Phosphorus (P) is a vital limiting nutrient for plants and plays a crucial role in driving primary productivity within key regional ecosystems. This study examined the relationships among soil calcium (Ca), total phosphorus (P), available phosphorus (AP), inorganic phosphorus (Pi), and leaf nutrients (carbon, nitrogen, and phosphorus), as well as the factors influencing these interactions in forest ecosystems developed on dolomite and limestone soils in the karst region. Results indicated that an increase in soil Ca content accelerated P transformation and that seasonal variations between dry and wet periods affected the phosphorus content in plant leaves. During the dry season, soil Ca content increased by an average of 89.8%, while soil and leaf P content decreased by 61.2% and 6.4%, respectively. Although the increase in soil Ca content intensified P limitation, it also promoted soil acidification, accelerating the transformation of poorly soluble Pi (Ca10-P) into moderately bound Pi (Ca2-P), thereby enhancing the release of AP in the soil. In the wet season, soil P content increased significantly (P < 0.05), and Ca could co-precipitate with soluble P to form Pi, reducing surface loss. Notably, the effect of Ca on P limitation did not continue to increase; when soil Ca content exceeded 14 g/kg, this effect gradually diminished. Study demonstrated that Ca accelerated the transformation and decomposition of soil P, altered the replenishment mechanism of Pi, and had a significant impact on phosphorus nutrient cycling in karst areas.