In the Southern Great Plains (SGP) of the United States, encroachment of the native invasive woody legume, honey mesquite (Prosopis glandulosa Torr.), has caused a decline in C4 mid‐grass abundance. Prosopis glandulosa invasion has also facilitated growth of the C3 mid‐grass species, Texas wintergrass (Nassella leucotricha [Trin & Rupr.] Pohl) initially beneath its canopy but extending to interspaces between P. glandulosa as stand density increases. Little is known about the stability of the Prosopis/Nassella association or C4 grass recovery following P. glandulosa disturbance. We quantified C3 and C4 grass production in interspaces, and basal cover in interspaces and P. glandulosa subcanopy microsites for 9 years following P. glandulosa suppression (top‐kill) and compared this to untreated P. glandulosa woodland (woodland). The Prosopis/Nassella association limited the window of C4 mid‐grass recovery to only a few years. Nassella leucotricha dominated grass production during the first 3 years after top‐kill. C4 mid‐grass recovery began in year 4, but was interrupted by severe drought in years 5 through 7. Recovery resumed in year 8, due to above‐average summer rainfall, but P. glandulosa regrowth was large enough by this time to limit C4 mid‐grass production to a third of its potential. Nassella leucotricha basal cover remained dominant and stable in woodland subcanopy microsites, even during drought, and only briefly declined in top‐kill subcanopy microsites before returning to pretreatment levels by year 8 as P. glandulosa regrowth increased and provided shade. Synthesis and applications. A single suppression event had little impact on disrupting the Prosopis/Nassella association and allowing C4 mid‐grass recovery. The coupling of a deciduous, N‐fixing C3 woody species with this C3 perennial grass may be a vegetative “state” that is resistant to multiple woody suppression disturbances and permanently limits the transition back to C4 grassland.
Most ecosystems are increasingly being degraded and reduced by human activities at the local and global scales. In contrast, urban environments are expanding as increasing portions of humanity move into cities. Despite the common perception among biologists that urban areas are biological deserts, cities offer habitat for many non-human species, but their ecology and conservation remain poorly studied. In this review, we first provide an update on the current state of knowledge on urban wildlife, then briefly examine the indirect effects of the COVID-19 pandemic on urban wildlife and add four components not previously included in comprehensive reviews. (1) We show that by reducing human activity, COVID-19 has temporarily enhanced urban habitat quality for some species and diminished it for others. (2) Thoughtful horticulture can contribute to urban wildlife by providing complex habitat structures that benefit biodiversity while enhancing human wellbeing. (3) Recent literature on urban invertebrate biodiversity has grown, though is still focused on pollinators. (4) Finally, employing insights from the discipline of communication can enhance the success of urban biodiversity conservation among both biologists and the public.
A study was conducted to determine how total phenolic (TP), protein precipitable phenolic (PPP), C, and N concentrations, and amount of protein bound (PB) by PPP in leaves of Desmodium paniculatum (panicled tick-clover; PTC) and Lespedeza cuneata (sericea lespedeza; SL) were affected by simulated herbivory and plant ontogeny. All PTC treatments resulted in a decrease (P ≤ 0.05) in TP, PPP, C, and N concentrations and PB between vegetative and seed set stages. All SL treatments resulted in increased (P ≤ 0.05) or stable TP and PPP concentrations from vegetative stage to seed set. The amount of PB was greatest (P ≤ 0.05) in SL plants submitted to 25% defoliation, and flowering and seed set stages had greater (P ≤ 0.05) PB than the vegetative stage. Ontogenesis and defoliation did not (P > 0.05) affect SL N and C concentrations. The protein binding characteristics of PPP from PTC, but not that of SL, appear to be altered in response to stress. Results might correspond with seed dispersal strategies of the two species, with PTC's epizoochory making increased palatability at seed set beneficial.