Mohammad A. Alrababah

Biodiversity of semi-arid Mediterranean grasslands: Impact of grazing and afforestation

ABSTRACT Question: What is the impact of grazing and/or afforestation on grassland diversity, species composition and cover parameters? Location: Semi-arid Mediterranean grasslands of Jordan. Methods: Vegetation, litter, bare soil and rock cover were compared among four management types - free grazing and protected from grazing with three levels of tree cover. Species composition, plant cover, species richness and evenness were used to evaluate differences in vegetation among management types. Species composition differences among management types were also investigated. Results: Semi-arid Mediterranean grasslands harbour appreciable levels of plant biodiversity. Grazing did not affect plant diversity, indicating the high resilience against and adaptation to grazing; however, grazing affected species composition and cover parameters. Afforestation seems to protect soil through higher litter cover but its impact on plant biodiversity was negative and markedly affected species composition. Conclusions: Neither protection from grazing or massive afforestation alone are sufficient for conserving biodiversity in this system. A management model is suggested where the landscape should be maintained as a mosaic of four management types: complete protection from grazing, grazing rotation, planting sparse trees in eroded areas and revegetating degraded areas using native, herbaceous and grazing tolerant species. Nomenclature: Zohary & Feinbrun (1966–1986).

Antioxidant activities, total phenolics and HPLC analyses of the phenolic compounds of extracts from common Mediterranean plants

In this study, the total phenolic amounts and antioxidant activities of plant extracts obtained from some common Mediterranean plant species collected from different places in Jordan were determined. The phenolic constituents of these extracts were also determined using HPLC. The total phenolic amounts ranged from 52.8 to 876.9 mg GAE per 100 g dry material. The antioxidant activities were evaluated according to the 2,2-diphenyl-1-picrylhydrazyl radical scavenger method. Sage (Salvia officinalis) showed the highest antioxidant activity (91%), while the lowest (11.3%) was seen in parsley (Petroselinum crispum). A strong correlation (r  =  0.85) between antioxidant activity and total phenolic content was found. The phenolic compounds identified by HPLC were gallic acid, protocatechuic acid, catechin, gentisic acid, chlorogenic acid, vanillic acid, syringic acid, caffeic acid, epicatechin and benzoic acid. All the investigated plants contain gallic acid, whose phenolic content ranged from 0.4 to 37.8 mg per 100 g, catechin (0.3–339.9 mg per 100 g), protocatechuic acid (0.3–41.9 mg per 100 g) and gentisic acid (0.3–35.8 mg per 100 g), while caffeic acid (0.3–2.6 mg per 100 g) was detected in six species only. These natural plant phenolics could thus be a good source of antioxidants for applications in food.

Land use/cover classification of arid and semi‐arid Mediterranean landscapes using Landsat ETM

Land use/cover classification in heterogeneous east Mediterranean landscapes is challenging, e.g. Jordan. Digital land use/cover maps are needed at an appropriate cost, spatial and temporal coverage. North‐western Jordan is appropriate for exploring the use of Landsat ETM imagery in land use/cover delineations as its biogeographic zones are very diverse and heterogeneous. Supervised and unsupervised classification schemes were used with and without spatial enhancement techniques. Sources of classification errors were inspected statistically. Results indicated that Landsat ETM images are effective in classifying heterogeneous Mediterranean landscapes with an accuracy of up to 83%. Accuracy was enhanced by approximately 9% using supervised classification. Spatial enhancement improved accuracy of certain classes and reduced it for others. Results call for class‐specific classification schemes. Areas of the different land use/cover classes of the study area were estimated from the classified image. Urban, shrubland and rangeland areas were estimated for the first time. There is a growing concern about the governmental census estimates of certain classes.

Allelopathic effects of Pinus halepensis and Quercus coccifera on the germination of Mediterranean crop seeds

Agroforestry is a leading alternative for food security and forest conservation. A full understanding of positive and negative, i.e. allelopathic, interactions between crops and forest trees is necessary for producing crops and conserving forests especially within the threatened Mediterranean forest ecosystems. The present study explored the allelopathic effects of green and senescent leaf and soil extracts of two agroforestry trees—Pinus halepensis and Quercus coccifera—on the germination of wheat, barley, lentil, chickpea, and fababean as the major grain crops of Jordan. Results revealed that allelopathic effects reduced seed germination of these crops. Germination reduction reached a maximum of 75% in fababean treated with green extracts of Q. coccifera and differed among crops and extract sources, but not between tree species. Comparing between green and senescent leaf and soil extract, regarding their effect on germination percentage, it was noticed that these effects were similar in some crops and were different in others. Germination responses were generally different between cereals and legumes where cereals tend to be less affected by allelopathic influences than legumes, especially fababean. We suggest using cereals such as wheat and barley in agroforestry practices in the Mediterranean region of Jordan.

