Acacia Tortilis Research Articles

English

Turkana County is prone to perturbations and famine owing to the prevailing climatic conditions. Due to degradation through natural and anthropogenic activities such as charcoal burning; over time, existing woodlands have been degraded, necessitating rehabilitation. Several drylands adapted plant species studied over the years for the response to the needs of the communities were identified and isolated through a survey. The species identified to be most useful to the communities included Cenchrus ciliaris, Tamarindus indica, Salvadora persica, Moringa oleifera, Aloe turkanensis, Acacia senegal, Acacia tortilis, Acacia mellifera, Cordia sinensis, Adenia  obesum, Dobera glabra, Parkinsonia acuelata and Balanites aegyptiaca. The final species planted were A. mellifera; A. senegal; A. tortilis; Adenium obesum; B. aegyptiaca; C. sinensis; D. glabra; P. aculeata, S. persica and Melia volkensii were introduced for observation on performance. This study's objectives were to determine the effectiveness of micro-catchments in rangeland rehabilitation and to compare species performance to appraise the species highly adaptable to the environment. This offered an opportunity to demonstrate climate-smart technologies regarding rangeland rehabilitation. The methodology was adapted from proving phase provenance trials using nested intensity design to give the best measurements that measure native and exotic plant species. The site was in Ekalees 10 km off Lodwar -Kerio road, Lodwar. Micro-catchment was used as a treatment where a similar number of species of the same age were grown with micro catchments and others without micro-catchments. The major result of this study was found in the site with micro-catchments having higher mean heights and root collar diameters for each species tested. The results indicated the usefulness of micro-catchments, especially in arid and semi-arid areas, as well as showing the performance of selected native species performance in the natural ecosystem.   Key words:  Water harvesting, land restoration,  climate-smart technology, native species.

Salt tolerance of selected halophytes at the two initial growth stages for future management options

Scarcity of water and the small area of the agricultural land are considered as the crucial environmental issues challenged the Arabian Gulf countries. In this study, experiments were conducted to identify the salt tolerance during the germination and the seedling stages of some native halophytes in the State of Qatar. Seeds of eight native species (Salsola setifera, Halopeplis perfoliata, Caroxylon imbricatum, Suaeda aegyptiaca, Acacia tortilis, Limonium axillare, Tetraena qatarensis and Aeluropus lagopoides) were investigated. Except for Tetraena qatarensis, Acacia tortilis and Suaeda aegyptiaca, all achieved ≥ 30% of seed germination at a concentration of 200 mM NaCl. Around 30% of Salsola setifera seeds were able to germinate in a salt concentration of 400 mM. Germination recovery of seeds that have been treated with 800 mM NaCl for 3 weeks was the greatest for Halopeplis perfoliata (94%) and the lowest for Aeluropus lagopoides (22%). Five halophytes were investigated for seedling growth under saline irrigation ranged from 0 to 600 mM NaCl. No significant differences obtained in growth biomass of seedlings of each of Caroxylon imbricatum, Suaeda aegyptiaca and Tetraena qatarensis between saline and non-saline treatments.

Effects comparison of co-occurring Vachellia tree species on understory herbaceous vegetation biomass and soil nutrient: Case of semi-arid savanna grasslands in southern Ethiopia

