LMC in the World: Saguaro National Park

First let's start with pronunciation because someone had to tell/correct me when I was talking about including this on my road trip. It sounds Spanish to me because the g is silent. It sounds like sawah-roh to me when people there said it. It refers to the Saguaro cactus which are protected and really were the purpose of the park. These are the really tall cacti with the arms - the quintessential desert scene or decoration seems to have these. They are native to the Chihuahuan Desert that runs across the southwest USA and northwest Mexico.

The land was first created as a National Monument and became a park much later. I'm not positive of the difference but I think a park gets more funding than a monument. There is an east and west park. The west park came later when locals were concerned that saguaros in the original park were dwindling. These parks are on either side of Tucson, AZ, the west being in the Tucson mountains and the east being in the Rincon mountains.

These cacti are like crazy old desert trees (my way to relate to them since I'm not from the desert). I actually thing they have very similar lives to trees but in their own ecosystem. The seeds are quite small and come from the fruit of the cactus. They are super slow growing. It may take 5-10 years for it to grow an inch. This makes them very fragile in the beginning stages of life. The large ones you see with the big arms may be 150 years old! When the land was still a monument, cattle grazing was practiced. Cattle are huge and don't mind their steps for little pin cushions trying to grow. The small cacti can only grow when it rains because they haven't yet developed the water retention systems inside themselves to sustain growth when there's no rain. When it only rains 8" a year or so, there's not much time to grow. The seeds tend to take hold underneath other small trees and shrubs that will provide some shade and protection. The cattle grazing in the east side of the park took out a generation of saguaro. Thus the introduction of the west park and the end to cattle grazing.

Once the cacti get a little bigger, they can store water better and continue to grow throughout the year, so the process speeds up a little. Cacti don't flower until 30-50 years. The park does growth surveys to measure the growth rates (there are no growth rings like trees). In the east park there is slightly more rain and those cacti first flower at 30/35 years. In the west with less water, they take 50/55 years. They definitely seem a bit temperamental when it comes to weather. Other desert systems can't support the cacti because it is either too hot and dry or gets too cold. Here's one that is likely around my age.

The saguaro cacti flower in May and the flowers appear on the very tops/ends of the main column and/or arms. There could be just one or twenty, it varies. The flowers are white and open at night, maybe around 10pm. Then they stay open a set amount of time so I could see them still open in the morning. Bats that eat nectar help to pollinate the flowers at night. However there aren't enough bats to do all the work, so lots of birds will work during the day to stick their head in and get some nectar, which puts pollen all over their heads for the next flower. Then a fruit grows. The fruit is a red flesh with tons of little black seeds. Tons of animals are fed by the fruit - basically anyone in the vicinity. It's very sweet and local Indians harvest them to make a syrup and set aside a little to make wine for a planting or harvest festival. Coyotes even eat the fruit. They know because they will find coyote scat that is purely made up of saguaro seeds. Then ants will come and carry it away seed by seed. If they take it to a nursery plant (tree or shrub that provides shade and protection), soon (well, actually not that soon) you have a new saguaro cactus.

Buds forming.

One of the flowers.

Harder to see, but there's a bird neck deep in one of the flowers at the top.

Flowers grow on the ends of arms no matter how the arms grow. Usually they are all too high for me to see down into the flower, but this one was very accommodating :).

When the cacti die, they also become food and housing material for animals. A few animals eat cacti when they are living. They have very strong stomachs. When someone takes a bite or a woodpecker drills a hole, the cactus immediately creates a callous to protect itself. The callous is very hard and allows the cactus to continue living. Sometimes though bacteria can take hold and the cactus slowly dies and disintegrates. You can see them in different stages in the park. I found it really neat because the core remains long after the outside decays. It looks like wooden rods (and these rods were used in building previously) in a circular core inside the cactus.

The saguaro cacti have a fairly shallow root system, however those roots extend around it in a circle with a radius equal to that of the height of the individual cactus. They have the ability to collect a lot of water (maybe a ton? I can't recall for sure). The water is sent back to the core and goes up to feed the rest of the cactus. So animals can eat the outer layer and it will be fine as long as the core is not disturbed.

The core has to be super strong. Some of the arms can weigh 80lbs. Imagine if there are four or more arms! It also expands and contracts based on water levels. After a rain and it is soaking up water, the cactus rounds out smoother like a barrel. But when it's using those stores in dry times, it will shrink back inwards and it looks like a star with deeper crevices. Also when they are holding that water and storms come through they are susceptible to lightning. When struck, it heats the water up so fast that the cactus basically explodes and arms fly everywhere! I saw a picture and it looked pretty cool.

It was hot in Tucson. I made it for their first 100+ degree day in 2015. Lucky me :). This also meant the parks were pretty dead. I was the only one to attend the ranger program on the life cycle of a saguaro. Bob was a retired botanist who had worked in the area for most of his career. He had a slide show and answered all of my questions. Even though I was the only one there he was still enthusiastic and you could tell it was his passion. Finding people like that at the parks has been the unexpected gem I've found.

I can't think of much else to share. Not much animal activity there as I walked around. The desert is interesting but I do miss grass ;). Here are some more pics.