Semi-arid Lands Research Articles

Spatial and Temporal Occurrence and Effects of Droughts on Crop Yields in Kenya

Increase in drought frequency, magnitude and duration affect crop production in Kenya. The limited food production resulting from drought leads to food insecurity in Arid and Semi-Arid Lands (ASALs) in the Kenya. This study reviewed literature on drought trends and its effects on crop yields in Kenya from 1950 to 2020. The systematic review was conducted in order to establish the drought trends and the effects of droughts on crop yields in the country. Content analysis was used for literature review on drought trends and its effects on maize, sorghum and wheat production in Kenya. From the study, a high uncertainty in global-scale drought trends in the last 60 years was established. However, an increase in drought frequency was observed from 1950 to 2002 in Africa. Few drought events were experienced in 1950s with a notable positive trend in drought frequency observed in 1960s in Kenya. In 1970s, an increased frequency and severity of droughts were observed while a decline in drought frequency was noted in 1980s. More frequent and severe droughts in Kenya were also established to have occurred in 1990s and 2000s. However, a decline in drought frequency and severity was reported in 2010s. The severity of the droughts negatively affected crop production where food insecurity was experienced in different regions of the country. The study also found that drought leads to famine and loss of human lives. Loss of livelihood such as livestock was also identified. The study identified limited information on decadal causes and recurrence of droughts and inadequate explanation on why 1950 to 2020 experienced global uncertainty in drought occurrence.

Effect of encroaching woody plant species on soil nutrients and selected soil chemical properties in communally managed semiarid savanna grazing lands in the North West province, South Africa

Woody plant encroachment is recognised as one of the major threats to biodiversity in ecosystems. In many arid and semiarid areas of South Africa, indigenous encroacher species are proliferating, but the factors that favor their abundance are poorly understood. This study investigated the effect of encroaching woody species on soil properties. The effects of two encroaching species, Senegalia mellifera and Dichrostachys cinerea, on soil nutrients and chemical properties were investigated in 8 communally managed grazing sites and compared to the effects of the non-encroacher, Vachellia karroo, in two non-encroached benchmark sites. Three belt transects were laid out to determine woody plant density. Three soil samples (0-20 cm deep) per belt were sampled to determine soil properties. Senegalia mellifera was the most abundant with a mean density of 5907 TE ha−1. Soil properties in the benchmark sites had no significant differences (p > 0.05) than soil under encroaching D. cinerea regarding organic C, total N, C:N, exchangeable Na, CEC, EC, ESP, SAR and soil texture. Plant influence on soil differed among encroaching species and between encroaching and non-encroaching species. Plant diversity explain the variation of soil properties and prove the important specific role of each species in the ecosystem.

Changes in soil organic carbon across an atmospheric CO2 gradient under natural and artificial vegetation of semi-arid lands

Soil organic carbon (SOC) was studied across a gradient of 400–550 ppm CO2 in calcareous contaminated semi-arid areas. An experiment was performed under natural and artificial vegetation cover of Atriplex canescens (Pursh) Nutt. SOC and vegetation cover were investigated every 2 years from 2012 to 2018. Findings disclosed that there was a polynomial relation between SOC and CO2 concentration. The SOC change rate had the highest positive relationship with CO2 concentration in the uppermost 20 cm of soil: R2 = 0.96 and 0.47 in plantation and control areas, respectively. Moreover, plant life forms had a significant effect on the SOC in CO2 contaminated areas (P < 0.01). The highest correlation (R2 = 0.93–0.99) was observed between SOC rate changes and perennial cover percentage at a depth of 0–20 and 20–40 cm, respectively, through the time.

Hydrogel as a soil conditioner affecting the growth, yield, and fruit quality of ‘Murcott’ mandarin trees under arid and semi-arid lands

‘Murcott’ mandarin fruits are suffering from sunburn injury in arid and semi-arid lands. In this regard, hydrogel represents a promising approach in the citrus industry, since it improves growth, yield, andfruit quality under abiotic stress. This investigation aims to study the effect of adding of hydrogel (as soil conditioner) with or without water regime on growth and yield of ‘Murcott’ mandarin trees budded on Volkamer lemon rootstock grown in sandy soil. The experimental farm location belongs to arid and semi-arid lands. The treatments were as follows 1: control (100 %) of crop evapotranspiration (Etc), 2: 75% of Etc, 3: 75% of Etc+250 g of hydrogel / tree, 4: 75% of Etc+500 g of hydrogel/tree and 5:75% of Etc+750 g of hydrogel/tree. The results indicated that all applications of hydrogel composite significantly improved vegetative growth, yield, and fruit quality characteristics of ‘Murcott’ mandarin trees compared to the control. Regarding the vegetative growth, hydrogel at 750 g/tree under 75% of Etc had the optimal values of vegetative growth parameters such as leaf area, shoot length, and tree canopy volume compared to all the other treatments. A similar trend was noticed regarding yield and fruit quality, as the best values were obtained when the hydrogel was used at 750 g /tree under 75% of Etc. In conclusion, the application of hydrogel agent can improve the productionand fruit quality of ‘Murcott’ mandarin trees in arid and semi-arid lands.

