不同风沙条件对几种植物生态生理特征的影响

 在野外风洞条件下，就不同风况的风沙胁迫对几种固沙植物生态生理特征的影响进行了实验研究。实验采用了沙坡头地区的野外植物和盆栽植物。在不同风速(5.9 m·s-1， 7.9 m·s-1， 9.9 m·s-1，14 m·s-1， 10 m·s-1，15 m·s-1， 20 m·s-1)和吹袭时间间隔(2 d, 4 d, 9 d)下测定了植物3个生理生态参数的变化。实验结果表明：1）净风和风沙流胁迫均可使植物的净光合速率（Pn）降低，蒸腾速率（E）升高，从而导致水分利用效率（WUE）下降。净风和风沙流对植物生理生态特征的影响显著不同。同样为14 m·s-1的风速时，风沙流使植物的Pn降低40.7%，而净风使其降低了35.88%。2）吹袭的时间间隔越短，植物的净光合速率降幅越大；风沙流比净风的影响更大。在2 d, 4 d, 9 d为间隔的风沙流吹袭下，油蒿（Artemisia ordosica）的Pn分别下降了20.13%、 11.76%、 7.72%。风沙胁迫强度越大，物质积累越少，植物的高生长越慢。3）由于风沙流降低了水分利用率，从而增加了对植物的干燥作用。从总体来看，沙生植物对风沙流胁迫有一定的适应响应，实验所用灌木较草本植物有更强的抗风性。

RESPONSE OF THE ECO-PHYSIOLOGICAL CHARACTERISTICS OF SOME PLANTS UNDER BLOWN SAND

Blown sand is very common in nature. In areas with frequent blown sand, especially arid and semi-arid areas, blown sand not only buries highways and railways but also poses a threat to the sustainable use and development of plant resources. In the past, researchers have conducted many studies of sand-burying and wind erosion, but there are few studies on the effect of blown sand on plant eco-physiology. The nature of the influence of blown sand on the eco-physiological characteristics of plants is an important question. Though scientists have observed and studied some effects of wind on morphological characters and transpiration ratios the effects of blown sand on the net photosynthetic rate, water use efficiency etc. of plants are unknown. In this paper, based on experimental methods we showed relations between different blown sand conditions and some ecophysiological characteristics in plants, and revealed adaptability of experimental plants to blown sand by observing the change of hotosynthesis and water use efficiency in plants. In this paper, using a field wind tunnel, the effects of blown sand on the growth characteristics of some sand-fixing plants (Eragrostis poaeoides Beauv.,Agriophyllum squarrosum, Bassia dasyphylla Kuntze,Caragana korshinskii Kom., Artemisia ordosica Krasch,Reaumuria soongorica Maxim, Ammopiptanthus mongolicus Cheng f., Hedysarum scoparium L.,Robinia pseudoacacia L.) were studied under different wind conditions including different wind velocities (5.9, 7.9, 9.9, 14 m·s-1 etc.) and blowing intervals (2 d, 4 d, 9 d), and some eco-physiological parameters were measured. The results showed: 1) Both wind and wind-sand current made net photosynthetic ratio (Pn) decrease and transpiration ratio　(E) rise, and thus made water use efficiency (WUE)　decrease. 2) The larger the wind velocity was or the shorter the blowing interval by wind-sand was, the larger the reduction in Pn; the effect of wind-sand current on the above index was greater than the effect of pure wind. The more fierce the wind-sand menace to the plants was, the less the substance accumulation was, and thus the more slowly the plant grew in height; 3) Wind-sand current aggravated desiccation of plants, due to the reduction in WUE. Meanwhile sand-fixing plants have adaptability to wind-sand current. The shrubs showed more adaptability to wind-sand current than the grasses. According to the change of WUE in experimental plants under blown sand conditions, the adaptability of experimental shrubs to blown sand ranks as follows: Reaumuria soongorica >Ammopiptanthus mongolicus > Caragana korshinskii>Artemisia ordosica >Hedysarum scoparium > Robinia pseudoacacia. This ranking corresponds with the order in their capability of resisting drought. (4) The affecting capability of the blown sand on different plants is different. In this experiment, the change in Pn and WUE for grasses is more than shrubs, and the change for Artemisia ordosica is less than for Agriophyllum squarrosum under higher velocity.