Tropical drylands are characterized by extreme environmental conditions that, coupled with anthropogenic habitat degradation, can limit the occurrence of native species. Species that are most sensitive to these pressures may be prone to disappear in the context of climate change. In this study, we evaluated the influence of environmental and anthropogenic variables on the occurrence of large mammals and birds at the Tatacoa Desert, an arid region in central Colombia. We tested the relationship between the magnitude of the species’ responses to environmental, human-related variables and to body mass, and percentage of carnivory. Overall, we found a positive association between forest cover and the occupancy of the largest mammals (> 8kg), negative associations between solar radiation and human footprint with individual species occupancy, and a positive association of species occupancy with distance to touristic sites. Our results suggest that the largest and/or more carnivore species may be affected positively by forest cover and negatively by intense solar radiation highlighting the consequences of the increasing process of desertification on large mammals and birds at the upper Magdalena River basin of Colombia under the current scenario of global climate change.

Iron (Fe) is an essential element for all organisms. Fe deficiency can limit plant production and cause anaemia in humans. The improvement of Fe homoeostasis could resolve both problems. Fe homoeostasis in Aegilops tauschii, the D genome donor of bread wheat, is not fully understood. Here, we analysed physiological traits in 42 accessions of Ae. tauschii associated with Fe homoeostasis, i.e. mugineic acid family phytosiderophores (MAs), phenylamides, SPAD values and metal concentrations. All traits showed diversity, suggesting the presence of candidate genes in the Ae. tauschii accessions, which could improve Fe homoeostasis in bread wheat. All accessions mainly produced and secreted mainly 2′-deoxymugineic acid among MAs, but eight of them secreted unknown products from their roots under Fe deficiency. It was revealed that 15 kinds of phenylamides and 2 kinds of bread wheat phytoalexins were produced in Fe-deficient roots of Ae. tauschii. Multivariate and principal component analyses showed that chlorophyll content was correlated with shoot Fe concentration. Genome-wide association study analysis associated several genomic markers with the variations in each trait analysed. Our results suggest that Ae. tauschii has alleles that could improve Fe homoeostasis to generate Fe-deficiency-tolerant or Fe-biofortified bread wheat.

Buffelgrass [Pennisetum ciliare (L.) Link] is a drought-tolerant invasive grass that is a threat to native biodiversity in the drylands of the Americas and Australia. Despite efforts from land managers to control P. ciliare, management approaches tend to have mixed success, treatment results can be poorly communicated among entities, and there are few long-term controlled studies. In this literature review, we synthesize data from both peer-reviewed and “gray” literature on the efficacy of management techniques to control P. ciliare and the secondary impacts to native plant communities. Our search resulted in 42 unique sources containing a total of 229 studies that we categorized into 10 treatment types, which included herbicide, seeding, manual removal, fire, grazing, biocontrol, fire + additional treatments, manual removal + additional treatments, herbicide + additional treatments, and herbicide + manual removal. We found that treatments that used multiple techniques in tandem along with follow-up treatments were the most effective at controlling P. ciliare. Fewer than one-third of the studies reported impacts of management on native species, and the most commonly studied treatment (herbicide, N = 130) showed detrimental impacts on native plant communities. However, the average time between treatment and outcome measurement was only 15 mo; we suggest the need for more long-term studies of treatment efficacy and secondary impacts of treatment on the ecosystem. Finally, we conducted a second literature review on P. ciliare biology and traits for mechanisms that allows P. ciliare to alter the invaded environment to facilitate a competitive advantage over native species. We found evidence of self-reinforcing feedbacks of invasion being generated by P. ciliare through its interactions with water availability, nutrient cycling, and disturbance regimes. We developed a conceptual model of P. ciliare based on these feedback loops and offer management considerations based on its invasion dynamics and biology.

