沙米表型可塑性对土壤养分、水分和种群密度变化的响应

研究了土壤营养、土壤水分和种群密度等环境因素对沙米表型可塑性的影响．结果表明：土壤营养、土壤水分和种群密度对沙米的形态特性和生物量具有显著影响;随着土壤营养的增加,沙米的根冠比从0．135减小到0．073,但与土壤水分和种群密度无显著相关关系．对土壤营养和土壤水分变化响应的沙米繁殖分配可塑性是“真正的可塑性”;沙米繁殖分配与土壤营养呈负相关,与土壤水分呈正相关;在高土壤营养或低土壤水分条件下,沙米的繁殖分配随个体大小变化的速率较大;种群密度对沙米的繁殖分配无影响,其繁殖分配主要受个体大小的制约．在3个环境因素中,土壤营养对沙米形态特性和生物量特性的可塑性影响最大．     

不同密度猪毛菜形态结构性状及生物量分配策略的异速关系

植物的生长特性随环境条件的变化具有可塑性,而不同的环境因素对植物可塑性的影响也不尽相同。利用异速分析的方法,通过模拟退化草地恢复过程中猪毛菜（Salsola collina）的不同种群密度（16、44、100、400株/m²）,研究其形态结构性状及生物量分配策略的异速关系在种群密度间的差异。结果表明,种群密度增大能抑制猪毛菜的生长,而且对猪毛菜的株高、根长、一级分枝数、二级分枝数、三级分枝数以及总分枝长均产生了极显著的影响,表明种群密度的变化使得植物的高生长和侧向生长发生了显著变化。种群密度的变化也引起了植物生物量的变化,其中植物根、茎、叶间的生物关系是一种表观可塑性,植物的生长策略未发生改变,只是植物个体大小发生改变引起的生物量分配的变化。植物株高、总分枝长、一级分枝数及繁殖分配的变化,是由种群密度变化引起的,植物的适应策略发生了改变,是真正的可塑性。种群密度改变了植物的繁殖分配策略,而未改变植物叶的分配策略,说明当环境发生变化时,植物调整了其繁殖策略以适应环境因素的改变,以保证种群的生存繁衍。     

高原鼢鼠繁殖特性与其栖息草地质量的关系

高原鼢鼠种群密度动态变化与其繁殖特性密切相关,而繁殖特性又与其栖息环境有关。为了解高原鼢鼠繁殖特性与其栖息草地质量的关系,本文在祁连山东段选择两个不同高原鼢鼠种群密度分布区,在其繁殖期调查各密度区雌雄个体不同月份的繁殖特性、草地生物量、植物组成、地下根系重量及根系可溶性糖含量、土壤紧实度和水分变化。通过多因素方差分析和独立样本T检验研究繁殖特性与草地质量的关系。结果显示：在高原鼢鼠繁殖期,5月为繁殖高峰期,6月进入繁殖末期;不同种群密度区之间个体繁殖强度无显著性差异（P>0.05）;雌性繁殖强度在繁殖高峰期无显著性差异（P>0.05）,而繁殖末期存在显著差异（P<0.05）;高原鼢鼠性比在繁殖高峰期表现为低密度区大于高密度区,而在繁殖初期和繁殖末期为高密度区大于低密度区;两个种群密度区之间,草地植物组成、草地地上生物量、可利用草地生物量和地下生物量无显著性差异（P>0.05）,而0-30 cm土层根系根可溶性糖含量存在显著性差异（P<0.05）;除高原鼢鼠采食深度（0-20 cm）外,不同密度区土壤紧实度无显著性差异（P>0.05）,而0-30 cm土层土壤水分含量存在显著性差异（P<0.05）。结果表明在一定种群密度下,高原鼢鼠繁殖特性的变化与地下根可溶性糖含量和土壤水分有关,而繁殖特性与草地植物学组成、草地生物量无显著关系。     

