Abstract: The spatial distribution and quantitative characteristic of Populus euphratica and Populus pruinosa fruits from different inhabited environment were studied. The results showed that the number of fructification was allocated to different crown according to definite percentage, the percentage order was upper > middle > lower and south > north, but there weren't significant differences among quantity of seed per fruit in upper, middle and lower parts of crown from different populations. Compared Populus euphratica with Populus pruinosa, Per fruit weight, thousand kernel weight, quantity of seed per fruit, quantity of seed per tree of Populus euphratica were 2.68, 1.33, 2.14 and 1.28 times than that of Populus pruinosa, respectively. However, the number of fructification per individual tree of Populus euphratica was 1.59 times than that of Populus pruinosa. Compared to different population from the same specie, whether Populus euphratica or Populus pruinosa were all significant differences among number of fructification per individual plant and fruit per fructification. In addition, per fruit weight and quantity of seed per fruit were not significant differences in different population of Populus euphratica, and that of Populus pruinosa was contrary. This indicated that Populus euphratica was higher than Populus pruinosa in matter and energy investing to progeny, and its reproduction strategy was the bigger quantity of seed per fruit insure definite quantity of seed per tree. But the quantity of seed per tree of Populus pruinosa was insured by the number of fructification per tree, and its potential occupied space niche was higher than that of Populus euphratica.

Key words: Populus euphratica, Populus pruinosa, fruit, spatial distribution, quantitative characteristics