观赏灌木小枝和叶性状在林下庇荫环境中的权衡关系
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摘要
小枝与叶片间的关系能够很好地反映植物对环境的适应策略。目前,从枝叶间权衡关系的角度研究树木对庇荫环境适应性的报道尚少,其中主要包括"生长-生长"权衡和"生长-生存"权衡两种假说。因此,为了探讨灌木在庇荫环境中,是否会在小枝和叶性状间采取权衡策略,来提高光照资源的利用能力或增强生存和防御能力,在城市绿地的林隙和林冠下两种光环境中,选择了没有人工修枝、整形等经营措施的金银木(Lonicera maackii)、小花溲疏(Deutzia parviflora)和连翘(Forsythia suspensa)等11种、79株观赏灌木作为研究对象,采集其当年生小枝,观测并计算了每棵灌木所处环境的有效光合辐射(PAR)相对累积光量和红光/远红光(R/FR),以及灌木的小枝干重(TDW)、单位小枝叶干重(LDW)、出叶强度(LN/TDW)、叶面积支持效率(LA/TDW)、比枝长(TL/TDW)和单叶面积(ILA) 6个性状。对数据进行标准化和数据转换后,运用Pearson相关检验分析光环境指标和灌木枝叶性状间的相关性;采用标准化主轴估计法进行异速生长方程的参数估计;使用多元回归分析不同光强下各性状的相互关系。结果表明:(1) PAR相对累积光量和R/FR与TDW和LDW呈极显著(P<0.01或P<0.001)正相关,与TL/TDW、LA/TDW、LN/TDW呈极显著(P<0.001)负相关,与ILA相关性不显著(P> 0.05)。整体上,R/FR与各灌木性状的相关性大于PAR相对累积光量;(2) TDW和LDW存在极显著(P<0.001)的异速生长正相关关系。随着光强的减小,灌木当年生小枝和叶片的生物量都趋于减小,但是表现出相对偏向于叶片生物量的投资偏好;(3) LA/TDW和TL/TDW存在极显著(P<0.001)的等速生长正相关关系。但随着光强的减小,比枝长随叶面积支持效率增加而增加的速率却减小,说明灌木在庇荫条件下,更倾向于采取忍耐型的光资源利用策略;(4) ILA和LN/TDW呈极显著(P<0.001)异速生长负相关关系。随着光强的减小,灌木趋向于表现出单位小枝上着生大量小叶的现象。所以总体上,庇荫环境下的观赏灌木存在投资偏好和权衡,倾向于通过枝叶生长提高光截获能力来适应弱光环境,与"生长-生长"的权衡假说相符,但整体上,观赏灌木的耐阴性较差,故不建议种植在庇荫环境中。
Understanding the relationships between twig and leaf traits provides valuable insights into the adaptive strategies of plant species. There are limited studies addressing the shade tolerance of woody species regarding trade-offs between twig and leaf traits. However,there are two contrasting hypotheses regarding the characteristics of shade tolerance; whethershade-tolerant species prefer maximized light interception and low respiration in the shade or are characterized by tough structures because of a reduction in organ turnover and promotion of plant survival. In this study,our objectives were to reveal whether the twigs and leaves of shrubs exerted trade-offs in the shade. Thus,twig dry weight( TDW),leaf dry weight unit twig( LDW),leafing intensity( LN/TDW),specific twig length( TL/TDW),leaf area supporting efficiency( LA/TDW),and individual leaf area( ILA) were measured for 11 shrub species,which have a relatively high ornamental value and limited management under the canopy at the Beijing Forestry University campus. In addition,the relative light summation of photosynthetically active radiation( PAR) and spectral ratio of red light and far-red light( R/FR) were measured for the habitats of target shrubs. Relationships between twig and leaf traits were determined using standardized major axis estimation( SMA). Effects of shade on relationships between twig and leaf traits were estimated using a multiple regression analysis. The study showed that( 1) light( relative light summation of PAR and R/FR) has significant positive relationships( P<0.01) with TDW and LDW and significant negative relationships( P<0.001) with TL/TDW,LA/TDW,and LN/TDW,whereas no significant relationship( P>0.05) was observed with ILA. In addition,the interactions between light and traits were more significant for R/FR than the relative light summation for PAR;( 2) furthermore,there was a significant positive correlation( P < 0. 001) and allometric relationship between TDW and LDW. A direct relation was observed between light and biomass of twigs and leaves,as biomass of both significantly decreased with decreasing light.However,shrubs reflected a relative bias in investment of leaf biomass;( 3) LA/TDW also showed significant( P<0.001)positive correlations and isometric relationships with TL/TDW. However,the steepness for TL/TDW-LA/TDW relationships in the lower R/FR decreased,indicating that shrubs presented a relatively conservative strategy for light interception in the shade;( 4) ILA showed a significant( P<0.001) negative correlation and allometric relationship with LN/TDW,implying that the twigs of shrubs tended to be made up of many smaller leaves in the shade. Therefore,together,the trade-offs of ornamental shrubs were similar to the hypothesis that suggested shade-tolerant species exert trade-offs in growth performance.However,generally,the shade tolerance of these shrubs was too weak to allow them to grow in the shade as ornamental species.
