity
rather than area per se is the most important predictor of species richness in the
studied system.
Keywords
Arthropods, central Hungary, community ecology, faunal survey, island ecology,
land cover, species–area relationship.