Anti-Oxidant, Anti-Diabetic, and Anti-Hypertensive Effects of Extracted Phenolics and Hydrolyzed Peptides from Barley Protein Fractions

This study was conducted to search for novel natural bioactive compounds (peptides and phenolic compounds) with hypoglycemic, antioxidant, and anti-diabetic potential from barley protein fractions and isolates. Protein isolate and globulin, prolamin, glutein-1, and glutein-2 fractions of barley flour were extracted from barley flour. Free and bound phenolic compounds were extracted from protein isolate and protein fractions. Protein isolate and protein fractions from barley were subjected to pancreatic hydrolysis to obtain peptides. Peptide and both free and bound phenolic compounds were subjected to determine antioxidant and their potential to inhibit the key enzymes relevant to diabetes and hypertension using in vitro models. The extracted phenolic from prolamin fraction and protein isolate revealed the highest content of total phenolics (2.0–2.4 mg/g), antioxidant activity (65–73%), angiotensin converting enzyme-inhibitory activity (73–87%), and α-amylase inhibitory activity (57–77%) as compared to that of other protein fractions. Hydrolysates of prolamin fraction exhibited the highest antioxidant activity (77.7%) and angiotensin converting enzyme-inhibitory activity (61.3%) as compared to all other protein fractions and protein isolate. Poor correlations were obtained between total phenolic content, antioxididant activity, ACE-inhibitory activity, and α-amylase inhibitory activity of phenolic compounds from protein fractions and isolate. On the other hand, positive correlations were obtained between antioxididant activities, angiotensin converting enzyme-inhibitory activity, and the degree of hydrolysis of peptides from hydrolyzed protein fractions and protein isolate. Our findings indicated that prolamin fraction and protein isolate were recommended to be used as hypoglycemic, antioxidant, and anti-diabetic ingredients as potential candidates in functional, nutraceutical, and pharmaceutical industries.

Quality Attributes of Halva by Utilization of Proteins, Non-hydrogenated Palm Oil, Emulsifiers, Gum Arabic, Sucrose, and Calcium Chloride

Emulsion stability (oil separation) in halva is a major problem that affects quality upon storage. Emulsion instability results in toughness, oil separation, and oil contamination on packaging materials. The objective of this study was to evaluate the effectiveness of improving halva quality by incorporating non-hydrogenated palm oil, glycerol, soy protein concentrate, gelatin, lecithin, pectin, gum Arabic, sugar powder, and calcium chloride. Halva was produced by heating sugar (sucrose) solution (65%) containing citric acid (0.65%) and heating to reach 105° C, adding halva root (Saponaria officinalis) extract solution (5.6%) and continuing heating for 60–70 min. This is followed with cooling at room temperature for 15 min and adding tahinia (sesame paste) (1:1) and mixing for 10 min. The additives to improve the quality of halva were incorporated with the sugar solution, during cooking, and with tahinia. The quality of halva was evaluated by measuring the amount of oil separation, microscopic examination, and oil viscosity. Microscopic examination of halva showed a porous non-crystalline sugar melt particles surrounded by a precipitated protein layer originating from tahinia. The oil was found as free non-emulsified fluid, filling in the spaces between solid particles. The saponin (from halva root extract) possibly precipitated the colloidal proteins of tahinia, and contributed to a fragile structure. Soy protein concentrate, gelatin, glycerol, and lecithin incorporation did not improve emulsion stability. However, calcium chloride, sugar powder, gum Arabic, and pectin minimized emulsion instability. Furthermore, 1.0% or 2.5% of non-hydrogenated palm oil increased viscosity of the oil phase and contributed to emulsion stability.