Assessment of Climate Change Related Disasters in Arid and Semi-Arid Lands. A Case of Baringo County, Kenya

The main objective of this study was to identify Climate Change Related Disasters (CCRDs) in Arid and Semi-arid Lands such as Baringo County. The study used a descriptive survey design. Purposeful sampling and stratified proportionate random sampling procedures were used to obtain the Sample. A sample of 376 households were selected for the study in Baringo County. Questionnaire, key informant interview schedule and observations were the main instruments of data collection. Analysis of data was done using the SPSS. Percentages were used to analyse CCRDs. Drought, storms and floods are climate change related disasters affecting Baringo County. About 80 percent of the households strongly agreed that drought is the most common disasters affecting the County. Vegetation clearance is the main cause of CCRDs in Baringo County hence there is need to increase awareness on climate change and encourage people to use alternative sources of energy and plant trees.

Climate resilience building in Semi-Arid Lands (SALs): institutional weaknesses and strengths in subnational governments in Brazil

Well established institutions are an essential factor for the successful realization of sustainable socio-economic and environmental potential in Semi-Arid Lands (SALs). SALs receive limited attention in international climate research and policies; thus, the institutional relationship between governance, policy, and implementation continues to suffer from inconsistencies across governance levels. This research carried out an analysis combining mixed-research methods to collect, record, and analyze data and information regarding institutional and organizational strengths, weaknesses, opportunities, and threats, and local level policy implementation challenges and scope to assess the effectiveness of Disaster Risk Management (DRM) and implementation of adaptation policies at State and local levels in SALs. The inefficiencies observed in the DRM/CCA adaptation processes are concentrated in areas of high governance of state and municipal governments and stem from local communities' reduced organizational and technical capacity. It results in the negligent application of measures and resources to address climate risks. Therefore, this paper contributes to the increasing understanding of the institutional framework's role in the facilitation of local adaptation, revealing what seems to be working well, what is not, how things could improve in Brazilian SALs.

Effects of Nitrogen Addition and Reproductive Effort on Nutrient Resorption of a Sand-Fixing Shrub.

Caragana microphylla is a sand-fixing leguminous shrub with strong resistance to drought, cold, and low soil fertility. As a result, it plays an essential role in combating desertification in northern China, but little is known about its nutrient budget. Nutrient resorption is a key process in plant nutrient conservation and has marked ecological implications for plant fitness and ecosystem nutrient cycling. We studied the effects of both nitrogen (N) addition and reproductive effort on leaf N resorption of C. microphylla in a temperate semi-arid sandy land in China. The results showed that sprouting of the early leaves from over-wintered buds employs a strategy for slow returns on nutrient investment with smaller specific leaf area (SLA) and higher N resorption efficiency, whereas the late leaves, which sprout from current-year buds, employ a strategy for quick returns on nutrient investment with higher SLA and lower N resorption efficiency. N addition significantly increased the N resorption efficiency from early leaves while exerting no impact on late leaves, suggesting that the increased N recovery from early leaves is done to sustain the high N demands of late leaves. Reproductive effort did not affect the N resorption from early or late leaves due to the temporal separation between fruit production and leaf senescence. Taken together, our results demonstrate that C. microphylla has evolved different investment strategies for leaf N in early and late leaves to conserve nutrients and facilitate its growth in desertified environments.

