Background: 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.

Living mulch intercropping systems are considered as nature-based solutions with a low environmental footprint for managing weeds, improving biodiversity and agroecosystem sustainability. In drylands, however, they may increase intra/inter-specific competition for water, reducing crop productivity. We tested conservation tillage (TLG) carob plots with and without irrigation (TLG_irr; TLG_dry) vs. rainfed intercropping systems of carob and (i) thyme (Thymbra capitata; T-System) or (ii) clover (Trifolium squarrosum; C-System), strategically planted on the south (sun)-exposed soil side (SES) of carobs, to reduce soil temperature/evaporation. Carob water relations, productivity and environmental footprints were examined for three years under semi-arid, low weed-competition (Skarinou-SKR) and arid high weed-competition (Vrysoules-VRY) conditions in Cyprus. Carob yield efficiency (kg/m³) in SKR, was >27% higher for the T-System (p < 0.05; SES cover ca. 85%; year-3), matching a higher leaf water content (p < 0.001) compared to TLG_dry. The T-System reached 28% and 56% of TLG_irr yields during very dry and normal rainfall years; TLG_dry yields approached zero. For VRY, no negative impacts on carob leaf water, at 25% SES cover, were found. SKR’s C-System improved leaf water content (p < 0.05) for only one year. The T-System also outperformed TLG_irr and TLG_dry in terms of reducing irrigation needs and energy consumption, breaking new grounds for dryland agroforestry.

Living mulch intercropping systems are considered as nature-based solutions of low environmental footprint for combating weeds, improving biodiversity and agroecosystem sustainability. In drylands, however, they may increase intra/inter-specific competition for water, reducing crop productivity. We tested conservation tillage carob plots with and without irrigation (TLGirr; TLGdry) vs. rainfed intercropping systems of carob and (i) thyme (Thymbra capitata; T-System) or (ii) clover (Trifolium squarrosum; C-System), strategically planted on the south (sun) exposed soil side (SES) of carobs, to reduce soil temperature/evaporation. Carob water relations, productivity and environmental footprints were examined for three years under semi-arid low-weed competition (SKR) and arid high-weed competition (VRY) conditions in Cyprus. Carob yield efficiency (kg/m3) in SKR, was >27% higher for the T-System (p<0.05; SES cover ca. 85%; year-3), matching higher leaf-water content (p <0.001) compared to TLGdry. The T-System reached 28% and 56% of TLGirr yields during very dry and normal rainfall years; TLGdry yields approached zero. For VRY, no negative impacts on carob leaf-water, at 25% SES cover, were found. SKR’s C-System, improved leaf-water content (p<0.05) for only one year. The T-System also outperformed TLGirr and TLGdry in terms of reducing irrigation needs and energy consumption, breaking new grounds for dryland agroforestry.

Tree intercropping systems with leguminous cover crops and aromatic plants may provide sustainable yields, which could be improved by beneficial microbes (BMs) and zeolite, while their effects on young tree growth remain unclear. We tested whether such systems enhance early growth in young carob trees compared with conservation tillage (TLG) trees growing under rainfed semi-arid conditions. Intercropping included carobs with (i) Lathyrus ochrus, Trifolium squarrosum, and Lens culinaris combined (CC-System), (ii) Thymbra capitata planted between legumes (CCT-System), and soil amended with (iii) BM (Micosat-F-Olivo) and zeolite. All systems outperformed TLG in annual tree height increase with the CC-System excelling (TLG +13%, CC-System +42%; p < 0.05). The CC-System also significantly outpaced TLG in stem thickening (TLG 62%, CC-System 167%; p < 0.01) with BM and/or zeolite also appearing as beneficial. Improved performance was related to significantly higher dry season soil moisture, while a high L. ochrus abundance reduced thyme survival (p < 0.01). The CCT-System was also found to be less capable in weed suppression during a wet year. Thus, applying our legume intercropping system (with BM/zeolite) represents an effective nature-based solution for enhancing young carob tree growth under rainfed conditions, while adding thyme may somewhat trade productivity for biodiversity and associated ecosystem services.