The high-elevation northeastern slopes of Haleakalā Volcano are home to some of the most remote and undisturbed forest ecosystems in Hawai‘i. These ecosystems are dominated with native vegetation, insects and bird species. Early Hawaiians did not use these high- elevation lands extensively (Burney et al., 1995) and current conservation efforts put forth by Haleakalā National Park and the Hawai‘i State Natural Area Reserve (NAR) have focused on reducing the spread of invasive species and protecting rare and endangered species in these areas (Loope et al., 1992). In August of 2005 a network of 12 climate stations was established to extend westward from HaleNet and to integrate with 134 permanent vegetation plots established from 2003-2006 on the northeast slope of Haleakalā Volcano (Figure 49; Crausbay and Hotchkiss, 2010). The climate stations (referred to as “Little HaleNet”) range from ~1980 m to ~ 2315 m in elevation and create three elevational transects from the Northeast Rift to Pu‘u Alaea. Each elevational transect consists of one station in the alpine grassland and three stations that bracket the upper cloud forest limit. The climate stations are equipped with instrumentation to measure precipitation (established 2005), soil moisture (established 2007), air temperature (established 2008), relative humidity (established 2008), photosynthetically active radiation (established 2011) and soil temperature (2005-2008). Vegetation plots are arranged along nine elevational transects and represent points within the upper ~300 m of cloud forest and ~ 300 m immediately above the forest line.

Little HaleNet climate network on the eastern slope of Haleakalā Volcano.

The Little HaleNet climate network has been used to: 1) create climate maps that describe spatial pattern of climate during strong El Niño and La Niña events relative to neutral climate (Crausbay et al., 2014), 2) identify the changes in plant species assemblage and structure due to changes in moisture (Crausbay and Hotchkiss, 2010), and 3) model the strong relationship between the cloud forest’s upper limit and humidity during strong El Niño events and to determine the relationships between cloud forest species assemblage and mean rainfall (Crausbay et al., 2014). The close spatial proximity of the climate stations along their respective transects provides essential information regarding variations in microclimate in relation to the cloud forest boundary. A recent study Gotsch et al. (2014) concluded that the microclimates along these transects affect stomatal conductance and transpiration of the dominant native species (ōhi‘a lehua, Metrosideros polymorpha) found there. The data obtained from Little HaleNet was integrated with data obtained from HaleNet station HN-162 (2260 m), which is located within the Little HaleNet domain, and HN-161 (2460 m) and HN-164 (1650 m) which are above and below Little HaleNet, respectively.

Sea-level rise (SLR) is the greatest future threat that intact Pacific island mangroves face. The loss of mangroves on Pacific Islands will have huge consequences on human populations that live on these islands as they rely heavily on mangroves for food, fiber, and fuel. Mangroves also protect human lives and coastal infrastructure from typhoons and tsunamis as well as flooding from king tides. The large amounts of carbon stored in mangrove sediments provide an important nature-based solution for climate change mitigation and adaptation. Mangroves have survived past increases in SLR by maintaining their forest floor elevation relative to sea level through root growth and sediment accumulation. Will mangroves continue to keep up with increased SLR rates predicted to occur over the next century and in the presence of human activities (e.g., deforestation, altered hydrology) that impede mangroves’ ability to pace SLR? Working together to monitor mangrove responses to rising seas in existing and new sites across PACMAN will provide this information, which can then be used by resource managers to more effectively conserve or restore mangroves that are resilient to SLR. More resilient mangroves can then continue to provide the goods and services vital for Pacific Islander existence.

Remote Automated Weather Stations () are weather stations set up on tripods, and they look like little “Lunar Landers.” The data collected from these stations are used in numerous applications, including fire weather, climatology, resource management, flood warning, noxious weed control, all-risk management, and air quality management. These solar-powered units gather important weather information on an hourly basis. 

RAWS sensors monitor: • Wind speed and direction 

• Wind gusts 

• Precipitation 

• Air temperature 

• Solar radiation 

• Relative humidity 

• Fuel moisture 

• Soil moisture and temperature

About 1,850 RAWS are strategically positioned throughout the United States. RAWS units collect, store, and forward data hourly (via satellite 22,300 miles above the equator) to a computer system located at the National Interagency Fire Center, Boise, Idaho. Weather information travels from the RAWS units to a satellite and then back to earth in one-quarter of a second. Each RAWS unit operates on eight to 10 watts of power, which is nearly equivalent to the power needed to operate a hand-held radio. The battery lasts about three years.

The long-term goal is to establish large-scale, permanent plots in native-dominated forest across elevation and precipitation gradients throughout the Hawaiian Islands. Long-term forest dynamics plots have been established worldwide; these plots establish Hawai’i as part of the network.

Of the eleven stations that once operated in the HaleNet climate network only eight are still in full operation (blue circles in the firgure above).  The Waikamoi station (HN-142) which was only erected on a temporary basis was removed in August of 2003. The Horseshoe Pu`u station (HN-163) at 1960 m elevation was badly damaged in 1996 by lightning and high winds and is no longer recording data.  The Pu`u Pahu station (HN-106) at 1650 m elevation was vandalized in 2003 and now only collects rainfall data. The entire Network has a vertical coverage 810 m (1650 – 2460 m) and 2030 m (960 – 2990 m) along the windward and leeward exposures respectively

The complex topography of Haleakalā interacts with atmospheric circulation to produce some of the most spatially complex rainfall patterns in the world.  Desert-like precipitation minimum zones and extreme wet conditions can be found within a few tens of kilometers distance

The 11 HaleNet stations still in operation are equipped with instrumentation that monitor: the upward and downward components of short and long wave radiation, net radiation, surface air, surface temperature, soil temperature,  wind speed, wind direction, relative humidity, soil moisture and precipitation. These variables can also be used to calculate, soil heat flux, vapor pressure deficit and potential evapotranspiration.