Application of Soil Fertility Capability Classification (FCC) in Dry Semi Arid Land of South Telangana Plateau, Andhra Pradesh

ABSTRACT Soil fertility capability classification (FCC) is a system of representing soils with a set of physical and chemical properties particularly fertility-related constraints of topsoil as well as sub-soil as which directly influences plant growth and production. An investigation was undertaken to study the soils in detail in a 1:10000 scale survey. Soils were classified into 10 series and 53 mapping units as per soil taxonomy based on morphological, physical, and chemical properties. Soil fertility capability classification was applied to all the identified soils from different land-use systems of the south Telangana plateau. The major soil constraints identified through condition modifiers in the descending order were dry soil moisture (d: 100%), gravelliness (>35%) (r++: 51.68%), low K reserve (k: 34.07%), basic reaction (b: 32.58%), low organic carbon content (m: 24.05%), acidity (h: 23.01%), low cation exchange capacity (e: 16.81%), and gravelliness (10–35%) (r+: 13.48%). The limitations identified in specific landform and land use through condition modifiers help to combat the deterioration of land quality and also helps to implement suitable land management practices for elevated production and productivity apart from reducing land degradation and erosion besides.

New measures of deep soil water recharge during the vegetation restoration process in semi-arid regions of northern China

Abstract. Desertification in semi-arid regions is currently a global environmental and societal problem. This research attempts to understand whether a 40-year-old rain-fed Artemisia sphaerocephala Krasch sand-fixing land as part of the Three North Shelterbelt Program (3NSP) of China can be developed sustainably or not using a newly designed lysimeter to monitor the precipitation-induced deep soil recharge (DSR) at 220 cm of depth. Evapotranspiration is calculated through a water balance equation when precipitation and soil moisture data are collected. A comparison of soil particle sizes and soil moisture distributions in artificial sand-fixing land and neighboring bare land is made to assess the impact of sand-fixing reforestation. Results show that such a sand-fixing reforestation results in a root system being mainly developed in the horizontal direction and a changed soil particle distribution. Specifically, the sandy soil with 50.53 % medium sand has been transformed into a sandy soil with 68.53 % fine sand. Within the Artemisia sphaerocephala Krasch sand-fixing experimental area, the DSR values in the bare sand plot and Artemisia sphaerocephala Krasch plot are respectively 283.6 and 90.6 mm in wet years, reflecting a difference of more than 3 times. The deep soil layer moisture in semi-arid sandy land is largely replenished by precipitation-induced infiltration. The DSR values of the bare sandy land plot and Artemisia sphaerocephala Krasch plot are respectively 51.6 and 2 mm in dry years, a difference of more than 25 times. The proportions of DSR reduced by Artemisia sphaerocephala Krasch are 68.06 % and 96.12 % in wet and dry years, respectively. This research shows that Artemisia sphaerocephala Krasch in semi-arid regions can continue to grow and has the capacity to fix sand. It consumes a large amount of precipitated water and reduces the amount of DSR considerably.

Quantifying the influences of land surface parameters on LST variations based on GeoDetector model in Syr Darya Basin, Central Asia

Spatiotemporal variability in the land surface energy flux is largely and comprehensively affected by many factors, including land surface temperature (LST), land coverage, soil characteristics, terrain conditions, etc. In contrast with other climatic zones, arid and semiarid lands have fragile ecological environments that are more sensitive to land surface energy flux changes. In this study, we used MODerate Resolution Imaging Spectroradiometer (MODIS) LST products (2001–2015) for air temperature comparisons. Then, we investigated the spatiotemporal variation in LSTs in the Syr Darya Basin (SDB) during 2001–2015. More specifically, a new statistical model known as GeoDetector was adopted to analyze the driving factors controlling the spatiotemporal variation in LSTs. The result shows that the MODIS LST can provide a good estimation of air temperature, especially at night. The LST change rate can be considered as an important indicator of climate change (rapid warming at high altitudes) and human activities (increased water consumption of crop). Based on the GeoDetector model, we determined that the elevation explained more of the LST distribution (84–90%) and spatiotemporal variation (22–26%) than any other land surface parameters. The combination of albedo and the other explanatory variables can significantly increase the explanatory power of each single factor, especially with elevation.

Indirect Effects of Grazing on Wind-Dispersed Elm Seeds in Sparse Woodlands of Northern China

Grazing leads to the reduction of biomass and plays a critical role in land degradation in arid and semiarid lands. However, the indirect effects of grazing on the ecosystem, e.g., the effect on seed dispersal, have not been well understood. In this study, we built an agent-based model (ABM) to simulate how grazing intensity affects the seed dispersal of elm trees, one of the native vegetation species of temperate woodlands in semiarid lands. The simulated results from the ABM and observed data from the real world were compared to assess the accuracy and validity of the ABM. The results show that elm seed densities in non-grazing, light, moderate, and heavy grazing lands were 74.97 ± 1.44, 57.63 ± 0.89, 37.73 ± 0.95, and 0.97 ± 0.05 seeds m−2, respectively—an apparently decreasing trend. Moreover, as grazing intensity increased, the values of nugget, sill, and partial sill decreased and the value of the ratio of nugget to sill increased. This study indicates that the grazing indirectly leads to the reduction of elm seed density and the increase of spatial heterogeneity of elm seed on the ground in sparse elm woodlands. Moreover, values of geostatistical indices from the ABM were not significantly different from field observation data except for the ratio of nugget to sill. It shows that ABMs can reasonably replicate the spatial pattern of elm seed densities in the field and thus are useful for simulating long-distance seed dispersal in sandy lands. This finding suggests that the indirect effects of grazing should be considered to effectively protect sparse elm woodlands.

