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land-cover changes in Central Asia
Quaternary International 311 (2013) 1–2
Contents lists available at ScienceDirect
Quaternary International journal homepage: www.elsevier.com/locate/quaint
Guest Editorial
Hydrological and ecological responses to climatic change and to land-use/landcover changes in Central Asia The Central Asian Arid Zone (CAAZ) is a geographic region that has been documented to be sensitive to global warming during the last 100 years, and is expected to be adversely impacted by projected future warming (IPCC: Climate Change 2007). CAAZ is here defined to include the arid-semiarid belt that stretches from the Caspian Sea (w50 E) in the west to the Hinggan Mountains (w120 E) in the east. In addition, rapid growth of human population and associated increases in demands for natural resources during the past 60–70 years have resulted in extensive land degradation, ecological deterioration, and adverse hydrological changes in the CAAZ. The close association between the observed drying trend and the observed warming trend during the past 100 years and well-documented adverse human impact on hydrological and ecological systems during the past 60–70 years further affirm that this region is at high risk in future water resource availability and ecological security. The most obvious threat to society from climate changes and from adverse human impact is the shortage of water resource in the CAAZ, which in turn threatens the social-economic sustainability, disrupts the ecosystem services, and adversely impacts the regional stability. There is thus a critical need to develop regional mitigation and adaptation strategies to cope with these adverse consequences from climate change and intensified human activities. This requires a full understanding of the following fundamental issues: (1) quantification of hydrological and ecological responses to climate changes, (2) assessment of hydrological and ecological responses to human factors, (3) understanding of coupling dynamics between natural and human systems, and (4) development of effective and coordinated management practices across administrative and political boundaries. There have been some international efforts in past several decades that attempted to address these issues, but they were sporadic, lacking in international coordination, and insufficient. To establish a multi-national cooperation network to share the experiences in addressing the existing and the emerging issues of climate change in this region, we conveyed an international conference on “Hydrological and Ecological Responses to Climatic Change and to Land use/land-cover changes (LUCC) in Central Asia” (August 6–9, 2012, Urumqi of Xinjiang, China) with financial and administrative supports from Xinjiang University. Over 100 scientists from 14 countries attended the conference and 68 papers were presented in the conference. The majority of the 21 papers included in this special volume were selected from those 68 presentations, and are classified into three categories: (1) Paleoclimatic and Paleoenvironmental Changes, (2) Modern Climate Changes and HydroEcological Responses, and (3) Hydro-Ecological Responses to Human Activities. 1040-6182/$ – see front matter Ó 2013 Elsevier Ltd and INQUA. All rights reserved. http://dx.doi.org/10.1016/j.quaint.2013.08.040
1. Paleoclimatic and paleoenvironmental changes Several points deserve special mention. The pollen-climate transfer functions developed by Wen and his colleagues have the potential to be applied to the entire eastern Asia and beyond for quantitative climate reconstructions. In total, 646 surface samples covering a latitudinal span of w2000 km (from 33.6 to 51.5 N) were used in this study. The acceptability of these transfer functions is enhanced by the authors’ efforts at excluding human disturbances and topographic distortions through two-step screenings of the original dataset using Canonical Correspondence Analysis (CCA) and Weighted Averaging Partial Least Squares (WAPLS) methods. Sun et al.’s pollen-based moisture reconstruction from Lake Achit in the western part of the Mongolian Plateau within Mongolia shows that the wettest period of the Holocene spanned from w6400 to w1600 cal. BP, and the reconstruction seems to be well corroborated by the synthesized moisture history in the neighboring northern Xinjiang where the wettest period of the Holocene lasted from w7000 to w1000 cal. BP (Wang et al., in this volume). A high-resolution climate reconstruction (MAT and MAP) of the past w2500 years from Lake Balkhash in eastern Kazakhstan, based on a core of 850-cm long (207 pollen samples, 389 samples for other proxies, and 17 dates), lent a strong support to the early proposition that the climate in the westerlies-dominated areas has been generally characterized by cool-wet and warm-dry modes (Feng et al., in this volume). The