ISWC OpenIR  > 水保所2018届毕业生论文
西北旱区典型生态经济树种地理分布与气候适宜性研究
张晓芹1,2
Subtype博士
Thesis Advisor杜盛 ; 李国庆
2018-05-28
Degree Grantor中国科学院研究生院
Place of Conferral西安杨凌
Keyword物种分布模型 Maxent 潜在分布区 气候适宜区 气候变化
Abstract土地退化和沙漠化是西北旱区(干旱和半干旱区)突出的环境问题。随着西部大开发的实施,该区脆弱的生态环境与经济的迅速发展使人地矛盾更加突出,以适应性良好的生态经济型树种造林成为缓解人地矛盾的理想选择。气候是宏观尺度上影响物种分布的决定性因子,其与物种分布的关系研究及时空变化对物种分布的影响预测越来越受到重视。在气候变化背景下,深入了解该区常见生态经济型树种的适宜区分布及其对气候变化的响应,不仅有助于提高造林的成效,而且对于实现提高人民生活水平和改善生态环境的共赢具有重要意义。
选择了沙枣(Elaeagnus angustifolia)、小果白刺(Nitraria sibirica)、黑果枸杞(Lycium ruthenicum)、多枝柽柳(Tamarix ramosissima)、梭梭(Haloxylon ammodendron)、柠条锦鸡儿(Caragana korshinskii)、沙拐枣(Calligonum mongolicum)、胡杨(Populus euphratica)、乌柳(Salix cheilophila)和文冠果(Xanthoceras sorbifolia )10个典型生态经济树种作为研究对象,基于13个来自BIOCLIM、Holdridge生命地带模型和Kria指数的气候因子和来自标本馆、出版文献的物种出现记录,通过物种分布模型(MaxEnt)与地理信息系统(ArcGIS)工具结合,模拟了10个树种当前(1950−2000年)气候情景下的潜在适宜分布区,分析了生境适宜性与气候因子的关系,预测了未来2070s(2060−2080年)四种温室气体排放浓度情景(RCPs)下树种适宜区的变化,并确定了各树种的最优造林区。主要结论如下:
(1)沙枣、小果白刺和多枝柽柳的潜在适宜区面积最大,跨越了干旱区、半干旱区、半湿润区和有明显干旱季节的湿润区。黑果枸杞、梭梭、沙拐枣和胡杨主要局限于西北干旱区,文冠果、乌柳和柠条锦鸡儿主要集中于半干旱区和半湿润区。
(2)湿润指数是影响大多数树种适宜性的最重要因子,其对沙拐枣、梭梭和胡杨的贡献率均超过50%,然而对柠条锦鸡儿和乌柳则不足5%。最湿月降水量、年均降水量、寒冷指数也较为重要,其中最湿月降水量对黑果枸杞的影响最大,年均降水量对文冠果的影响最大。
(3)与热量相关的气候因子在影响沙枣、柠条锦鸡儿的分布方面起到较重要的作用,与水文相关气候因子对于其它树种起到更为重要的作用。多数树种生境适宜性对水文相关因子的响应曲线呈正偏态分布,对热量相关因子的响应曲线呈高斯分布。
(4)沙枣在高浓度排放情景(RCP8.5)下适宜区范围扩张幅度最大,其适宜区净增加率高达57.5%。柠条锦鸡儿在低浓度排放情景(RCP2.6)下适宜区范围缩减幅度最大,其适宜区消失率高达61.4%。多数树种的当前适宜区在低浓度排放情景下缩减,而在高浓度排放情景下扩张,并且随着温室气体排放浓度的增加,缩减趋势逐渐减弱,扩张趋势逐渐增强。
(5)所有树种当前的东部边缘适宜区将会缩减,不同树种缩减的幅度不同。在西北干旱区分布的树种,将在塔里木盆地、吐鲁番盆地及河西走廊的北部获得新增适宜区。多数树种适宜区范围的地理质心向西移动,移动速度约每十年4~53km。多数树种适宜区范围的海拔质心移动不明显,以约每十年1~22m速度略微向低处或高处移动;乌柳例外,在四种情景下以每十年约18~73m的速度向更高海拔移动。
本研究结果表明MaxEnt模拟的各树种潜在适宜区的范围与实际调查的数据基本一致。不同区域的树种,对不同气候变化情景的响应不同,多数树种当前的适宜区是稳定的,能够适应持续的气候变化。分布在西北干旱区的树种,在未来气候变化下的适宜区面积将会增加,未来在塔里木盆地、吐鲁番盆地及河西走廊北部可以进一步增加沙枣、小果白刺、梭梭等本地树种的造林面积。本研究结果有助于更好地理解西北干旱半干旱区植物种分布与气候的关系,同时能够为管理者制定适应气候变化的造林措施时提供参考。
Other AbstractLand degradation and desertification are severe environmental problems in the arid and semi-arid regions of Northwest China. With the development of the western regions, the fragile ecological environment and the rapid development of economy have generated more prominent contradiction between people and land. Afforestation with eco-economical species has been an ideal choice to ease the contradiction. Since climate is the decisive factor affecting species distribution on macro-scale, the relationship between suitability and climate factors, and the impact of climatic spatial-temporal changes on species distribution have attracted increasing attentions. Within the context of global climate change, understanding the distribution of common eco-economical species and their responses to climate change will contribute to the improvement of afforestation in the arid and semi-arid areas of Northwest China. It is also of great significance to achieve a win-win outcome for improving people's living standards and improving the ecological environment.
