---
title: bull kelp and giant kelp are not the same forest
canonical_url: https://ensurance.app/guide/bull-kelp-and-giant-kelp-are-not-the-same-forest
markdown_url: https://ensurance.app/guide/bull-kelp-and-giant-kelp-are-not-the-same-forest.md
subtitle: one stipe and a float is not the same plant as a perennial stand
category: natural-capital
---

# bull kelp and giant kelp are not the same forest

*one stipe and a float is not the same plant as a perennial stand*

**Bull kelp** puts one stipe and one float on the surface. **Giant kelp** keeps a perennial stand, with a float on each blade. Both are canopy kelps on the Pacific nearshore. A program that only says kelp can still fund the wrong forest.

This page is for coastal programs and the regional collaboratives that share a nearshore. The species in the water is the forest you can actually fund.

:::johnson
**bull kelp and giant kelp are not the same forest.** A missed recruitment year takes the bull kelp canopy. A giant kelp stand can put canopy back from the base.

[name the canopy in the water →](/guide/what-a-kelp-forest-actually-is?from=guide)
:::

## what bull kelp is

*Nereocystis luetkeana* is a brown alga. A holdfast grips rock. Kelp has no roots in soil. A single stipe rises to one gas-filled float, the pneumatocyst, and the blades grow from that bulb across the surface.

[NOAA Fisheries](https://www.fisheries.noaa.gov/west-coast/habitat-conservation/kelp-forest-habitat-west-coast) draws the shape in one line. Bull kelp has one pneumatocyst holding several blades. Giant kelp has a pneumatocyst on each blade.

Springer, Hays, Carr, and Mackey (2010) recorded the fact a budget has to live with. Each bull kelp plant makes one stipe in its life. Once the upper stipe is destroyed, that plant cannot regrow from the holdfast. The species is essentially annual. Individuals that start late can overwinter and see a second year, more often in shallow or protected water. That second year is one plant finishing.

Next year's canopy is a new recruitment. If the spores do not settle and grow, the forest is gone for that season. The fish and the abalone that used the blades are still why the canopy mattered. A [kelp forest](/guide/what-a-kelp-forest-actually-is?from=guide) is that living canopy.

## what giant kelp is

*Macrocystis pyrifera* carries many fronds from one base. A small float sits at the base of each blade along the stipe, so the alga holds itself through the water column from those floats, not from a single bulb at the top. It is perennial. The same review describes giant kelp harvest, which cuts the upper canopy, as replaced by growth of fronds from the base. The reproductive tissue sits low on the plant and stays in place through that cut.

A bull kelp forest has to appear again. A giant kelp forest can still be last year's plants.

## where each canopy stands

[NOAA's marine sanctuaries](https://sanctuaries.noaa.gov/earthisblue/wk210-bull-kelp-vs-giant-kelp.html) describe bull kelp as the most abundant kelp in Oregon, Washington, British Columbia, and Alaska, and giant kelp as the canopy that dominates to the south. [NOAA Fisheries](https://www.fisheries.noaa.gov/west-coast/habitat-conservation/kelp-forest-habitat-west-coast) notes that both species grow in California waters, and that bull kelp is the predominant canopy in Washington waters.

Oregon and the California north coast are bull kelp water. Farther south, the canopy is more often giant kelp. The two also share shores. Where they do, bull kelp is typically on the more exposed rock, in places where giant kelp is thin (Springer et al. 2010). Count the cove for the kelp that is growing in it.

Fund the forest that is actually in the water in front of you.

## an urchin barren is not a third kelp

| | bull kelp | giant kelp | urchin barren |
|---|---|---|---|
| form | One stipe. One float. Blades on the surface. | Many fronds. A float on each blade. A stand. | Bare rock and urchins. No canopy. |
| years | Largely annual. A missed recruitment is a missing forest. | Perennial. Canopy can return from the base of the same plants. | Not a kelp. The forest that stood here is gone. |
| water | Oregon, the California north coast, and north through Alaska. | Farther south, where it dominates. Both occur in California. | The reef that lost whichever canopy belonged there. |

Purple urchins are native. A barren is the reef with the forest gone. That loss has its own page: [you don't have an empty reef. you have a missing forest](/guide/you-dont-have-an-empty-reef-you-have-a-missing-forest?from=guide).

A short run of seeded twine can be the right first tool on a cove that just went bare. [A line of twine is not a kelp forest](/guide/a-line-of-twine-is-not-a-kelp-forest?from=guide).

Mangrove, seagrass, and salt marsh [are not the same coast](/guide/mangroves-seagrass-and-salt-marsh-are-not-the-same-coast?from=guide). Kelp is a brown alga in a different water. A coral reef is an animal city. [What coral reefs actually are](/guide/what-coral-reefs-actually-are?from=guide) is that living system.

## fund the forest in the water

Bull kelp and giant kelp already grow in the Pacific nearshore. The fish, the abalone, and the otters that use them exist whether or not anyone buys a certificate. A certificate is funding tied to one named forest. [Ensurance](/coastal-resilience.syndicate?from=guide) funds the living forest. It is not the forest.

If the canopy in front of you is bull kelp, fund that canopy under its own name. If it is giant kelp, fund that canopy under its own name. The unminted line sits on the page about who already pays. This page's job is the species in the water.

[Coastal systems](/coastal-systems.ensurance?from=guide) is tidal marsh, mangrove, and seagrass. [Marine systems](/marine-systems.ensurance?from=guide) is the marine coin. Kelp is not the coral that coin sits beside.

Oregon Kelp Alliance, Reef Check, the California Ocean Protection Council, and The Nature Conservancy already work these waters. Name the species in the cove, then fund that forest.

## sources

[NOAA Fisheries — kelp forest habitat on the West Coast](https://www.fisheries.noaa.gov/west-coast/habitat-conservation/kelp-forest-habitat-west-coast) — kelps as large brown algae; one pneumatocyst on bull kelp and a pneumatocyst on each blade of giant kelp; both species in California waters; bull kelp predominant in Washington waters.

[NOAA Office of National Marine Sanctuaries — what's the difference between bull kelp and giant kelp?](https://sanctuaries.noaa.gov/earthisblue/wk210-bull-kelp-vs-giant-kelp.html) — November 2018. Bull kelp is the most abundant kelp in Oregon, Washington, British Columbia, and Alaska. Giant kelp dominates to the south.

[Springer, Hays, Carr, and Mackey (2010)](https://farallones.org/wp-content/uploads/2018/09/Ecosystem-Based-Management-of-Bull-Kelp.pdf) — *Oceanography and Marine Biology: An Annual Review* 48:1–42. One stipe and no regrowth from the holdfast; essentially annual, with some overwintering in shallow or protected water. Giant kelp is perennial and replaces canopy from the base. Where the two co-occur, bull kelp is typically on the more exposed rock.

## the series

- [what a kelp forest actually is](/guide/what-a-kelp-forest-actually-is?from=guide)
- [you don't have an empty reef. you have a missing forest](/guide/you-dont-have-an-empty-reef-you-have-a-missing-forest?from=guide)
- [bull kelp and giant kelp are not the same forest](/guide/bull-kelp-and-giant-kelp-are-not-the-same-forest?from=guide)
- [a line of twine is not a kelp forest](/guide/a-line-of-twine-is-not-a-kelp-forest?from=guide)
- [who already keeps the forest in the water](/guide/who-already-keeps-the-forest-in-the-water?from=guide)