INVESTIGADORES
AIZEN Marcelo Adrian
artículos
Título:
Structural-functional approach to identify post-disturbance recovery indicators in forests from northwestern Patagonia: a tool to prevent state transitions
Autor/es:
CAVALLERO, L., D.R. LÓPEZ, E. RAFFAELE Y M.A. AIZEN
Revista:
ECOLOGICAL INDICATORS
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2015 vol. 52 p. 85 - 95
ISSN:
1470-160X
Resumen:
Ecological integrity is a key concept in sustainable ecosystem management and conservation. In a scenario of high disturbance pressure on ecological systems, it is essential to generate tools to detect thresholds associated with post-disturbance recovery of ecological integrity. Recovery thresholds can be identified by non-linear changes in structural and functional variables. The ultimate goal of this study is to propose a structural-functional approach based on a reference system (i.e. chronosequence) as a tool to detect recovery thresholds of ecological integrity. Fire largely modulates the dynamic and stability of plant communities worldwide, and is this the case in northwestern (NW) Patagonia. In this study we test for the existence of recovery thresholds based on structural and functional variables in post-fire forests from NW Patagonia. We expect non-linear changes in structural and functional attributes during post-fire vegetation recovery, allowing for identification of thresholds indicative of ecological integrity recovery of ecological integrity. In NW Patagonia (40-42°S), we sampled 25 Austrocedrus chilensis and Nothofagus spp communities differing in post-fire age (0.3-180 yr). In each community we recorded structural (woody species cover and height, solar radiation, air temperature, relative humidity) and functional (annual recruitment of woody and tree species) attributes. We modelled these attributes in function of post-fire age and analized the relationship between a functional attribute and a Structural Recovery Index (SRI). Communities varying in time-since-last-fire were structurally and functionally different. Structural and functional variables showed a threshold response along the chronosequence, allowing the selection of recovery indicators. We suggest to use vegetation variables instead of environmental variables as structural recovery indicators. Horizontal and Vertical Vegetation Heterogeneity indices provided the information necessary to describe vegetation spatial reorganization after fire. Tree species annual recruitment was a good indicator of the functional recovery of forest communities. The relationship between a functional attribute and SRI allowed us to detect the recovery threshold of ecological integrity. Pre-threshold communities (< 36 yr old) had the highest horizontal vegetation heterogeneity and scarce tree seedling density (< 7,000 seedlings.ha-1.yr-1). Whereas, post-threshold communities (> 36 yr old) had the highest vertical vegetation heterogeneity and tree species seedling density (> 10,000 seedlings.ha-1.yr-1). Therefore, pre-threshold communities would be less resilient to antropic pressure (e.g. livestock raising, logging) than post-threshold communities. The proposed approach contributes to the sustainable management of forest communities because it allows to estimate the minimum structural-functional levels from which forest communities could be harvested.