| Summary: | Invasive C<sub>4</sub> grasses can inhibit the natural regeneration of secondary forest in tropical landscapes after the cessation of intensive use for grazing and agriculture. In Panama, invasive <i>Saccharum spontaneum</i> forms dense stands that require active management to re-establish forest successional processes. In this region, restoration strategies typically involve clearing grass cover manually and applying fertilizer prior to planting tree seedlings. However, if fertilizers alleviate nutrient limitation and enhance grass competition with tree seedlings, these practices may exacerbate the costs of <i>Saccharum</i> control and hamper restoration goals. Here, we evaluated how <i>S. spontaneum</i> responds to nitrogen and phosphorus addition in the field to determine whether <i>S. spontaneum</i> is nutrient limited in this system. <i>S. spontaneum</i> was limited by both nitrogen and phosphorus, as revealed through increased foliar nutrient concentrations. <i>S. spontaneum</i> biomass was significantly greater in both nitrogen and phosphorus addition plots after both the first growth period (early rainy season) and second growth period (late rainy season), with stronger effects of nutrient limitation during the second growth period for both N limitation and N and P co-limitation. Nutrient limitation in <i>S. spontaneum</i> highlights a potential risk of fertilizer applications during restoration, agriculture, and agroforestry activities in which invasion of this aggressive weed is a challenge to land management.
|
|---|