Reduced ecosystem services of desert plants from ground-mounted solar energy development

<p>Deserts are prioritized as recipient environments for solar energy development; however, the impacts of this development on desert plant communities are unknown. Desert plants represent long-standing ecological, economic and cultural resources for humans, especially indigenous peoples, but their role in supplying ecosystem services (ESs) remains understudied. We measured the effect of solar energy development decisions on desert plants at one of the world’s largest concentrating solar power plants (Ivanpah, California; capacity of 392 MW). We documented the negative effects of solar energy development on the desert scrub plant community. Perennial plant cover and structure are lower in bladed treatments than mowed treatments, which are, in turn, lower than the perennial plant cover and structure recorded in undeveloped controls. We determined that cacti species and Mojave yucca (Yucca schidigera) are particularly vulnerable to solar development (that is, blading, mowing), whereas Schismus spp.—invasive annual grasses—are facilitated by blading. The desert scrub community confers 188 instances of ESs, including cultural services to 18 Native American ethnic groups. Cultural, provisioning and regulating ESs of desert plants are lower in bladed and mowed treatments than in undeveloped controls. Our study demonstrates the potential for solar energy development in deserts to reduce biodiversity and socioecological resources, as well as the role that ESs play in informing energy transitions that are sustainable and just.</p>

DIET OF EIGHT SPECIES OF LIZARDS FROM GRANITE GAP, HIDALGO COUNTY, NEW MEXICO

Granite Gap is a desert scrub habitat located in the Chihuahuan Desert in southwestern New Mexico about 200 km from the Texas border. In May 2016, we collected specimens of eight lizard species, six of which range into Texas: Callisaurus draconoides, Cophosaurus texanus, Uta stansburiana, Urosaurus ornatus, Gambelia wislizenii, and Aspidoscelis sonorae (a parthenogenetic species), plus two species not found in Texas: Sceloporus clarkii and Aspidoscelis tigris. We analyzed stomach contents of the preserved lizards and computed diet breadth and overlap for each. All lizard species consumed arthropods only. Considering the entire sample, there was a significant correlation between lizard snout-vent length (SVL) and total volume of arthropods consumed, and between lizard SVL and mean volume per prey item, but not between lizard SVL and number of arthropods consumed. This suggests larger lizards did not consume more arthropods than smaller lizards, but they did consume larger ones. Overall, A. sonorae was the most specialized lizard species at Granite Gap whereas C. texanus seemed to be the most generalized owing to its high numeric and high volumetric diet breadth. The dietary overlap data suggest there were two groups of lizards at Granite Gap: one that consumes a large number and volume of termites (Callisaurus, Cophosaurus, and the two species of Aspidoscelis) and the other that consumes a large number and volume of ants (Uta, Urosaurus, small Sceloporus) plus cicadas when lizard size is large enough to consume them (large Sceloporus and Gambelia).

Classification of plant communities in Sierra Rica, Manuel Benavides, Chihuahua, Mexico

Sierra Rica is a mountain island located in the plains of the northeastern region of the Chihuahua Desert and has a diversity of vegetation patterns. To study this patterns the vegetation was characterized using GIS and cluster analysis, which identified five community types: pine forest (780 ha), oak forest (1640 ha), grassland (550 ha), desert scrub (866 ha), and rosetophyllous desert scrubland (628 ha). By the use of TWINSPAN software, four main vegetation groups containing 10 main plant associations were identified: (1) Pinus-Quercus forest, (2) grassland, (3) pine forest, (4) Rhus-Juniperus, (5) Pinus-Quercus and xeric species, (6) grassland-desert scrub, (7) desert microphyll scrub, (8) Quercus-Aloysia-Bouteloua association, (9) Acacia constricta scrubland, and (10) Larrea tridentata scrubland. The association among groups and species was significant (P < 0.0001). The subsequent analysis shows a high dependence among species inside the main groups and independence between groups.

A new species of grass spider, Agelenopsis riechertii, from the Southwestern USA, with notes on its courtship behavior (Araneae: Agelenidae)

We describe a new spider species of the genus Agelenopsis Giebel 1869 (Agelenidae) from adult males and females. Agelenopsis riechertii is found in dry desert scrub habitats in the southwestern United States. While A. riechertii is similar to other sympatric congeners (A. aleenae, A. aperta, and A. spatula) in morphology and courtship behavior, it can be distinguished by an examination of its genitalia. Males possess an embolus that gradually narrows into a twisted tip which displays a convex edge from the lateral view. The female epigyna are harder to distinguish from congeners, but have a flatter anterior atrial edge that lacks strong bi-lobing. The spermatheca in female A. riechertii are also more elongate and comma-shaped than the other species. We describe the sequence of courtship behaviors exhibited by males, including the use of web pulses, abdomen waggling, and web flexing, in which males with fewer pauses, longer waggling bouts, and fewer web flexes are more likely to successfully copulate.

Hunting of migratory birds in North Sinai, Egypt

SummaryDuring autumn migration, people set trammel nets along most of the Mediterranean coast of Egypt, with migrating Common Quail Coturnix coturnix as their primary target. These nets capture large numbers of quail, but also illegally capture other birds, which are then killed. We present the results of surveys from 2008 to 2012 along these lines of nets on the coast of North Sinai, Egypt. In desert scrub, which covers most of the Sinai coast, the mean number of quail killed reached a high of 357.1 per km per day in 2012, with a grand mean over the study period of 191.9 per km per day. Trammel nets also captured 54 other bird species in 28 families. Species captured at the highest rates in desert scrub included Corncrake Crex crex, Isabelline Wheatear Oenanthe isabellina and Greater Short-toed Lark Calandrella brachydactyla. Based on mean rates of capture from 2008 to 2012 in desert scrub and sand bar habitats, we estimate 2.0 million quail and 0.5 million birds of other species are killed annually in North Sinai during the 45 days of peak migration. In 2012, however, after the use of MP3 players to attract quail became widespread, we estimate that 3.3 million quail and 0.5 million other birds were captured. Hunters near the coast have recently begun covering shrubs and trees with mist nets to catch passerines. From 2010 to 2012, mist nets along our survey routes caught birds of 17 species in three families, with seven of these species caught only in this type of net. Hunting is likely to be a contributing factor to population declines for some species that migrate across Egypt and further studies of migratory bird hunting along the southern Mediterranean shore are badly needed.

Relationships between annual plant productivity, nitrogen deposition and fire size in low-elevation California desert scrub

Although precipitation is correlated with fire size in desert ecosystems and is typically used as an indirect surrogate for fine fuel load, a direct link between fine fuel biomass and fire size has not been established. In addition, nitrogen (N) deposition can affect fire risk through its fertilisation effect on fine fuel production. In this study, we examine the relationships between fire size and precipitation, N deposition and biomass with emphasis on identifying biomass and N deposition thresholds associated with fire spreading across the landscape. We used a 28-year fire record of 582 burns from low-elevation desert scrub to evaluate the relationship of precipitation, N deposition and biomass with the distribution of fire sizes using quantile regression. We found that models using annual biomass have similar predictive ability to those using precipitation and N deposition at the lower to intermediate portions of the fire size distribution. No distinct biomass threshold was found, although within the 99th percentile of the distribution fire size increased with greater than 125 g m–2 of winter fine fuel production. The study did not produce an N deposition threshold, but did validate the value of 125 g m–2 of fine fuel for spread of fires.