Presentation on theme: "Sevilleta NWR LTER CJ Jewell. Effects of Fire: release of nutrients breakdown of hydrophobic plant litter breakdown of dormancy removal of inhibiting."— Presentation transcript:
Sevilleta NWR LTER CJ Jewell
Effects of Fire: release of nutrients breakdown of hydrophobic plant litter breakdown of dormancy removal of inhibiting chemicals Impact on plant communities varies among seasons and across sites
Belowground plant community Dispersed seeds germinate immediately die remain dormant Transient seeds Persistent seeds Seed bank Benefits of seed dormancy (Fenner & Thompson, 2005)
Species diversity Biodiversity Genetic diversity Food sources Environmental stimuli
Fire triggers seed germination and seedling recruitment by the Removal of vegetation Intense temperatures recorded in the soil
Dominant vegetation is perennial grasses grow in the summer dormant in fall and winter More seeds available during spring/summer Abundance decreases in autumn/winter Blue Grama Black Grama
Sevilleta studies: Establishment ecology of Creosote Recruitment studies from seed banks Seedling establishment after removal of dominant species How fire affects vegetation and insect diversity
1) What is the composition and size of the seed banks in the fall, summer, and control burn plots? 2) Does the seasonality of fire affect seed bank size and content? 3) How does fire affect seedling germination in the field?
Fire will cause an overall decrease in the size and species diversity in the seed bank The summer burn plots will have a greater amount of viable seeds and species richness compared to the fall burn plots
Pictures provided by Laura Calabrese Sevilleta NWR/LTER McKenzie Flats, 2.8 miles south of Black Butte gate 34° N 106° W Vegetation dominated by the grasses blue grama ( Bouteloua eriopoda ), and black grama ( Bouteloua gracilis ).
10m 40m 60m 2m 40m 40m transect with flags every 2m Collected 20 10cm (length) x 10cm (width) x 2cm (depth) samples per plot Total of 20 samples from 6 plots = 120 soil samples
3 Treatments X 2 Plots per Treatment X 20 soil samples per plot = 120 samples Randomly selected 15 soil samples per plot 90 soil samples used; 30 per treatment Randomly distributed selected samples in the Sevilleta Lath House
cm x 53.3cm flats in Sev Lath House Soil mixture contains half Metromix 360 and half sandbox sand Spread soil sample over mixture Watered daily Marked and counted new seedlings weekly Recorded if monocot or dicot
Monocots: Embryo as one cotyledon Flower parts in 3s Parallel Veination Grasses-no secondary growth Dicots: Embryo has two cotyledons Flower parts in 4s or 5s Reticulated/Branched Veination Woody species-secondary growth
SAS Wald Chi-Squared= P= DF=2
SAS Monocots Wald Chi-Square= p value= DF=2 Dicots Wald Chi-Square=0.242 p value= DF=2
9 sample areas from each of the 6 plots=54 areas A 30cm X 30cm niner was used to count number of naturally germinating seedlings in each sample area Specific species were identified when possible
Fires negatively affect the seed bank in the short term Semi-arid grasslands are not adapted to fire Monocots and dicots are equally affected by seasonal fire After a summer burn, there is more space available for newly released seeds, so more can germinate right away Species found in the field are a fair representation of what may be found in the seed bank, but not an absolute reference
Limited sample size Lath house conditions Time since burns
Long term effects of fire Flotation method to mechanically find the seeds in soil samples (30 extra samples) Assess spring seed bank Assess how fire affects the seed bank and vegetation of shrublands and woodlands on the Sevilleta
Sevilleta NWR LTER UNM Jennifer Johnson Diane Marshall Tim Lowrey Terri Koontz All Sev 2008 REUs Especially Damon Lowrey Molly Ladd And everyone who helped me water!!
Lath House seedlings at the end of the rainbow!