Agroforestry has the potential to enhance climate change adaptation. While benefits from agroforestry systems consisting of cash crops and shade trees are usually attributed to the (shade) trees, the trees can also have negative impacts due to resource competition with crops. Our hypothesis is that leaf phenology and height of shade trees determine their seasonal effect on crops. We test this hypothesis by categorizing shade tree species into functional groups based on leaf phenology, shade tree canopy height and shade tree light (wet and dry season) interception as well as the effects. To this end, leaf phenology and the effects on microclimate (temperature, air humidity, intercepted photoactive radiation (PAR)), soil water, stomatal conductance and cocoa yield were monitored monthly during wet and dry seasons over a two-year period on smallholder cocoa plantations in the northern cocoa belt of Ghana. Seven leaf phenological groups were identified. In the wet season, highest buffering effect of microclimate was recorded under the trees brevi-deciduous before dry season. During dry season, high PAR and lowest reduction in soil moisture were observed under the trees in the group of completely deciduous during dry season. The evergreen groups also showed less reduction in soil water than the brevi-deciduous groups. In the wet season, shade tree effects on cocoa tree yields in their sub canopy compared to the respective control of outer canopy with full sun ranged from positive (+10 %) to negative (-15 %) for the deciduous groups, while yield reductions for the evergreen groups ranged from -20 % to -33 %. While there were negative yield impacts for all phenological groups in the dry season, the trees in completely deciduous during dry season group recorded least penalties (-12 %) and the trees with evergreen upper canopy the highest (-35 %). The function of shade trees in enhancing climate resilience is therefore strongly dependent on their leaf phenological characteristics. Our study demonstrates how the key trait leaf phenology can be applied to successful design of climate-resilient agroforestry systems.

Crop management affects the anatomical and physiological characteristics of gladiolus floral stems. Particulary, shading screens are important in gladiolus production. The aim of the study was to evaluate the meteorological conditions, physiological indicators, stomatal characteristics, and quality of gladiolus flower stems grown in different seasons under shading screens and mulching. Field experiments were conducted during the four growing seasons: 1 (March-June 2019), 2 (August-November 2019), 3 (August-November 2020), and 4 (OctoberDecember 2021). Gladiolus cv. White goddess was grown in beds with and without mulch. Shading treatments included 35% black, silver, and red shading screens, and an unshaded control. Weather conditions during four growing seasons over two years were within the range of maximum and minimum temperatures suitable for the crop. The black and red shading screens resulted in higher stomatal density (374.9; 362.0 stomatal mm-2), which improved the photosynthetic rate of the leaf resulting in greater flower stem length (116.32 cm) and number of florets (19.00) in the red shading screen. The highest relative chlorophyll index (57.75) was recorded in season 2, which contributed to a greater accumulation of assimilates and resulted in longer stems and better-quality florets. Planting under a red shading screen and mulched soil produced longer stems (8.60 %; 9.05 %, respectively), and a greater number of florets in seasons 2 (8.43 %) and 4 (14.74 %), compared to growing unshaded control. The lowest percentage of damage to flower stems was found in the silver shading screen (3.6%) and mulched soil (6.7%). Long flower stems without damage to the sepals and petals, and with a large number of florets are of better quality, have greater ornamental value and are more attractive to flower consumers. Our results showed that planting in seasons 2 and 4, and using red shading screens and mulching soil, are sustainable and conservation soil-management practices to provide a favorable environment which allowed us to obtain high-quality gladiolus flowers. The results of this study are parameters for future research with different soil mulchings and shading screen colors.

Stable Zn isotopes fractionation was studied in main biogeochemical compartments of a pristine larch forest of Central Siberia developed over continuous permafrost basalt rocks. Two north-and south-oriented watershed slopes having distinctly different vegetation biomass and active layer depth were used as natural proxy for predicting possible future climate changes occurring in this region. In addition, peat bog zone exhibiting totally different vegetation, hydrology and soil temperature regime has been studied. The isotopic composition of soil profile from Central Siberia is rather constant with a delta Zn-66 value around 0.2 parts per thousand close to the value of various basalts. Zn isotopic composition in mosses (Sphagnum fuscum and Pleurozium schreberi) exhibits differences between surface layers presenting values from 0.14 to 0.2 parts per thousand and bottom layers presenting significantly higher values (0.5 - 0.7 parts per thousand) than the underlain mineral surface. The humification of both dead moss and larch needles leads to retain the fraction where Zn bound most strongly thus releasing the lighter isotopes in solution and preserving the heavy isotopes in the humification products, in general accord with previous experimental and modeling works [GCA 75:7632-7643, 2011]. The larch (Larix gmelinii) from North and South-facing slopes is enriched in heavy isotopes compared to soil reservoir while larch from Sphagnum peatbog is enriched in light isotopes. This difference may result from stronger complexation of Zn by organic ligands and humification products in the peat bog compared to mineral surfaces in North- and South-facing slope. During the course of the growing period, Zn followed the behavior of macronutrients with a decrease of concentration from June to September. During this period, an enrichment of larch needles by heavier Zn isotopes is observed in the various habitats. We suggest that the increase of the depth of rooting zone, and the decrease of DOC and Zn concentration in soil solution from the root uptake zone with progressively thawing soil could provoke heavy isotopes to become more available for the larch roots at the end of the vegetative season compared to the beginning of the season, because the decrease of DOC will facilitate the uptake of heavy isotope as it will be less retained in strong organic complexes.