喜旱莲子草沿河岸带不同生境的盖度变化及形态可塑性

doi:10.17521/cjpe.2006.0106

摘要/Abstract

摘要：

喜旱莲子草(Alternanthera philoxeroides)原产南美洲,是中国国家环保总局公布的9种危害最大的外来入侵植物之一。该文比较了分布于河岸带4种小生境中,喜旱莲子草和它的同属土著植物莲子草(Alternanthera sessilis)的盖度和生长特征变化,以了解影响喜旱莲子草入侵的生境和生长特征。按照距水体的距离远近,这些小生境依次为:废弃农田、沼泽、河边沙石滩及河间卵石滩。结果表明,这4种生境在基质性质、土壤养分和生产力方面存在显著的差异。在生产力较高的生境中(如废弃地和沼泽),喜旱莲子草是优势种,但在生产力较低的生境中(即河边砾石滩及河间卵石滩)土著种莲子草的相对盖度大于喜旱莲子草。随着生境土壤养分的增加,喜旱莲子草表现出明显的形态可塑性。喜旱莲子草与觅光相关的几个形态指标,如茎的长度、节间长度和节的数目以及单叶面积都显著增加;同时,那些着生叶片的分枝也从匍匐状转变成直立生长。在生产力较高的生境中,喜旱莲子草的植冠高度和茎干密度成正相关,表明喜旱莲子草对极度密集的种群环境有很强的适应能力。这些结果说明,较高的形态可塑性和优先占据具有较高土壤养分的小生境是喜旱莲子草沿河岸带入侵的基本特征,可能也是促成其入侵的重要的内部(植物自身)和外部(生境)条件。

关键词: 喜旱莲子草, 莲子草, 生物入侵, 光竞争, 入侵性, 资源比率模型

Abstract:

Background and Aims Biological invasions by non-native species have become a major environmental problem and a focus of ecological research. Relatively few studies have focused on invasibility and invasivness among microhabitats within communities. We compared the abundance and performance of non-native Alternanthera philoxeroides (alligator weed) and its co-occurring native congener, Alternanthera sessilis (sessile joyweed), in a wetland community along a riparian zone in southeast China to test the hypotheses that: 1) the degree of invasion differs between different types of microhabitats within the community; 2) microhabitat types that differ in invasion also differ in soil resource availability or in sediment characteristics likely to affect resource availability; and 3) phenotypic plasticity must have played a key role in adaptation to diverse habitats for A. philoxeroides because of its extremely low genetic diversity throughout China.

Methods Field surveys of natural distribution and performance of the two varieties on adjacent and contrasting microhabitat types (abandoned field, swamp, marsh dunes and gravel dunes) along a riparian zone were conducted in the autumn of 2003.

Key Results Soil organic matter, total N, available P and K were significantly higher and pH was lower in dryland and swamp than in dunes. Total vegetation coverage was significantly higher in dryland and swamp than in dunes. The relative coverage of A. philoxeroides was much higher than that of A. sessilis in more productive habitats (i.e. dry land and swamps), but this pattern reversed in less productive habitats (i.e. marsh and gravel dunes). A. philoxeroides showed greater morphological plasticity in response to habitat variation. Especially, the CV (coefficient of variation) of leaf area and branch angle in A. philoxeroides was 70 and 83 times greater than those in A. sessilis, respectively. Several morphological traits related to light foraging increased significantly from marsh and gravel dunes to more productive habitats (dry land and swamps). These traits included stem length, internode length, the number of nodes, and leaf length and width. Moreover, the leaf-bearing stems grew more vertically in dry land and swamps. Meanwhile, these traits in A. sessilis had no obvious variations among microhabitats.

Conclusions These results suggest that high plasticity in vertical growth and occupancy of soil microhabitat of rich nutrient resources may facilitate the invasions of A. philoxeroides.

Key words: Alternanthera philoxeroides, Alternanthera sessilis, Biological invasions, Light competition, Invasiveness, Resource ratios model

潘晓云, 耿宇鹏, 张文驹, 李博, 陈家宽. 喜旱莲子草沿河岸带不同生境的盖度变化及形态可塑性. 植物生态学报, 2006, 30(5): 835-843. DOI: 10.17521/cjpe.2006.0106

PAN Xiao-Yun, GENG Yu-Peng, ZHANG Wen-Ju, LI Bo, CHEN Jia-Kuan. COVER SHIFT AND MORPHOLOGICAL PLASTICITY OF INVASIVE ALTERNANTHERA PHILOXEROIDES ALONG A RIPARIAN ZONE IN SOUTH CHINA. Chinese Journal of Plant Ecology, 2006, 30(5): 835-843. DOI: 10.17521/cjpe.2006.0106

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2006.0106

https://www.plant-ecology.com/CN/Y2006/V30/I5/835

图/表 8

图1 研究地点示意图 DL: 废弃地Dry land MD: 河边沙石滩地Marsh dunes SW: 沼泽Swamp GD: 河间砾石滩地Gravel dunes

