Incidence of Galls on Sympatric California Oaks: Ecological and Physiological Perspectives

Galls are abnormal outgrowths on the external tissues of plants caused by a restricted group of organisms. In this study, we surveyed the incidence and diversity of galling structures in sympatric oak species of a biological preserve (Jasper Ridge Biological Preserve, NC, USA). We also measured different physiological parameters (SLA-specific leaf area, chlorophyll, nitrogen, flavonol, anthocyanin, and water content) in galled and ungalled leaves on the same individuals of the most abundant oak species (Quercus agrifolia, Q. lobata, and Q. douglasii). Overall, Q. lobata showed the highest gall incidence, with 64.5% of the sampled leaves affected by galls, followed by Q. douglasii, Q. agrifolia, Q. durata, and Q. kelloggii. The proportion of stems with galls was considerably lower than for leaves in all oak species, ranging from 0% incidence in Q. kelloggii to 27.4% in Q. lobata. The highly schlerophyllous Q. agrifolia supported the most diverse galling community at Jasper Ridge, with ten species, mostly belonging to the Cynipidae family. Our results show that leaf galling had no significant impact on the studied ecophysiological variables. The lack of differences between galled and ungalled leaves under controlled conditions (same tree and position in the tree) suggests that the ecophysiological variables measured are not significantly affected by galling agents or that our data collected for fully-developed galls (end of summer) are not sensitive enough to detect differences. However, there were some trends in plant responses to galling. Changes in galled vs. ungalled leaves were greater in flavonols, followed by chlorophyll, nitrogen, anthocyanin, SLA, and water content, indicating a nutrient deficiency in the plant nutrients. Our findings underscore the complexity of the gall-plant interaction and suggest some promising lines of future research.

A Meditation on Stillness: Ann Carlson’s Picture Jasper Ridge

Ann Carlson’s Picture Jasper Ridge was a performance hike in nature: spectators walked through tableaux vivants based on archival photographs. Carlson’s investigation of the apparatuses of archive, performance, natural preserve, and photography fostered meditative thinking about the phenomenology of performance that unfolded through the experience of performing still.

Animals, Fungi, and Microorganisms

Although plants are the major living components of terrestrial geoecosystems, other organisms are very important. Some animals move large amounts of soil, and many microoganisms promote the weathering of rocks and minerals in soils. Perhaps the greatest effects of animals, fungi, and microorganisms on geoecosystems are indirect through their effects on plants and plant communities. Mycorrhizal fungi are beneficial to plants in nutrient-limiting substrates where the fungi can scavenge phosphorous and nitrogen for plants. Many animals, from large ungulates (moose, elk, deer, etc.) to microscopic nematodes, graze on the leaves and roots of plants. Microorganisms cause many diseases in plants. A complete inventory of plant interactions with other organisms is virtually limitless. This chapter concentrates on organisms that live in serpentine soils, that live on ultramafic rocks, or that are dependent on plants that grow on serpentine soils. There have been few field investigations of living organisms, other than plants, on serpentine soils. Many of the investigations on animals, fungi, and microorganisms in serpentine soils of the western North America have been conducted on Jasper Ridge in San Mateo County, and some have been on Coyote Ridge in Santa Clara County and on the McLaughlin Reserve in Napa and Lake counties, California. Some investigations of animals and other organisms for which there are no published accounts relating to serpentine soils in western North America (e.g., termites) are cited from other areas. The associations of organisms with serpentine soils, whether utilization or avoidance, largely depend on the chemistry of the soil parent materials. Therefore, this chapter begins with a review of the effects of serpentine chemistry on living organisms. Organisms are about 50% or more water. Moss plants that are less than 50% water when desiccated can absorb much more water than their dry weights to increase their weights several fold within hours. About half of the biomass of living organisms that is not water is carbon. Other than water, carbon dominates the chemistry of all organisms. It forms large polymers that are far beyond the capabilities of other elements. Carbon dioxide in the atmosphere is the primary source of carbon in soils.