Home gardens: an assessment of their biodiversity and potential contribution to conservation of threatened species and crop wild relatives in Benin

Despite growing literature supporting the importance of home gardens (HG) as biodiversity hotspots, knowledge of patterns of their contribution to conservation of threatened species and crop wild relatives (CWR) across climate and culture in Africa is still limited. This investigation was conducted across three climatic zones to assess the floristic diversity of home gardens and the extent to which they contribute to conservation of threatened species and CWR. Overall, 240 home gardens were sampled and their floristic diversity assessed. The ecological importance of recorded species was determined per climatic zone using the importance value index (IVI). A cluster analysis was performed to group the species according to their IVI-values and a principal component analysis helped to identify the most important species. 285 species were inventoried throughout the study area. Home garden species’ diversity globally declined from the drier to the wetter zone but was highest in the transition zone. The average number of species found per HG was 10.1 and varied weakly across zones (9.07, Guineo-Congolean zone; 10.77, Sudano-Guinean zone; and 10.53, Sudanian zone). The most important home gardens species in the Sudanian, the Sudano-Guinean and the Guineo-Congolean zones were respectively: Abelmoschus esculentus (L.) Moench and Hibiscus asper Hook.f.; Solanum lycopersicum L. and Zea mays L.; Ipomoea aquatica Forssk. and Senna occidentalis (L.) Link. They were mainly vegetables and used as food and/or medicinal plant species. Twenty CWR and twelve threatened species were recorded and were also mainly used for food and medicinal purposes. Thorough research on socioeconomic factors supporting possession of HG and choice of managed species as well as indigenous management strategies of HG and dynamic of traditional knowledge related to HG may help to deeply assess home gardens’ effectiveness in biodiversity conservation.     

美国市民农园生态植被景观营建及其启示

美国市民农园是一个值得借鉴的兼具生产、生态和生活等多功能的植被景观模式,本研究针对市民农园的生态服务功能,依据市民农园结构模式及经营群体的不同,随机选取了洛杉矶市14个市民农园,采用样地调查、半结构式访谈等方法,基于植被物种功能组合和乡土植物组成,定量化研究了城市植被物种多样性及其分布格局对种植者族裔背景及营建模式等影响因素的响应,进而评析对我国城市绿地建设和休闲农业的启示。本研究共计调查到439种植物,分属90科,242属,分析结果显示:市民农园是城市生态系统中重要的物种库,能维护较为丰富的乡土植物资源;其植物功能以食用植物为主,观赏植物、药用植物次之,这在保护族裔传统文化、区域乡土文化具有重要价值;其植被景观结构和功能受到族裔背景及营建模式等不同程度影响。研究证明,市民农园作为生态多样性和文化多样性的交汇景观,是实现城镇绿色基础建设和休闲农业发展的重要营建模式。以此为经验,我国在进行绿地规划和生态植被建设时要考虑不同利益相关者,尤其是关注外来者的生活习俗和选择偏好;同时也要注意监测外来物种,以防造成物种入侵,这对于建设文化强国背景下开展城镇生态植被建设和发展休闲农业具有启示意义。     

Consequences of ex situ cultivation of plants: Genetic diversity, fitness and adaptation of the monocarpic Cynoglossum officinale L. in botanic gardens

Ex situ collections in botanic gardens have great potential in contributing to the conservation of rare plants. However, little is known about the effects of cultivation on the genetic diversity and fitness of garden populations, about genetic changes due to unconscious selection and potential adaptation to the artificial conditions. We compared the genetic variability and fitness of the rare, short-lived perennial Cynoglossum officinale from 12 botanic gardens and five natural populations in Germany. Genetic variability was assessed with eight nuclear microsatellites. Plants were grown in a common garden and performance was measured over 2 years. Mean genetic diversity was very similar in botanic garden and natural populations. However, four of the garden populations exhibited no genetic variability at all. Moreover, the genetic diversity of garden populations decreased with increasing duration of cultivation, indicating genetic drift. Plant performance from natural and garden populations in terms of growth, flowering and seed production was similar and in garden populations only seed mass was strongly related to genetic diversity. Several lines of evidence indicated genetic changes in garden populations in response to cultivation. Seed dormancy was strongly reduced in garden populations, and in response to nutrient addition garden plants increased the size of their main inflorescence, while wild plants increased the number of inflorescences. These changes could be maladaptive in nature and reduce the suitability of garden populations as a source for reintroductions. We suggest that botanic gardens should pay more attention to the problem of potential genetic changes in their plant collections.     