Balkhash Basin has experienced three stages of climate change: cool-wet from w2500 tow1800 cal. BP, moderate from w1800 to 650 cal. BP, and cooling and wetting during the past w650 years with the past w100 being warming and drying. The reconstructed salinity history shows that the lake salinity was primarily controlled by basin-wide temperature. That is, low temperature raises the lake salinity through reducing the ice-melt water supply to the lake. Warm-wet and cold-dry modes of shorter timescales were documented in tree-ring data of w300 years from the northern slop of the western Tianshan Mountains in Xinjiang by Zhang et al. Warmer intervals (i.e., 1696–1708, 1730–1748, 1784–1804, 1832–1855, 1892–1903, 1924–1928, 1937–1943, and 1987–2006) were wetter, and colder intervals were drier. 2. Modern climate changes and hydro-ecological responses The rates of warming during the past 60–100 years in most parts of the CAAZ are higher than the global average (0.14 C /10 y). For example, the rate is 0.29 C /10 y in Uzbekistan (1950–2005); 0.26 C /10 y in Kazakhstan (1936–2005); 0.18 C /10 y in
2
Guest Editorial / Quaternary International 311 (2013) 1–2
Turkmenistan (1961–1995); and 0.39 C /10 y in northwestern China (1950–2010) (data from the presentation in the conference by Dr. Stulina with the title of “Hydrological and Ecological Situation in Aral Sea Region due to Climate Change”). Stulina and Eshchanov focused on the Pre-Aral Sea area and demonstrated that the temperature has been rising and the air humidity has been dropping during the past w70 years with a nearly constant line of long-term average of the precipitation. Their data further substantiated the wellknown fact that the observed decreases in river discharges and in groundwater levels have been resulted from excessive use of water for irrigation. Precipitation in the five Central Asian counties (Kazakhstan, Tajikistan, Uzbekhstan, Krygyzstan, Turkmenistan) does not exhibit either an increasing trend or a decreasing trend (data from the presentation by Dr. Stulina). However, Xinjiang, the eastern neighboring region of Kazakhstan and Krygyzstan, seems to be quite unique in two aspects. First, the temperature rising during the past w50 years is not only faster than the global average but also faster than those in other regions of the CAAZ. Second, an increasing trend of the precipitation replaced the decreasing trend in the early 1980s and the climate was thus transformed from warm-dry to warm-wet with considerable increases in 5-day maximum and daily intensity of precipitation (Wang et al., in this volume; Fang et al., in this volume; Fu et al., in this volume). In other words, the climate in Xinjiang region is pronouncedly characterized by a recent warming and wetting trend. 3. Hydro-ecological responses to human activities Several points need to be highlighted here. Remotely-sensed data show that the areal extents of high-cover vegetation and water-covered area decreased dramatically during the past 34 years in the Tarim Basin and the decreases are interpreted to be contributing factors to the observed decrease in the genetic diversity of the Tarim Red Deer (Cervus elaphus yarkandensis), an endangered and endemic animal (Tunur et al., in this volume).
An in-depth examination into the ecological effects of the “Ecological Water Diversion Project” (EWDP) shows that with the water transfers from Bosten Lake to the Tarim mainstream only some of the Populus euphratica trees reached a more vital status along the mainstream (Ginau et al., in this volume). Another indepth examination concluded that the water diversion projects in the lower reach of the Tarim River have made significant achievements in forest recovery near the riverbeds, but had rather limited positive effects on more distant floodplain sites (Tayierjiang et al., in this volume). Dukhovny and his two colleagues, Sokolov and Ziganshina, presented the practical outputs of the Integrated Water Resources Management (IWRM) pilot implementation in the Fergana Valley, shared by three countries of Central Asia (Kyrgyzstan, Tajikistan and Uzbekistan). Their paper addressed the water-related issues that were newly emerged after the dissolution of the former Soviet Union. The newly-emerged water-related issues stemmed from the following factors: (1) fragmented policies, (2) lack of regulatory frameworks, (3) different trends and paths of economic and water reforms, (4) continuing environmental degradation, (5) infrastructure deterioration, (6) institutional inconsistencies, and (7) omission of stakeholders and mismanagement of water resources. Their study reported that on the basis of 10-year study a strict vision was formulated for future steps towards a much wider implementation of IWRM. Z.-D. Feng Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, South Beijing Road #818, Urumqi 830011, Xinjiang, China E-mail addresses: [email protected], [email protected], [email protected] Available online 18 September 2013
