Data from: A case study of grassland responses to fuel reduction treatment on the mount Hamilton range of California

In many grasslands, mowing and grazing are common management methods that
can decrease fuel loads and alter community composition to achieve
specific targets, such as increasing diversity or reducing grass
dominance. Communities may respond with changes in their taxonomic,
phylogenetic, and functional diversity, species turnover, functional
shifts, and individualistic species responses. We address these in a 4-yr
case study of grazing and mowing in a California grassland located in the
Mount Hamilton Range of Santa Clara County. We hypothesize that both
grazing and mowing will reduce grass cover and residual dry matter,
allowing competitive release of a more diverse range of forbs, likely
increasing functional and phylogenetic diversity. On the other hand, these
treatments may impose filters on the community (e.g., mowing may eliminate
tall species), reducing functional diversity and shifting the community
towards particular functional compositions. In contrast to our
expectations, grass cover did not respond strongly to either treatment,
and there were weak effects on residual dry matter. However, there were
still strong compositional responses. Mowing led to a reduction in tall,
large-seeded, and perennial species and generally higher functional and
phylogenetic diversity. The most pronounced response in grazed communities
was a marked increase in nitrogen-fixing species, paired with reductions
in functional and phylogenetic diversity. Similar results have been
observed in previous studies of grazing and mowing impacts at other
Californiagrasslands sites, providing a basis for predicting species
responses to these treatments. Both can be useful tools to filter the
community for particular species compositions, but showed no benefit for
commonly used restoration targets such as increasing species richness or
native cover. Continued monitoring of the sites will track potentially
slow compositional changes and investigate the interactions between
treatments and interannual weather variation.