Native weed protects species that sustain cattle raising in semi-arid natural grasslands

COCK, MARINA C.; HIERRO, JOSÉ L.

JOURNAL OF ARID ENVIRONMENTS

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Año: 2020 vol. 175 p. 1 - 8

0140-1963

Facilitation may contribute to conserving natural systems disturbed by humans. We hypothesized that the unpalatable native weed, Baccharis ulicina (Baccharis) protects palatable plants from cattle grazing in centralArgentina grasslands. We tested this hypothesis through observational and experimental studies. In the observational study, we compared consumption and performance of plants growing in Baccharis and Baccharis-free(open) microsites. We also recorded photosynthetically active radiation, soil moisture, and total soil nitrogen (N)in both microsites. In the experiment, we removed Baccharis aboveground biomass and compared herbivory andplant performance in Baccharis, Baccharis-removed, and open microsites. Palatable plants were less consumedwhen growing with than without Baccharis, and palatable grasses with the highest forage values were moreabundant, taller, and fecund in Baccharis than open microsites in our observational study. Additionally, exceptfor increased radiation in the open, there were no differences in abiotic variables between microsites. Resultsfrom the plant removal experiment were consistent with those from the observational study and did not offerevidence for direct facilitation. We conclude that protection from cattle is an important mechanism throughwhich Baccharis benefits neighboring plants. Our work emphasizes the need to recognize the facilitative role ofweeds in the management of semi-arid grasslands.