MOROCCAN STRAWBERRY TREE (Arbutus Unedo L.) LEAVES: COMPARATIVE STUDY OF THE NUTRITIONAL VALUE AND MINERAL COMPOSITION

Strawberry tree (Arbutus Unedo L.) is one of the evergreen trees that grow spontaneously in Moroccan forests. This tall shrub is traditionally used in grazing zones of some Moroccan areas, especially during the dry season, but its value in Morocco has still been underestimated. In this paper, the nutritional composition of A. unedo leaves sample collected from seven Moroccan regions has been assessed. For this, the leaves were dried, crushed, and chemically analyzed for their proximate composition, energetic value, total and reducing sugar, and mineral composition. Results of this study suggested that samples from BniAarouse (BA) region showed the highest contents of essential nutrients such as proteins, dietary fiber, ashes, and fat with average values of 7.53, 17.89, 4.14, and 8.05 g/ 100 g of dry weight, respectively, which positively influences its consumption by small ruminants. Cluster analysis based on surveyed parameters separated the strawberries individuals into four distinct groups, providing a high variability among and within studied locations. That could be related to the diversity of the edaphoclimatic conditions between regions and to the genetic effect. The results of the present study highlighted the potential use of leaves as livestock feed, with intermediate quality, and promotes their optimal cultivation and subsequent domestication in Morocco.

Ulex europaeus (gorse).

U. europaeus was spread intentionally through most of the world in the 1800s and 1900s as a hedge plant, an ornamental and as a forage, although it is unlikely that it will be distributed to new areas for these purposes in future. It has large seeds and there is a threat from inadvertent introduction, but this is not high. U. europaeus was already declared a noxious weed 100 years ago in Australia and New Zealand, and is now a serious weed in many other countries, and poses a threat elsewhere where it is present but not yet invasive. It is an aggressive colonizer of disturbed habitats, and the risk from continued invasion in suitable climatic zones in countries where present is high. It is a tough, spiny, long-lived, tall shrub with a long-lived seed bank and is difficult to control. Thickets displace vegetation in grassland habitats, and outgrow and supplant tree seedlings in plantation forests. Heavy infestations modify soil and hydrological conditions, and so modify ecosystem processes. This plant poses a serious fire risk for indigenous ecosystems as well as managed habitats and human habitations.

Elaeagnus angustifolia (Russian olive).

E. angustifolia is a tall shrub (up to 15 m and 1 m d.b.h.), with a dense, rounded crown, native to Europe and Asia and an important deciduous species of arid and semi-arid areas of northwestern China. It was introduced into the USA in the early 1900s, and has now become extensively naturalized in riparian areas of western states bordered on the east by North and South Dakota, Nebraska, Kansas, Oklahoma and Texas (Olson and Knopf, 1986a, 1986b; Shafroth et al., 1995). It also occurs in southern Canada from Ontario to British Columbia. It grows in some eastern USA states, but is not naturalized (Tesky, 1992). This fast-growing (up to 1.8 m per year), nitrogen-fixing species has silver-grey leaves with entire margins (4.5-9 cm), olive-shaped fruit and long thorns. The branches are flexible, pubescent (grey and scaly) and often have a short thorn at the end. The bark is brown, thin with shallow fissures, peeling in long strips. It has a deep taproot and well-developed lateral root system. The small, yellow flowers occur in late spring and have a distinctive spicy aroma. Trees produce seed after 3-5 years, with birds and small mammals dispersing them in their droppings. The seeds can remain viable for up to 3 years and are capable of germinating over a broad range of soil types (Knopf and Olson, 1984). Germination is enhanced by stratification in moist sand for 90 days at 41°C (Vines, 1960). E. angustifolia is found in a range of environments as it is tolerant of drought and saline, alkaline or infertile soils (Vines, 1960; Olson and Knopf, 1986a, 1986b), and has a well-developed root system. It is commonly found growing along floodplains, river banks, stream courses, marshes and irrigation ditches in the western states of the USA, and in desert or dry (150 mm annual rainfall) areas of Western Asia. It bears few fruits if the annual precipitation is >400 mm and also grows slowly if the water table is below 4 m. E. angustifolia is mainly established from seed, although cuttings are used in areas with sufficient moisture. It is relatively shade-tolerant once established and can withstand competition from other shrubs and trees, and can become a dominant climax species, replacing native cottonwoods and willows along water courses in the USA. E. angustifolia has been widely planted in shelterbelts, windbreaks or protective plantings as it is hardy, adaptable to a wide range of soil and moisture conditions and has a dense growth form (Brothers, 1988). It has also been used to revegetate land contaminated by paper mill wastewater (Wagner et al., 1994), potassium (Heinze and Liebmann, 1998) and bentonite (Uresk and Yamamoto, 1994), mine spoilings and as a bioindicator of heavy metal pollution (Aksoy and Sahin, 1999). The timber is hard and brownish-yellow with a beautiful grain, being similar to that of white elm (Ulmus pumila, U. americana). It can be used to make farm tools, furniture and for mining poles and civil construction. The fruits and leaves are valuable for food and animal fodder, whilst the tree is considered a good source for bee foraging. The leaves, shoots, flowers, fruits and bark have been traditionally used in Chinese medicine.

