Kaua`i Field Notes Note: This is an experimental system that is designed to explore an alternative way for students to take field notes.
Devised and prototyped by K. W. Bridges based on field trips led by Mike Huddleston, Brian Yamamoto and Ron Beecham. Please note that the stories used in this example are not necessarily the most accurate, the most current or the most important information provided to students on these field trips.
These notes provide background information for a field trip to Waimea Canyon and along the Pihea Trail. They also provide a vehicle for a student to record observations. There are three purposes for these field notes. ● Each student gets a preview of the important things that are likely to be seen and a brief story about each one. ● The format allows a student to add text and (especially) photos to illustrate each story. ● The assembled text and illustrations allows a student an opportunity to review what she has seen on the field trip. Where possible, a student should use her own photos to replace those which are provided in these notes. It won’t be possible to photograph all of the materials described here; flowering season, weather, available time and a few other ad hoc reasons limit what can be seen. Each student should also add text that enhances the stories told in the field and which come from her own observations. Adding new stories, along with illustrations, is also important.
A specific format is used in each of the stories. It is called the “assertion + evidence� style. Assertion: This is a short statement written as a single complete sentence. This appears at the top of each story. Evidence: There are two parts to the evidence. A short description is given first. This is accompanied by photographs or diagrams that illustrate the point of the story. Together, the assertion and evidence document important points in concrete ways. In addition, some stories are accompanied by comments that are intended to provoke further consideration of the story. This style should be used as the notes are enhanced with new observations and additional stories. Note that the order of the stories is not critical.
Knowing the names of places and their geographical relationships provides needed orientation. This map provides some, but not all, of the places that will be visited.
Credit: encounterkauai.com
The island of Kaua`i is a shield volcano that was formed by eruptions from the “hot spot.� The island is a shield-shaped volcano that was formed as it passed over a fixed hot spot where magma comes to the surface. This happened about 5.1 million years ago. The Pacific Plate continues to move and carry the island to the north-west.
Movement of the Pacific Plate over the “hot spot�
Pacific Plate Mantle
The shape of Kaua`i is the result of slow geologic processes. The volcano is smaller now due to subsidence (sinking) and erosion. In addition, there is evidence that there have been two or three massive landslides. The landslides on the north side of the island have produced the striking cliffs. The landslides on the south side removed part of the island and has also redirected the drainage pattern. The result is Waimea Canyon.
Kaua`i is the 4th largest of the eight main Hawaiian islands. Kaua`i is about 33 by 25 miles. The total area is about 552 square miles. Waimea Canyon is about 10 miles long. The highest peak is 5,148 feet (Kawaikini), about 1 mile south of Wai`ale`ale.
Kaua`i, viewed from the south; 3X exaggeration Credit: Google Earth
Waimea Canyon shows a long history of erosion. The shield-shaped volcano that created the island had a large caldera that collapsed. The caldera was 10-12 miles across. The caldera then filled with new lava where it ponded in horizontal layers. These events have shaped the island by redirecting the flow of streams.
Credit: M. Huddleston
The Alaka`i Swamp is perched high in the mountains. The Alaka`i Swamp is a prominent feature of Kaua`i. This wet area extends out to the NW and forms a plateau that is about 9 miles long and 2 to 3 miles wide.
After Van’t Woundt and Nelson, 1963.
There is a pronounced rainfall gradient across Kaua`i. Mount Wai`ale`ale, at an elevation of 5,080 ft, has a measured median annual rainfall of 466 inches (about 39 ft) and a maximum of 624 inches (52 feet). The wettest area, the Alaka`i Swamp, has about 200 inches of rain each year. The coast, about 19 miles to the west of Mt. Wai`ale`ale receives only about 25 inches of rain each year. That is a decrease of almost 25 inches per mile.
Rain crosses the forest near Mt. Wai`ale`ale Credit: M. Huddleston
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You pass through major ecological zones as you go up in elevation.
Dry air cools at the rate of 5.5 F for every 1,000 feet of elevation increase. This is called the “adiabatic lapse rate� and it allows you to calculate how much cooler the air will be as you go up a mountain. Combine the different air temperatures with different amounts of rainfall and you get distinctive ecological zones.
