Ok, our competition trials never look that good.
useful paper: Designs for greenhouse studies of interactions between plants
- Aboveground harvest: clip from soil surface.
- Belowground harvest: need to harvest entire plant at once by removing plants and roots from pot experiments (for instance) and gently washing to remove all soil but keeping roots and shoots intact. Then, snip aboveground growth from below.
- Depending on level of replication and lowest possible independent sample unit, harvest one individual, one species, or all individuals of one species per pot into independent paper bags.
- Place in ovens at 68F for at least 2 days.
- Leave all plants in paper bags in oven until the moment you are ready to weigh.
- Remove from paper bags to weigh for small plants. Typically, I weigh to 3-4 decimal grams for small desert annual plants.
- Return plants to bag, do not return to oven, store in a paper box for a few weeks or until all data entered and checked.
Sheep hole valley
Heart of Mojave
They look pretty different right!!
Photos courtesy of Dr. Filazzola
I want my final paper to be useful for and applicable to restoration ecology. This led me to inquire what data I should collect for my second census. My germination rates are up, and all four species are present, so would relying on number of individuals and biomass of each species per pot be enough data? I decided that since I am using light as a limiting factor I must include height in my data; the plants may have somewhat similar biomass, but if it is due to leggy growth in the shaded pots then it will be important to note that although biomass was similar resource allocation was not equal. Are great amounts of leggy, weak, and nutrient deficient plants with few leaves better for ecosystems then having fewer shorter but thicker, more leafy plants? I measured the number of individuals per species per pot, alongside with the height and number of leaves the tallest member of each species had per pot. I have yet to analyze these numbers, but did notice trends when doing the census!
Side note: I conducted a germination experiment in the greenhouse prior to using these seeds, and have let them grow out. My Phacelia tanacetifolia is growing a beautiful flower!
Salvia columbariae, Phacelia tanacetifolia, and Plantago insularis are key phytometers (plants that indicate ecosystem conditions) in the San Joaquin Desert of California. As the highly invasive exotic Bromus madritensis colonizes in this non-native environment it lacks the environmental suppressors and competitors it faces in its native habitat. This leads to native Californian desert ecosystems to shift to a new model where native plants are excluded due to competitive disadvantages. decreases in native biodiversity are directly correlated to the health of an ecosystem, ecosystem services, resiliency to climate change, as well as the resources and for these reasons, identifying methods of restoration ecology is crucial.
Using my 3 factor (ambient light vs shaded conditions, low vs high B.madritensis density, native seeds at 6 levels of density (0,3,6,9,15, or 30 natives)) greenhouse competition trials I aim to identify what density of native species must present in a pot with a surface area of 153cm2 to outcompete an exotic one.I have previously run an experiment to identify optimal density in pots of the same surface area using each of the native species in monoculture, implementing the same light versus shade conditions with a total of 365 replicates. I will assess if I am able to compare these differences in optimal monoculture mix density to a polyculture mix with invader presence. If my data finds an optimal density using these methods, I hope to further my research and apply my findings to population ecology by estimating necessary population metrics required to apply this to ecosystem for large scale restoration and contribute it towards field work.
My experiment currently contains 200 pots, 100 of which are shaded by a bamboo structure I suspended. Germination has begun, yet it is still difficult to differentiate among species this early on. As predicted, the shaded individuals have demonstrated leggy growth as they reach towards the light source, yet there seems to be leaf production in possibly higher concentrations in the shaded pots than the ones experiencing ambient light. It appears that the shaded pots have a higher germination and growth rate (measured by number of individuals and number of leaves per pot). Is it possible that the shade-preferring B.madritensis is facilitating growth through positive density dependence? Am I witnessing an Allee effect in the form of environmental conditioning? Or is the answer as simple as light levels in the shaded conditions being sufficient for the natives as well as B.madritensis? Using the metrics of germination of species per pot as well as leaves per species and finally above ground biomass at the end of my experiment I will continually assess success through the different factors and levels I have designed and implemented in my experiment and hope to achieve a successful conclusion.
I am currently running an experiment to observe how an invasion of red brome impacts the growth and success of 3 native Californian plants (Plantago insularis, Phacelia tancetifolia, Salvia columbariae) across 5 different watering regimes. These watering regimes simulate conditions from extreme drought to very wet years. The experiment utilizes a total of 300 pots with 10 replicates per treatment; 100 pots are being used for each species, with 50 of those pots containing brome and 50 lacking brome.
As the experiment progresses 4 measurements will be obtained:
- Germination Success
- Establishment by 5 weeks
- Final Census
- Total Biomass production at the conclusion of the experiment
My native versus exotic competition experiment is all set up in the greenhouse, so just waiting on germination now. Have planted additive densities of 0,3,6,9,15 and 25 natives with brome at high (10 seeds) and low (5 seeds) densities, 10 reps per treatment at ambient light versus shaded conditions for a total of 200 pots. I hung up a wooden bamboo structure to provide shade and imitate shrub presence to half of the pots, and hung it in a way that it is easy to suspend for pot censusing. Here are photos of what it all looks like.
Photo courtesy of Jacob Lucero
Code, data, and exploration on GitHub.
Do native species density trials at two scale – micro and mesoscale using pots and large plastic buckets. Mix of potting soil and sand best – 50:50.
Consider intra and interspecific competition series – with replacement, i.e. keep net densities per pot consistent. Finally, perhaps consider competition with an exotic such as red brome.
with and without shade mimic in greenhouse
umbrella over buckets in mesocosm experiment
natives against brome in density series
then a*b, a*c, b*c
Or run each out in solo then against red brome.
a vs rb
b vs rb
c vs rb
at 1,2, 5, 10, 25 seeds etc or a simple with-replacement density series.
THEN, ready for it…. red brome from cali and red brome from Israel
a+b vs rb
We had a more ambitious set of goals this season.
- Habitat use frequency estimates. Tools: a. telemetry of blunt-nosed leopard lizard with a total at least 1200 relocations split between AM/PM with an estimate of shrub-open and behavior. b. cam traps at shrub-open on still mode.
- Behavior estimates. Tools: a. cam traps on video mode at a total of 100 hours recording time. b. direct observation (with recording too) by humans of lizards and grasshoppers at a total of 100hrs.
- Shrub-plant-animal interaction estimates. Tools: exclosures at two sites to exclude different taxa in shrub-open mesohabitats. a. cages. b. cams c. vacuums. d. sweeps.
- Temperature profile estimates. Tools: a. pulse of collars on lizards b. loggers at microhabitat scales.
- Census grasshoppers. Tools: stick, sweep, and vacuum. Also do direct observation to assess whether they are significant consumers.
1a. Mario and Steph. Goals 1,2,3,5.
1b. Malory and Nargol. Goals 1,2,5.
2. Emily and Kat. Goals 1 & 4.
Deploy one set of cam traps on still mode at a total no-shrub zone.
Get a solid handle on behavior by verts and inverts in the context of paired interactions with plants (at micro-scale) and shrubs at mesoscale.
Need an assay of insect diversity.