Morphophysiological dormancy (MPD) is predominantly found in seeds of temperate regions and is uncommon in arid biomes. MPD has been reported in a number of Hibbertia (Dilleniaceae) species of temperate Australia, and in a single species of the arid zone, H. glaberrima. This study aimed to examine the dormancy and germination ecology of seeds of H. glaberrima. Seeds were subjected to temperature stratification treatments designed to mimic summer and autumn conditions in the Pilbara region of Western Australia. Seed germination and embryo growth were measured. We also tested the interaction between temperature stratification and cycles of drying and wetting designed to mimic sporadic rainfall events. All temperature and moisture treatments were tested in combination (+/–) with the smoke-derived chemical karrikinolide (KAR1). Exposing dormant seeds to temperatures suitable for warm stratification (35°C) for ≥ 8 weeks, followed by incubation at 25°C, resulted in significantly higher germination compared with non-stratified seeds. Exposing seeds to dry/wet cycling in conjunction with temperature stratification did not significantly increase germination. Exposure to KAR1 increased germination under most conditions. Once seeds are shed during October to December, they are exposed to hot and sporadically wet conditions over summer, allowing MPD to be overcome in a proportion of the seed population. Seeds may germinate in autumn (March to April), in conjunction with cooler temperatures. More deeply dormant individuals may require more than one summer to overcome dormancy. Similar to other species occurring in fire-prone ecosystems, fire also plays a crucial role in the germination ecology of H. glaberrima.

The demand for more ecologically and economically sustainable agriculture arises because we currently integrate products economically in a fashion that distorts ecologica I relationships. Earfy farms were ecologically integrated through feeding of forage crops and crop residues to livestock, with livestock contributing draft power and manure for crops. Today we have almost entirely uncoupled plant and animal production, eliminating the contribution that each can make to the productivity of the other. Barriers to integrating farming systems include the large volume of information needed for sophisticated production systems and the lack of infrastructure. Also, many chemicals used on crops have not been evaluated for their safety in food animals. Winter feeding and calving may conflict with crop production cycles; balancing year-round forage supplies is another obstacle. Opportunities include using the Conservation Reserve Program to shift land to livestock production. Domestic demand for meat is changing, and range livestock production is seen by some people as more humane than confinement. Animals fed less grain may be more acceptable in some markets. As agriculture responds to changes in society, ecologica I integration may become more compatible with economic integration.

Yield losses from insect pests were determined by the insecticide check method in 60 crops in the Philippines from 1976–1986 in three rice environments with traditional and modern cultivars in 10 sites. Plot size of 100 m2 minimized interplot interference from insecticide protection on untreated plots. Low and high crop losses were recorded across sites in drylands (2–39%, = 25%), rainfed wetlands (13–24%, = 21%), and irrigated wetlands (5–40%, = 18%). Weighted crop loss for the Philippines based on production by environment and cultivar type averaged 18.3% or 0.57 t/ha per crop. Consistently greater yield loss occurred in the vegetative (50%) than reproductive (30%) or ripening (20%) stages across environments and cultivars. No epidemics affected the trials therefore crop losses were those from chronic pests. The major chronic pests in the wetlands were stem borers, leaffolders, whorl maggot, and rice bug; and in the drylands were ants, seedling maggots, white grubs, leaffolders, stem borers and rice bug. Yield loss variability was greater between fields than crops or sites, therefore a control strategy based on corrective actions when pest numbers reach threshold levels is more efficient than prophylactic actions. Yield loss was more in early maturing cultivars stressing the importance of compensation in tolerating insect damage. Insect stresses perhaps can be compensated by total crop management to increase the plant's ability to tolerate insect damage.

Pearl millet, sorghum, maize and cowpea are important food crops in dryland areas of the Sahel. Losses caused by insects on these low input crops are variable but generally substantial. Basic information on the role of natural enemies is scant. An example of a recent applied research which is mainly directed towards the management of millet earhead caterpillar, Raghuva albipunctella Joannis is narrated. Results of a study initiated on conservation and encouragement of Bracon hebetor Say against Raghuva in a traditional village environment are highlighted. These results demonstrate that such an approach of biological control has a place in even the temporary, already fragile agro-ecosystems and in habitats of low durational stability in the drought-hit Sahel.

Extensive additional base field data have been assembled since 1981 on the natural enemies of other pests, including Heliothis armigera (Hb.) in Senegal. Based on these results, the scope of conservation and encouragement on natural enemies in the Sahelian zone is discussed. Future research, development and training needs, for both short and more importantly long-term planning in this important aspect of pest management are briefly mentioned.