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Decoupled responses of native and exotic tree diversities to distance from old‐growth forest and soil phosphorus in novel secondary forests
Author(s) -
Lai Hao Ran,
Tan Germaine Su Yin,
Neo Louise,
Kee Carmen Yingxin,
Yee Alex Thiam Koon,
Tan Hugh Tiang Wah,
Chong Kwek Yan
Publication year - 2020
Publication title -
applied vegetation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.096
H-Index - 64
eISSN - 1654-109X
pISSN - 1402-2001
DOI - 10.1111/avsc.12548
Subject(s) - introduced species , species richness , ecology , phosphorus , soil fertility , secondary forest , biology , native plant , agroforestry , native forest , old growth forest , invasive species , soil water , chemistry , organic chemistry
Abstract Questions How (de)coupled are native and exotic tree diversities in their relationships with local soil conditions and landscape configurations? Can (de)coupled diversity–environment relationships be used to manage native and exotic species separately to minimize unintended impacts on one another? Location The tropical city‐state of Singapore, Southeast Asia. Methods In two types of novel, exotic‐dominated secondary forests regenerating from land abandonment, we surveyed both native and exotic trees ≥5 cm diameter‐at‐breast height (DBH) in 97 plots and correlated taxonomic and functional diversities to soil fertility (nitrogen, phosphorus, and potassium) and landscape configuration gradients (distance to old‐growth forests and patch area). Results Native and exotic tree species had unshared or decoupled responses to distance to old‐growth forest and soil phosphorus. The taxonomic and functional diversities of native, but not exotic, species declined rapidly with increasing isolation from old‐growth forests. Exotic, but not native, species richness increased with soil phosphorus levels. Neither native nor exotic diversities were associated with soil nitrogen, potassium, and patch area. Conclusions Native and exotic tree species could be managed separately without unintended impacts on one another because of their decoupled responses to distance from old‐growth forest and soil phosphorus. The native–distance‐to‐old‐growth relationship suggests that novel secondary forests adjacent to old‐growth forests can accrue native species with minimal intervention, while enhancement plantings of old‐growth native species should target more isolated patches. The exotic‐phosphorus relationship suggests that restoring soils to historically‐low phosphorus levels can help to reduce exotic diversity, without negative impacts on native diversity. Our study highlights the importance of understanding (de)coupled species or species‐group responses to identify optimal management solutions with minimal non‐target effects.