Ecological Archives E093-127-A6

Angela J. Brandt and Eric W. Seabloom. 2012. Seed and establishment limitation contribute to long-term native forb declines in California grasslands. Ecology 93:1451–1462.

Appendix F (Table F1). A table showing model coefficients and significance of predictors included in statistical mixed effects models describing the number of reproductive individuals of six native annual forb species seeded into competition removal plots located inside and outside the reserve boundary of the Hastings Natural History Reservation. Each model included nested random effects of sampling date within experimental block within side of reserve boundary within site. Seven models were examined: one for each species and one for the total number of reproductive individuals of all seeded species per plot. Litter present and live grass present refer to competition removal treatments of plant litter removal and grass-specific herbicide, respectively, applied to plots in a factorial design. Inside boundary refers to plot location inside the reserve boundary vs. outside it. Never observed vs. present, gone extinct vs. not, and stable presence vs. colonizing refer to orthogonal contrasts of recruitment conducted based on each species' occupancy of a transect during long-term monitoring (see Table 1). Mean observed abundance refers to a species' overall mean abundance in a transect documented during long-term monitoring. Litter mass refers to the mean mass of plant litter removed from the two litter removal plots within each experimental block. Total forb cover, exotic forb cover, and total grass cover refer to visually estimated cover of each plant group in each plot in May 2010. PC1 and PC2 refer to the first two principal components in a PCA ordination of the community composition in monitoring transects using mean cover observed from 2005–2010 (see Appendix C). Canopy cover refers to visually estimated percent canopy cover at the ends and middle of each monitoring transect in 2008.

Species Predictors
Litter present Live-grass present Inside boundary Litter × live-grass Litter × boundary Live-grass × boundary Litter × live-grass × boundary Never observed vs present Gone extinct vs not Stable presence vs colonizing Mean observed abundance Litter mass Total forb cover Exotic forb cover Total grass cover PC1 PC2 Canopy cover
Total reproductive individuals -0.08 0.09 -0.06 -0.32** -0.33** 0.20 0.45** NA NA NA NA -0.002* 0.009** -0.006* NA NA 0.02 -0.006*
Castilleja exserta -1.13** 0.73 NA NA NA NA NA -0.53* -0.09 NA NA NA 0.04** -0.04* NA 0.08 NA NA
Clarkia purpure 0.05 0.27 0.50 -0.59 0.03* NA NA NA NA NA NA NA 0.01** -0.02** NA 0.06** NA NA
Collinsia heterophylla 0.47** -0.03 0.30 -0.46 NA NA NA -0.93** NA NA NA -0.002 0.02** NA 0.02** 0.03* NA NA
Nemophila menziesii -0.92** 0.68* -0.63 0.58 NA NA NA -0.08 0.41 1.98** NA NA 0.02** -0.02 -0.02* NA NA NA
Plantago erecta -0.16 -0.20* -0.26 NA -0.25* 0.42** NA -1.28* -2.94* NA -15.76* -0.004** NA NA NA NA NA -0.01**
Trifolium microcephalum 0.18 0.42* -0.12 -1.32** -0.42 0.01 1.24** NA NA NA NA NA 0.02** -0.02** NA NA 0.02* NA

indicates statistical significance at P < 0.1
* indicates statistical significance at P < 0.05
** indicates statistical significance at P < 0.01
NA indicates the predictor was not included in the final model.


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