Treeline dynamics with climate change at the central Nepal Himalaya

Abstract. Treeline shifting in tandem with climate change has widely been reported from various parts of the world. In Nepal, several impacts of climate change on the physical environment have been observed, but study on the biological impacts is lacking. This dendrochronological study was carried out at the treeline in the high mountain slope of Kalchuman Lake (3750–4003 m a.s.l.) area of Manaslu Conservation Area in the central Nepal Himalaya to explore the impact of climate change on the treeline dynamic. Two belt transect plots (size: 20 m wide, > 250 m long) were laid which included treeline as well as tree species limit. Ecological mapping of all individuals of dominant trees Abies spectabilis and Betula utilis was done and their tree cores were collected. Stand character and age distribution revealed an occurrence of more matured B. utilis (max. age 198 years) compared to A. spectabilis (max. age 160 years). A. spectabilis contained an overwhelmingly high population (89%) of younger plants (< 50 years) indicating its high recruitment rate. Population age structure along the elevation gradient revealed an upward shifting of A. spectabilis at the rate of 2.61 m year-1 since AD 1850. The upper distribution limit of B. utilis was found to be stagnant in the past few decades. An increment in plant density as well as upward shifting in the studied treeline ecotones was observed. The temporal growth of A. spectabilis was correlated negatively with the monthly mean and minimum temperature of June to September of the current and previous year. The regeneration of A. spectabilis, on the other hand, was positively correlated with August precipitation and monthly maximum temperature of the month of the current year. The growth and regeneration of A. spectabilis was more sensitive to maximum and minimum temperature rather than average temperature. The growth of the B. utilis was mainly limited by moisture stress during the pre-monsoon season. As these two species presented species-specific responses to climate change with differential pattern in regeneration condition, much wider differences are anticipated in their population status as climate continues to change throughout the century.

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Treeline dynamics with climate change at Central Nepal Himalaya

Climate of the Past Discussions ◽

10.5194/cpd-9-5941-2013 ◽

2013 ◽

Vol 9 (5) ◽

pp. 5941-5976 ◽

Cited By ~ 8

Author(s):

N. P. Gaire ◽

M. Koirala ◽

D. R. Bhuju ◽

H. P. Borgaonkar

Keyword(s):

Climate Change ◽

Plant Density ◽

Elevation Gradient ◽

Age Distribution ◽

Recruitment Rate ◽

Conservation Area ◽

Nepal Himalaya ◽

The Past ◽

Central Nepal ◽

Tree Ring Data

Abstract. Global climate change has multidimensional impacts with several biological fingerprints, and treeline shifting in tandem with climate change is a widely observed phenomenon in various parts of the world. In Nepal several impacts of climate change on physical environments have been observed. However, studies on the biological impacts are lacking. This dendrochronological study was carried out at the treeline ecotone (3750–4003 m a.s.l.) in the Kalchuman Lake (Kal Tal) area of the Manaslu Conservation Area in central Nepal Himalaya with the aim to study the dynamic impact of climate change at the treeline. The study provides an insight into regeneration and treeline dynamics over the past 200 yr. Two belt transect plots (size: 20 m wide, >250 m long) were laid covering forest line, treeline as well as tree species Abies spectabilis and Betula utilis was done and their tree-cores were collected. Stand character and age distribution revealed an occurrence of more matured B. utilis (max. age 198 yr old) compared to A. spectabilis (max. age 160 yr). A. spectabilis contained an overwhelmingly high population (89%) of younger plants (<50 yr) indicating its high recruitment rate. Population age structure along an elevation gradient revealed an upward shifting of A. spectabilis at the rate of 2.61 m yr−1 since 1850 AD. The upper distribution limit of B. utilis was found stagnant in the past few decades. An increment in plant density as well as upward shifting in the studied treeline ecotones was observed. Thus, two species presented species-specific responses to climate change and much wider differences anticipated in their population status as climate continues to cha spectabilis correlated negatively with the mean monthly temperature of May–August of the current year and with September of the previous year. The regeneration of A. spectabilis, on the other hand, was positively related with May–August precipitation and January–April temperature of the current year. The reconstructed average summer temperature (May–August) using tree ring data revealed alternate period of cool and warm period with warming in the 2nd half of the 20th century. Further palynological and geochronological studies of sediments of the Kalchuman Lake would advance our understanding of past climatic trends and dynamics of the associated treeline and vegetation in the area.