紫翅猪毛菜、钠猪毛菜不同个体大小繁殖分配差异及随海拔的变化

以新疆准噶尔盆地藜科猪毛菜属植物紫翅猪毛菜(Salsola affinis C.A.Mey)、钠猪毛菜(Salsola nitraria Pall)为研究对象,用繁殖分配比例的方法对比分析了两种猪毛菜不同海拔同一种群内不同个体大小繁殖分配的特点,并用异速生长模型分析了不同海拔繁殖生物量与营养生物量之间分配与个体大小的依赖关系。结果发现:1)不同海拔繁殖生物量(R)与营养生物量(V)呈不同程度的异速生长。紫翅猪毛菜随海拔的升高R-V的异速生长斜率显著升高,截距随海拔的升高没有显著增加;而钠猪毛菜的斜率随海拔升高显著降低,截距则显著升高。2)紫翅猪毛菜在较低海拔个体大小与繁殖分配呈负相关,在较高海拔呈正相关;钠猪毛菜在较低海拔个体大小与繁殖分配呈正相关,在较高海拔呈负相关;两种猪毛菜繁殖分配的适应对策相反。3)将同一种群个体大小分成大、中、小3种类型,多重比较发现紫翅猪毛菜在较低海拔,中小个体的繁殖分配显著高于大个体的繁殖分配;在较高海拔,大个体的繁殖分配显著高于中小个体的繁殖分配。钠猪毛菜在较低海拔,大个体的繁殖分配显著高于中、小个体的繁殖分配;在较高海拔,小个体的繁殖分配显著高于大、中个体的繁殖分配。综合分析认为:两个物种随海拔变化产生不同的繁殖分配策略,除遗传效应外,环境和个体大小对钠猪毛菜繁殖分配的变化均产生重要影响,而紫翅猪毛菜繁殖分配的变化主要由海拔差异导致。由于微生境对同一种群的个体大小产生影响,进而产生不同的繁殖分配模式,所以在干旱区更应重视个体大小对繁殖分配的影响。     

荒漠草原猪毛蒿种群繁殖特征的土壤驱动因子分析

繁殖是植物生命活动的重要环节,了解植物的繁殖特征是解释植物生态适应性和制定有效管理措施的重要依据。该研究以荒漠草原猪毛蒿(Artemisia scoparia)种群为研究对象,通过测定不同土壤类型的理化性质和猪毛蒿的繁殖特征,以期探讨影响其繁殖特征的主要土壤驱动因子。结果表明:灰钙土、风沙土和基岩风化残积土的水溶性碳含量、全氮含量、全磷含量、全盐含量、土壤水分含量、土壤硬度存在显著差异。猪毛蒿平均个体大小、单株头状花序的平均质量和数量均以灰钙土生境下最大,基岩风化残积土最小。繁殖分配在不同土壤类型下无显著差异,但与单个头状花序质量、单株头状花序数量和质量间呈极显著正相关关系。单株头状花序数量与单个头状花序质量间呈负相关关系。在风沙土生境下,单株头状花序质量主要受到土壤水溶性碳含量、土壤水分含量以及p H值的共同影响;单株头状花序数量受全盐含量的影响最大;繁殖分配和单个头状花序质量主要受全碳含量的影响。灰钙土生境下,单株头状花序质量与土壤水溶性碳含量、土壤水分含量和有机碳含量呈正相关关系;速效氮含量显著影响着单株头状花序数量。而基岩风化残积土生境下,繁殖特征的变异主要受到土壤水溶性碳含量、土壤硬度、土壤水分含量、全磷和速效磷含量的影响。综合分析发现,土壤因子对猪毛蒿繁殖特征的影响程度不同,其中单株头状花序数量和质量极显著地受到土壤水溶性碳含量和土壤水分含量的影响,繁殖分配和单个头状花序质量与土壤水溶性碳含量、土壤水分含量呈负相关关系。因此,土壤水溶性碳含量和土壤水分是荒漠草原地区影响猪毛蒿种群繁殖特征的主要土壤因子。     

种群密度对大果虫实形态特征与异速生长的影响

为揭示种群密度与植物形态特征、器官生物量间的异速生长关系,阐明植物在退化土地恢复过程中的适应策略,以大果虫实为材料,通过异速生长分析方法,研究种群密度对其形态特征、生物量分配与异速生长的影响。结果表明,种群密度对大果虫实的株型构建产生了显著地影响。随着密度增大,大果虫实株高呈减小趋势,其分枝数及分枝长度明显减小。大果虫实各器官生物量随密度增大而显著减小。随密度增大,茎和繁殖器官生物量分配呈减小趋势,根和叶片生物量分配呈增大趋势。这与最优化分配理论中水分、营养物质及光资源受限时的情况一致。密度对大果虫实株高:根生物量间异速生长具有显著影响,且对株高与器官生物量间异速指数和个体大小产生了极显著影响。密度对根:地上部分、叶片:根、繁殖器官:根生物量间的影响属于表观可塑性,而对根:茎、茎:地上部分、叶:其他器官及繁殖器官:其他器官生物量间的影响属于真正可塑性,说明密度改变了大果虫实的株型发育系统,并影响各器官间的异速生长,进而权衡器官生物量分配以完成生活史。     

