年 月 重庆师范大学学报(自然科学版) 摇 2012 5 May 2012 第 卷 第 期 ( ) 29 3 Journal of Chongqing Normal University Natural Science Vol. 29 No. 3

摇 Proceedings of the International Symposium on Conservation and 摇 Eco鄄friendly Utilization of Wetland in the Three Gorges Reservoir Revegetation Strategies for Water鄄Level Fluctuation Zone of the Three Gorges Reservoir Region*

, , 1 2 , 1 2 LU Zhi鄄jun JIANG Ming鄄xi ( , , 1. Key Laboratory of Aquatic Botany and Watershed Ecology Wuhan Botanical Garden , , , ) 2. Wuhan Botanical Garden Chinese Academy of Sciences Wuhan 430074 China

Abstract: ( ), After the full functioning of the Three Gorges Dam TGD the hydrologic regime will be markedly changed and ( ) most of the pre鄄dam vegetation in the new Water鄄Level Fluctuation Zone WLFZ may fail to persist. How to revegetate ( ) WLFZ of the Three Gorges Reservoir Region TGRR has become a hot topic for the scientific community and the govern鄄 , ments. Based on review of scientific literature and the findings of our research we here bring forward a scheme addressing , strategies for revegetation of WLFZ of TGRR. Firstly monitor vegetation dynamics based on permanent plots along the Three , , Gorges upstream from TGD potentially providing suitable plants for the future revegetation plans. Secondly examine the po鄄 , tential of soil seed bank for revegetation of the above鄄ground vegetation and evaluate self鄄regeneration of the post鄄dam vege鄄 , tation. Based on these data select suitable plants for revegetation that integrate desirable physiological and life鄄history traits. , (Nelumbo nucifera) Specifically wetland vegetation could be constructed with lotus and aquatic plants. For sites with gentle , , terrain and fairly hospitable soil conditions vertical planting of trees shrubs and grasses / forbs along the elevation gradient , could be considered. To attain the sustainable vegetation cover the newly artificial vegetation should be monitored for at least 5 years. Key words: ; ; ; water鄄level fluctuation zone rehabilitation restoration ecology Three Gorges Reservoir Chinese Library Classification: Document Code: Article ID: ( ) Q948 A摇 摇 摇 1672鄄 6693 2012 03鄄 0117鄄 05

摇 摇 After the first stage impoundment of the TGR to There were fertile pre鄄dam cultivated fields and 135 m (2003), the second stage impoundment to 156 forest lands, or towns, docks and other populated are鄄 m ( 2006 ), the experimental impoundment in 2008 as, which have been changed into areas seasonally (172. 8 m) and 2009 (171. 4 m), on October 26th of flooded. In artificial wetlands created after impound鄄 2010 the water level behind the Three Gorges Dam ment by the TGD, former terrestrial plants cannot per鄄 (TGD hereafter) reached 175 m for the first time, in鄄 sist due to their lack of adaptation to flooding. The dicating the full functioning of the Three Gorges Reser鄄 WLFZ has become one of the most significant environ鄄 voir. The water level now fluctuates from 145 m (dur鄄 mental concerns of both central and local governments ing the flood season) to 175 m ( during the non鄄flood because of its vast area and outstanding ecological and season), which has created a new Water鄄Level Fluctu鄄 environmental issues, as well as its strong impacts on ation Zone (WLFZ hereafter) between the highest and the long鄄term and normal functioning of the TGD, wa鄄 lowest water level, with a difference in surface鄄water ter quality of the Yangtze River, and the production elevation of 30 m creating a total drawdown area of a鄄 and life of residents in the Three Gorges Reservoir Re鄄 2 [1] bout 300 km . gion (TGRR hereafter).