Understanding the relationships between twig and leaf traits provides valuable insights into the adaptive strategies of plant species. There are limited studies addressing the shade tolerance of woody species regarding trade-offs between twig and leaf traits. However,there are two contrasting hypotheses regarding the characteristics of shade tolerance; whethershade-tolerant species prefer maximized light interception and low respiration in the shade or are characterized by tough structures because of a reduction in organ turnover and promotion of plant survival. In this study,our objectives were to reveal whether the twigs and leaves of shrubs exerted trade-offs in the shade. Thus,twig dry weight( TDW),leaf dry weight unit twig( LDW),leafing intensity( LN/TDW),specific twig length( TL/TDW),leaf area supporting efficiency( LA/TDW),and individual leaf area( ILA) were measured for 11 shrub species,which have a relatively high ornamental value and limited management under the canopy at the Beijing Forestry University campus. In addition,the relative light summation of photosynthetically active radiation( PAR) and spectral ratio of red light and far-red light( R/FR) were measured for the habitats of target shrubs. Relationships between twig and leaf traits were determined using standardized major axis estimation( SMA). Effects of shade on relationships between twig and leaf traits were estimated using a multiple regression analysis. The study showed that( 1) light( relative light summation of PAR and R/FR) has significant positive relationships( P<0.01) with TDW and LDW and significant negative relationships( P<0.001) with TL/TDW,LA/TDW,and LN/TDW,whereas no significant relationship( P>0.05) was observed with ILA. In addition,the interactions between light and traits were more significant for R/FR than the relative light summation for PAR;( 2) furthermore,there was a significant positive correlation( P < 0. 001) and allometric relationship between TDW and LDW. A direct relation was observed between light and biomass of twigs and leaves,as biomass of both significantly decreased with decreasing light.However,shrubs reflected a relative bias in investment of leaf biomass;( 3) LA/TDW also showed significant( P<0.001)positive correlations and isometric relationships with TL/TDW. However,the steepness for TL/TDW-LA/TDW relationships in the lower R/FR decreased,indicating that shrubs presented a relatively conservative strategy for light interception in the shade;( 4) ILA showed a significant( P<0.001) negative correlation and allometric relationship with LN/TDW,implying that the twigs of shrubs tended to be made up of many smaller leaves in the shade. Therefore,together,the trade-offs of ornamental shrubs were similar to the hypothesis that suggested shade-tolerant species exert trade-offs in growth performance.However,generally,the shade tolerance of these shrubs was too weak to allow them to grow in the shade as ornamental species.
引文
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[26]李钰,赵成章,侯兆疆,马小丽,张茜.高寒退化草地狼毒种群个体大小与茎、叶的异速生长.生态学杂志,2013,32(2):241-246.
[27]Meng F Q,Zhang G F,Li X C,Niklas K J,Sun S C.Growth synchrony between leaves and stems during twig development differs among plant functional types of subtropical rainforest woody species.Tree Physiology,2015,35(6):621-631.
[28]徐程扬.不同光环境下紫椴幼树树冠结构的可塑性响应.应用生态学报,2001,12(3):339-343.
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[31]蒋运生,柴胜丰,唐辉,李虹,黄夕洋,李锋.光照强度对广西地不容光合特性和生长的影响.广西植物,2009,29(6):792-796,723-723.
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[2]Westoby M,Falster D S,Moles A T,Vesk P A,Wright I J.Plant ecological strategies:some leading dimensions of variation between species.Annual Review of Ecology and Systematics,2002,33(1):125-159.
[3]Sun S C,Jin D M,Shi P L.The leaf size-twig size spectrum of temperate woody species along an altitudinal gradient:an invariant allometric scaling relationship.Annals of Botany,2006,97(1):97-107.
[4]张艳茹,陈红,王海洋.低海拔常绿杜鹃小枝繁殖分配与异速生长关系研究.西南大学学报:自然科学版,2016,38(3):77-82.
[5]Maiti R,Rodriguez H G,Sarkar N C,Sarkar A.Branching pattern and leaf crown architecture of some tree and shrubs in northeast Mexico.International Journal of Bio-resource and Stress Management,2015,6(1):41-50.
[6]Cai H Y,Di X Y,Jin G Z.Allometric models for leaf area and leaf mass predictions across different growing seasons of elm tree(Ulmus japonica).Journal of Forestry Research,2017,28(5):975-982.
[7]李曼,郑媛,郭英荣,程林,卢宏典,郭炳桥,钟全林,程栋梁.武夷山不同海拔黄山松枝叶大小关系.应用生态学报,2017,28(2):537-544.
