Spatiotemporal assessment of Prosopis juliflora invasion: linking invasion pattern to meteorological conditions

The spatial information on the invasion of alien plant species is considered necessary to develop policies aimed at management since there are significant threats to local biodiversity. The present study was conducted in the Salalah plains, located in the Southern part of Oman, and is severely affected by the invasion of Prosopis juliflora. Spatial analyses of the extent of invasive colonies along with the rate of spread were carried out. The impact of the meteorological parameters, precipitation, temperature, and relative humidity, on the growth dynamics of P. juliflora was also carried out. During the study period of approximately three decades from 1984 to 2013, more than 100 hectares of the natural land cover were converted into mono-dominant stands of P. juliflora. Although different programs to cut the P. juliflora were organized in the study area between 2000 and 2002, these programs have contributed unintentionally to the spread of the seeds and cuttings over larger areas amplifying the rate of increase from 1 ha per year to more than 9 ha. The photosynthetic activity of P. juliflora is directly affected by relative humidity and precipitation. Linear regression analysis showed a significant negative relationship between cumulative monthly precipitation and Normalized Difference Vegetation Index (NDVI) with an r-squared value of 0.59 (r = − 0.77) and between mean monthly relative humidity and NDVI with an r-squared value of 0.63 (r = − 0.80). At the same time, there was no relationship between mean monthly temperature and NDVI. Cross-correlation analysis showed that P. juliflora’s vigor was sensitive to the previous month’s high relative humidity and precipitation in a negative way. The adverse effects of precipitation and relative humidity on the growth dynamics of P. juliflora, especially during the monsoon season, should be taken into consideration when planning for integrated prevention and control programs of the invasive species.