荒漠草原猪毛蒿种群繁殖特征的土壤驱动因子分析

繁殖是植物生命活动的重要环节, 了解植物的繁殖特征是解释植物生态适应性和制定有效管理措施的重要依据。该研究以荒漠草原猪毛蒿(Artemisia scoparia)种群为研究对象, 通过测定不同土壤类型的理化性质和猪毛蒿的繁殖特征, 以期探讨影响其繁殖特征的主要土壤驱动因子。结果表明: 灰钙土、风沙土和基岩风化残积土的水溶性碳含量、全氮含量、全磷含量、全盐含量、土壤水分含量、土壤硬度存在显著差异。猪毛蒿平均个体大小、单株头状花序的平均质量和数量均以灰钙土生境下最大, 基岩风化残积土最小。繁殖分配在不同土壤类型下无显著差异, 但与单个头状花序质量、单株头状花序数量和质量间呈极显著正相关关系。单株头状花序数量与单个头状花序质量间呈负相关关系。在风沙土生境下, 单株头状花序质量主要受到土壤水溶性碳含量、土壤水分含量以及pH值的共同影响; 单株头状花序数量受全盐含量的影响最大; 繁殖分配和单个头状花序质量主要受全碳含量的影响。灰钙土生境下, 单株头状花序质量与土壤水溶性碳含量、土壤水分含量和有机碳含量呈正相关关系; 速效氮含量显著影响着单株头状花序数量。而基岩风化残积土生境下, 繁殖特征的变异主要受到土壤水溶性碳含量、土壤硬度、土壤水分含量、全磷和速效磷含量的影响。综合分析发现, 土壤因子对猪毛蒿繁殖特征的影响程度不同, 其中单株头状花序数量和质量极显著地受到土壤水溶性碳含量和土壤水分含量的影响, 繁殖分配和单个头状花序质量与土壤水溶性碳含量、土壤水分含量呈负相关关系。因此, 土壤水溶性碳含量和土壤水分是荒漠草原地区影响猪毛蒿种群繁殖特征的主要土壤因子。     

阿拉善荒漠不同密度白沙蒿人工种群生长、繁殖与土壤水分的关系

研究了阿拉善荒漠飞播建植的不同密度人工白沙蒿 (Artemisia sphaerocephala)种群的生长、繁殖与土壤水分的关系 ,主要结果是 :(1)不同密度白沙蒿人工种群的生长与繁殖特征存在明显差异 ,它反映在白沙蒿单株地上生物量、根量、生殖枝数和种子产量随着种群密度的增加而下降。 (2 )不同密度白沙蒿种群的存活率明显不同 ,当种群密度超过 3.1株 /m2时 ,个体植物生长发育不良 ,并出现密度制约死亡 (自疏 )现象 ,植株死亡率急剧上升。(3)不同密度白沙蒿草地不同深度土壤含水量存在明显差异 ,特别是 0～ 2 0和 2 0～ 4 0 cm两个土层的土壤含水量随种群密度的增加显著下降 ,与水资源容量相适应的白沙蒿种群密度约为 2 .1株 /m2 ,在该密度下土壤水分含量基本上能够满足白沙蒿的生理生态需水。 (4 )回归分析显示 ,白沙蒿单株地上生物量与0～ 2 0和 2 0～ 4 0 cm的土壤含水量呈显著正相关 ,而与 4 0 cm以下土层的土壤含水量无显著相关性 ,表明白沙蒿种群的生长主要受 0～ 4 0 cm土层土壤含水量的影响     

