An enhanced understanding of plant water uptake is critical for making better-informed management decisions involving vegetative manipulation practices aimed to improve site productivity. This is particularly true in arid and semiarid locations where water is a scarce, yet precious commodity. In this project, we evaluated the interannual and seasonal variability of soil moisture and transpiration in sapling, juvenile, and mature western juniper (Juniperus occidentalis) trees in a semiarid rangeland ecosystem of central Oregon, USA. Transpiration levels were greatest in mature juniper trees in an untreated juniper watershed (Jensen WS), while the lowest transpiration levels were observed in juniper saplings in a treated watershed (Mays WS) where most mature juniper trees were removed in 2005. Significant differences (p ≤ 0.05) in leaf water potential levels observed between predawn and midday readings for all juniper growth stages indicated water is lost over the course of the day. Results showed seasonal precipitation was highly variable over the course of the study (2017 through 2019) and this was reflected in soil water available for tree uptake. This resulted in considerable intra- and inter-annual variation in transpiration. In years with greater winter precipitation amounts (2017 and 2019), juniper transpiration rates were highest during the summer, followed by spring, autumn, and winter. On average, transpiration rates during the summer in the wettest (329 mm) year 2017 were 115 and 2.76 L day−1 for mature and sapling trees, respectively. No data were collected for juvenile trees in 2017. In the drier (245 mm) year 2018, higher transpiration rates were observed in the spring. On average, spring transpiration rates were 72.7, 1.61, and 1.00 L day−1 for mature, juvenile, and sapling trees, respectively. Study results highlight the sensitivity of western juniper woodlands to variations in seasonal precipitation and soil moisture availability.

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Rangelands of Tunisia show a great indigenous species diversity with considerable potential as forage for livestock. However, information on their fodder yield and quality is scanty and restricted to few species. The objective of the study was to evaluate the nutritive values of selected key perennial species based on their biomass yield, chemical composition, in vitro organic matter digestibility (IVOMD), and mineral composition. The species evaluated included four grass species (Stipa lagascae Roem. and Schult., Stipa tenacissima L., Stipagrostis plumosa (L.) Munro ex T. Anderson, and Stipagrostis pungens (Desf.) de Winter.) and eight shrub species (Anthyllis henoniana Coss. ex Batt., Argyrolobium uniflorum (Deene.) Jaub. and Spach., Echiochilon fruticosum Desf., Gymnocarpos decander Forssk., Helianthemum kahiricum Delile., Helianthemum lippii (L.) Dum. Cours., Plantago albicans L. and Rhanterium suaveolens Desf.). Results showed that shrub species contained higher concentrations of the crude protein (CP), acid detergent lignin (ADL), but lower neutral detergent fiber (aNDFom) and acid detergent fiber (ADFom) concentrations than grasses. The greatest concentration of CP was 135 g/kg DM for R. suaveolens. The greatest aNDFom concentration was found within the grasses with maximum of 744.5 g/kg DM in S. plumosa. The shrub species E. fruticosum, A. uniflorum, P. albicans, G. decander, R. suaveolens, and A. henoniana had the highest IVOMD with over 500 g/kg DM and have the potential to supply energy to livestock. Overall, the moderate to high protein, low fiber, and high in vitro digestibility measured for shrubs, suggest they have high nutritional values and can be used to enhance local livestock production.

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