Gardens benefit bees and enhance pollination in intensively managed farmland

The recent loss of pollinating insects and out-crossing plants in agricultural landscapes has raised concern for the maintenance of ecosystem services. Wild bees have been shown to benefit from garden habitats in urban and suburban areas. We investigated the effects of distance from garden habitats on wild bees and seed set of a native out-crossing plant Campanula persicifolia, in intensively managed agricultural landscapes in Southern Sweden. Bee abundance and species richness, as well as plant seed set, were higher closer to gardens (<15 m) than further away (>140 m). This highlights private gardens as a landscape wide resource for pollinators but also the lack of sufficient pollination of wild plants in contemporary agricultural landscapes.     

The potential for genetic contamination vs. augmentation by native plants in urban gardens

Native plants in gardens can potentially aid conservation by contributing to genetic diversity and buffering small and otherwise isolated populations from extinction. However, gene flow from such plantings may threaten the genetic integrity of natural populations. We assessed the morphological and genetic diversity of garden plants in an urban population of Grevillea macleayana in south-eastern Australia. There were two main groups of garden plants: some similar to plants in nearby natural populations; others with unusual morphology. Multivariate analysis of morphological characters separated these groupings, which were confirmed by genetic analysis. Both groups produced seeds and flowering phenologies overlapped, indicating a potential for gene flow. Hand pollination showed that plants in each group could fertilize flowers of the other. Thus, these garden plants contributed to genetic variation in an urban/bushland metapopulation but there was potential for gene flow from the unusual plants. Unless carefully managed, garden plants may therefore cause disruption of the genetic integrity of nearby natural populations.     

Urban domestic gardens (IX): Composition and richness of the vascular plant flora, and implications for native biodiversity

Garden floras interact with native biodiversity by providing resources for wildlife and by acting as a source of non-native species. Understanding the composition and richness of garden floras will help evaluate the relationships between these floras and the wider environment. The composition and richness of vascular plant floras were measured in a stratified sample of 61 urban, domestic gardens in Sheffield, UK, based on complete garden inventories. The entire garden flora contained 1166 species, of which 30% were native and 70% alien. Across gardens, aliens showed lower occupancy than natives, comprising 79% of the species recorded only once. The garden flora contained 146 plant families, which included 72% of the native, naturalised or recurrent casual families recorded in the wild in Britain and Ireland. Gardens contained on average 45% natives, irrespective of garden size. Garden area explained 30% of the variation in species richness within individual gardens. Doubling garden size led to an increase in species richness of 25%. The garden flora comprised 10% annuals, 63% biennial/perennials, 18% shrubs and 8% trees; shrubs were disproportionately composed of alien species. The floras of urban domestic gardens probably form the greatest source of potentially invasive alien plants. However, the plants found in domestic gardens have closer affinities with the uncultivated flora than is often perceived, and their role for wildlife in gardens deserves reassessment. Declines in garden size that result from recommendations on the density of new housing are unlikely to have major consequences for plant richness in gardens.     