A total of 10 tree species (Elaeagnus angustifolia, Nitraria sibirica, Lycium ruthenicum, Tamarix ramosissima, Haloxylon ammodendron, Caragana korshinskii, Calligonum mongolicum, Populus euphratica, Salix cheilophila and Xanthoceras sorbifolia) were selected in this study. Based on occurrence records from herbaria and published literature, and 13 climate factors from BIOCLIM, Holdridge life zone, and Kria index, the potential suitable distribution areas of the 10 species in the present climate scenarios (1950-2000) were simulated, using MaxEnt (maximum entropy method) and GIS (geographic information system). Furthermore, the dominant climate factors that affected the distribution of each species were determined, and the relationship between the suitability and climate factors were analyzed. The 2070s (2060-2080) changes of suitable areas of each species under the four representative concentration pathways (RCPs) of greenhouse gases (GHGs) were also predicted. The main results are as follows:
(1) The potentially suitable distribution areas of E. angustifolia, N. sibirica, and T. ramosissima are the largest, which span the arid, semi-arid, and semi-humid regions and humid regions with obvious dry seasons. The potential suitable distribution areas of L. ruthenicum, H. ammodendron, C. mongolicum, and P. euphratica are mostly confined to arid regions in Northwest China, while those of X. sorbifolia, S. cheilophila, and C. korshinskii are mostly concentrated in the semi-arid and semi-humid regions of Northwest and Northern China.
(2) Humidity index (HI) is the most important factor affecting the suitability of most species, with the contribution rate of 56.1%, 53.1%, and 52.3% for C. mongolicum, H. ammodendron, and P. euphratica, respectively, while only 4.7% and 1.0% for C. korshinskii and H. rhamnoide, respectively. Precipitation of wettest month (PWM), annual precipitation (AP), coldness index are important factors as well, among which, the effect of PWM is most significant on L. ruthenicum, while the effect of AP is most significant on X. sorbifolia.
(3) Thermal-related climate factors play important roles in affecting the distribution of E. angustifolia and C. korshinskii, while for other species, hydrology-related climate factors play more important roles. Species habitat suitability curves in response to hydrology-related factors deviate from normal distribution in right for most species. Those curves in response to thermal-related factors mostly followed Gaussian distribution.
(4) E. angustifolia is expected to benefit most from high GHGs emission scenarios (RCP 8.5), with a net increase of 57.5% for its suitable area. The shrink of suitable area of C. korshinskii is expected to be up to 61.4% under low GHGs emission scenarios (RCP 2.6), indicating that the adverse effects of climate changes were larger on C. korshinskii than other species. For almost all species, current suitable areas are expected to shrink under low emission scenarios, while would expand under higher emission scenarios. In addition, with the increase of GHGs emission rates, the shrink tendencies of current suitable areas would change weaker, while the expansion trend will be stronger.
(5) The eastern edges of current suitable areas of all species are expected to shrink under the effects of future climate changes. The shrinking rate of different tree species is different. The tree species distributed in the arid regions of Northwest China would own new suitable areas in Tarim basin, Turpan basin and the northern part of the Hexi corridor. For most species, the geographical centriods of suitable ranges are predicted to move west at the speed of 4 ~ 53 km per decade. The movement of most altitudinal centriods are not obvious. The altitudinal centriods are predicted to lower or higher at the speed of 1 ~ 22 m per decade, except for S. cheilophila, whose suitable altitudinal centers are predicted to move upward at the speed of 18 ~ 73 m per decade.
The results in this study indicate that the potentially suitable ranges of each species simulated by MaxEnt are basically consistent with the investigation data. The response to climate changes are different between tree species due to variable distribution areas and climate scenarios. For most species, the current suitable areas are stable, and can adapt to sustained climate change. Those presently appearing in the arid regions of Northwest China might benefit from the future climate change. In the future, afforestation areas of local tree species, such as E. angustifolia, N. sibirica, and H. ammodendron, can further increase in the Tarim basin, Turpan basin and the northern part of Hexi corridor. This study contributes to better understanding the relationship between the distribution and climate for species in the northwest arid/semi-arid regions, and can provide reference for afforestation measures that adapt to climate change.
Document Type学位论文
Identifierhttp://ir.iswc.ac.cn/handle/361005/8157
Collection水保所2018届毕业生论文
Affiliation1.中国科学院教育部水土保持与生态环境研究中心
2.菏泽学院
Recommended Citation
GB/T 7714
张晓芹. 西北旱区典型生态经济树种地理分布与气候适宜性研究[D]. 西安杨凌. 中国科学院研究生院,2018.
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