Standing up for the strawberry guava: The hiker's kind of tree.

"Stawberry guava" has become somewhat of a "four letter word". It's not considered
politically correct to like strawberry guava trees, because they're an invasive species (from South America) that spreads rapidly on the islands in wild pig poop. However, I have yet to meet someone that don't take absolute delight at eating fresh fruit from the hundreds of trees that line several of the trails on Oahu; what a joy they are!

Native forest and watershed restoration projects in the Ko'olau mountains make a point of trying to not only halt their progressive spread, but also to eradicate existing populations. Various state- and federal governement and other conservation agencies have tried applying toxic chemicals, and looked for bugs that could eat them. They've found a bug from South America (a Scale) that apparently can't kill the guava (there's nothing that can apparently), but the bug will slow it down. There has been opposition the Big Island against introducing yet another foreign bug into Hawaii's native ecosystems, but the conservationists say it won't evolve to bother native trees. As a side note, the reason is because it takes thousands to millions of years, according to them, for such an evolution to happen. Which means that it will eventually happen, and maybe even faster than they can predict. But I think the legislation may have passed, I can't remember. Anyway, the opposition consists of hunters, woodcrafters, ecologists and I assume some native Hawaiians. The State says that the bug won't eradicate the guava, only slow it's growth, to give natives a chance to fight back. However, I've seen documents that suggest that with the slow down, it'll be easier to eradicate and permanently extract them, so I choose to assume that they will try to kill it all as much as they can.

I was baffled by this hard-line approach, so I tried to figure out what the deal was. Why do they hate the strawberry guava THAT much. What I found was that allegedly, strawberry guava trees suck up more water out of the ground than native vegetation or something to that extent; hence less water ends up in the groundwater system that supplies the islands with water. This by itself is a serious matter, if true, so I can understand the need to keep them out of the high altitude rainy summits of the mountains. I also imagine that several native fauna rely on native vegetation to survive, and of course, we want to preserve the islands as much as possible. And ofcourse, I truly love the native fauna and flora as much as the next hiker. Except that bitchy, stinging, super fly/wasp thing that lives on the summit of Wailupe--man what's its problem?!

Having expressed my love fo the natives, I just can't bring myself to support guava eradication, everywhere. Tasty snacks aside, these trees appear more hardy and survivable against pests (based on my own observations). I have been to very remote ridges where uluhe ferns grow interspersed with native Ohia trees, and the Ohias are all dead. Not a strawberry guava in sight. What there is, however, are ANTS. These days it seems there literally isn't a spot in the wilderness of Oahu that does not teem with red ants. Try it yourself—go hike and look at a tree branch for a while, or on the ground. Some places you can't even sit down for a rest! I suspect that these ants are somehow killing the native trees. While this sounds weird, you see tons of ants on, and inside, the dead trees. In extreme cases, I have noticed that strawberry guavas are also affected, but more often the strawberry guava will be standing when the natives are dead. The importance of this resilience lies in fighting soil erosion and promoting water capture to the ground water system. Even though strawberry guavas suck more water than natives, when the natives are dead, the guava will still allow some water to filter into the ground, as opposed to running on the bare unvegetated surface and ultimately into the sea. Soil erosion takes readily place where there is no vegetation, and when the fertile soil erodes, it is difficult for anything to grow in large numbers. Not to mention that soil erosion would degrade our hiking trails and make the narrow ridges even more precarious to hike! I think the roots of the dense guavas do a good job in binding the soil below the surface.

Also, I think without strawberry guava trees, many hiking trails we have here, would not be hikeable to the extent they are now; some might even be completely unhikeable. There are many steep ridges and offtrail sections where stands of strawberry guava provide the only means of ascent or descent, because they provide something to grip on to pull you up, or prevent your fall, on the mountain. Any hiker who has tried to climb a steeply eroded slope vegetated by only uluhe, knows this to be true. The guava trees thus provide an access route of sorts that facilitate the  exploration of higher elevation native-vegetated sections.

To conclude, without the strawberry guava, hiking in Hawaii would be much more difficult, unsafe, less enjoyable, and the ground water supply might even be in more trouble (in my opinion). I support the eradication of these trees outside the highest rainfall, high elevation areas in the Ko'olaus, through the eradication/containment of wild pigs that spread their seeds. But given the joy they've brought me out in nature, I don't want to see them completely eradicated.

Anyway, my 2 cents. Leave some comments!
Aloha! 

[--Feb 2015]

Above photo: Invasive versus native...a difficult balance to keep: Looking towards the summit direction on top of a ridge. A dead Ohia lies between a guava forest and Uluhe ferns. The Ohia is dead, maybe from ants. The trail through the Uluhe has not been maintained for 1 year. It is almost completely reclaimed by the tangled, scratchy uluhe. On the other hand, the ground under the guava is clear, and you can freely hike through it. This trail is not officially maintained, and few hikers would ever be able to hike it if it weren't for the guava keeping parts of the ridge hikeable. While the guava also becomes more dense within the forest, it does not do so as fast as the uluhe.  In another year, this portion of the uluhe trail will be completely reclaimed and you'd have to spend several days with several people to open it up again. Sadly, too few hikers invest their time into that kind of goodwill.

Above photo: A dead tree fallen onto a trail. The light brown patches are invested by red-brown ants. Maybe they killed it. If only the conservationists would target the ants!

Above photo: A steep hill being overtaken by strawberry guava. Dead Ohias standing in uluhe in the foreground. Bright green uluhe interspered within darker green strawberry guava and native Kopiko. The guava makes this ridge hikeable, allowing you to enjoy the peace and quiet of the wilderness, and you get to see some of the native vegetation. We should strive for a balance between the two!

Above photo: The best time of the year to be hiking. Strawberry guava season!