Contents lists available at ScienceDirect
Quaternary International journal homepage: www.elsevier.com/locate/quaint
Guest Editorial
Hydrological and ecological responses to climatic change and to land-use/landcover changes in Central Asia The Central Asian Arid Zone (CAAZ) is a geographic region that has been documented to be sensitive to global warming during the last 100 years, and is expected to be adversely impacted by projected future warming (IPCC: Climate Change 2007). CAAZ is here defined to include the arid-semiarid belt that stretches from the Caspian Sea (w50 E) in the west to the Hinggan Mountains (w120 E) in the east. In addition, rapid growth of human population and associated increases in demands for natural resources during the past 60–70 years have resulted in extensive land degradation, ecological deterioration, and adverse hydrological changes in the CAAZ. The close association between the observed drying trend and the observed warming trend during the past 100 years and well-documented adverse human impact on hydrological and ecological systems during the past 60–70 years further affirm that this region is at high risk in future water resource availability and ecological security. The most obvious threat to society from climate changes and from adverse human impact is the shortage of water resource in the CAAZ, which in turn threatens the social-economic sustainability, disrupts the ecosystem services, and adversely impacts the regional stability. There is thus a critical need to develop regional mitigation and adaptation strategies to cope with these adverse consequences from climate change and intensified human activities. This requires a full understanding of the following fundamental issues: (1) quantification of hydrological and ecological responses to climate changes, (2) assessment of hydrological and ecological responses to human factors, (3) understanding of coupling dynamics between natural and human systems, and (4) development of effective and coordinated management practices across administrative and political boundaries. There have been some international efforts in past several decades that attempted to address these issues, but they were sporadic, lacking in international coordination, and insufficient. To establish a multi-national cooperation network to share the experiences in addressing the existing and the emerging issues of climate change in this region, we conveyed an international conference on “Hydrological and Ecological Responses to Climatic Change and to Land use/land-cover changes (LUCC) in Central Asia” (August 6–9, 2012, Urumqi of Xinjiang, China) with financial and administrative supports from Xinjiang University. Over 100 scientists from 14 countries attended the conference and 68 papers were presented in the conference. The majority of the 21 papers included in this special volume were selected from those 68 presentations, and are classified into three categories: (1) Paleoclimatic and Paleoenvironmental Changes, (2) Modern Climate Changes and HydroEcological Responses, and (3) Hydro-Ecological Responses to Human Activities. 1040-6182/$ – see front matter Ó 2013 Elsevier Ltd and INQUA. All rights reserved. http://dx.doi.org/10.1016/j.quaint.2013.08.040
1. Paleoclimatic and paleoenvironmental changes Several points deserve special mention. The pollen-climate transfer functions developed by Wen and his colleagues have the potential to be applied to the entire eastern Asia and beyond for quantitative climate reconstructions. In total, 646 surface samples covering a latitudinal span of w2000 km (from 33.6 to 51.5 N) were used in this study. The acceptability of these transfer functions is enhanced by the authors’ efforts at excluding human disturbances and topographic distortions through two-step screenings of the original dataset using Canonical Correspondence Analysis (CCA) and Weighted Averaging Partial Least Squares (WAPLS) methods. Sun et al.’s pollen-based moisture reconstruction from Lake Achit in the western part of the Mongolian Plateau within Mongolia shows that the wettest period of the Holocene spanned from w6400 to w1600 cal. BP, and the reconstruction seems to be well corroborated by the synthesized moisture history in the neighboring northern Xinjiang where the wettest period of the Holocene lasted from w7000 to w1000 cal. BP (Wang et al., in this volume). A high-resolution climate reconstruction (MAT and MAP) of the past w2500 years from Lake Balkhash in eastern Kazakhstan, based on a core of 850-cm long (207 pollen samples, 389 samples for other proxies, and 17 dates), lent a strong support to the early proposition that the climate in the westerlies-dominated areas has been generally characterized by cool-wet and warm-dry modes (Feng et al., in this volume). The Balkhash Basin has experienced three stages of climate change: cool-wet from w2500 tow1800 cal. BP, moderate from w1800 to 650 cal. BP, and cooling and wetting during the past w650 years with the past w100 being warming and drying. The reconstructed salinity history shows that the lake salinity was primarily controlled by basin-wide temperature. That is, low temperature raises the lake salinity through reducing the ice-melt water supply to the lake. Warm-wet and cold-dry modes of shorter timescales were documented in tree-ring data of w300 years from the northern slop of the western Tianshan Mountains in Xinjiang by Zhang et al. Warmer intervals (i.e., 1696–1708, 1730–1748, 1784–1804, 1832–1855, 1892–1903, 1924–1928, 1937–1943, and 1987–2006) were wetter, and colder intervals were drier. 