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Growth performance of planted population of Pinus roxburghii in central Nepal

Journal of Ecology and Environment ◽

10.1186/s41610-020-00171-w ◽

2020 ◽

Vol 44 (1) ◽

Author(s):

Achyut Tiwari ◽

Nita Thapa ◽

Sugam Aryal ◽

Prabina Rana ◽

Shankar Adhikari

Keyword(s):

Growth Performance ◽

Negative Correlation ◽

Radial Growth ◽

Himalayan Region ◽

Maximum Temperature ◽

High Mountain ◽

Positive Trend ◽

Pinus Roxburghii ◽

Central Nepal ◽

The Impact

Abstract Background Climate change has altered the various ecosystem processes including forest ecosystem in Himalayan region. Although the high mountain natural forests including treelines in the Himalayan region are mainly reported to be temperature sensitive, the temperature-related water stress in an important growth-limiting factor for middle elevation mountains. And there are very few evidences on growth performance of planted forest in changing climate in the Himalayan region. A dendrochronological study was carried out to verify and record the impact of warming temperature tree growth by using the tree cores of Pinus roxburghii from Batase village of Dhulikhel in Central Nepal with sub-tropical climatic zone. For this total, 29 tree cores from 25 trees of P. roxburghii were measured and analyzed. Result A 44-year long tree ring width chronology was constructed from the cores. The result showed that the radial growth of P. roxburghii was positively correlated with pre-monsoon (April) rainfall, although the correlation was not significant and negatively correlated with summer rainfall. The strongest negative correlation was found between radial growth and rainfall of June followed by the rainfall of January. Also, the radial growth showed significant positive correlation with that previous year August mean temperature and maximum temperature, and significant negative correlation between radial growth and maximum temperature (Tmax) of May and of spring season (March-May), indicating moisture as the key factor for radial growth. Despite the overall positive trend in the basal area increment (BAI), we have found the abrupt decline between 1995 and 2005 AD. Conclusion The results indicated that chir pine planted population was moisture sensitive, and the negative impact of higher temperature during early growth season (March-May) was clearly seen on the radial growth. We emphasize that the forest would experience further moisture stress if the trend of warming temperatures continues. The unusual decreasing BAI trend might be associated with forest management processes including resin collection and other disturbances. Our results showed that the planted pine forest stand is sub-healthy due to major human intervention at times. Further exploration of growth climate response from different climatic zones and management regimes is important to improve our understanding on the growth performance of mid-hill pine forests in Nepal.

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Impact of Climate Change on Rice and Wheat Yield in Punjab State of India: A District-Level Analysis

10.21203/rs.3.rs-612890/v1 ◽

2021 ◽

Author(s):

Mandeep Bhardwaj ◽

Pushp Kumar ◽

Siddharth Kumar ◽

Ashish Kumar

Keyword(s):

Climate Change ◽

Least Squares ◽

Minimum Temperature ◽

Rice Yield ◽

Wheat Yield ◽

Ordinary Least Squares ◽

District Level ◽

Maximum Temperature ◽

Impact Of Climate Change ◽

The Impact

Abstract The present study aims to examine the impact of climate change on wheat and rice yield of the Punjab state of India. Using district-level panel data from 1981 to 2017, the study employs fully modified ordinary least squares (FMOLS), dynamic ordinary least squares (DOLS), and pooed mean group (PMG) approaches. The Pedroni cointegration has established a long-run relationship of climate variables with rice and wheat crops. The results of FMOLS and DOLS show that minimum temperature has a positive effect on both wheat and rice, while maximum temperature is found to be negatively contributing to both the crops. Rainfall has a significant adverse effect on wheat yield. Seasonal rainfall has been detrimental to wheat and rice yield in the study period, indicating that excess rainfall proved counterproductive. Pooled mean group (PMG) model confirms the robustness of the results obtained by FMOLS and DOLS techniques. Moreover, Dumitrescu-Hurlin causality test has revealed a unidirectional causality running from minimum temperature, rainfall & maximum temperature to rice and wheat yield. The findings of the study suggest that the government should invest in developing stress-tolerant varieties of wheat and rice, managing crop residuals to curb further environmental effect and sustain natural resources for ensuring food security.

