Land-use intensification effects on functional properties in tropical plant communities

CARREÑO-ROCABADO, GEOVANA; PEÑA-CLAROS, MARIELOS; BONGERS, FRANS; DÍAZ, S; POORTER, LOURENS

ECOLOGICAL APPLICATIONS

ECOLOGICAL SOC AMER

Año: 2016 vol. 26 p. 174 - 189

1051-0761

Abstract . There is consensus that plant diversity and ecosystem processes are negativelyaffected by land- use intensifi cation ( LUI ), but, at the same time, there is empirical evidencethat a large heterogeneity can be found in the responses. This heterogeneity is especiallypoorly understood in tropical ecosystems. We evaluated changes in community functional properties across fi ve common land- usetypes in the wet tropics with different land- use intensity: mature forest, logged forest, secondaryforest, agricultural land, and pastureland, located in the lowlands of Bolivia. For thedominant plant species, we measured 12 functional response traits related to their life history,acquisition and conservation of resources, plant domestication, and breeding. We used threesingle- trait metrics to describe community functional properties: community abundance- weightedmean ( CWM ) traits values, coeffi cient of variation, and kurtosis of distribution. The CWM of all 12 traits clearly responded to LUI . Overall, we found that an increasein LUI resulted in communities dominated by plants with acquisitive leaf trait values.However, contrary to our expectations, secondary forests had more conservative trait values(i.e., lower specifi c leaf area) than mature and logged forest, probably because they weredominated by palm species. Functional variation peaked at intermediate land- use intensity(high coeffi cient of variation and low kurtosis), which included secondary forest but, unexpectedly,also agricultural land, which is an intensely managed system. The high functionalvariation of these systems is due to a combination of how response traits (and species)are fi ltered out by biophysical fi lters and how management practices introduced a rangeof exotic species and their trait values into the local species pool. Our results showed that, at local scales and depending on prevailing environmental andmanagement practices, LUI does not necessarily result in communities with more acquisitivetrait values or with less functional variation. Instead of the widely expected negativeimpacts of LUI on plant diversity, we found varying responses of functional variation,with possible repercussions on many ecosystem services. These fi ndings provide a backgroundfor actively mitigating negative effects of LUI while meeting the needs of localcommunities that rely mainly on provisioning ecosystem services for their livelihoods.