The spread of woody plant encroachment is a major concern as it adversely affects herbaceous plant community composition in a savanna ecosystem. Assessing the canopy effects of co-occurring encroaching and non-encroaching woody plant species on the understory herbaceous vegetation biomass and the soil nutrient status can improve our understandings of the link between biological invasions and herbaceous plant community ecology. We examined the canopy and adjacent inter-canopy effects of encroaching and non-encroaching Vachellia species which was previously known as Acacia on herbaceous vegetation biomass in Southern Ethiopia. A total of 12 encroaching (Vachellia drepanolobium) and 12 non-encroaching (Vachellia tortilis) tree species were selected both at an upland and a bottomland site. A 1 m × 1 m quadrat was used to investigate the canopy effects of individual tree species and inter-canopy habitats on herbaceous vegetation biomass. Soil samples were collected under the canopy of selected tree species and the adjacent inter-canopy habitat at a depth of 0–10 cm and 10–20 cm both at the upland and bottomland site. With fixed effect ANOVA, we evaluated the effects of landforms (upland or bottomland), tree species (Vachellia drepanolobium or Vachellia tortilis) and habitats (canopy or inter-canopy habitat) on total herbaceous biomass, perennial herbaceous species biomass and annual herbaceous species biomass. There was no significant (P > 0.05) difference between the canopy and inter-canopy habitat of V. drepanolobium and V. tortilis in terms of the total herbaceous biomass and annual herbaceous vegetation at the bottomland position. The canopy of V. drepanolobium had a negative effect on the biomass production of herbaceous perennial species both at the bottomland and upland site. On the contrary, the canopy of V. tortilis had a significantly positive (P < 0.05) effect on the biomass production of herbaceous perennial plants at the bottomland site. Generally, more soil organic matter accumulation was recorded under the canopy of V. tortilis than it was either under the canopy of V. drepanolobium or in the open savanna grasslands. Our findings indicated that encroaching tree species canopy and co-occurring non-encroaching tree species canopy had a predominantly different influence on herbaceous vegetation biomass. It seemed that encroaching tree species in savannas had a high acquisition and competition for resources. The findings can help improve our understanding on the herbaceous biomass predictions of different life forms in a community of encroached grasslands and non-encroached grasslands in southern Ethiopia.

English

Acacia woodlands are ecologically important and it is necessary to understand its structures and dynamics to develop sustainable conservation strategies. This study aimed to provide baseline information on the composition and growth of Acacia woodlands in the Hawtat Bani Tamim and Al Duwadmi regions of central Saudi Arabia. Height, diameter at breast height, crown diameter, seedling density, and soil seed bank content of Acacia tree species were characterized for 27 remote, circular, 0.1-ha plots in both study areas. At Hawtat Bani Tamim, Acacia raddiana, A. tortilis, and A. ehrenbergiana accounted for 45.53, 37.5 and 16.96% of all species present there. Most DBH were in the 6–10 cm class. A. raddiana was the main species in most diameter classes. Most trees were 4.1–5.0 m tall and A. raddiana predominated in this height class. Acacia ehrenbergiana had 92.63% damaged seeds. At Al Duwadmi, A. raddiana represented 78.99% of all Acacia trees there. A. gerrardii and A. tortilis accounted for 11.93 and 9.07% of the species there, respectively. Most of the DBH values were in the 6–10 cm and 11–15 cm classes, and A. tortilis and A. raddiana were abundant in both classes. Most trees were in the 4.1–5 m height class, which was dominated by A. raddiana. A. ehrenbergiana had 88.26% damaged seeds. In both areas, there was a gradual decline in the number of trees in DBH classes &gt; 35 cm. The Acacia species in the two areas showed a fair regeneration status. There were more seedlings than saplings and fewer saplings than trees. This baseline study could contribute towards future sustainability planning initiatives after other assessment studies have been conducted to identify changes in the Acacia woodlands of this region. © 2021 Friends Science Publishers

Restoration thinning reduces bush encroachment on freehold farmlands in north-central Namibia

Abstract Bush encroachment affects ~45 million ha of Namibia and, without appropriate restoration measures, it negatively affects rangeland productivity and biodiversity. Thinning is a common method to counteract bush encroachment. The thinning strategy applied in north-central Namibia was assessed to examine how effective it has been in reducing bush encroachment. Trees/shrubs were selectively thinned manually, targeting all height classes, except individuals with stem diameters ≥18 cm. We investigated the effects on the vegetation and soil properties using surveys on three freehold farms (in 2016 and 2017) in bush-encroached and previously thinned habitats. Our results revealed significant differences in the mean total nitrogen (TN) content between the treatments; thinned areas had higher TN content which would be beneficial for fast-growing grasses. In the thinned plots, the occurrence probability of red umbrella thorn (Vachellia reficiens Warwa) was significantly reduced, indicating that it was the most harvested species; and umbrella thorn (Vachellia tortilis (Burch.) Brenan spp. heteracantha) was increased, indicating that it favoured reduced densities of dominant species. Natural regeneration was rapid; the tree/shrub abundance in the 0–1-m height class in the thinned area surpassed those in the non-thinned by 34 per cent, ~7.2 years since thinning. Thinning significantly reduced tree/shrub abundances of the 1–3- and &amp;gt;3-m height classes, which was still evident 7.2 years since thinning. Based upon the generalized linear mixed-effects model, tree/shrub counts between treatments may equalize in ~14 and 15 years for the 1–3- and &amp;gt;3-m height classes, respectively. Thinning was effective in reducing tree/shrub abundances and can be used to restore wildlife habitat on the Namibian farmland: however, post-thinning management is required to maintain an open savannah vegetation structure as the 0–1-m height class cohort will eventually grow into mature trees/shrubs.

