Bioacoustic monitoring of lower North Island bird communities before and after aerial application of 1080

Abstract

Woody plants in arid and semi-arid environments may enhance soil nutrient status, the so-called 'fertile island' effect, but this mechanism has never been tested in the drylands of New Zealand. In this study I investigated effects of Kunzea serotina, Discaria toumatou, Rosa rubiginosa, and Coprosma propinqua on soil properties in the drylands of central Otago, New Zealand. Soils had significantly higher organic matter under C. propinqua and significantly higher nitrate and phosphorus concentrations under K. serotina than soils in the adjacent open grassland. A bioassay using oat (Avena sativa) growth indicated higher fertility in soils from under K. serotina than from under grassland. A review of 28 other studies revealed that fertile island effects of woody plant species on soil nitrogen and phosphorus concentrations decreased significantly with increases in annual precipitation. The occurrence of fertile islands under only two of the four shrub species in the current study in a dry sub-humid environment is consistent with this trend of decreased fertile island effect with increased annual precipitation. The higher concentration of nitrogen in soils under woody plants such as C. propinqua may be explained by the plants depositing organic matter on the surface, but some species such as K. serotina, D. toumatou, R. rubiginosa and C. propinqua, may also preferentially establish in areas of high soil phosphorus availability. I conclude that the occurrence of fertile islands under woody plants may be due to both effects of the woody plant canopy, and the plants preferentially establishing in areas of high soil fertility.

Fertile Island Effect by Three Typical Woody Plants on Wetlands of Ebinur Lake, northwestern China

“…In a study on soil properties at three different altitudes in the Qilian Mountains, researchers showed that with the increase in altitude, the soil nutrition and microbial-biomass parameters mostly decreased, and the 'fertilizer island' effect increased (Zhao and An, 2021). In woody plants and shrub communities, such as Haloxylon ammodendron, Tamarix ramosissima, and Populus euphratica, the nutrient enrichment in the topsoil under the canopies was obvious, and the 'fertilizer island' effect in the upper soil layer was greater than that in the lower soil layer (Reynolds et al, 1999;Chen et al, 2018;Guo et al, 2020;Bomans et al, 2021). Researchers investigated the soil moisture, nutrient content, and fine root density, and they found that the interaction between plants and soil was important for the formation and development of fertile islands and that its influence was not only related to the soil surface but also extended to the depth of the root contact (Cao et al, 2021).…”