2. Modern climate changes and hydro-ecological responses The rates of warming during the past 60–100 years in most parts of the CAAZ are higher than the global average (0.14 C /10 y). For example, the rate is 0.29 C /10 y in Uzbekistan (1950–2005); 0.26 C /10 y in Kazakhstan (1936–2005); 0.18 C /10 y in
2
Guest Editorial / Quaternary International 311 (2013) 1–2
Turkmenistan (1961–1995); and 0.39 C /10 y in northwestern China (1950–2010) (data from the presentation in the conference by Dr. Stulina with the title of “Hydrological and Ecological Situation in Aral Sea Region due to Climate Change”). Stulina and Eshchanov focused on the Pre-Aral Sea area and demonstrated that the temperature has been rising and the air humidity has been dropping during the past w70 years with a nearly constant line of long-term average of the precipitation. Their data further substantiated the wellknown fact that the observed decreases in river discharges and in groundwater levels have been resulted from excessive use of water for irrigation. Precipitation in the five Central Asian counties (Kazakhstan, Tajikistan, Uzbekhstan, Krygyzstan, Turkmenistan) does not exhibit either an increasing trend or a decreasing trend (data from the presentation by Dr. Stulina). However, Xinjiang, the eastern neighboring region of Kazakhstan and Krygyzstan, seems to be quite unique in two aspects. First, the temperature rising during the past w50 years is not only faster than the global average but also faster than those in other regions of the CAAZ. Second, an increasing trend of the precipitation replaced the decreasing trend in the early 1980s and the climate was thus transformed from warm-dry to warm-wet with considerable increases in 5-day maximum and daily intensity of precipitation (Wang et al., in this volume; Fang et al., in this volume; Fu et al., in this volume). In other words, the climate in Xinjiang region is pronouncedly characterized by a recent warming and wetting trend. 3. Hydro-ecological responses to human activities Several points need to be highlighted here. Remotely-sensed data show that the areal extents of high-cover vegetation and water-covered area decreased dramatically during the past 34 years in the Tarim Basin and the decreases are interpreted to be contributing factors to the observed decrease in the genetic diversity of the Tarim Red Deer (Cervus elaphus yarkandensis), an endangered and endemic animal (Tunur et al., in this volume).
An in-depth examination into the ecological effects of the “Ecological Water Diversion Project” (EWDP) shows that with the water transfers from Bosten Lake to the Tarim mainstream only some of the Populus euphratica trees reached a more vital status along the mainstream (Ginau et al., in this volume). Another indepth examination concluded that the water diversion projects in the lower reach of the Tarim River have made significant achievements in forest recovery near the riverbeds, but had rather limited positive effects on more distant floodplain sites (Tayierjiang et al., in this volume). Dukhovny and his two colleagues, Sokolov and Ziganshina, presented the practical outputs of the Integrated Water Resources Management (IWRM) pilot implementation in the Fergana Valley, shared by three countries of Central Asia (Kyrgyzstan, Tajikistan and Uzbekistan). Their paper addressed the water-related issues that were newly emerged after the dissolution of the former Soviet Union. The newly-emerged water-related issues stemmed from the following factors: (1) fragmented policies, (2) lack of regulatory frameworks, (3) different trends and paths of economic and water reforms, (4) continuing environmental degradation, (5) infrastructure deterioration, (6) institutional inconsistencies, and (7) omission of stakeholders and mismanagement of water resources. Their study reported that on the basis of 10-year study a strict vision was formulated for future steps towards a much wider implementation of IWRM. Z.-D. Feng Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, South Beijing Road #818, Urumqi 830011, Xinjiang, China E-mail addresses: [email protected], [email protected], [email protected] Available online 18 September 2013