Diversity, population structure and regeneration status of woody species in different habitats in Maun Educational Park, northern Botswana

ABSTRACT The diversity and population structure of woody species at Maun Educational Park (MEP) was investigated from June to July 2018. A total of 23, 18 and 30 quadrats of 20 × 20 m size were laid down at 50 m intervals along a transect line at riparian, seasonal floodplain and upland habitat, respectively. The Shannon diversity index and evenness were 1.87 and 1.54 in the riparian habitat, 2.01 and 0.77 in the seasonal floodplain habitat, 0.71 and 0.80 in the upland habitat. The species richness was 22, 14 and 19 in riparian, seasonal floodplain and upland habitat, respectively. The patterns of population structures of the woody species revealed that 32% and 21% of the woody species recorded in riparian and upland habitat, respectively, had a “reverse J-shaped” distribution, indicating a healthy or good regeneration. Vachellia tortilis and Combretum imberbe showed healthy regeneration in both riparian and upland habitat. Healthy regeneration in these species was attributable to their adaptive and defence mechanisms to herbivory. Most of the woody species showed either hampered seedling recruitment or hampered regeneration as a result of anthropogenic disturbance and herbivory. Almost all of the woody species (86%) in the seasonal floodplain habitat exhibited relatively good seedling recruitment and discontinued regeneration in the subsequent middle and higher diameter classes, suggesting that flooding inhibited regeneration of woody species.

DISTRIBUTION OF INVASIVE SPECIES &lt;i&gt;PROSOPIS JULIFLORA&lt;/i&gt; (MIMOSACEAE) IN FUJAIRA (UAE)

The article analyzes the secondary area in the Emirate of Fujairah, as well as the peculiarities of seed dispersing, seed germination and early seedling development of Mesquite, or Prosopis juliflora - the alien species of Mimosaceae, which appeared on the territory of the Emirates in the twentieth century, and one of the first collected herbarium specimen is dated 1983. In the secondary area most often, the Mesquite is found in anthropogenic habitats: in gardens, as well as near roads, on waste grounds, less frequent on the streets of settlements, garden fences etc. In regions represented by herbarium collections, P. juliflora is successfully naturalized and creates stable self-sustaining populations. It has a complex of specific helio-mesomorphic features that allow it to take root successfully in relatively open moderately wet, and even dry or saline habitats and compete with native species of acacia ( Acacia tortilis, A. ehrenbergii ) and local prosopis ( P. cineraria ). Characteristics such as good germination, significant morphological, dimensional and temporal variability of premature individuals of P. juliflora , identified in this work, undoubtedly contribute to the successful naturalization of the species in the secondary range and its wide distribution throughout the Emirate. Due to the high aggressiveness of Mesquite, it is necessary to develop a method of dealing with this plant in the UAE, which will stop its uncontrolled settlement in the region. We have compiled a map of Mesquite distribution in Fujairah and surrounding areas, which clearly shows the scale of the disaster. A method for assessing invasion on a five-level scale based on reproductive success has been developed and applied. The structure of ecotopes at an early and middle stage of penetration of P. juliflora was analyzed using large wastelands (2 and 1.2 ha) in the village Mirbah and the city of Fujairah on the coast of the Gulf of Oman.

