With their relatively low moisture content, the woody structure of Formosan acacias possess just the right degree of firmness, not at all like the damp and spongy wood of the Okinawa pine or the gunpowder trees commonly seen in rural northern Taiwan. The lower moisture content makes the heartwood of the acacia resistant to parasitic insects, allowing it to remain standing long after the tree's outer layers have rotted away.
相思樹木質結構軟硬適中，不似北台灣郊區常見的琉球松、山黃麻潮濕鬆軟，由於含水量較低，不易滋生寄生蟲，常常邊材腐爛了，樹心卻堅固完好，成為鳥兒最愛築巢的樹種。