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Drought, Climate Change, and Dryland Wheat Yield Response: An Econometric Approach

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17145264 ◽

2020 ◽

Vol 17 (14) ◽

pp. 5264 ◽

Cited By ~ 1

Author(s):

Samira Shayanmehr ◽

Shida Rastegari Henneberry ◽

Mahmood Sabouhi Sabouni ◽

Naser Shahnoushi Foroushani

Keyword(s):

Climate Change ◽

Linear Model ◽

Climatic Change ◽

Minimum Temperature ◽

Wheat Yield ◽

Maximum Temperature ◽

Yield Variability ◽

Non Linear ◽

The Mean ◽

The Impact

Agriculture has been identified as one of the most vulnerable sectors affected by climate change. In the present study, we investigate the impact of climatic change on dryland wheat yield in the northwest of Iran for the future time horizon of 2041–2070. The Just and Pope production function is applied to assess the impact of climate change on dryland wheat yield and yield risk for the period of 1991–2016. The Statistical Downscaling Model (SDSM) is used to generate climate parameters from General Circulation Model (GCM) outputs. The results show that minimum temperature is negatively related to average yield in the linear model while the relationship is positive in the non-linear model. An increase in precipitation increases the mean yield in either model. The maximum temperature has a positive effect on the mean yield in the linear model, while this impact is negative in the non-linear model. Drought has an adverse impact on yield levels in both models. The results also indicate that maximum temperature, precipitation, and drought are positively related to yield variability, but minimum temperature is negatively associated with yield variability. The findings also reveal that yield variability is expected to increase in response to future climate scenarios. Given these impacts of temperature on rain-fed wheat crop and its increasing vulnerability to climatic change, policy-makers should support research into and development of wheat varieties that are resistant to temperature variations.

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Climate Change Dry Spell Impact on Agriculture in Salyantar, Dhading, Central Nepal

Nepal Journal of Science and Technology ◽

10.3126/njst.v16i1.14358 ◽

2016 ◽

Vol 16 (1) ◽

pp. 59-68 ◽

Cited By ~ 5

Author(s):

Pramila Paudyal ◽

Dinesh Raj Bhuju ◽

Manoj Aryal

Keyword(s):

Climate Change ◽

Soil Moisture ◽

Statistical Significance ◽

Maximum Temperature ◽

Trend Test ◽

Moisture Condition ◽

Soil Moisture Condition ◽

Central Nepal ◽

Dry Spell ◽

The Impact

Understanding the problem increasingly posed by climatic change is one of the critical challenges of our time. A study was carried out in Salyantar village in Dhading district of central Nepal to understand and assess the extent of climate change impacts on agriculture. The impact assessment was performed through analysis of meteorological data, Landsat images, and people’s perception on changes relative to agriculture sector. Mann-Kendall statistical trend test was used to assign statistical significance to the trend whereas temperature vegetation dryness index (TVDI) was used to identify soil moisture condition as an assessment criterion. The perception of local people on climate change and its impacts was studied through generalized questionnaire survey and participatory rural appraisal. The results of the study portrayed rise in temperature in the study area in the recent years in comparison to the past. The maximum temperature increment was 0.03p C per year. As for precipitation, it showed decreasing trend by 1.855mm per year. The TVDI obtained from Landsat image, showed decreasing trend of soil moisture in different years, which indicate an increased longer dry spell. This has unswerving effect on agriculture as the entire Salyantar village is dependent upon rain-fed agriculture. The perceived impacts on agriculture were decreased crop yield, reduced soil moisture, and increased incidence of new pests and invasive plant species. Such impacts were fairly heterogeneous in distribution. The Salyantar village, a raised flat-land of river deposition already stuck in the grip of water stress, was found exacerbated by the effect of climate change.Nepal Journal of Science and Technology Vol. 16, No.1 (2015) pp.59-68

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Trends Analysis of Rainfall and Temperature over Nagwan Watershed, Hazaribagh District, Jharkhand

Current Journal of Applied Science and Technology ◽

10.9734/cjast/2020/v39i1930798 ◽

2020 ◽

pp. 112-128

Author(s):

Raj Bahadur ◽

R. K. Jaiswal ◽

A. K. Nema ◽

Anshu Gangwar ◽

Sandeep Kumar

Keyword(s):

