Tropicals & Tender Perennials: Hoya macgillivrayi, F. M. Bailey -In Habitat and Cultivation, 0 by mattadeus

mattadeus wrote:
3. THE CLIMATE OF CAPE YORK PENINSULA, N. QUEENSLAND


3a. SEASONS

Being in the tropical belt of northern Australia, The Cape York Peninsula is subject to two very distinct seasons:

Wet Season: - November to April (spring and summer in the Southern Hemisphere,)
Cyclones can occur any time during the wet season and are generally responsible for frequent and massive flooding. During the wet season it is not uncommon for the rivers in the region to raise their levels up to 5 - 6 metres above normal.

Dry Season: - May to October (autumn and winter in the Southern Hemisphere)



3b. HUMIDITY

Humidity levels rise during the wetter months and decrease during the dry months when hot breezes
sweep through inland areas.

Months with Highest average relative humidity: February and March; 79% and 77%
respectively (wet season)

Months with Lowest average relative humidity: September, October and November; 67%, 66% and 67% respectively. (dry season)

Annual average relative humidity: 71.9%



3c. TEMPERATURE

Maximum average daytime temperature: occurs in October and November; 85.8F (29.9C) and 87.6F (30.9C) respectively. (wet season)

Minimum average daytime temperature: occurs in July and August; 70.7F (21.5C) and 70.8F (21.6C) respectively. (dry season)

Night time temperatures in this cooler period can sometimes drop to 53.6F (12C) to 57.2F (14C)


Average annual temperature: 79.1F (26.15C)



3d. RAINFALL

Maximum average monthly rainfall: occurs in February and March; 14.8 inches (370.6mm) and 14.8 inches (370.9mm) respectively. (wet season)

Minimum average monthly rainfall: occurs in August and September; 0.4 inches (9.6mm) and 0.26 inches (6.4mm) respectively. (dry season)

Average annual rainfall: 70.0 inches (1749.4mm)



3e INTERPRETATION OF ABOVE DATA IN RESPECT OF HOYA macgillivrayi

• The wet season is the time for maximum growth in the tropics of northern Queensland and roughly equates to spring and summer in the northern hemisphere, which is also the period of maximum growth found there.
Not only does rainfall dramatically rise in the wet season, with an average monthly high of 15 inches in the wettest months, but atmospheric humidity rises too - up to a daily average of 80%, while daytime temperatures soar to around 90F.

Conversely, the dry season which is the period of least growth, roughly equates to autumn and winter in the northern hemisphere. Average daytime temperatures in the dry season however, are never lower than 70F. The occasional night time lows of 54F would only be experienced by the plant for a few hours, after which the temperatures would begin to rise again following the sunrise.

• It is during these dryer months with less cloud cover that sunlight is likely to be more constant.

• The atmospheric humidity in the rainforests where H. macgillivrayi is found is always high, even during the cooler, dry season when the average humidity never gets below 66%. This is essential for the well being of this epiphytic plant, which exists with its roots often exposed and clinging to the bark of the host tree. In drier atmospheric conditions, these roots would inevitably dehydrate and die, eventually leading to the death of the plant itself

• The leaf litter and other detritus collecting in the angles of branches and the crevices of rocks into which this Hoya roots, is open and fibrous in structure, affording sharp drainage and allowing air to easily penetrate to the roots growing through it. It is mildly acidic and is generally low in nutrients, mainly because of the leaching effect the rains have, especially during the wet seasons. These nutrients are supplemented to a small extent, by weak solutions washed down from the branches above, from sources such as bird droppings and other decomposing organic matter.

Image is of :H. macgillivrayi ‘Mt Tozer rock face, Iron Rnge, Qld ' ML 0278