Discrimination of Samar and Talh honey produced in the Gulf Cooperation Council (GCC) region using multivariate data analysis

Lately, ensuring clear discrimination of the authenticity of natural honey is a concern not only to consumers but also to producers, traders and industries. The intrinsically simple nature of the honey composition, the distinguished health benefits as well as the high price make adulteration and falsification of the honey very common and the detection of authenticity very difficult. Samar honey (n = 59) and Talh honey (n = 64) produced from two species of Acacia trees (Acacia tortilis and Acacia gerrardii Benth, respectively) in different countries, including the United Arab Emirates, Saudi Arabia, Oman, and Yemen, has been studied by applying Multivariate Data Analysis. The discrimination is based on the official chemical quality parameters that inform about the nectary sources, including glucose, fructose, sucrose content, total reducing sugar, moisture content, acidity and diastase activity. Results show that the total reducing sugar, glucose and fructose were the most important positive loading descriptors that influence the quality of Samar and Talh honey. In addition, most of the Talh honey samples clustered at the top of the hierarchy, while Samar honey samples clustered at the bottom. The Multivariate Data Analysis indicates that the acidity and diastase activity are the most effective characteristics influencing the floral and geographical discrimination of both types of honey. This is the first study in the GCC area to discriminate between Samar and Talh honey using Multivariate Data Analysis by applying the principal component analysis and hierarchical cluster analysis. The Multivariate Data Analysis can be a helpful method to differentiate between Talh and Samar honey.

Metallic nutrients in enset (Ensete Ventricosum) corm and soil sample from some West Shoa Zone, Oromia Regional State, Ethiopia

This study conducted during the season 2017 at ED-Duem Locality which is laid at Northern White Nile State of Sudan, the main objectives of this study was measurement, listing of all <em>acacia raddiana</em> tree sites their assessed the physical characteristics of the height, diameter at breast height and were account the abundance, dominance, and survival % of natural regeneration of <em>acacia raddiana</em> tree as the main species. The researcher used the systematic circular sampling plots methodology which established with total number of 130 sample plots. The sample plots were circular in shape with a radius of 17.84 m (0.1 ha in area.).

Effect of water stress on growth and dry matter distribution of four dryland species used in tree planting in the Sahel

AbstractWater stress is the most important factor limiting early survival and growth of seedlings in arid and semi-arid zones. Many woody species develop adaptive mechanisms in response to water stress. This study assesses survival rate, growth and dry matter distribution in response to water stress in four dryland species (Senegalia dudgeonii, Senegalia gourmaensis, Vachellia nilotica and Vachellia tortilis). A total of 240 seedlings (60 per species) were grown using a completely randomized block design with three replicates in each of three water treatments (control = 100 percent of field capacity; moderate water stress = 50 percent of field capacity; severe water stress = 25 percent of field capacity) with a 7 day watering frequency. Data were collected on seedling survival, height, collar diameter, leaf production and dry matter distribution. Survival rate of the four species was not affected by water stress. However, the morphological responses to water stress were significantly different between species. Water stress resulted in significant reductions in height and collar diameter, higher below-ground biomass and significant increase in shedding of leaves. Under water stress, S. dudgeonii, S. gourmaensis and V. tortilis invested more in root growth. The allocation pattern from above-ground to below-ground parts was found to be the main adaption to drought. In contrast, V. nilotica gave preference to above-ground development, which could be an indication that the seedlings are adapted to grow under severe water stress. The results confirm the interspecific genetic differences in growth and dry matter distribution among species. These variations in water stress response may be used as criteria for species selection for degraded land reforestation.

Ecological situation of acacia tortilis subspecies raddiana. Case study: In white nile state, Sudan

This study conducted during the season 2017 at ED-Duem Locality which is laid at Northern White Nile State of Sudan, the main objectives of this study was measurement, listing of all <em>acacia raddiana</em> tree sites their assessed the physical characteristics of the height, diameter at breast height and were account the abundance, dominance, and survival % of natural regeneration of <em>acacia raddiana</em> tree as the main species. The researcher used the systematic circular sampling plots methodology which established with total number of 130 sample plots. The sample plots were circular in shape with a radius of 17.84 m (0.1 ha in area.).

