The relationship between ancient trees health and soil properties

Abstract

This study focuses on the representative ancient trees including Pinus bungeana Zucc.ex Endl., Platycladus orientalis (Linn.) Franco, Pinus tabulaeformis Carr., Sophora japonica Linn. in the Beijing City as these trees have increasingly high cultural and aesthetic values. We employed tree visual assessment to evaluate the level of health of ancient trees. This study also analyzed soil physical and chemical properties, and the relationship between the ancient trees health level and their soil physical and chemical properties. These results show that among the 110 ancient trees evaluated, 3.64, 29.09, 60.00, 5.45 and 1.82% were found for healthiest, healthier, healthy, unhealthy and dying trees, respectively. The average soil water content was recorded as 10.62%, while the mean bulk density was recorded as 1.20 g/cm3, and the average compactness was recorded as 3.94 kg/m². The average total porosity, mean capillary porosity and medial non-capillary porosity of soil samples were found as 20.72, 11.77 and 8.96%, respectively. The mean soil pH, organic matter, total N, total P, total K, available N, available K and available P were 7.79, 3.41%, 1.41 g/kg, 0.99 g/kg , 16.48 g/kg, 88.90 mg/kg, 335.97 mg/kg and 15.36 mg/kg, respectively. All soil physical properties had medium variant characteristic. The soil pH and total K had low variations and the soil organic matter, total N and available N had medium variations. Other chemical indicators such as total P, available P and available K varied strongly. Our results indicate that with an increasing health level of the ancient trees, the soil bulk density decreased, and the soil compactness, total K, available K, total P and available P increased, however, soil pH and organic matter remained unchanged. This research provides the scientific basis for the rejuvenation and management of the ancient and popular trees in cities like Beijing.

Key words: Ancient trees health, soil properties, Beijing.