Assessing plant extinction debt in a fragmented chaco serrano landscape after a decade

AGUILAR, R; CAGNOLO, L. ; ASHWORTH, L. ; CALVIÑO, A. ; CARBONE, L. ; AGUIRRE-ACOSTA, N.

San Salvador de Bahia

Congreso; XI Congreso Latinoamericano de Botánica; 2014

The subtropical dry forest of Central Argentina (Chaco Serrano) has suffered theloss of nearly 95% of its original area during the past 40 years as a result of the expansion of urban and agricultural boundaries. Today, the Chaco Serrano forest remains as a fragmented mosaic of forest remnants of different sizes immersed in highly modified anthropogenic matrices. In a previous floristic survey conducted in 2003 across a forest fragment-size gradient, we found a positive and significant plant species- forest area relationship. In the present work, we repeat the same floristic survey ten years after (2013). In April 2013 we conducted identical surveys in the same sites within each of the 18 sampling forest fragments of different size sampled in April 2003. After a decade, we observed that not only the positive species-area relationship is maintained, but also the sampled number of species per site significantly decreases in all forest fragments,including the larger ones. Moreover, we observed a relative increase in non-native invasive species richnes swithin the smaller forest fragments. Thus, after a decade there was an increment in local species extinction, implying the payment of an extinction debt and an incipient and progressive invasion of non-native species in smaller remaining forest fragments. We conclude that the loss and fragmentation of Chaco Serrano forest caused local extinction debts, that is, the loss of plant species that become evident only after certain amount of time has elapsed from the original event of habitat destruction. This is the first work that empirically measures the extinction debt process in real time within the same fragmented landscape.