Sustainable livelihood approach for assessing the impacts of slaughterhouses on livelihood strategies among pastoralists in Kenya

The social, physical, financial, natural, and human dimensions within slaughterhouses have taken a central position in diversifying livelihoods among pastoralists in the arid and semi-arid lands (ASALs) in Kenya. There is a need to expound on the literature about these dimensions and assess how they impact on livelihood strategies and outcomes. This research aimed to bring out how these dimensions impact livelihood strategies among Kenyan pastoralists using the sustainable livelihood approach. Qualitative data was collected from four counties in Kenya’s ASALs predominantly inhabited by pastoralists, using focus group discussions, and narratives Observations were analysed using the RQDA package within the R statistical computing environment. The results revealed increasingly diversified social-economic activities, value addition of slaughter by-products, better rangeland management, and diversified diets. Gender, age, and roles significantly (P < 0.01) influenced the extent of diversification. Diversified social-economic activities and value addition directly impacted food security through increased utilization of slaughter by-products, provision of an alternative livelihood source, and better resilience during calamities. To conclude, social, economic, and human activities were central in diversified and advanced pastoral livelihoods.

EFFECT OF MICROFINANCE SERVICES ON FINANCIAL INCLUSION IN ARID AND SEMI-ARID LANDS IN KENYA

Micro-Finance Institutions (MFIs) have been known to offer various financial services that include savings mobilization, micro-credits, money transfers and financial education to its clients which are important to financial inclusion. However, there is uncertainty over the effect of microfinance services on financial inclusion in Arid and Semi-arid lands in Kenya such as Baringo County where currently 14 MFIs are operating. The objectives of this study, therefore, were to determine the effect of savings products and lending services provided by microfinance institutions on financial inclusion in Baringo County grounded on the Financial Intermediation theory. The study adopted descriptive research study method targeting 14 microfinance institutions operating in the area from which the accessible population was 476 individuals comprising 56 MFIs managers and credit officers and 420 clients of the MFIs. A total sample size of 254 respondents was used. Data was collected using pretested structured questionnaires and was analyzed using both descriptive and inferential statistics. The findings revealed that both savings products and lending services significantly affected financial inclusion in the area with lending services having a more significant effect than savings products. Cumulative savings were the most important assessment tools for loans qualification compared to guarantors and ability to pay. Low access to savings impeded savings mobilization. most of the loans were processed within one month. Majority of the microfinance institutions offered standardized products and services. All the microfinance institutions respondents indicated that the considered client’s ability to pay and a considerable percentage indicated to consider cumulative savings and guarantors when awarding loans. A significance level of 95% (α=0.05) was used in the analysis of the effect of microfinance institutions services on financial inclusion. The probability values for the variables; lending services, savings products, payment services and financial education were 0.037, 0.000, 0.016 and 0.024 respectively. The probability values of the independent variable were less than α=0.05 thus implies that the predictor variables were significant to influence financial inclusion.

Applying Multi-Index approach from Sentinel-2 Imagery to Extract Urban Area in dry season (Semi-Arid Land in North East Algeria)

&lt;p&gt;The mapping of urban areas mostly presents a big difficulty, particularly, in arid and semi-arid environments. For that reason, in this research, we expect to increase built up accuracy mapping for Bordj Bou Arreridj city in semi-arid regions (North-East Algeria) by focusing on the identification of appropriate combination of the remotely sensed spectral indices. The study applies the ‘k–means’ classifier. In this regard, four spectral indexes were selected, namely normalized difference tillage index (NDTI) for built-up, and both bare soil index (BSI) and dry bare-soil index (DBSI), which are related to bare soil, as well as the normalized difference vegetation index (NDVI). All previous spectral indices mentioned were derived from Sentinel-2 data acquired during the dry season. Two combinations of them were generated using layer stack process, keeping both of NDTI and NDVI index constant in both combinations so that the multi-index NDTI/BSI/NDVI was the first single dataset combination, and the multi-index NDTI/DBSI/NDVI as the second component. The results show that BSI index works better with NDTI index compared to the use of DBSI index. Therefore, BSI index provides improvements: bare soil classes and built-up were better discriminated, where the overall accuracy increased by 5.67% and the kappa coefficient increased by 12.05%. The use of k-means as unsupervised classifier provides an automatic and a rapid urban area detection. Therefore, the multi-index dataset NDTI/ BSI / NDVI was suitable for mapping the cities in dry climate, and could provide a better urban management and future remote sensing applications in semi-arid areas particularly.&lt;/p&gt;