Recieved: 鄄 鄄 * 01 26 2012 Foundation: ( ) 摇 摇 China Key Technology Research & Development Program No. 2006BAC10B01 First author biography: , , , 摇 摇 LU Zhi鄄jun male Ph. D. in ecology his research interests settle around adaptation strategies of plant population and Corresponding Author: , : community to disturbances. JIANG Ming鄄xi E鄄mail mxjiang@ wbgcas. cn ( ) : 118 Journal of Chongqing Normal University Natural Science http / / www. cqnuj. cn摇 摇 摇 摇 摇 摇 摇 摇 Vol. 29

Vegetation in the drawdown zones of reservoirs en鄄 markedly different WLFZ after the TGD has become hances the productivity of the riparian zone, provides fully functional. physical structures and biological elements for wildlife [2] habitats, and has aesthetic values . Due to the flood鄄 season reversal and prolonged duration of flooding, the new drawdown zone will dramatically change the envi鄄 [3] ronmental conditions of the riparian zone , which is expected to negatively influence biodiversity, water quality and human utilization of the area. Revegetation is one of the effective measures for improving the adap鄄 [4] tation of drawdown zone ecosystems . Conducting re鄄 search on rehabilitation to protect the ecological envi鄄 ronment of the TGRR is therefore significant. Based on Fig. 1 Revegetation strategies of Water鄄Level Fluctuation Zone of Three Gorges Reservoir Region review of scientific literature concerning revegetation of reservoir drawdown zones, we here bring forward reha鄄 Topography, species composition, and anthropo鄄 bilitation strategies for the drawdown zone of the TGRR genic disturbance should be considered when exami鄄 [11] and provide theoretical support for revegetation projects ning vegetation dynamics . Judging from data col鄄 in this area. lected from 12 monitoring sites we established along the 1 Revegetation Strategies for the main channel of the Yangtze River from Banan to Zigui WLFZ of TGRR upstream of TGD, impoundment has significantly As important types of ecotones, WLFZ of reser鄄 changed species composition and diversity of the pre鄄 voirs are markedly different from those of natural riv鄄 dam drawdown zone vegetation, but has had no signifi鄄 ers. Vegetation inhabiting the littoral (riparian) zones cant influence on annual plant richness and biomass of [12] of natural rivers has resulted from long periods of adap鄄 the herbaceous layer . Vegetation below 175m will tation and evolution. How long it will take to revegetate be dominated by annuals, which has been confirmed by [13] [14] the WLFZ of the TGRR remains unclear. Thus, we the findings of Wang et al , Sun et al , Liu et [15] [16] have developed an overall outline concerning rehabilita鄄 al and Wang et al . tion of the WLFZ of the TGRR (Fig. 1). There is a distinct differentiation of vegetation a鄄 2 Vegetation Dynamics in WLFZ of TGRR long the Three Gorges section of the river valley, featu鄄 ring a change in the longitudinal gradient at Fengjie as Research on impacts of the hydrological regime on well variation in community composition with elevation. the drawdown zone vegetation of reservoirs has a long However, regarding the drawdown zone vegetation in the history since successful revegetation needs understand鄄 TGRR, there was no significant difference either on the ing of the influences of water level fluctuation on local longitudinal gradient of the gorges or the elevation gradi鄄 [5] [12] vegetation, diversity, and function . With this infor鄄 ent (145 ~ 156 m,156 ~ 165 m,165 ~ 175 m) . mation, specific technical notes can be integrated and When selecting suitable plants for rehabilitation of [4] developed for reservoir managers . As for the TGRR the reservoir WLFZ, plant physiology, morphology, itself, impacts of impoundment on local plants and veg鄄 and especially life history adaptation strategies should etation in the WLFZ were first studied by Chen et be considered. Persistent grasses / forbs and shrubs at [6] [7] al , and Jiang et al examined the patterns of ripari鄄 elevations lower than 156 m can be used as optional [8鄄9] [12] an vegetation in relation to elevation. Wang et al plants for rehabilitation of WLFZ of TGRR . [10] and Bai et al predicted the vegetation below 175m 3 Natural Recovery Potential of draw鄄 elevation after the creation of the TGD based on exist鄄 Down Zone Vegetation in TGRR ing natural WLFZ vegetation. However, there will be a , : 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 LU Zhi鄄jun et al Revegetation strategies for Water鄄Level Fluctuation No. 3摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 摇 Zone of the Three Gorges Reservoir Region 119 dens bipinnata Polygonum hydropiper