Multiple Stable Equilibria or Competitive Superiority in California Grasslands: light data

We began work on this project in December of 1999 by setting up three large experiments in which we are investigating the relative importance of burning, watering, nitrogen deposition, and pocket gopher disturbance on the relative invasiblity of native perennial and exotic annual grasslands. As a part of setting up these experiments we established 136 plots which ranged in size from 9 to 25 square meters. These plots start out as either dominated by exotic annual or native perennial grasses. In addition to their initial composition, we subject these plots to a variety of treatments including seed additions, burning, nitrogen addition, watering, and pocket gopher exclusion. Data include annual sampling of plant cover (1 m2 pinframes), seed production and aboveground plant production (0.2 m2), as well as soil moisture and nutrient concentrations.

本项目于1999年12月启动，我们设置了三项大型实验，以探究火烧、灌溉、氮沉降（nitrogen deposition）及囊鼠（pocket gopher）干扰在影响本土多年生草本与外来一年生草地相对易入侵性方面的相对重要性。作为实验搭建的组成部分，我们共建立136个样地，样地面积介于9至25平方米之间，这些样地初始均以外来一年生草本或本土多年生草本为优势群落。除初始群落组成外，我们还对这些样地施加了多种处理，包括种子添加、火烧、氮添加、灌溉及囊鼠排除处理。本数据集涵盖的采样数据包括：每年采用1平方米针框（pinframes）法测定的植被盖度、0.2平方米样方测得的种子产量与地上生物量，以及土壤湿度与养分浓度数据。