The final days of the state’s last sugar plantation punctuates the close of a long-lived, influential industry in Hawaii. It shaped immigration policies and labor law and ultimately served as the dominant thread in the society woven together from a diverse population.

The closure of Hawaiian Commercial &Sugar Co. — after its last 36,000-acre harvest operation Monday at Puunene, Maui — allows an end date to be inscribed in the Hawaii annals. But this merely completes a decline that began decades ago, when the world economics of sugar cut into the competitiveness of the U.S. product.

That’s why it’s distressing that so much uncertainty clouds the future of the lands formerly dedicated to sugar. Acreage should be kept in agriculture to enable Hawaii to secure supplies of food, as well as energy: Some of that land should be used for biomass or biofuels development.

The concern arises with many proposals for the use of land — and water. The state Board of Land and Natural Resources, weighing a request from Alexander &Baldwin Inc., the parent company of HC&S, last week voted to grant a conditional one-year permit allowing A&B to continue diverting water from some streams in East Maui.

It’s a sorely contested issue in Maui, especially among farmers who say the diversion has affected the cultivation of taro. Sugar is a thirsty crop, which is why water was reserved for the sustenance of a critical industry, but with its departure, environmentalists have joined farmers questioning why A&B should retain its claim on a precious public resource.

Some of the deference the land board has accorded A&B is defensible on the basis of its sheer longevity on Maui. The first plantation was established near Makawao in 1870, and the company went on to become one of Hawaii’s “Big Five” anchor firms.

But that indulgence does not justify continued extensions of the permit, which should remain limited, at least until the point where A&B actually produces a business plan for continued agriculture.

Company executives repeatedly have underscored that A&B is studying future agricultural uses for its land and has test crops in the ground. It should be time soon to scale up whichever of these crops shows the greatest promise.

The company website chronicles the growth of the sugar industry, noting that in 1876 Samuel Thomas Alexander and Henry Perrine Baldwin were expanding their holdings and soon were irrigating their fields with water from the windward slopes of Haleakala.

The A&B board included men with surnames such as Cooke and Castle as well as the founders. These are names threaded through the chronicles of Hawaii.

A&B may have been the last sugar grower in the state; among the first was a plantation in Kauai, which eventually became the property of George Norton Wilcox, a son of missionaries. These were industrialists who pursued various means of developing Hawaii’s natural resources.

It necessitated a labor force, which brought in immigrants from Asia and the Pacific, people whose origins defined what is “local” about Hawaii. The plantation work ethic and its culture of cooperation became the core of the organized labor movement, which further shaped Hawaii law and politics.

Initially the sugar plantations ruled with an iron fist, bringing in a surplus of labor in order to keep the workers compliant. But a series of strikes culminated in the creation of a work force that, newly empowered, realigned the state’s political power structure.

That effect persists to this day. And looking forward: The final page of the story of sugar in Hawaii now has been written, but its echoes will resonate for years to come.