The structure of urban and peri-urban gardens in Khartoum,Sudan

A verdant strip of urban and peri-urban agriculture (UPA) lines the banks of the River Nile at Khartoum (Sudan), but little is known about its physical structure and species composition. This study was conducted in 120 gardens, covering 160 ha at the urban locations of Tuti Island and Shambat and the peri-urban location of El Halfaya to determine the extent and plant composition of UPA gardens in Greater Khartoum, which includes the cities of Khartoum, Khartoum North and Omdurman. The survey identified 84 plant species from 35 plant families, of which 47 were utilised as crops predominantly for commercial production of fruits, vegetables, spices and condiments, grains, and fodder. The gardens of Tuti Island, where production of lime (Citrus aurantiifolia (L.) Swingle) was widespread, had a mean species richness of 1.7 and a Shannon index of 0.4. The gardens of Shambat, where leafy vegetables were common, had higher crop diversity levels with a mean species richness of 4.4 and a Shannon index of 1.2. The gardens of El Halfaya, which was the only location where the production of some spices and condiments was recorded, had a mean species richness of 3.7 and a Shannon index of 1.0. All three study locations were largely dominated by monocultural commercial production relying heavily on external inputs. The four groups of gardens distinguished by cluster analysis were cultivated by 21 ethnic groups, 46% of the surveyed households relied on additional off-farm income and gardens supplied 12% of household food. Economic and ecological benefits of the studied UPA gardens might be enhanced if crop diversity and structural complexity of these gardens were increased.     

Use of native and exotic garden plants by suburban nectarivorous birds

A lack of food resources is often used as a reason for the decline in native birds in cities. This study investigated the use of exotic and native nectar resources by the nectarivore guild of birds, which often forms a major component of suburban bird communities in Australia. We investigated the food resource (nectar volume, concentration and sugar reward) of two common native and two exotic garden plant genera. We also determined the relative preference of the nectarivorous bird community for native and exotic plants and examined the relationship between nectarivore foraging preferences and particular garden characteristics. Banksias and grevilleas (native genera) produced significantly higher volumes of nectar than camellias and hibiscus (exotic genera) per floral unit, per plant and per cubic metre of foliage. Banksias also produced significantly more concentrated nectar and consequently a higher sugar reward per floral unit than the other three genera. Fourteen bird species were recorded using the study plants, although only three species were commonly observed feeding: the Red Wattlebird (Anthochaera carunculata), Little Wattlebird (Anthochaera chrysoptera) and Noisy Miner (Manorina melanocephala). Banksia and grevillea plants were preferred by all bird species, which spent significantly more time in banksia than in any other genus. Other variables influencing the time birds spent in a plant were the number of floral units per plant and the number of banksia and callistemon plants present in the garden. Overall, the native genera, banksia and grevillea were not only a more valuable source of food than the exotic genera, camellia and hibiscus, but they were also the preferred foraging sites for suburban nectarivorous birds. Whether the surplus of nectar from native shrubs is associated with territories of larger and aggressive honeyeaters competitively excluding small birds from gardens, is an important research agenda for understanding these urban bird communities.     

Does variation in garden characteristics influence the conservation of birds in suburbia?

Can enhancement of garden habitat for native birds have conservation benefits, or are garden bird assemblages determined by landscape and environmental characteristics? The relative roles of vegetation structure, floristics and other garden attributes, and environmental and landscape controls, on the abundance and richness of bird species in 214 back or front gardens in 10 suburbs of Hobart, Tasmania, Australia, are addressed to answer this question. Birds were counted in each garden and the resources they utilized noted. Vascular plant species and other attributes of the garden were noted, along with rainfall, altitude, distance from natural vegetation, distance from the city and garden size. Garden floristics and bird assemblages were ordinated, and garden groups characterized by particular assemblages of birds identified. General linear modelling was used to determine the combinations of independent variables that best predicted the richness of birds and the abundance of individual bird species and groups of species. The models for bird richness, bird species and groups of bird species were highly individualistic. Although native birds showed a preference for native plants, they also utilized many exotic plants. Exotic birds largely utilized exotic plants. Variation in garden characteristics does substantially affect the nature of garden bird assemblages in Hobart, with weaker environmental and landscape influences. The fact that gardens can be designed and managed to favour particular species and species assemblages gives gardeners a potentially substantial role in the conservation of urban native avifauna.     