Amaran鄄 The soil seed bank is an important source of , , and thus viridis[25鄄28] propagules for natural revegetation and may play an im鄄 . portant role during the course of rehabilitation of WLFZ 5 Artificial Revegetation of WLFZ of TGRR in TGRR. To evaluate the potential of the soil seed bank to develop standing vegetation, we collected 45 In a study of the WLFZ of Kinbasket Reservoir, [29] soil samples from four sites ( Changshou, Zhongxian, Carr and Moody found that the limiting factor for rev鄄 Wushan and Zigui) along the main channel of the Yan鄄 egetation was not water level fluctuation but the initial gtze River upstream from the TGD and found the soil plants which can be established through artificial plant鄄 seed bank was dominated by annuals which had low ing. Successful species selections for revegetation have similarity to the above鄄ground vegetation, indicating it been realized in Oregon (USA) reservoirs, Upper Ar鄄 is difficult for some non鄄annual plants to regenerate via [17] row and Ontojfirvi lake, and some reservoirs of B. C. the soil seed bank . This was confirmed by the find鄄 [18] Hydro in Canada. Bald cypress, Salix and Carex had ings of Wang et al . However, the soil seed bank the best performance indicating their adaptation to hab鄄 should still be taken into account with regard to vegeta鄄 itats that are strongly disturbed by water level fluctua鄄 tion management in TGRR. tion. The revegetation plan has to last at least 5 yr to 4 Plant Selection for Drawdown Zone facilitate the self鄄sustaining restoration of vegetation Revegetation of TGRR cover. To select suitable plants and planting model for 4. 1 Physiological adaptation revegetation of WLFZ of TGRR, we have established the artificial rehabilitation experiment and demonstra鄄 Selecting plants that are adapted to long鄄term, tion base in Zhong County, Chongqing, China. complete and deep submergence is the first strategy for 5. 1 Structuring wetland vegetation with aquatic plant selection for WLFZ revegetation in TGRR. Eco鄄 plants physiology is the main field of interest at present, such [21] Before the impoundment of the TGR, there were a as studying photosynthesis during submergence , and [22] lot of paddy fields in the potential drawdown zone. Af鄄 high content of non鄄structural carbohydrates . Simu鄄 Paspal鄄 ter pre鄄treatments, it is feasible to establish wetland lating flooding effects on common perennials ( um distichum Cynodon dactylon and Hemarthria alti鄄 vegetation with aquatic plants in this region. The phe鄄 , Nelumbo nucifera ssima nology of ( lotus) is consistent with ) revealed their strong submergence resistance the hydrological regime of TGRR, and its root acts as a and suitability for WLFZ revegetation, while also show鄄 ing that they got over the long鄄term and complete sub鄄 storage organ. Water lily grows sufficiently in the sum鄄 [23] mergence by means of different strategies . mer, flowering, fruiting, beautifying the landscape, 4. 2 Life history strategy accomplishing its life history and then gets over the There have been fewer studies of plant selection winter with high water level with storage root stocks. based on life history than those concerning physiology Furthermore, it can protect water and soil, deplete soil and morphology, and the potential of annuals that can nutrition and decrease the release of nutrition elements complete their life cycle between drawdown and re鄄im鄄 to the reservoir. Lotus seed also has economical bene鄄 [12] poundment has been underestimated . Nevertheless, fits and can bring profits to local farmers. This model [24] Little and Jones suggested herbaceous plants be can be applied to establish wetland vegetation in WLFZ [30鄄31] used in drawdown zone revegetation. According to ger鄄 of TGRR . 5. 2 Vertical planting with trees shrubs and herbs mination performance under storage and submergence , to revegetate the drawdown zone conditions, plants suitable to revegetate WLFZ of Echinochloa crusgalli Xanthium sibiricum [32] TGRR are , , Bao et al suggested enhancing the ecological Amaranthus paniculatus Aeschynomene indica Ama鄄 , , function of the drawdown zone and protecting water and ranthus Artemisia annua Eclipta prostrata Bi鄄 H. sp. , , , soil by using self鄄locking concrete modules in which ( ) : 120 Journal of Chongqing Normal University Natural Science http / / www. cqnuj. cn摇 摇 摇 摇 摇 摇 摇 摇 Vol. 29 altissima C. dactylon F. tikoua , and can be planted. [2]摇 B C Hydro. CLBMON鄄33:Kinbasket arrow lakes reservoir However, at lower elevation with, woody plants may inventory of vegetation resources [ EB / OL]. 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