密度制约决定的植物生物量分配格局

基于自然环境下红葱(Allium cepa var.proliferum)个体各器官生物量积累动态、生物量分配比例动态、生物量比率动态和形态性状对不同种群密度(36、49、64、121和225株·m-2)响应的模拟实验,分析了密度制约对其生物量分配格局的影响。结果表明:红葱地上部分、叶和鞘的生物量分配比例均随密度的增加而增加,地下部分和鳞茎的分配比例随密度的增加而下降,而根的分配比例未随密度发生显著变化。除根:叶、根:地上比在密度处理间无显著差异外,各器官间生物量比率均表现出明显的密度依赖性。随着个体的生长,根:鞘、根:叶、根:地上比逐渐减小,鳞茎:叶、鳞茎:鞘、鳞茎:地上比先减小后增加,而地上:地下比先增加后减小。比叶面积与密度呈显著正相关(P<0.01),叶面积和根长与密度呈显著负相关(P<0.05),而比根长不受密度的影响。由此可见,种内竞争水平会对植物体内的资源分配产生较大影响;植物生物量分配格局响应不同密度具有可塑性,随着密度的增加,红葱个体会增加地上营养器官的生物量分配,并以减小地下无性繁殖器官的生物量分配为代价。最优化分配理论仅在无竞争存在的情况下适用,当竞争发生时,种群密度及其制约性调节是决定...     

不同生境下黄帚橐吾（Ligularia Virgaurea）个体大小依赖的繁殖分配

 研究了不同生境和密度下黄帚橐吾(Ligularia virgaurea)个体大小依赖的繁殖分配。结果表明无论在种群水平还是在个体水平上,黄帚橐吾都表现出：1) 在不同的生境和种群密度中,个体大小与繁殖体大小均不相同,其排列顺序依次为沙地＞坡地＞滩地、裸地＞非裸地、低密度＞高密度;2) 繁殖分配和单株种子均重在不同生境和种群密度中,其差异程度均从不显著(p>0.05)到极显著(p<0.01)不等;3) 繁殖体大小与个体大小在不同生境和种群密度中均呈极显著的正相关关系(p<0.01);4) 单株种子均重与个体     

Allometry of Salsola collina in response to soil nutrients,water supply and population density

The allometry of greenhouse‐grown Salsola collina Pall. in response to variation in soil nutrient content, water supply and population density has been compared. The results showed that the biomass allocation was size‐dependent. Root, stem, leaf and reproductive allocation showed a ‘true’ plasticity in response to soil nutrient variation. At low soil nutrient content, plants tended to allocate more biomass to the development of reproductive organs than to stem and leaf, but root allocation was consistent due to a tradeoff between the effects of plant size and soil nutrient content. The plasticity of stem allocation and reproductive effort was ‘true’, while the plasticity of root allocation was ‘apparent’, but there was no plasticity for leaf allocation in response to soil water variation. At lower soil water content, plants tended to allocate more biomass to the stem than to development of reproductive organs. With the exception of ‘apparent’ plasticity of root allocation, no plasticity was detected in biomass allocation when population density was varied.     

Allometric Effects of <Emphasis Type="Italic">Agriophyllum squarrosum</Emphasis> in Response to Soil Nutrients,Water, and Population Density in the Horqin Sandy Land of China

We monitored the allometric effects for greenhouse-grown Agriophyllum squarrosum plants in response to variations in population density and the availability of soil nutrients and water. Biomass allocations were size-dependent. The plasticity of roots, stems, leaves, and reproductive effort was “true” in response to changes in nutrient content. At a low level of soil minerals, plants allocated more resources to the development of roots and reproductive organs than to leaves, but data for stem allocations were consistent for tradeoffs between the effects of nutrients and plant size. The plasticities of leaf allocation and reproductive effort were “true” whereas those of root and stem allocations were “apparent” in response to fluctuations in soil water, being a function of plant size. Decreasing soil water content was associated with higher leaf allocation and lower reproductive effort. Except for this “apparent” plasticity of leaf allocation, none was detected with population density on biomass allocation. Architectural traits were determinants of the latter. For roots, the determining trait was the ratio of plant height to total biomass; for stems and reproduction, plant height; and for leaves, the ratio of branch numbers to plant height.     