Urban domestic gardens (XIII): Composition of the bryophyte and lichen floras, and determinants of species richness

Private, residential gardens form a substantial proportion of the undeveloped land in urban areas. Evaluating their role in supporting biodiversity is crucial to (i) predicting which plant and animal species can persist in towns and cities, (ii) understanding the regional impacts of urbanisation, and (iii) guiding sympathetic garden management by owners. To obtain baseline information on a poorly-studied component of garden biodiversity, we measured the size and composition of the cryptogam assemblages in 61 domestic gardens in the city of Sheffield, UK. A total of 67 bryophyte and 77 lichen taxa were recorded. Bryophytes ranged from 3 to 24 species per garden, with a mean richness of 11.3 species; lichens ranged from 2 to 30, with a mean of 14.9 species. Stone substrates supported the highest lichen richness, although minor substrates contributed unique species. Just over one fifth of bryophyte species were recorded in grass lawns, and these were more widespread than those of other habitats. Most cryptogams were scarce, with around one quarter of both bryophytes and lichens occurring in single gardens, and only 10% were found in more than half of the gardens. Garden area - correlated with substrate richness - and garden altitude were the only two factors explaining variation in cryptogam richness (bryophytes 39.1%, lichens 32.4%). Positive correlations existed among bryophyte, lichen and vascular plant richness, and these were only partially mediated by the effect of garden area. Therefore the opportunity remains for garden owners to support cryptogam richness, the most effective action being to enhance substrate diversity.     

Effect of the presence of nectar feeders on the breeding success of Salvia mexicana and Salvia fulgens in a suburban park near México City

The use of nectar feeders has grown a lot as a result of people wanting to attract hummingbirds to their gardens. This has caused an increment in the density and diversity of these birds in urban and suburban habitats. The feeders not only represent a bonanza resource for hummingbirds but they can also result in reduced visitation to native plants. We experimentally assessed the effect of placing nectar feeders in the vicinity of two native plant species in a suburban area of Mexico City. The plants with feeders showed a reduced visitation rate and in one case (Salvia fulgens) produced fewer seeds than the controls. Salvia mexicana was not only visited by hummingbirds but it was also by bees that were not attracted to the feeders, probably resulting in the lack of effect on this plant. Native plants in urban and suburban habitats can be threatened by reduced visitation rates and reduced seed sets resulting from the use of feeders.     

Mycorrhizal colonization of plants in set-aside agricultural land

Agricultural overproduction has led the European Union to encourage long-term abandonment of agricultural land and the adoption of management practices which enhance transition to semi-natural grassland or forest. This paper reports the results of a field study conducted in newly abandoned agricultural land where the development of the mycorrhizal community was investigated in response to manipulation of the above-ground vegetation. The field site consisted of plots where the plant diversity was managed by (1) sowing 15 plant species, (2) sowing four plant species, and (3) allowing plots to be naturally colonized by plants. The plant mixture contained grasses, legumes and forbs that were all expected to occur on the site following succession. Each of the low diversity replicates contained a different subset of the high diversity mixture, in order to avoid confounding diversity effects with sampling effects. A subset of these plots was inoculated with soil cores from a later successional stage and the experiment was arranged in a randomized block design. The catch plants, Fagus sylvatica, Picea abies and Plantago lanceolata, were planted in the experimental plots and the presence of ecto- or arbuscular mycorrhizal (AM) fungi on their roots was determined. The level of AM colonization of P. lanceolata and the ectomycorrhizal colonization of F. sylvatica was lower in the sown treatments with high and low plant diversity compared to areas that were naturally colonized by plants. The survival of catch plants of the tree species was also higher in the naturally colonized plots. Soil inoculations had no effect on either of the mycorrhizal types or the survival of catch plants. The establishment of non-introduced woody plant species was more successful in the naturally colonized treatments.     