Three common species of native plants have a wide elevation range. Styphelia, `Ĺ?hi`a (Metrosideros), and Vaccinium can be found from near sea level up to high elevations in the mountains. This demonstrates that these species have a wide ecological amplitude.
Styphelia tameiameiae (Family Ericaceae) is now considered to be Leptecophylla tameiameiae
Styphelia tamehameha
Credit: M. Huddleston
Fruit Credit: K. Bridges
Metrosideros polymorpha Some growth forms Credit: M. Huddleston
Credit: K. Bridges
Seed pods Vaccinium reticulatum leaves & seed pods Credit: M. Huddleston
Credit: M. Huddleston
The leaves of an `ohi`a tree are often very different than those of a neighboring `ohi`a tree. The name of the species, Metrosideros polymorpha, gives a first hint of its morphological plasticity. Leaves with different shapes and surface textures provide different benefits to the tree.
Smooth Leaves
Pubescent Leaves
Credit: M. Huddleston
Credit: K. Bridges
Adult `Ĺ?hi`a trees come in many sizes. You can find huge adult Metrosideros polymorpha (Hawaiian: `Ĺ?hi`a) trees in the forest. In bogs, the adult trees can be small. In both cases, you recognize that they are adult plants by seeing them with their characteristic red flowers. Family: Myrtaceae
Tiny `Ĺ?hi`a adults in a bog Credit: M. Huddleston
Large `Ĺ?hi`a at the Kalalau Overlook Credit: K. Bridges
Adult koa trees have sickle-shaped “leaves.” Acacia koa (Hawaiian: koa) is one of the dominant trees in Hawai`i’s forests. Young koa trees have bipinnately compound leaves with 12 to 24 pairs of leaflets. At about 6 to 9 months of age, thick sickle-shaped “leaves” begin to grow. These are thickened expansions of the leaf petiole, called a “phyllode.” Family: Fabaceae The flowers are pale yellow spheres, about ⅓ inch in diameter. The species is endemic to Hawai`i.
Adult Koa “leaves” and seed pods
Koa Flowers
Credit: M. Huddleston
Credit: K. Bridges
The spread of Lantana is has been reduced by using biocontrol. The alien plant species Lantana camara was introduced to Hawai'i in 1858. It spread quickly, forming dense stands. This is the first plant species subjected to biological control by any government agency. Over two dozen biocontrol species have been used. Several are effective but there are still areas with Lantana infestations. Family: Verbenaceae
Photo to be inserted: Lantana
The silversword alliance is an example of adaptive radiation in Hawai`i. A single immigrant to Hawai`i has given rise to over 50 species. These include the silverswords and greenswords of Maui and Hawai`i. On Kaua`i, there are two species of Wilkesia (iliau). Family: Asteraceae (sunflower) The more common iliau species is Wilkesia gymnoxiphium. The iliau blooms only once at the end of its life cycle, around 7 years. The blooming often occurs in June and July and it can be spectacular.
Flowering iliau plants Credits: K. Bridges
Soil erosion is one of the threats to the native iliau plants. A number of endemic plant species occur in small populations, sometimes with only a few hundred individuals found in a small area. Environmental change, such as erosion, can put these populations at risk. The relatively small populations of Wilkesia gymnoxiphium (Hawaiian: iliau) populations are found in only a few areas on the west side of Waimea Canyon.
Iliau on a heavily eroded slope Credit: M. Huddleston
Soils form distinctive layers. The layers, often called the “horizons,� start at the surface as the O-layer. Below that are the A and B layers. The parent material is below these weathered layers. Most of the plants are rooted in the O-layer which consists of weathered soil and organic matter, such as the decomposing leaves of the vegetation.
To be supplied: Photo of soil horizons
The Iliau Nature Loop is a refuge for the endemic Wilkesia. Most of the iliau are found inside the 0.3 mile loop trail. A few Wilkesia are also seen on the outside of the trail and on the steep slopes of Waimea Canyon. There are a few other locations with this species, but the Nature Loop is where the abundance is highest.