Hydrological implications of vegetation change in a subarctic, alpine catchment, Yukon Territory, Canada

<p>As a result of altitude and latitude amplified impacts of climate change, widespread alterations in vegetation composition, density and distribution are widely observed across the circumpolar north. The influence of this vegetation change on the timing and magnitude of hydrological fluxes is uncertain, and is confounded by changes driven by increased temperatures and altered precipitation (P) regimes. In northern alpine catchments, quantification of total evapotranspiration (ET) and evaporative partitioning across a range of elevation-based ecosystems is critical for predicting water yield under change, yet remains challenging due to coupled environmental and phenological controls on transpiration (T). In this work, we analyze 6 years of surface energy balance, ET, and sap flow data at three sites along an elevational gradient in a subarctic, alpine catchment near Whitehorse, Yukon Territory, Canada. These sites provide a space-for-time evaluation of vegetation shifts and include: 1) a low-elevation boreal white spruce forest (~20 m), 2) a mid-elevation subalpine taiga comprised of tall willow (Salix) and birch (Betula) shrubs (~1-3 m) and 3) a high-elevation subalpine taiga with shorter shrub cover (< 0.75 m) and moss, lichen, and bare rock. Specific objectives are to 1) evaluate interannual ET dynamics within and among sites under different precipitation regimes , and 2) assess the influence of vegetation type and structure, phenology, soil and meteorological controls on ET dynamics and partitioning.  Eddy covariance and sap flow sensors operated year-round at the forest and during the growing season at the mid-elevation site on both willow and birch shrubs for two years. Growing season ET decreased and interannual variability increased with elevation, with June to August ET totals of 250 (±3) mm at Forest, 192 (±9) mm at the tall shrub site, and 180 (± 26) mm at the short shrub site. Comparatively, AET:P ratios were the highest and most variable at the forest (2.4 ± 0.3) and similar at the tall and short shrub (1.2 ± 0.1).  At the forest, net radiation was the primary control on ET, and 55% was direct T from white spruce. At the shrub sites, monthly ET rates were similar except during the peak growing season when T at the tall shrub site comprised 89% of ET, resulting in greater total water loss. Soil moisture strongly influenced T at the forest, suggesting the potential for moisture stress, yet not at the shrub sites where there was no moisture limitation. Results indicate that elevation advances in treeline will increase overall ET and lower interannual variability; yet the large water deficit during summer implies a strong reliance on early spring snowmelt recharge to sustain soil moisture. Changes in shrub height and density will increase ET primarily during the mid-growing season. This work supports the assertion that predicted changes in vegetation type and structure will have a considerable impact on water partitioning in northern regions, and will also vary in a multifaceted way in response to changing temperature and P regimes.  </p>

A new species of Bauhinia from coastal areas in Northeastern Brazil

Bauhinia includes about 150 species distributed across the tropics. Most Neotropical species belong to Bauhinia ser. Cansenia that includes unarmed trees and shrubs, mostly from areas under seasonally dry climate. A new species of this series is described here from the northeastern Brazilian states of Bahia and Sergipe. Bauhinia corifolia occurs in open vegetation on sandy soils of Restinga vegetation at the Atlantic coastal forests. It is morphologically similar to B. acuruana by sharing the entire and ovate leaflet with a retuse to emarginate apex and a cordate base, but differing by its tall shrub to treelet habit, larger leaves with a glabrous and glossy upper surface, shorter bracts, and longer flowers. We provide description, illustration and distribution map for the new species.

Lantana caudata (Verbenaceae), a new species from the Brazilian Atlantic Forest

Lantana caudata, a new species of Verbenaceae, endemic to the Brazilian Atlantic Forest is described and illustrated. It is a tall shrub, characterized by the presence of pedicellate glandular trichomes on all parts of the plant; branches conspicuously prickly; lanceolate to elliptical leaves, with obtuse to cuneate base and caudate apex; peduncle long; and yellow, red or orange corolla. This species occurs in the transition between dense rainforest and inselbergs in Espírito Santo and between the same type of forest and campos de altitude in Minas Gerais. We discuss the diagnostic characters, morphological affinities and conservation status, and present a distribution map and illustration.

Patterns of shrub abundance and relationships with other plant types within the forest–tundra ecotone in northern Canada

Throughout the forest–tundra ecotone where trees and tall shrubs are becoming more abundant, knowledge of associations between shrubs and surrounding vegetation could inform predictions of their changing relationships. We assessed shrubs in 1 m × 1 m contiguous quadrats along two ∼450 m transects across tundra and ecotone landscapes near Churchill, Canada to determine patterns in relation to lakeshore edges, soil pH, microtopography, and other plant groups. We used wavelet analysis to assess patterns and generalized least squares for relationships with environmental variables. Shrubs were taller and more diverse at edges, particularly in tundra. The ecotone was more complex than tundra with greater variation in tall shrub and tree cover, shrub height, and microtopography. Shrub richness was positively correlated with microtopography but exhibited no relationship with pH. Bivariate relationships of shrubs with other plant groups varied for different scales. In tundra, shrub richness was negatively correlated with graminoids, forbs, and moss, but positively correlated with lichens within 1 m; opposite relationships were found at 4–60 m scales. Relationships in the ecotone were reversed and more complex at different scales. As trees encroach in the tundra, the spatial pattern of shrubs will become more complex at a variety of scales, likely with cascading effects on other plant types.