Na Pohaku o Hauwahine

Nā Pōhaku o Hauwahine

INTRODUCTION
Seasons

Seasons in Hawai‘i

End of the wet season

SECTIONS

There are only two seasons in Hawai‘i: a wet season (November through April) and a dry season (May through October). On further reflection, however, we could say there are only two real seasons on the mainland: summer and winter. Spring and fall are transition periods between the cold and hot annual extremes in weather. And so it is here: April/May are transition months between the wet and dry; October/November a transition from dry to wet conditions. We do not call these transitions spring or fall, repectively, because the changeover is subtle in comparison with places where the difference between summer and winter (particularly temperature)is far more substantial. Spending time at Nā Pōhaku teaches us just how different—from a plant's perspective—the seasons are in Hawai‘i. Or at least used to be. No doubt we can still count on our "winter" months to deliver the majority of our rainfall. In the last two years (2011-2012) we have seen somewhat wetter than expected "summer" months and maybe less rainfall in the wet season.

Latest Monthly Rainfall Totals (inches) at Nā Pōhaku:

	-= 2014 =-
DECEMBER
NOVEMBER	3.80
OCTOBER	7.23	DRY SEASON = 15.45
SEPTEMBER	1.54
AUGUST	1.64
JULY	0.89
JUNE	1.31

End of the wet season at Nā Pōhaku

April 2011, April 2012—The progression of low pressure storms drifting from west to east across the vast Pacific Ocean have slowed in their intensity, or at least in their influence on Hawai‘i. The storms are now generally milder (surf is going down on the North Shore) and are further north, drawing less moisture up from the tropics. Consequently, rainfall is diminishing. Of import with respect to the plants is the lengthening daylight. With adequate soil moisture and longer days, the plants—both native and non-native—have reached an annual zenith in leaf production, and for many this is the time of flowers and ripening fruit. Oddly, the monkeypods have lost most of their leaves (2011), temporarily reducing their harmful shading of misplaced plantings beneath their broad canopies and, presumably, their withdrawal of moisture from the ground.

The really troublesome weeds—Chinese violet, Guinea grass, white shrimp plant, amaranths—are also in full vegetative expansion and seed production. Over the last several months of 2011, we have fallen steadily behind in weeding; areas that were completely cleared of weeds and planted to natives this last wet season are now overgrown with weeds. In some areas, it is unclear if the new plantings are still present. Places of moderately dense native growth are likewise infested, but the natives here are holding their own. With diminishing effort at adding new plantings (the ground will be drying out soon) we shift our focus to weeding, weeding, and more weeding. As we end the wet season in 2012, we have clearly managed this year to keep well ahead of the weeds in almost all areas, aided by Waimea directing the WCCC crew<1> and, possibly as well, by a drier than usual late wet season.

June 2011—I had no intention of writing this section in diary or blog mode, merely to let recent experiences reflect what we do at different times of the year. However, this June has been so unusually wet (see sidebar) that our ability to make progress with dry-season weeding has been seriously challanged. The site has received nearly 6.3 inches of rain this month alone, an amount that would typify a wet season month. While one consequence is enhanced growth of the mature natives (the trees have shown no propensity to shed leaves), the weeds in the soil seed bank are germinating and crowding out natives planted but a few months back. Normally in June through September we would be clearing non-natives from around all the plantings, comfortable in our belief that throughout the dry season these cleared areas would remain more or less weedless. Also, we would be prepariung new areas for planting in the next wet season. Instead, the small NPG crew has been overwhelmed and many of the newest planting areas may be in jeopardy of losing those natives unable to keep up with the Guinea grass, white shrimp plant, and Chinese violet.

Monthly Rainfall Totals (inches) at Nā Pōhaku:

2010-11 WET SEASON = 40.24
2011 DRY SEASON = 14.15
		2012
	JANUARY	0.40
	FEBRUARY	1.34
	MARCH	>10
	APRIL	~0.64	WET SEASON = >16.55
	MAY	0.39
	JUNE	1.14
	JULY	1.37
	AUGUST	0.39
	SEPTEMBER	1.52
	OCTOBER	0.51	DRY SEASON = 5.32
	NOVEMBER	0.69
	DECEMBER	0.82
		2013
	JANUARY	2.34
	FEBRUARY	4.76
	MARCH	~1.75
	APRIL	1.96	WET SEASON = 12.32
	MAY	2.57
	JUNE	2.11
	JULY	0.76
	AUGUST	3.66
	SEPTEMBER	1.98
	OCTOBER	2.93	DRY SEASON = 14.01
	NOVEMBER	3.14
	DECEMBER	3.62
		-= 2014 =-
	JANUARY	3.53
	FEBRUARY	7.00
	MARCH	~3.55
	APRIL	1.56	WET SEASON = 22.40
	MAY	2.84
	JUNE	1.31
Monthly totals derived from raingage readings made once a week on Saturday.

PAGE NOTES:

Note <1> –Moved temporarily from CB-directed weed-whacking and attendant harm to native plantings, to a useful conservation effort of removing dense Guinea grass stands. Mahalo WCCC crew!