Complex sentence: Several studies have shown that native plant biomass, especially that of bunchgrasses, negatively effects "B. tectorum" cover and biomass, suggesting that a diverse native perennial community will be more resistant to "B. tectorum" invasion.
Split into simpler sentences: Several studies have shown that native plant biomass, especially that of bunchgrasses, negatively effects "B. tectorum" cover and biomass. Suggesting that a diverse native perennial community will be more resistant to "B. tectorum" invasion.