Climate Change ◽

Global Warming ◽

Minimum Temperature ◽

Summer Season ◽

Annual Rainfall ◽

Maximum Temperature ◽

Annual Average ◽

Increasing Trend ◽

Z Value ◽

The Impact

Trend analysis is performed to find the pattern that prevails in Nagwan watershed area located in Hazaribagh district of Jharkhand (India) having very high average annual rainfall in the range of 1146 mm. The study aims to investigated the impacts of global warming by examine precipitation and temperature change over a period. Non-parametric MK test and Sen’s Slope estimator were used to assess the trend in long-term rainfall and temperature time series (1981-2019). The analysis has been carried out on monthly, seasonal and annual scale to identify meso-scale climate change effect on hydrological regime. The precipitation in the summer showed an increasing trend (Z value +1.67) and there was increasing trend in the seasonal rainfall which influences the total water availability in the watershed. There was increase in minimum temperature during summer season which shows the impact of global warming and may results in increasing the duration of the summer season. The annual average minimum temperature in the watershed showed an increasing trend (Z value +2.08) at 0.05 level of significance indicated hot nights in the summer. The annual average maximum temperature in the watershed showed a decreasing trend (Z value -1.26). Fluctuation and change in trend of rainfall and temperature possess potential risk hence it is important to understand and identify the pattern of rainfall and temperature for assessing impact of climate change and it is necessary to adopt appropriate steps for agriculture crop planning and improving farmer’s capability to cope with challenging situations due to environmental and climate changes.

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The impact of climate change in wheat and barley yields in the Iberian Peninsula

Scientific Reports ◽

10.1038/s41598-021-95014-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Virgílio A. Bento ◽

Andreia F. S. Ribeiro ◽

Ana Russo ◽

Célia M. Gouveia ◽

Rita M. Cardoso ◽

...

Keyword(s):

Climate Change ◽

Iberian Peninsula ◽

Climate Model ◽

Global Climate Models ◽

Maximum Temperature ◽

Historical Period ◽

Early Winter ◽

Impact Of Climate Change ◽

The Impact ◽

Spring Maximum

AbstractThe impact of climate change on wheat and barley yields in two regions of the Iberian Peninsula is here examined. Regression models are developed by using EURO-CORDEX regional climate model (RCM) simulations, forced by ERA-Interim, with monthly maximum and minimum air temperatures and monthly accumulated precipitation as predictors. Additionally, RCM simulations forced by different global climate models for the historical period (1972–2000) and mid-of-century (2042–2070; under the two emission scenarios RCP4.5 and RCP8.5) are analysed. Results point to different regional responses of wheat and barley. In the southernmost regions, results indicate that the main yield driver is spring maximum temperature, while further north a larger dependence on spring precipitation and early winter maximum temperature is observed. Climate change seems to induce severe yield losses in the southern region, mainly due to an increase in spring maximum temperature. On the contrary, a yield increase is projected in the northern regions, with the main driver being early winter warming that stimulates earlier growth. These results warn on the need to implement sustainable agriculture policies, and on the necessity of regional adaptation strategies.

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Strong controls of daily minimum temperature on the autumn photosynthetic phenology of subtropical vegetation in China

Forest Ecosystems ◽

10.1186/s40663-021-00309-9 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Peixin Ren ◽

Zelin Liu ◽

Xiaolu Zhou ◽

Changhui Peng ◽

Jingfeng Xiao ◽

...

Keyword(s):

Climate Change ◽

Minimum Temperature ◽

Vegetation Index ◽

Climatic Factors ◽

Time Lag ◽

Evergreen Forest ◽

Maximum Temperature ◽

Daily Minimum Temperature ◽

Study Region ◽

Cumulative Precipitation

Abstract Background Vegetation phenology research has largely focused on temperate deciduous forests, thus limiting our understanding of the response of evergreen vegetation to climate change in tropical and subtropical regions. Results Using satellite solar-induced chlorophyll fluorescence (SIF) and MODIS enhanced vegetation index (EVI) data, we applied two methods to evaluate temporal and spatial patterns of the end of the growing season (EGS) in subtropical vegetation in China, and analyze the dependence of EGS on preseason maximum and minimum temperatures as well as cumulative precipitation. Our results indicated that the averaged EGS derived from the SIF and EVI based on the two methods (dynamic threshold method and derivative method) was later than that derived from gross primary productivity (GPP) based on the eddy covariance technique, and the time-lag for EGSsif and EGSevi was approximately 2 weeks and 4 weeks, respectively. We found that EGS was positively correlated with preseason minimum temperature and cumulative precipitation (accounting for more than 73% and 62% of the study areas, respectively), but negatively correlated with preseason maximum temperature (accounting for more than 59% of the study areas). In addition, EGS was more sensitive to the changes in the preseason minimum temperature than to other climatic factors, and an increase in the preseason minimum temperature significantly delayed the EGS in evergreen forests, shrub and grassland. Conclusions Our results indicated that the SIF outperformed traditional vegetation indices in capturing the autumn photosynthetic phenology of evergreen forest in the subtropical region of China. We found that minimum temperature plays a significant role in determining autumn photosynthetic phenology in the study region. These findings contribute to improving our understanding of the response of the EGS to climate change in subtropical vegetation of China, and provide a new perspective for accurately evaluating the role played by evergreen vegetation in the regional carbon budget.