Abundance, distribution, and growth characteristics of three keystone Vachellia trees in Gebel Elba National Park, south-eastern Egypt

This study was conducted to evaluate the abundance and distribution pattern of three keystone Vachellia taxa in wadi Khoda and wadi Rahaba, Gebel Elba National Park, a protected area in south-eastern Egypt. These taxa included Vachellia tortilis subsp. tortilis, Vachellia tortilis subsp. raddiana, and Vachellia ehrenbergiana. In wadi Khoda, only two of these taxa were detected (V. tortilis subsp. raddiana and V. tortilis subsp. tortilis), while all three taxa were encountered in wadi Rahaba. The density of trees in wadi Khoda was 34.3 plant ha−1 compared to 26.3 plant ha−1 in wadi Rahaba. Vachellia tortilis subsp. raddiana was the most frequently observed tree, with an average of 47.93% and 68.25% in wadi Rahaba and wadi Khoda, respectively. Crown depth and tree height were mainly associated with elevation, indicating that elevation plays a key role in the growth of these Vachellia taxa. Our results suggest that human activities have had limited effect on the distribution of these three keystone taxa. Thus, management in Gebel Elba National Park should continue to limit the impact of human activities on these three keystone species.

Balancing Bees and Livestock: Pastoralist Knowledge, Perceptions and Implications for Pollinator Conservation in Rangelands, Northern Tanzania

Insect pollinators provide numerous ecosystem services that support other living organisms. While pollinators play a large role in cropping systems, little is known about their presence and function in rangeland ecosystems, which have recently become fragmented and overexploited at an extraordinary rate. We assessed local Maasai knowledge on insect pollinators and how pollinators affect livelihood diversification in Simanjiro rangelands, Tanzania. Through questionnaires, key informant interviews, focus group discussions, and field observations, we found varied insect knowledge among Maasai herders. Lasioglossum of sub genus Ipomalictus and Syriphidae were the least commonly recognized pollinators as only 24%, and 7% of participants could identify them, respectively. Responses varied significantly between men and women (F = 7.397, p = .007). Commiphora africana, Acacia mellifera and Albizia anthelmintica were noted as most important bee forage plants while observations showed Aspilia mossambicensis, Justicia debile and Acacia tortilis. Most (77%) of Maasai herders showed limited ability to link pollinators and rangeland wellbeing. Beekeeping contributed to livelihood diversification for 61% of respondents, with women participating more frequently than men (χ2 = 46.962, p = .0001). Beekeeping was positively influenced by education level ( R = .421, p &lt; .0001) and occupation ( R = .194, p = .009). Pollinator declines were attributed to climate change (47%), agriculture (37%), and habitat destruction (8%). We conclude that Maasai have limited knowledge of common pollinator groups and their roles. Community outreach and training should bridge the knowledge gap in pastoralist communities to fully realize pollinator benefits and highlight the importance of rangeland health.

The effects of land use and microsite availability on early seedling recruitment of Acacia tortilis (synonym: Vachelia tortilis) in a southern African savanna

Many tree recruitment studies in African savannas target individual factors that limit recruitment, yet recruitment of some species could be limited by an interplay of environmental filters. This study investigated the effects of land use and microsite availability on early seedling recruitment of Acacia tortilis in riverine woodlands in north-western Zimbabwe. The riverine woodlands were divided according to the level of human disturbance into protected and unprotected sites. Each site was further divided into riverine and off riverine microsites. In each microsite, we laid five main plots (100 × 50 m) and nine seedling subplots (5 × 5 m) nested in each main plot, making a total of 60 main plots and 180 subplots. We found higher seedling recruitment in unprotected than protected sites. Although seeder density was twice greater in protected than unprotected sites, seed bank density was lower in the former by a factor of 1.5. Tree cover and herbaceous biomass was 1.4 and 1.8 times greater in protected than unprotected sites, respectively but were negatively correlated with seedling density. Across all microsites, herbivory-related mortality was less than 40% while drought-related mortality was more than 60%. Put together, the results suggest that higher recruitment in unprotected sites was most likely facilitated by domestic ungulates through seed dispersal and grass suppression which enhanced the quality of regeneration sites. We conclude that encroachment of A. tortilis in communal grazing sites is not only important for its conservation but for a variety of goods and services derived from it.