Greenswords stand out in the Iliau Nature Loop Credit: M. Huddleston
Sandalwood trees are hemiparasitic plants that are no longer common in Hawai`i’s forests. Trade in sandalwood from Hawai'i to China was vigorous between 1814 and 1830. Heavy logging and fires ravaged the forests. Some sandalwood trees survive in less accessible mountain areas. Santalum paniculatum are parasites on their host plants, but they also use photosynthesis to some degree. Family: Santalaceae
Sandalwood with emerging flowers Credit: M. Huddleston
Several Scaevola species have evolved in Hawai`i. The beach naupaka (S. taccada) is found throughout the Pacific. The other nine Scaevola species found in Hawai`i are endemic. The two species which are often found in the Kaua`i forests are S. glabra and S. gaudichaudiana. The flowers have a characteristic of looking like a half-flower. Family: Goodeniaceae.
Credit: K. Bridges
Credit: M. Huddleston
The endemic mint is a member of a a group that shows adaptive radiation. Stenogyne purpurea plants are semi-woody, branching vines. This mint species is found in Kaua`i’s wet forests. The large, purple, tubular flowers suggest that they were once pollinated by native honeycreepers. Family: Lamiaceae The Hawaiian endemic species lack the aromatic defenses which are characteristic of mint species elsewhere. There were about 61 species in four genera which were derived from a single immigrant ancestor.
Credit: K. Bridges
Credit: K. Bridges
The Pihea trail follows the ridgeline about 4,000 feet above Kalalao valley. Erosion has carved bowl-shaped valleys that feature steepsided cliffs. Most of these valleys were once inhabited by Hawaiians. Clouds often form above Kalalau valley. The valley itself is about 2 miles long and 0.5 miles wide.
Trail at the crest of Kalalau Valley
Credit: K. Bridges
Kalalau Valley & the ocean beyond
Credit: K. Bridges
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The view from the Pihea trail toward the Alakai shows the native forest with areas invaded by Kahili ginger. The view toward the east from the Pihea trail shows mostly `Ĺ?hi`a trees (Metrosideros polymorpha). There is a dense patch in the valley of Kahili ginger (Hedychium gardnerianum) plants (lighter green). This is an aggressive invading species.
Credit: B. Yamamoto
Ornamental Hydrangea are planted in Kokee. There is an endemic Hydrangea species in the forest. Family: Hydrangeaceae Hydrangea flower heads come in two forms. The “mophead� flowers look like pom-poms. The other flowers are round and flat. Ornamental Hydrangea with mophead flowers are commonly planted in gardens. The endemic Broussaisia arguta, with round flat flowers, is found in the mesic and wet forests of all main Hawaiian islands. Plants have either male or female flowers.
Mistletoe is another hemiparasite. There are several Korthalsella species growing on host trees on Kaua`i. Family: Viscaceae? (now Santalaceae?)
Strap-like form of local mistletoe Credit: M. Huddleston
Credit: M. Huddleston
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The Hawai'i greenbrier is an endemic climbing vine.
There are few vines among the plants in Hawai`’s forests. Smilax melastomifolia is one of the woody vines. This species is endemic to Hawai`i. Family: Smilacaceae There is considerable starch in the roots. This may have been a famine food for early Hawaiians. The name “Smilax” comes from the Greek word meaning “rasping.” This could refer to the prickles on the stems and leaves of many Smilax species.
Credit: K. Bridges
Aerial roots can be seen on some `Ĺ?hi`a trees. Aerial roots are those which originate on the trunk or a stem and which do not reach the ground.
Photo to be inserted: Aerial roots of Ohia
Kahili ginger is an invasive species that presents a danger to the native plants. The alien Hedychium gardnerianum is a widely cultivated ornamental plant. It is very destructive in Hawai`i’s forests as its dense growth covers other plants. These plants form dense patches as they spread by the growth of their large rhizomes. New areas are invaded when the seeds are dispersed by birds. Kahili ginger is listed as one of the World's 100 worst invasive alien species. Family: Zingiberaceae
Credit: M. Huddleston
Sundew plants are adapted to nutrient-poor soils. The sundew species found on Kaua`i is Drosera anglica. This is a widespread species that grows in northern areas around the World. In Hawaii it is only found on Kaua`i in bogs. This small plant has leaves that excrete a viscous fluid which traps insects. The insects provide phosphorous and nitrogen that is otherwise limited in the acidic bog. A leaf curls around an insect when it is trapped. Family: Droseraceae
Credit: K. Bridges