Adoption of water harvesting technologies among agro-pastoralists in semi-arid rangelands of South Eastern Kenya

BackgroundThe arid and semi-arid lands experience inherently unpredictable rainfall and frequent droughts, which are exacerbated by climate change. This consequently leads to deterioration of land resources, and eventually forage and water shortages that negatively impact livestock productivity. In Kenya, development and government agencies have been supporting on-farm adaptation strategies such as water harvesting conservation structures to cope with climate hazards that affect agricultural production and food security in agro-pastoral and pastoral systems. The various water harvesting structures that have been promoted include Zai pits for growing crops and trees, water pans and shallow wells for livestock and domestic use, as well as for irrigation. However, the impact of such interventions with regard to improvement of range productivity and therefore welfare of agro-pastoral and pastoral communities has not been felt owing to low adoption rate by households.ResultsThis study determined social, economic and institutional factors influencing the adoption of water harvesting technologies by households in pastoral areas of Tana river County of Kenya. The data was collected through household survey, focus group discussions and key informant interviews. The results show that access to extension services and training, level of monthly income, main source of livelihood, land tenure, membership in social groups and availability of active farm labor significantly influenced the adoption of water harvesting structures.ConclusionPastoralists therefore need to be mobilized and trained on how to construct and use water harvesting structures and sensitized on the potential socioeconomic benefits of adopting them.

Plants of the same place do not have the same metabolic pace: soil properties affect differently essential oil yields of plants growing wild in semiarid Mediterranean lands

The chemical composition and structure of the soil strongly affect the growth and development of plants. Ecophysiologically, the effects of soil are translated in changes in plant primary and secondary metabolism. Among the secondary metabolites of plants affected by soil properties are essential oils. In this work, we resume our study on the effect of soil properties on the accumulation of essential oils in two spontaneous plants growing in Algerian semiarid region: Rosmarinus officinalis L. and Thymus algeriensis Boiss & Reut. after studying the effect of climate on these plants in the same period (2010–2014) and at the same collection site in our previous study. The results showed significant differences (P < 0.001) between the oil contents during the period of the study in both plants. The yield of oils was significantly affected by the soil parameters. The pH, total calcium carbonate (CCE), active calcium carbonate (ACCE), and N:P ratio exhibited significant positive correlation (P < 0.001 and P < 0.05) with Rosmarinus officinalis essential oil amount contrary to total nitrogen and salinity that had negative effects. Regarding Thymus algeriensis, the pH, salinity, and N:P ratio had a significant positive effect (P < 0.001) on the content of essential oil. However, CCE, ACCE, and carbon exerted negative effects on oil amount.

Spatial distribution of root systems of Pinus sylvestris var. mongolica trees with different ages in a semi-arid sandy region of Northeast China