Status and Properties of Soils under Some Woody Species of Degraded Glacis in Northern Burkina Faso

Land degradation is a threat to biodiversity and has negative impacts on agricultural communities by aggravating food insecurity. The objective of this study was to examine the responses of native woody species and soil variables to different levels of glacis degradation in the Sahelian zone of Burkina Faso. Field investigations were performed according to the degradation gradient outlined in the Braun-Blanquet method. Soil samples were collected and analyzed in the laboratory. The results indicate that the diversity and diametric structure of woody species are functions of the glacis degradation stage. A total of eight (08) woody species were recorded on the glacis (7 species in non-degraded glacis, 7 species in moderately-degraded glacis and only 1 species in degraded glacis). Acacia raddiana is the only local woody species present in all three glacis degradation stages. It is recommended to rehabilitate degraded glacis in the Sahel in response to desertification. The high levels of sand, nitrogen (N) and carbon (C) characterize the non-degraded and moderately-degraded glacis, whereas the high levels of silt, clay, bulk density, pH-H20 and pH-Kcl indicate degraded glacis. This study can inform the future rehabilitation and management of Sahelian glacis.

50 years of woody vegetation changes in the Ferlo (Senegal) assessed by high-resolution imagery and field surveys

Woody vegetation dynamics in the Sahel have been debated since the great droughts of the 1970s–1980s. Here, we combined high-resolution satellite and aerial imagery, field inventory, and historical botanical records to study woody vegetation trends over the years 1965, 1980, 2008, and 2018 in the Ferlo, the Sahelian sylvo-pastoral zone of Senegal. While tree density has decreased from 1965 (14.8 trees ha−1) to 1980 (13.4 trees ha−1) and 2008 (11.9 trees ha−1), tree density has stabilized in 2018 (12.2 trees ha−1). The relatively moderate decrease in tree density over 50 years characterized by extensive human pressure and droughts, as well as the rather stable woody cover following the drought years after the 1980s, do not support narratives of widespread desertification in this region. However, we observed a shift in the composition of species. While the drought-resistant tree Balanites aegyptiaca showed a stable abundance, Acacia tortilis showed strong increases and other species like Sclerocarya birrea and Combretum glutinosum decreased. In addition, recent field surveys show that the ratio between shrubs and trees has increased towards more shrubs. The observed loss of species diversity combined with the increase of drought-resistant species is in line with current observations for savanna ecosystems in the context of an increased aridity.

Unexpectedly low δ 13C in leaves, branches, stems and roots of three acacia species growing in hyper-arid environments

AbstractAimsIn plant eco-physiology, less negative (enriched) carbon 13 (13C) in the leaves indicates conditions of reducing leaf gas exchange through stomata, e.g. under drought. In addition, 13C is expected to be less negative in non-photosynthetic tissues as compared with leaves. However, these relationships in δ 13C from leaves (photosynthetic organs) to branches, stems and roots (non-photosynthetic organs) are rarely tested across multiple closely related tree species, multiple compartments, or in trees growing under extreme heat and drought.MethodsWe measured leaf-to-root 13C in three closely related desert acacia species (Acacia tortilis, A. raddiana and A. pachyceras). We measured δ 13C in leaf tissues from mature trees in southern Israel. In parallel, a 7-year irrigation experiment with 0.5, 1.0 or 4.0 L day−1 was conducted in an experimental orchard. At the end of the experiment, growth parameters and δ 13C were measured in leaves, branches, stems and roots.Important FindingsThe δ 13C in leaf tissues sampled from mature trees was ca. −27‰, far more depleted than expected from a desert tree growing in one of the Earth’s driest and hottest environments. Across acacia species and compartments, δ 13C was not enriched at all irrigation levels (−28‰ to ca. −27‰), confirming our measurements in the mature trees. Among compartments, leaf δ 13C was unexpectedly similar to branch and root δ 13C, and surprisingly, even less negative than stem δ 13C. The highly depleted leaf δ 13C suggests that these trees have high stomatal gas exchange, despite growing in extremely dry habitats. The lack of δ 13C enrichment in non-photosynthetic tissues might be related to the seasonal coupling of growth of leaves and heterotrophic tissues.

