Effects of Climate and Weeds on the Establishment of Thyme-Based Living Mulch Systems in Drylands of Cyprus

Abstract

Backround: Mulching systems are at the spotlight of sustainable soil management as nature-based solutions for combating desertification.
 Aims: We tested how living mulch systems based on rainfed Thymbra capitata [(L.) Cav.], can be established under different pressure from drought and weeds in dryland carob plantations.
 Study design: 10 thyme plots in semi-arid climate (SKR); 11 plots in arid climate (VRY); different weed competition intensity (60 thymes per plot).
 Place and Duration of the Study: South-eastern Cyprus, between December 2019 and 2022.
 Methodology: Survival and soil cover for 1260 T. capitata seedlings (3-5 cm tall, 16 seedlings per m2) was assessed at the end of 3 dry seasons (d.s.) together with weed community composition, weed abundance (w.a.) and biomass. Climate data and De Martone’s Aridity Index (DMAI) were used to assess drought severity.
 Results: Around 80% of the thymes survived at the end of the first d.s, that followed a very rainy year (ca. 600 mm annual precipitation; P; ca. +50% than normal; ca. 19 DMAI). Thyme survival appeared unaffected by w.a. in both sites. After a severe drought that occurred the second year (ca. 300 mm P; ca. -22% than normal; ca. 9.5 DMAI) thyme survival rates dropped at the end of the d.s. to ca. 20% at the site with 3 times higher w.a./ biomass (mostly from Avena sp.). However, they were unaffected under low w.a. creating a 29% soil cover (vs.7% in VRY). These results remained till the end of the third d.s.
 Conclusions: To combat desertification and drought intensification under climatic change, rainfed T. capitata as living mulch appears unaffected by weeds during wet years, or in very dry years under low w.a. However, under high w.a., a weed management system is required if climate is arid.