Fig.1 Location of the study area at the cross between Puyang River and Zhejiang-Jiangxi railway in Zhuji, Zhejiang Province, China

表1 4种小生境的主要地理和植被特征

Table 1 Description of the four substrates and their vegetation characteristics

	河间砾石滩 Gravel dune	河边沙石滩 Marsh dune	废弃地 Dryland	沼泽 Swamp
海拔 Elevation (m)	37	34	39	30
坡度Slope (%)	3.1	1.7	<0.3	0
朝向Aspect	NW-SE	NW-SE	NW-SE	N-S
砾石含量Rocks and gravel content (%)	76	50	5	9
土壤含量Soil content (%)	3	30	81	76
有机质Organic matter (g·kg^-1)	0.83	2.53	16.54	24.10
总N Total N (g·kg^-1)	0.05	0.15	1.04	1.58
有效P Available P (mg·kg^-1)	0.31	0.89	12.72	17.49
有效K Available K (mg·kg^-1)	1.53	7.41	66.45	115.16
pH	7.9	7.6	7.3	7.1
植被盖度Vegetation cover (%)	13.7	27.6	94.4	98.1
优势种 Dominant plant species	莲子草 Alternanthera sessilis	莲子草 A. sessilis	喜旱莲子草 A. philoxeroides	喜旱莲子草 A. philoxeroides
次优势种 Sub-dominant species	喜旱莲子草 A. philoxeroides	喜旱莲子草 A. philoxeroides	莲子草 A. sessilis	凤眼莲 Eichhornia crassipes

图2 喜旱莲子草(黑色)、莲子草(白色)和其它种(灰色)的盖度在4种小生境下的变化 DL、MD、SW、GD:同图1 See Fig.1

Fig.2 Cover of Alternanthera philoxeroides (Black bar), A. sessile (White bar), and the other species (Grey bar) among the four microhabitats at the end of the growing season (Oct. 2003)

图3 分布于两种沙石滩地上的喜旱莲子草(P)和莲子草(S)的冠丛高度和直径误差棒代表95%的置信区间 Error bars represent 95% confidence interval of the means GD、MD: 同图1 See Fig. 1

Fig.3 Canopy height and diameter of patchy distributed Alternanthera philoxeroides (P) and A. sessile (S) on gravel dune and marsh dune at the end of the growing season (Oct. 2003)

图4 分布于4种生境下的喜旱莲子草(灰色)和莲子草(黑色)的茎叶形态变化平均值±标准差 Mean±SE SW、DL、MD、GD:同图1 See Fig. 1

Fig.4 Plasticity in stem length, mean internode length, number of nodes, stem diameter, mean leaf area, and branch angle of leaf-bearing stems of Alternanthera philoxeroides (Grey)and A. sessilis (Black) across the four microhabitats at the end of the growing season (Nov. 2003)

表2 喜旱莲子草和莲子草枝叶形态指标在小生境间的变异系数

Table 2 Coefficient of variation (CV) for several morphological parameters of Alternanthera philoxeroides and A. sessilis among different microhabitats

形态指标 Morphological parameters	喜旱莲子草(%) Alternanthera philoxeroides	莲子草(%) Alternanthera sessilis	相对值 Relative values
茎长 Stem length (cm)	97.7	10.8	9.1
节间长 Internode length (cm)	76.5	1.1	6.9
节数 Nodes number	21.8	11.2	2.0
茎直径 Stem diameter (mm)	44.1	2.7	16.7
叶面积 Leaf area (cm²)	94.0	1.4	69.8
分枝角度Branch angle (°)	24.9	0.3	83.0

图5 喜旱莲子草毯状居群中植冠高度和茎杆密度的相关图 DL: y=0.89x-14.11, r2=0.93, p<0.01; SW: y=0.66x-20.75, r2=0.94, p<0.01 DL、SW: 同图1 See Fig. 1

Fig.5 Relationship between stem density (30 cm×30 cm quadrate-1) and mean canopy height (above ground on dryland and above water surface on swamp) in monotypic stand of Alternanthera philoxeroides on dryland and swamp substrate at the end of the 2003 growing season

图6 喜旱莲子草(P)和莲子草(S)优势度沿河岸带不同生境转变的资源比率模型当资源状况位于①和②区时, 入侵种喜旱莲子草成为优势种;当资源状况位于③和④区时, 土著种莲子草成为优势种;在⑤区时2物种可以共存(Tilman, 1982) At the area of ① and ②, invasive Alternanthera philoxeroides wins; at the area of ③ and ④ native A. sessile wins; at the area of ⑤ two species co-exist (Tilman, 1982) ZNGI: 零增长曲线 Zero net growth isoline

Fig.6 Conceptual model of the shift in dominance of Alternanthera philoxeroides (P) and A. sessile (S) as a result of competitive outcomes between the two species for different limiting resources

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