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Modeling the Impact of Climate Changes on Crop Yield: Irrigated vs. Non-Irrigated Zones in Mississippi

Remote Sensing ◽

10.3390/rs13122249 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2249

Author(s):

Sadia Alam Shammi ◽

Qingmin Meng

Keyword(s):

Climate Change ◽

Crop Yield ◽

Crop Yields ◽

Negative Impact ◽

Positive Impact ◽

Information Criterion ◽

Growing Season ◽

Maximum Temperature ◽

Linear Regression Models ◽

The Impact

Climate change and its impact on agriculture are challenging issues regarding food production and food security. Many researchers have been trying to show the direct and indirect impacts of climate change on agriculture using different methods. In this study, we used linear regression models to assess the impact of climate on crop yield spatially and temporally by managing irrigated and non-irrigated crop fields. The climate data used in this study are Tmax (maximum temperature), Tmean (mean temperature), Tmin (minimum temperature), precipitation, and soybean annual yields, at county scale for Mississippi, USA, from 1980 to 2019. We fit a series of linear models that were evaluated based on statistical measurements of adjusted R-square, Akaike Information Criterion (AIC), and Bayesian Information Criterion (BIC). According to the statistical model evaluation, the 1980–1992 model Y[Tmax,Tmin,Precipitation]92i (BIC = 120.2) for irrigated zones and the 1993–2002 model Y[Tmax,Tmean,Precipitation]02ni (BIC = 1128.9) for non-irrigated zones showed the best fit for the 10-year period of climatic impacts on crop yields. These models showed about 2 to 7% significant negative impact of Tmax increase on the crop yield for irrigated and non-irrigated regions. Besides, the models for different agricultural districts also explained the changes of Tmax, Tmean, Tmin, and precipitation in the irrigated (adjusted R-square: 13–28%) and non-irrigated zones (adjusted R-square: 8–73%). About 2–10% negative impact of Tmax was estimated across different agricultural districts, whereas about −2 to +17% impacts of precipitation were observed for different districts. The modeling of 40-year periods of the whole state of Mississippi estimated a negative impact of Tmax (about 2.7 to 8.34%) but a positive impact of Tmean (+8.9%) on crop yield during the crop growing season, for both irrigated and non-irrigated regions. Overall, we assessed that crop yields were negatively affected (about 2–8%) by the increase of Tmax during the growing season, for both irrigated and non-irrigated zones. Both positive and negative impacts on crop yields were observed for the increases of Tmean, Tmin, and precipitation, respectively, for irrigated and non-irrigated zones. This study showed the pattern and extent of Tmax, Tmean, Tmin, and precipitation and their impacts on soybean yield at local and regional scales. The methods and the models proposed in this study could be helpful to quantify the climate change impacts on crop yields by considering irrigation conditions for different regions and periods.

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Influence of climate change on soil erosion in high mountain area: a case study of upper Heihe river basin

10.5194/ismc2021-71 ◽

2021 ◽

Author(s):

Li Wang ◽

Fan Zhang ◽

Guanxing Wang

Keyword(s):

Climate Change ◽

Soil Erosion ◽

River Basin ◽

Effect Of Temperature ◽

Heihe River ◽

High Mountain ◽

Mountain Area ◽

Impact Of Climate Change ◽

High Mountain Area ◽

The Impact

The impact of climate change on soil erosion is pronounced in high mountain area. In this study, the revised universal soil loss equation (RUSLE) model was improved for better calculation of soil erosion during snowmelt period by integrating a distributed hydrological model in upper Heihe river basin (UHRB). The results showed that the annual average soil erosion rate from 1982 to 2015 in the study area was 8.1 t ha-1 yr-1, belonging to the light grade. To evaluate the influence of climate change on soil erosion, detrended analysis of precipitation, temperature and NDVI was conducted. It was found that in detrended analysis of precipitation and temperature, the soil erosion of UHRB would decrease 26.5% and 3.0%, respectively. While in detrended analysis of NDVI, soil erosion would increase 9.9%. Compared with precipitation, the effect of temperature on total soil erosion was not significant, but the detrended analysis of temperature showed that the effect of temperature on soil erosion during snowmelt period can reach 70%. These finding were helpful for better understanding of the impact of climate change on soil erosion and provide a scientific basis for soil management in high mountain area under climate change in the future.

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