Plant Life in the Taklimakan Desert

The Taklimakan Desert second in size only to Africa’s Sahara Desert, occupies some 337, 600 square kilometers 1 (130, 300 square miles) of northwestern China — an area about the size of Finland. Sparse rainfall, daily temperature swings of up to 20°C (68°F), and violent sandstorms make it one of the most extreme environments on Earth. Eighty-five percent of the Taklimakan Desert consists of shifting sand dunes, some up to 250 meters tall, that are largely free of vegetation. Yet, transitional areas between the open desert and oases on the desert fringe support diverse plant forms that not only have adapted to the harsh conditions but actually thrive there. Successful desert plants are resilient to scorching summers and frigid winters, drought, and high-salt conditions. The plants’ principal defense against these environmental stressors consists of drawing in as much water as possible while minimizing moisture loss. Three Taklimakan plants — Populus euphratica, Tamarix ramosissima, and Alhagi sparsifolia — represent some of the most diverse, prolific vegetation in the area; although they share many survival strategies, each has developed unique coping mechanisms of its own. The Euphrates poplar, Populus euphratica, the only tall tree in the Taklimakan ecosystem, has an extensive root system that allows it to absorb water far from the standing tree. P. euphratica controls evaporation by opening and closing the stomata, or tiny pores, on the leaf surface in response to the amount of moisture being lost through the leaves to the surrounding air. These stomata generally remain open during the day while the plant conducts photosynthesis. P. euphratica can endure high-salt concentrations in the soil. It takes in unlimited amounts of salt through the roots, up the stem, and into leaves, where it dilutes the normally toxic salt by increasing the number and volume of its cells. Tamarix ramosissima, a small tree with needlelike leaves commonly known as tamarisk or salt cedar, takes in enormous amounts of water via a far-reaching root system many times the size of the plant above ground. Like P. euphratica tamarisk can naturally determine when to close stomata to inhibit evaporation and regulate photosynthesis. Tamarisk has a high tolerance for salty conditions and even produces its own salt, which it accumulates in special glands between the leaves and then releases onto leaf surfaces. Leaves dropping to the ground make the soil more saline, or salty, giving Tamarisk a competitive advantage over less salt-tolerant plants. Alhagi sparsifolia, a spiny shrub, thrives in the Taklimakan Desert even though it uses large amounts of water, especially during the summer months. With only a few wispy roots in the upper soil, it is unaffected by occasional flooding. Most of its roots reach down deep, where they take up water from as far as sixteen meters below ground. Unlike P. euphratica and T. ramosissima, which open and close stomata according to conditions on the leaf surface, A. sparsifolia does so according to hydraulic conductance — that is, the ease with which it takes up groundwater. Although desert plants have adapted for their own survival, they also help protect their ecosystem by stabilizing sand dunes, preventing erosion, presenting a barrier to sandstorms, and conserving biodiversity.