Estimating east Mediterranean forest parameters using Landsat ETM

The conservation of Jordans Mediterranean forest requires the use of remote sensing. Among the most important parameters needed are the crown-cover percentage (C) and above-ground biomass (A). This study aims to: (1) identify the best predictor(s) of C using Landsat Enhanced Thematic Mapper (ETM) bands and the derived transformed normalized difference vegetation index (TNDVI); (2) determine if C is a good predictor of A, volume (V), Shannon diversity index (S) and basal area (B); and (3) generate maps of all these parameters. A Landsat ETM image, aerial photographs and ground surveys are used to model C using multiple regression. C is then modelled to A, V, S and B using linear regression. The relationship between C and Landsat ETM bands (1 and 7) plus the TNDVI is significantly high (coefficient of determination R 2 = 0.8) and is used to produce the C map. The generated C map is used to predict A (R 2 = 0.56), V (R 2 = 0.58), S (R 2 = 0.50) and B (R 2 = 0.43). Cross validation for the predicted C map (cross-validation error = 5.3%) and for the predicted forest-parameter maps (cross-validation error = 13.7%–19.9%) shows acceptable error levels. Results indicate that Jordans east Mediterranean forest parameters can be mapped and monitored for biomass accumulation and carbon dioxide (CO2) flux using Landsat ETM images.

Genetic diversity of the easternmost fragmented mediterranean Pinus halepensis Mill. populations

The genetic structure of fragmented Aleppo pine (Pinus halepensis Mill.) populations in Jordan was investigated using RAPD markers. The level of within-population polymorphism was low, while differentiation among populations was large, suggesting a low level of gene flow. Population differentiation and genetic distance between populations were not related to geographical distance. Clustering based on multivariate discriminant analysis showed that geographically distant populations clustered together with a high clustering accuracy and strong relationship to rainfall. Results supported that the current population configuration is the result of fragmentation of a once larger and contiguous population due to Holocene conditions exacerbated by increased human disturbance of forest ecosystems. Implications for conservation strategies are discussed.

Environmental gradients and community attributes underlying biodiversity patterns of semi-arid Mediterranean grasslands

Protection and/or establishment of forest plantation have been used as a management strategy to conserve and stop the deterioration of semi-arid Mediterranean grasslands ecosystems, producing a mosaic of vegetation types. This study was intended to investigate the changes in grassland community in response to protection and forest tree plantation practice as well as to explore the underlying environmental gradients responsible for the observed differences or similarities among these vegetation types. Two multivariate analysis methods including discriminate analysis and non-metric multi-dimensional scaling were used to quantify changes in community composition and attributes following different management practices (free grazing, protection with open grassland, sparse and dense forest tree plantations). This was investigated using species frequency, species abundance, or habitat characteristics. The study results showed that habitat types differed significantly between each other and were significantly separated using multivariate approaches. Discrimination based on habitat characteristics and species composition indicated that protection (or grazing) and light (or shade) explained more than 90% of the observed variability in community changes in response to the protection and forest tree plantation. Also, results indicated that shade effect can be attributed to tree canopy cover and/or litter accumulation on the ground. It could be hypothesized that protection from grazing and afforestation resulted in complex environmental gradients of which shade, litter accumulation as well as protection from grazing disturbance are major constituents. A careful manipulation of protection and afforestation can be used to create a spatially different environmental gradients leading to greater habitat diversity as well as a greater species diversity, and better conservation means of grassland in semi-arid areas.

The impacts of biologically induced micro-environments on biodiversity in a dry Mediterranean grassland

Background: Many dryland plant communities are characterised by scattered shrubby vegetation. In such dry ecosystems, individual shrubs modify the local micro-environment and affect the surrounding plant community. Aims: The present study was conducted in a dry Mediterranean grassland community, with scattered shrubs, to determine the impacts of biologically induced micro-environments on the surrounding plant community. Methods: The plant community was sampled at four distances in four micro-environments, defined by cardinal compass directions (north, south, east and west) to assess vegetation composition near individual shrubs and at increasing distances from them. To quantify the impact of shrubs on surrounding species composition, we used a rarefaction approach in addition to alpha and beta diversity and cover parameters. Also, the productivity–diversity relationship was investigated. Results: We found significant micro-environment differences in non-shrub communities in terms of vegetation, bare ground and litter cover, above-ground biomass, species richness and Shannon diversity index. The diversity–productivity relationship was best fit by unimodal and linear models. Rarefaction analysis accumulated more species in the west aspect than in the other aspects. Beta diversity values for consecutive distances were significantly higher than the farthest distances. Conclusions: These findings suggest that shrubs create micro-environments and influence plant community characteristics according to distance and aspect, and therefore add to the complexity and biodiversity of the system; by creating diverse microhabitats they contribute to enhanced plant diversity.