A comparison of phenotypic plasticity between two species occupying different positions in a successional sequence

We compared the phenotypic plasticity of two greenhouse-grown species (Corispermum macrocarpum and Salsola collina) occupying different positions in a successional sequence in Horqin Sandy Land, by treating with different population density and the availability of soil nutrients and water. The same species can exhibit different patterns of plasticity in response to different environmental factors. In the soil nutrient treatments, the plasticity pattern of S. collina could be described as “master-of-some”. However, in the soil-water and population-density treatments, it showed no significant difference from C. macrocarpum in the reaction norm for plasticity. It was similar to a “jack-of-all-trades” plasticity pattern. Contrary to the previous conclusion that late successional species had higher reproductive allocation than early successional species, in this successional sequence, the late species had lower reproductive allocation in all treatments. Reproductive allocation of both species increased with the increase in water availability and also increased with a decrease in nutrient levels. However, density had no effect on reproductive allocation. Although the root:shoot ratio increased with decreasing water availability, there were no differences in the plasticity pattern for this trait in both species. Root:shoot ratio was, however, not significantly affected by nutrient availability and density. In a word, the plasticity patterns of invaders are adapted to the analyses of succession.     

Effects of competition on root–shoot allocation in <Emphasis Type="Italic">Plantago lanceolata</Emphasis> L.: adaptive plasticity or ontogenetic drift?

We investigated how shoot and root allocation in plants responds to increasing levels of competitive stress at different levels of soil fertility. In addition, we analyzed whether different responses were due to adaptive plasticity or should be attributed to ontogenetic drift. Plantago lanceolata plants were grown during 18 weeks at five plant densities and four nutrient supply levels in pots in the greenhouse. Thereafter root and shoot biomass was measured. There were clear negative effects of increasing plant densities on plant weights revealing strong intraspecific competition. At the lower N-treatments, the proportional allocation to root mass increased with increasing competitive stress, indicating the important role of belowground competition. At the higher N-supply rate, the relationship between competitive stress and shoot to root ratio was neutral. These responses could not be attributed to ontogenetic drift, but could only be explained by assuming adaptive plasticity. It was concluded that at lower N-supplies belowground competition dominates and leads to increased allocation to roots, while at the higher N-supply competition for soil resources and light had balanced impacts on shoot and root allocation. An alternative hypothesis explaining the observed pattern is that light competition has far less pronounced impacts on root–shoot allocation than nutrient deprival.     

Phenotypic plasticity of <Emphasis Type="Italic">Chenopodium murale</Emphasis> across contrasting habitat conditions in peri-urban areas in Indian dry tropics: Is it indicative of its invasiveness?

Phenotypic plasticity is an important plant trait associated with invasiveness of alien plants that reflects its ability to occupy a wide range of environments. We investigated the phenotypic response of Chenopodium murale to resource variability and ontogeny. Its plant-level and leaf-level traits were studied at high-resource (HR) and low-resource (LR) sites in peri-urban areas in Indian dry tropics. Plants at LR had significantly higher root length, root/shoot biomass ratio, stem mass and root mass fractions. Plants at HR had higher shoot length, basal diameter, leaf mass fraction and leaf area ratio. Leaf-level traits like leaf area and chlorophyll a were also higher here. Mean plasticity indices for plant- and leaf-level traits were higher at HR. With increasing total plant biomass, there was significant increase in the biomass of leaf, stem, root, and reproductive parts, and root and shoot lengths, whereas root/shoot length ratio, their biomass ratio, and leaf and root mass fractions declined significantly. Allocation to roots and leaves significantly decreased with increasing plant size at both sites. But, at any size, allocation to roots was greater at LR, indicative of optimization of capture of soil nutrients, whereas leaf allocation was higher at HR. Consistently increasing stem allocation equaled leaf allocation at comparatively higher shoot lengths at HR. Reproductive biomass comprised 10–12% of the plant’s total biomass. In conclusion, the success of alien weed C. murale across environmentally diverse habitat conditions in Indian dry tropics can be attributed to its high phenotypic plasticity, resource utilization capability in low-resource habitats and higher reproductive potential. These characteristics suggest that it will continue to be an aggressive invader.     

三江源地区不同建植期人工草地植被特征及其与土壤特征的关系

研究了三江源地区不同建植期人工草地群落生物量、物种组成、多样性指数和土壤理化特征,并用多元逐步回归分析法探讨了土壤理化特征对群落生物量、多样性变化的响应.结果表明:研究区不同建植期人工草地植物群落的种类组成、植物功能群组成和群落数量特征存在显著差异;土壤含水量随着物种多样性指数的增加而增加,土壤容重随着物种多样性的增加而减小;土壤微生物生物量碳与土壤含水量、土壤有机质呈极显著正相关,与土壤容重呈极显著负相关;土壤有机碳含量明显呈"V"字型变化,且与土壤含水量的变化趋势相一致,随土壤容重的增加而减少;群落生物量与土壤养分和土壤含水量之间呈显著正相关,群落地上、地下生物量的增加有利于提高土壤养分含量.     