[8]Urbas P,Zobel K.Adaptive and inevitable morphological plasticity of three herbaceous species in a multi-species community:field experiment with manipulated nutrients and light.Acta Oecologica,2000,21(2):139-147.
[9]Poorter L.Leaf traits show different relationships with shade tolerance in moist versus dry tropical forests.New Phytologist,2009,181(4):890-900.
[10]史青茹,许洺山,赵延涛,周刘丽,张晴晴,马文济,赵绮,阎恩荣.浙江天童木本植物Corner法则的检验:微地形的影响.植物生态学报,2014,38(7):665-674.
[11]李亚男,杨冬梅,孙书存,高贤明.杜鹃花属植物小枝大小对小枝生物量分配及叶面积支持效率的影响:异速生长分析.植物生态学报,2008,32(5):1175-1183.
[12]Kleiman D,Aarssen L W.The leaf size/number trade-off in trees.Journal of Ecology,2007,95(2):376-382.
[13]史元春,赵成章,宋清华,杜晶,陈静,王继伟.兰州北山刺槐枝叶性状的坡向差异性.植物生态学报,2015,39(4):362-370.
[14]王雁.北京市主要园林植物耐荫性及其应用的研究[D].北京:北京林业大学,1996.
[15]殷东生,沈海龙.森林植物耐荫性及其形态和生理适应性研究进展.应用生态学报,2016,27(8):2687-2698.
[16]张斌斌,姜卫兵,翁忙玲,韩健.遮阴对园艺园林树种光合特性的影响.经济林研究,2009,27(3):115-119.
[17]陆銮眉,阎光宇,杜晓娜,卞阿娜.8种园林植物耐荫性与光合特性的研究.热带作物学报,2011,32(7):1249-1254.
[18]Dlugos D M,Collins H,Bartelme E M,Drenovsky R E.The non-native plant Rosa multiflora expresses shade avoidance traits under low light availability.American Journal of Botany,2015,102(8):1323-1331.
[19]冯秋红,史作民,董莉莉.植物功能性状对环境的响应及其应用.林业科学,2008,44(4):125-131.
[20]徐程扬.紫椴幼苗、幼树对光的响应与适应研究[D].北京:北京林业大学,1999.
[21]Pérez-Harguindeguy N,Díaz S,Garnier E,Lavorel S,Poorter H,Jaureguiberry P,Bret-Harte M S,Cornwell W K,Craine J M,Gurvich D E,Urcelay C,Veneklaas E J,Reich P B,Poorter L,Wright I J,Ray P,Enrico L,Pausas J G,de Vos A C,Buchmann N,Funes G,Quétier F,Hodgson J G,Thompson K,Morgan H D,ter Steege H,van der Heijden M G A,Sack L,Blonder B,Poschlod P,Vaieretti M V,Conti G,Staver A C,Aquino S,Cornelissen J H C.New handbook for standardised measurement of plant functional traits worldwide.Australian Journal of Botany,2013,61(3):167-234.
[22]Wright I J,Reich P B,Westoby M,Ackerly D D,Baruch Z,Bongers F,Cavender-Bares J,Chapin T,Cornelissen J H C,Diemer M,Flexas J,Garnier E,Groom P K,Gulias J,Hikosaka K,Lamont B B,Lee T,Lee W,Lusk C,Midgley J J,Navas M L,Niinemets,Oleksyn J,Osada N,Poorter H,Poot P,Prior L,Pyankov V I,Roumet C,Thomas S C,Tjoelker M G,Veneklaas E J,Villar R.The worldwide leaf economics spectrum.Nature,2004,428(6985):821-827.
[23]杨冬梅,毛林灿,彭国全.常绿和落叶阔叶木本植物小枝内生物量分配关系研究:异速生长分析.植物研究,2011,31(4):472-477.
[24]李肇锋,潘军,王金盾,周东雄,欧建德.光环境对闽楠幼树生长及其表型可塑性的影响.西南林业大学学报,2014,34(6):65-69.
[25]张志浩,杨晓东,孙宝伟,黄海侠,马文济,史青茹,阎恩荣.浙江天童太白山不同群落植物构型比较.生态学报,2015,35(3):761-769.
[26]李钰,赵成章,侯兆疆,马小丽,张茜.高寒退化草地狼毒种群个体大小与茎、叶的异速生长.生态学杂志,2013,32(2):241-246.
[27]Meng F Q,Zhang G F,Li X C,Niklas K J,Sun S C.Growth synchrony between leaves and stems during twig development differs among plant functional types of subtropical rainforest woody species.Tree Physiology,2015,35(6):621-631.
[28]徐程扬.不同光环境下紫椴幼树树冠结构的可塑性响应.应用生态学报,2001,12(3):339-343.
[29]蒙凤群.浙江天童亚热带常绿阔叶林木本植物小枝构型的功能生态学研究[D].南京:南京大学,2014.
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