Factors influencing use of multipurpose trees and shrubs in arid and semiarid lands of Kenya

Multipurpose trees and shrubs are vital components of arid and semiarid ecosystems. They offer both regulatory and production services, yet there is inadequate information on their actual use and factors affecting utilization of these plant resources. A study was carried out in three agroecological zones (counties) of southeastern Kenya: Machakos (subhumid zone), Kajiado (semiarid zone), and Kitui (arid zone). The research objective was to assess the local uses of multipurpose trees and shrubs and determine how socioeconomic factors (gender, type of occupation, and education level) influenced their use. A field survey was conducted along a 324-km transect across the three agroecological zones. Data were collected from 196 respondents using focus group discussions, key informants, and individual household questionnaires. A total of 86 plant species belonging to 47 plant families were recorded. The Mann-Whitney U-test revealed that women significantly used a higher number of different plant species than men (P < 0.05). The level of education and type of occupation also significantly affected plant use (P < 0.05), with subsistence farmers having primary or no formal education, reporting the highest number of species. Fifteen plant-use categories comprising production and service provision were identified. Plant species use-value index (UVI) revealed 10 indigenous and wild woody species of high value in the study area. Acacia tortilis (Forssk.) Hayne had the highest UVI of 0.33, followed by Commiphora africana (A. Rich.) Engl. (0.17), Terminalia brownii Fres. (0.13), and Zanthoxylum chalybeum Engl. (0.12). There was a significant positive correlation between the reporting frequency for woody species and the overall UVI (P < 0.05). Economic development, climate change, and land use changes jeopardize distribution, utilization, and knowledge preservation of multipurpose woody species. There is a need for monitoring and adoption of gender-sensitive strategies for their sustainable utilization in order to safeguard these unique plant resources from degradation and overexploitation.

The Impact of Terrestrial Oil Pollution on Parasitoid Wasps Associated With Vachellia (Fabales: Fabaceae) Trees in a Desert Ecosystem, Israel.

Oil is a major pollutant of the environment, and terrestrial oil spills frequently occur in desert areas. Although arthropods account for a large share of animal diversity, the effect of oil pollution on this group is rarely documented. We evaluated the effects of oil pollution on parasitoid wasps associated with Vachellia (formerly Acacia) tortilis (Forssk.) and Vachellia raddiana (Savi) trees in a hyper-arid desert that was affected by two major oil spills (in 1975 and 2014). We sampled the parasitoid populations between 2016 and 2018 in three sampling sites and compared their abundance, diversity, and community composition between oil-polluted and unpolluted trees. Parasitoid abundance in oil-polluted trees was lower in one of the sites affected by the recent oil spill, but not in the site affected by the 1975 oil spill. Oil-polluted trees supported lower parasitoid diversity than unpolluted trees in some sampling site/year combinations; however, such negative effects were inconsistent and pollution explained a small proportion of the variation in parasitoid community composition. Our results indicate that oil pollution may negatively affect parasitoid abundances and diversity, although the magnitude of the effect depends on the tree species, sampling site, and the time since the oil spill.

Investigation of the mechanical properties of Acacia tortilis fiber reinforced natural composite

The work presented in this paper is motivated by the fact that use of natural fiber materials for structural and non-structural applications have increased within the last two decades. In addition to the known benefits of composite materials as structural elements such as high specific modulus, high specific strength and low thermal conductivity, composites of natural fibers are eco-friendly materials and have minimum effect on environment and human health. However, the mechanical and structural performance of diverse natural fiber composites still need closer scrutiny. The objective of this study is to characterize the mechanical properties of a novel Acacia tortilis fiber reinforced polyester composite using experimental methods. In particular, the study focuses on determining the tensile and flexural properties of the composite at different fiber volume ratio, which was fabricated by hand lay-up methods. The results show that Acacia tortilis fiber reinforced polyester composites have generally competitive strength and Young’s modulus compared with common natural fiber reinforced composites such as sisal, kenaf, coir natural fiber reinforced composite materials. In addition, NaOH treated samples exhibited higher strength and Young’s modulus compared with their untreated counterparts, with few exceptions.