HONOLULU (KHON2) -- Invasive plant species have a long history in Hawaiʻi. Over the years, many non-native plants were introduced to the islands, either intentionally or accidentally.
These plants often outcompete native species, leading to significant ecological changes. It's crucial not to simply remove these invasive plants but to find ways to help native species thrive despite their presence.
One such native species is the ‘ōhi‘a tree, which plays a vital role in Hawaiʻi's eco- and watershed systems.
Dr. J.B. Friday, an Extension Forester with the University of Hawaiʻi Cooperative Extension Service, sat down to talk story with KHON2.com. He has extensive knowledge about ‘ōhi‘a trees and their importance.
In our walaʻau, he shared valuable insights about how these trees can help mitigate flash flooding and support Hawaiʻi's water systems.
Dr. Friday began by providing some historical context.
“The big deforestation started before the plantation era, mainly during the whaling era. Whalers needed wood to boil whale oil, so there was a big market for firewood,” he explained.
This deforestation was further worsened by unmanaged livestock farming, which led to significant watershed degradation and flooding, especially in Honolulu.
Hawaiʻi was ahead of its time in conservation efforts.
“The Hawaiian Kingdom was doing forest conservation and replanting as far back as the 1870s, well before such efforts were common on the mainland,” Dr. Friday noted. This early awareness of the importance of forests set the stage for modern conservation efforts.
The ‘ōhi‘a tree, in particular, is crucial for Hawaiʻi’s ecosystem. These trees help capture and store water, which is vital for the islands' aquifers. Aquifers are underground layers of water-bearing rock that provide fresh water to the islands.
“We want less water running off the land and causing erosion and silting our reefs. More water needs to sink into the ground and recharge aquifers,” Dr. Friday explained.
However, protecting existing forests is easier and more cost-effective than restoring them after they have been destroyed.
“Think of the forest like your health. It’s easier to maintain good health than to try and regain it after losing it,” Dr. Friday said. This analogy highlights the importance of proactive conservation efforts.
Urbanization adds another layer of complexity to the issue of flooding. “Urban areas with blacktop and cement prevent water from soaking into the ground. This significantly contributes to flooding,” Dr. Friday said.
While reforestation can help, engineering solutions are also necessary to address the specific challenges of urban areas.
Climate change has increased the frequency of extreme weather events, making it even more important to address both environmental and engineering aspects of water management.
“With climate change, we’re getting more heavy rain events. There’s nothing on earth you can do to make the land absorb that much water during these extreme events,” Dr. Friday pointed out.
Engineering solutions, such as larger culverts, are necessary to manage the water from these heavy rainfalls.
Dr. Friday also mentioned the need for collaboration between environmental scientists and civil engineers.
“Solving these issues requires an amalgamation of environmental and civil engineering approaches,” he said.
By working together, these experts can create comprehensive solutions to manage regular and extreme weather flooding effectively.
To further understand where efforts should be focused, Dr. Friday referred to maps created by the U.S. Geological Survey. Click here, here and here to view for yourself.
“These maps show where aquifer recharge occurs, which is crucial for planning conservation and reforestation efforts,” he explained. The maps highlight areas like the Ko‘olau Mountains on Oahu, where the majority of aquifer recharge happens.
Dr. Friday shed light on the critical role of ‘ōhi‘a trees and other native species in Hawaiʻi’s ecosystem. Protecting existing forests, replanting where possible, and integrating engineering solutions are key strategies in mitigating flooding and preserving Hawaiʻi’s natural resources.
By understanding and acting on these insights, we can work towards a more sustainable and resilient future for Hawaiʻi.
Dr. Friday's insights underscore the importance of proactive conservation efforts and the need for collaborative solutions to address environmental challenges.
Ongoing conversations about environmental protection can lead to significant positive changes for Hawaiʻi and beyond.