About This Project

Biological soil crusts—communities of mosses, lichens, and microbes—stabilize soils, retain water, and regulate carbon in drylands. While these communities are well studied as a whole, less is known about how individual members respond to changing conditions. This project focuses on Syntrichia, a dominant desert moss genus, examining how drought, seasonality, and rainfall patterns influence its photosynthetic performance across time (seasons) and space (two California deserts).

Ask the Scientists

What is the context of this research?

Biological soil crusts (“biocrusts”) are communities of mosses, lichens, and microbes that live on the surface of desert soils. They play an important role in dryland ecosystems by helping store carbon and nitrogen, stabilizing soil, and retaining water and nutrients (1,2) . Previous research shows that intact biocrusts store more carbon than those disturbed by trampling, and that rainfall patterns strongly influence carbon balance in Syntrichia mosses (3,4).

However, much of what we know about biocrusts comes from studies of whole communities, while mosses are often studied under controlled laboratory conditions (5). As a result, less is known about how individual species function in natural environments across seasons, especially in different desert ecosystems. To address this gap, this project will investigate how Syntrichia mosses photosynthesize across seasons in two deserts in Southern California.

What is the significance of this project?

The Sonoran and Mojave deserts differ in when and how they receive precipitation (1). The Sonoran experiences summer monsoons as well as fall and winter rain, while the Mojave receives most of its precipitation during the cooler months (2). As climate change alters temperature and rainfall patterns, it is unclear how these ecosystems and the organisms within them will respond.

This is especially important for biological soil crusts, which play a key role in carbon and nitrogen fixation in drylands (3). Mosses like Syntrichia are common members of these communities across California deserts. Because biocrusts influence soil stability, water retention, and nutrient cycling, (4,5) changes in their function can have broader ecosystem impacts. By understanding how they respond to seasonal conditions in different deserts, this project will help predict how biocrusts, and the essential functions they support, may change under future environmental conditions.

What are the goals of the project?

The main goal of this project is to understand how Syntrichia mosses vary in their photosynthetic activity across seasons and between the Mojave and Sonoran deserts, and to predict how they may respond to changing drought conditions. To do this, I will collect moss samples every three months from field sites in both deserts.

These samples will be analyzed to measure how efficiently they photosynthesize and protect themselves from environmental stress. This includes measuring carbon uptake, light use, and photoprotective or accessory pigments. I will also use publicly available weather data from the UC Natural Reserve System to link moss responses to real environmental conditions.

By comparing seasonal patterns across two deserts, this project will identify how environmental differences shape moss function and improve predictions of how these organisms respond to environmental change.