Plasticity of seed output in response to soil nutrients and density in Abutilon theophrasti: implications for maintenance of genetic variation

 Seed output is determined by two processes: resource acquisition and the allocation of resources to seeds. In order to clarify how the reaction norm of seed output is controlled by the phenotypic expression of its two components, we examined the genetic components of plasticity of seed dry mass, plant size, and reproductive allocation under different conditions of soil nutrient availability and conspecific competition among eight families of Abutilon theophrasti. Without competition, the reaction norm of seed mass of the families crossed between the lowest and other nutrient levels, although neither of its components, plant size and reproductive allocation, showed such a response. The crossing reaction norm (i.e., reversal of relative fitnesses of different genotypes along the environmental gradient) of seed mass resulted from (1) a trade-off between plant size and reproductive allocation, and (2) changes in the relative magnitude of genetic variances in plant size and reproductive allocation with soil nutrient availability. While allocation was more important in determining seed mass under limiting nutrient conditions, plant size became more important under high-nutrient conditions. There were no significant genetic variances in seed mass, plant size, and reproductive allocation in the competition treatment, except at the highest nutrient level. The results show that plant competition mitigated the effects of genetic differences in plant performance among the families. We discuss the results in relation to maintenance of genetic variation within a population. Received: 16 August 1996 / Accepted 26 April 1997     

不同月份采集的贝加尔针茅地上部的分解特征及影响因素

利用植物生长过程中植物组织内养分元素化学性质的季节性变化特点,在2009年生长季的不同月份(5—9月)采集了呼伦贝尔地区贝加尔针茅地上部(茎和叶),作为分解底物,采用分解袋法,研究其分解特点及其影响因素。结果表明:不同月份采集的贝加尔针茅分解底物之间的分解速度存在明显差异,依采集月份逐渐递减,5月>6月>7月>8月>9月;分解底物初始N、P、Zn、K、Mg和Mn含量与分解速度均呈显著正相关,而碳含量和C∶N与分解速度呈显著负相关,初始钙含量、N∶P与分解速度无显著相关性;土壤微生物生物量N与分解底物的残余质量(%)相关性明显;另外,土壤微生物生物量N与凋落物C、N含量也具有明显的相关性;分解底物质量损失与土壤水分含量显著正相关,而与土壤温度的相关性较弱,说明降水变化通过调节土壤湿度来影响凋落物分解。     

Effects of habitat fragmentation and soil quality on reproduction in two heathland Genista species

Habitat fragmentation decreases plant population size and increases population isolation, as well as altering patterns of plant–animal interactions, all of which may reduce plant fitness. Here, we studied effects of habitat fragmentation (in terms of population size and isolation) and soil quality on the reproduction of two rare legume species, Genista anglica (13 populations) and Genista pilosa (14 populations), confined to remnants of acidic and nutrient‐poor Calluna heathlands. Single individuals of the Genista plants are impossible to distinguish; population size was therefore estimated according to the area occupied (referred to as population size hereafter). We collected soil samples in all heathland sites to determine content of soil water, C, N, P, Ca, K and Mg. In both species values of soil pH and C/N ratio, as well as content of soil P and base cations, reflected the highly acidic and nutrient‐poor environment of the heathlands. Population sizes were unrelated to soil quality. Although the two Genista species are similar in morphology and ecology, effects of explanatory variables on reproduction were largely inconsistent across species. In G. anglica, population size had a positive impact on all reproductive variables except germination rate, which, in contrast, was the only variable affected positively by population size in G. pilosa. In both species, mean total reproductive output, calculated as the product of total seed mass per shoot and total germination, increased with increasing water content and decreased with increasing P. In G. anglica, we found positive effects of the C/N ratio on all reproductive variables except mean single and total seed mass per shoot. In summary, in both species reproductive success per shoot decreased with increasing soil nutrient availability in the heathland sites. The infestation of two large populations of G. pilosa with the pre‐dispersal, seed‐predating weevil Apion compactum had no significant effect on reproduction of the populations.