Hydrologic alterations impact plant litter decay rate and ecosystem resilience in Mojave wetlands

Abstract

Understanding ecosystem processes is vital for effective restoration of degraded ecosystems, especially wetlands. Restoration has become a necessity for management and conservation of the federally endangered Amargosa vole (Microtus californicus scirpensis) endemic to small, bulrush (Schoenoplectus americanus) dominated wetlands in the Mojave Desert. Recent data indicate catastrophic decrease of the vole population and its habitat from local alterations to hydrology, combined with diminished decomposition rates of bulrush, persistence of plant litter, and minimal plant growth except along narrow margins along stream edges. We conducted a series of three field and one greenhouse experiment(s) testing the effect of (1) moisture level on plant decay rate, (2) litter removal on plant regeneration, (3) the interactive effect of litter removal and moisture level increase on plant regeneration, and (4) potential germination rate of bulrush seeds under multiple hydrologic regimes to understand how hydrologic alteration and litter decay ultimately influences marsh regeneration. Results revealed decrease in water level caused a 20‐fold reduction in decomposition rates of a degraded marsh. Litter removal alone and in combination with water table restoration significantly and positively affected bulrush resprouting (p < 0.0001 for both). Seed bank experiments showed high rates of germination in saturated and flooded soil conditions, emphasizing the potential role of seedlings in ecosystem recovery. This study shows how the interaction of hydrologic change and decreased decomposition can shift an ecosystem toward limits of resilience. These results inform restoration strategies in arid‐region wetlands dominated by plants with slow litter decay where strategic litter removal may beneficially increase plant growth.

Subpopulation augmentation among habitat patches as a tool to manage an endangered Mojave Desert wetlands-dependent rodent during anthropogenic restricted water climate regimes

“…In 2013, only Marsh 1 in the northeast corner of the study area appeared to have a sustainable subpopulation of voles based on trapping studies and population demographic analyses [22]. However, anthropogenically mediated impacts to Marsh 1 hydrology caused a significant decline in water level and reduction of bulrush density [15] such that in 2014, voles at Marsh 1 exceeded carrying capacity with survival rates of only 0.35 per month (R Klinger, USGS, and Foley, unpub. data) [23].…”

“…Endangered species management in this region must contend with anthropogenic hydrologic alterations (e.g. groundwater pumping and land clearing) and climate changes that often manifest locally as reduced and less reliable available water [14, 15]. With ongoing habitat degradation and loss of available water, the population status of the Amargosa vole is now dire.…”

Effect of vegetation distribution driven by hydrological fluctuation on sedimental stoichiometry regulating N&lt;sub&gt;2&lt;/sub&gt;O emissions in freshwater wetland

“…5d and S4). The litter of reed was more difficult to be utilized by microorganisms (Castle et al, 2019), which resulted in the lower phyla and diversity of reed zone than that of carex and phalaris (Figs. 5d and S4).…”

Host species and environment drivers of ectoparasite community of rodents in a Mojave Desert wetlands

“…Ongoing habitat degradation and loss of water driven by anthropogenic hydrologic alterations (e.g. ground-water pumping and land clearing) and climate change [ 42 , 43 ] may have considerable impacts on ecological interactions among hosts and ectoparasites and vector-borne diseases in this region.…”