Changes of the Flowering Time of Trees in Spring by Climate Change in Seoul, South Korea

Flowering onset has attracted much attention in ecological research as an important indicator of climate change.Generally,warmer temperatures advance flowering onset.The effect of climate warming on flowering onset is more pronounced in spring because the difference between atmospheric and water temperatures creates more rapid convection than in other seasons.We analyzed the correlation between 73 species of spring woody plants in Hongneung Arboretum in Seoul,South Korea and the spring minimum temperature and average precipitation over the past 50 years(1968–2018).The spring minimum temperature and average precipitation have increased over the past 50 years,resulting in the advance of the first flowing date(FFD)in all 73 species by 8.5 days on average.A comparison of FFD changes over time by dividing the survey period into three time periods confirmed the advance of the FFD in 50 species(68%of investigated species)by 11.1 days on average in both Period 2(1999–2008)and Period 3(2009–2018)relative to Period 1(1968–1975).Additionally,a delay of the FFD by 3.2 days on average was observed in 8 species.The FFD of Lonicera chrysantha(Caprifoliaceae)advanced by over 40 days and was highly correlated with the increased spring minimum temperature.Analysis of the sensitivity of plant responses to climate change revealed that a temperature rise of 1℃ was associated with an FFD advance of 1.2 days in all species.The species that was most sensitive to temperature change was Spiraea pubescens for.leiocarpa(Rosaceae),whose FFD advanced by 4.7 days per 1℃ temperature rise.Each increase in precipitation by 1 mm was found to result in a 0.1-day advance of the FFD of all species.Prunus tomentosa(Rosa-ceae)was the most sensitive species,that advanced by 2.6 days for each 1 mm increase in precipitation.Thus,for all species,the FFD was more sensitive to the change in temperature than in precipitation.Assuming that the current greenhouse gas(GHGs)emission levels or atmospheric CO_(2) concentration is maintained,Seoul’s spring minimum temperature is projected to rise by 2.7℃ over the next 50 years.Accordingly,considering only the global temperature change,the mean FFD of the study’s 73 species is projected to advance by an additional 3.4 days.

Recent advances in assessment of soil erosion vulnerability in a watershed

Soil erosion is one of the most critical hazards adversely affecting both environment and economy.Assessment of the annual soil erosion rate provides information on soil erosion risk zones indicating the areas with high,severe and low risks.Modelling and prediction of soil erosion has a long history of more than seven decades.It becomes imperative to be familiar with the quantum of studies conducted and methods employed across the world to assess vulnerability of ecosystems to soil erosion to plan strategies for their conservation.There are several methods based on various factors like land use,soil quality,topography etc.available to assess the susceptibility of a region to soil loss.With time the gap in understanding of such models and their use around the world has increased.Numerous models for assessing soil erosion exist but there is a lack of knowledge on spatial distribution of the methods being used.Academic papers related to assessment of soil erosion vulnerability published during the past three decades(1991—2019)were reviewed.Total 160 studies were reviewed to understand advances in the methods used to assess soil erosion vulnerability worldwide,identification of the most popular methods and proportion of studies conducted in the fragile region of Himalayas.The results show that 18 different methods have mainly been used to assess soil erosion risk in different regions.These methods include statistical,physical,process based and empirical models.The use of few physical methods like ANSWERS and SHE has decreased with time while that of physical and process methods like RUSLE,SWAT,WEPP and PESERA has increased with time.The review highlighted that various models being used worldwide are based on their suitability to the region.It also brings to attention that few models like PESERA,EUROSEM and WEPP are mostly being used concentrated in a particular region.Models like PESERA and EPM are mostly used in European region and may be encouraged to estimate soil erosion in Himalayan region.The review also highlights lack of studies with inclusion of water quality as an important parameter while assessing soil erosion vulnerability in the region.The review suggests that in case of lack of data,various statistical methods like PCA,CF,FUZZY etc can be preferred for qualitative assessment over quantitative assessment Considering availability of accurate input,researchers need to attempt more methods and perform comparative studies to attain accurate results for assessing soil erosion vulnerability leading to strategizing soil conservation in fragile regions.