Mongolian pine (Pinus sylvestris var. mongolica), the most important tree species for sand fixation in semi-arid sandy lands, experiences dieback in plantations after approximately 35–40 years since planting. Water limitation was considered as an important cause for the dieback. The spatial distribution of root systems plays a key role in determining water resources used by trees. However, it is still unknown for the spatial distribution of Mongolian pine trees with different ages, which constrains our understanding of the mechanism underlying the dieback and management of Mongolian pine plantations. Horizontal and vertical distributions of coarse roots [root diameter (RD) ≥ 5 mm] of Mongolian pine trees with 10, 20, 30, 40, 50 years old were estimated by ground-penetrating radar. Meanwhile, the distributions of fine roots (RD ≤ 2 mm) were simultaneously measured using soil coring method. Results showed that the horizontal distance of coarse roots from trees increased with tree ages up to 30–40 years, i.e., 3.0–4.0 m for 10- and 20-year-old trees, ca. 6.1 m for 30- and 40-year-old trees; but merely 4.85 m for 50-year-old trees. The fine root densities kept relatively even within 4.0 m from the trees for 10- and 20- year-old trees (ca. 0.02 mg cm−3), whereas, they decreased sharply with increasing of distances from the trees for 30-, 40- and 50-year-old trees (0.015–0.025 mg cm−3 at 1.0 m from trees to ca. 0.00 mg cm−3 at 5.0 or 6.0 m from trees). In the vertical direction, the rooting depth, at which 95% of roots located, was 83.5, 99.9, 123.6, 105.2 and 125.9 cm for the coarse roots of 10-, 20-, 30-, 40- and 50-year-old trees, respectively, whereas it was 140.6, 152.2, 135.5, 144.2 and 127.0 cm for fine roots, respectively. These findings indicated that the spatial distribution of roots of Mongolian pine trees shrank for the 50-year old trees, possibly due to being close to mature stage in plantation sites. Based on spatial distribution of roots, we suggested that the stand densities should be determined according to the area occupied by tree root systems in order to avoid the dieback or mortality due to water competition, i.e., 403–515, 321–402, 217–290, 139–179 trees ha−1 for 10-, 20-, 30- and 40-year-old trees, respectively (none for 50-year-old plantations as they were close to mature stage). Our findings provide new insights into stand density optimization of plantations from tree belowground competition for water in semi-arid and arid sandy regions.

Demography of baobab (Adansonia digitata L.) population in different land uses in the semi-arid areas of Tanzania

Baobab is a deciduous non-timber tree species that are facing severe threats from both anthropogenic and climatic pressures across its range states. This study assessed natural rates of recruitment and associated threats of baobabs within and across different land-use types in semi-arid areas of Tanzania. The study was based on a stratified random sampling design composed of the following land-use types: strictly protected areas, non-strictly protected areas, and unprotected areas. Rates of recruitment were measured from a total of 337 grids (representing 40% of semi-arid land) in three different land-use types in a plot measuring 1 km long and 50 m wide. Results show that juvenile, sub-adult and adult baobab populations varied significantly (p < 0.001) within and across land-use types with only 4.7% of surveyed plots having a few juveniles (about four stems per plot) across the study area. The density of adult, sub-adult and juvenile populations were 1.53 ± 0.105, 0.82 ± 0.149 and 0.33 ± 0.253 plants/ha respectively with strictly protected areas (national parks) supporting the most abundant (53%) of the adult trees. Furthermore, the results show inverse J-shaped and bell-shaped distribution in the strictly protected areas and unprotected areas, respectively. The densities of mature baobabs were found to be higher than juvenile baobabs in all three land-use types. The number of baobabs damaged was higher than undamaged in all land-use types. Our results suggest that anthropogenic threats are higher than biophysical factors in driving the species to mortality and population extirpation. Likely, baobab size and distribution across land-use types are mostly influenced by herbivory and fire that likely limit the establishment in most of these areas. Strategies promoting the recruitment and sustainable harvesting practices of baobab would perhaps be the best options to support the population persistence in different land uses in semi-arid areas. The study recommends more studies to understand the factors affecting germination and recruitment rates in order to predict future distributions in semi-arid environments. Also in defining and planning for different land-use system, baobab species should be taken into consideration and in particular in agroforestry farms can easily qualify as a tree crop. Promotion of active recruitment through planting especially in communal lands and protection from herbivory is required if we are to overcome the recruitment bottlenecks as influenced by increasing impacts of land use and climate change and overexploitation. The intentional growing of trees and shrubs in combination with crops cultivation and forage production is also recommended to smallholder farmers.

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.

Susceptibilidade a desertificação para o estado de Pernambuco

A desertificação tem sido considerada um dos mais graves problemas ambientais da atualidade. Os efeitos de tal processo atingem a ordem política, econômica, social, cultural e ambiental. Para tanto, uma das formas mais úteis e aplicadas para estudos de verificação susceptibilidade a desertificação é através do cálculo do Índice de Aridez (IA), visto que é o único que utiliza variáveis quantitativas para esta análise. A aridez é a característica do clima que relaciona a insuficiência de precipitação adequada para manter uma vegetação, onde o grau de aridez de certa região depende da quantidade de água proveniente da precipitação e da perda máxima possível de água através da evaporação e transpiração, ou evapotranspiração. Portanto, este trabalho tem como objetivo obter a distribuição espacial do índice de aridez para o Estado de Pernambuco, com o auxílio de sistema de informação geográfica, visando a identificação de áreas que apresentam uma maior susceptibilidade à ocorrência da desertificação.