Climatic context and current agricultural practices modify the chances of woody invasion in extensive crops

ARANDA, MJ; TOGNETTI, PM; MAZÍA, CN

Louisville, Kentucky

Congreso; Annual Meeting for the Ecological Society of America-2019; 2019

Ecologial Society of America

Background/Question/MethodsLand use changes associated to agricultural activities can regulate woody invasion in grasslands. Once dispersion is overcome, competition generated by crops or disturbances associated to their management, like chemical control of weeds, could affect tree survival or growth. However, tree plants can survive by tolerating disturbances and resprouting from accumulated reserves. Gleditsia triacanthos invades different biomes in Argentina, and recent evidences indicate an increase of tree invasion in extensive crops.For maize and soybean crops, we examined how climatic conditions and agricultural practices affect the survival, growth and reserves accumulation during early establishment of G. triacanthos. During a wet and a dry growing season, we performed field experiments in soybean and maize crops under zero tillage. We controlled management (with/without agrochemicals) and crop cover (with/without soybean or maize plants) under a split-plot design. In each plot, we transplanted G. triacanthos seedlings (initial basal diameter: 2.2±0.4mm, height: 9.1±2.1cm) and recorded survival, growth and starch content, the main storage compound associated with resprout capacity, after crop harvest.Results/ConclusionsG. triacanthos survival decreased by 40% in the dry respect to wet year, and by 27% in soybean respect to maize crops. Plant survival decreased without crop cover and with management, especially for soybean. Seedlings were 76% shorter in soybean than in maize and were taller without cover, independently of crop type. Starch content in stem and roots of G. triacanthos, was higher for plants growing in maize, and 19% lower in plots with management. Starch content was positively related to plant survival.Our results suggest a hierarchy of factors controlling G. triacanthos establishment in cropping systems. First, climatic conditions more than crop type and management limited survival. Second, maize was more favorable than soybean for G. triacanthos survival, growth and starch accumulation. Therefore, weed control strategies would be particularly important under wet years, and focusing on carbon storage, in order to reduce tree tolerance to combined stresses. Overall, our study highlighted the importance agricultural matrix as a refuge of woody plants in modern landscapes.