Lost forever? Ecosystem functional changes occurring after agricultural abandonment and forest recovery in the semiarid Chaco forests

BASUALDO, M.; HUYKMAN, N.; VOLANTE, J.N.; PARUELO, J.M.; PIÑEIRO, G.

THE SCIENCE OF TOTAL ENVIRONMENT

Elsevier

Año: 2019 vol. 650 p. 1537 - 1546

0048-9697

Semiarid forests are worldwide threatened by land use changes, particularly agriculture. However, in some cases,due to particular economic or social processes, agriculture ends and forests may or may not recover to their original state. Using different databases and satellite images integrated into a geographical information system, welocated in the central region of the semiarid Chaco forests of Argentina adjacent land use patches of secondaryforest (SF), remnant forest (RF) and crops (CP). Using a chronosequence approach, we evaluated changes inthe fraction of the photosynthetic active radiation absorbed by the vegetation (FAPAR) between SF and RF andCP, using the enhanced vegetation index (EVI). We evaluated both intra and inter-annual changes in EVI mean(EVImean), EVI maximum (EVImax), EVI minimum (EVImin), and EVI relative range (EVIrr) as descriptors ofFAPAR dynamics and analyzed their changes through time (2000 to 2010) and their relation to rainfall. Secondary forests showed higher seasonality and higher EVImean values than RF, but differences disappeared as timesince agricultural abandonment increased, suggesting that SF recover their functioning (when compared to RF)after 10 to 15 years. Our results suggest that Chaco´s SF have intermediate seasonal patterns in-between RFand CP, as expected by successional theory, and that FAPAR interception by RF appears to be dependent on previous year´s precipitation. We found that, although all land uses showed similar precipitation use efficiency(PUE), SF and cropland´s productivity were less stable across the years and showed faster increases or decreasescompared to RF, depending on precipitation (higher precipitation marginal response- PMR). Our results suggestthat at least some aspects of ecosystem functioning can be restored after agricultural abandonment. Future research that combines floristic and structural changes is necessary to fully understand secondary forests regrowth process after agricultural abandonment in the Chaco region