Background The characteristics of plant growth architecture are the performance of adaptation to its habitat. In order to explore whether the plant architecture of Haloxylon ammodendron forests will change with the increase of growth years in the process of salt lake protection. To study the clade configuration characteristics of H. ammodendron forests of different ages, and to understand the relationship between the configuration characteristics and the environment, so as to further understand the population dynamics and ecological adaptability of H. ammodendron. It provides a theoretical basis for the ecological adaptability and evolution mechanism of H. ammodendron forests and the selection and optimal allocation of windbreak and sand-fixing forests.

Methods H. ammodendron forests planted artificially in the Jilantai Salt Lake area were selected as the research object, and five forest ages (2, 5, 10, 15 and 30 years) were selected for plot setting. The phenotypic growth characteristics and clade configuration changes of H. ammodendron under different stand ages were investigated and analyzed.

Results The changes of plant height, crown width, base diameter and branch length of H. ammodendron showed a trend of increasing significantly with the increase of forest age (P < 0.05).The growth ability of big forest age of H. ammodendron was stronger, which was beneficial to the regeneration of H. ammodendron population.The branching angle of H. ammodendron of five forest ages decreased with the increase of branch level. The branch angle showed that the closer it was to the main stem of the H. ammodendron, the larger the branch angle, and its carrying capacity increased with the increase of forest ages. The overall configuration of H. ammodendron with different forest ages was flexible. The overall appearance of H. ammodendron at 2, 5, 10 and 15 years was "tall and thin" and with forest ages of 30 ages was "low and fat".

Conclusions The protection forest of H. ammodendron in the Jilantai Salt Lake area was dominated by vertical spatial resource exploration in the forest age of less than 5 years, and the horizontal spatial resource exploration was mainly used in the forest age of 30 years. Afforestation pattern allocation can be optimized according to different afforestation ages and vegetation characteristics in arid and semi-arid areas.