基于层次分析法的豫北地区雨水花园植物综合评价

[目的]研究豫北地区雨水花园植物的筛选,为雨水花园和海绵城市的建设提供理论支撑。[方法]对国家级海绵城市鹤壁市和河南省省级海绵城市安阳市境内的典型雨水花园植物进行研究,采用AHP层次分析法对29种雨水花园植物进行综合评价,从3个准则层和9个指标层构建植物评价体系。[结果]指标层中的抗旱性、抗湿性、绿化美化特性、去污降污能力4个指标对于雨水花园植物的选择具有重要影响。千屈菜、红蓼、东方狼尾草、鸢尾、细叶芒、花叶芒6种植物综合评价等级为1级;再力花、常夏石竹、八宝景天、美人蕉、金鸡菊、马鞭草、大丽花7种植物综合评价等级为4级;香彩雀、紫叶狼尾草、蜀葵等16种植物综合评价等级为2—3级。[结论]综合评价值为1级的植物是豫北地区建设雨水花园的首选植物;综合评价等级为4级的植物是雨水花园慎重选择的植物材料;综合评价等级为2—3级的植物,选择合适的区域如蓄水区、缓冲区、边缘区进行雨水花园植物的种植。     

<Emphasis Type="Italic">Eryngium caucasicum</Emphasis> Trautv. cultivated as a vegetable in the Elburz Mountains (Northern Iran)

Eryngium caucasicum was found as a new cultivated vegetable plant in home gardens in northern Iran. Young leaves are used as a cooked vegetable and for flavouring in the preparation of several local foods.     

Species groups occupying different trophic levels respond differently to the invasion of semi-natural vegetation by Solidago canadensis

We studied the impact of the invasive plant species Solidago canadensis on the species richness of vascular plants and the abundance, species richness and diversity of butterflies, hoverflies and carabid beetles in herbaceous semi-natural habitats near Ljubljana, Slovenia. The species groups were sampled in sites dominated by S. canadensis and paired nearby sites covered by semi-natural vegetation. Plant species richness and species richness, abundance and diversity of butterfly species were lower in plots dominated by S. canadensis. Hoverfly abundance, diversity and species richness were negatively affected only in July just before the onset of flowering of S. canadensis, but tended to be positively affected in August during the height of flowering of S. canadensis. Only the abundance of carabid beetles was reduced in plots dominated by S. canadensis. The responses of the insect groups seem largely driven by the effects of Solidago on the availability of essential resources like food or larval host plants. Our results suggest that insect species that are closely related to plant species composition are more vulnerable to the effects of invasive plant species than those that are loosely or only indirectly related to plant species composition.     

Relationship between vegetation diversity and soil functional diversity in native mixed-oak forests

Most studies on the interactions between aboveground vegetation and belowground soil diversity have been carried out in microcosms or manipulated field plots. In the current study, we investigated the relationship between forest vegetation diversity and soil functional diversity (calculated from the activity of soil enzymes) in naturally developed plant communities of native mixed-oak forests without imposing any disturbances to already existing plant–soil relationships. In order to do so, five different vegetation types, i.e., herbaceous plants, climbing plants, trees, shrubs, and ferns, were considered. Correlations between plant diversity, soil physicochemical properties, and soil enzyme activities were determined. Soil physicochemical parameters appeared strongly correlated with both enzyme activities (e.g., pH was positively correlated with amidase and arylsulphatase, and negatively with acid phosphatase; OM content was positively correlated with β-glucosidase, acid and alkaline phosphatase and urease, and negatively with amidase; total N was positively correlated with β-glucosidase, and acid and alkaline phosphatase, and negatively with amidase) and soil functional diversity. For ferns, strong correlations between enzyme activities and plant diversity indexes were found (i.e., dehydrogenase was positively correlated with species richness and Shannon's diversity; acid and alkaline phosphatase were negatively correlated with Shannon's diversity; acid phosphatase was also negatively correlated with species richness). Most interestingly, herbaceous plants and ferns showed a strong positive correlation between Shannon's plant diversity and soil functional diversity. Furthermore, herbaceous plants showed a strong positive correlation between species richness and soil functional diversity. Although these correlations between plant diversity and soil functional diversity might possibly be due to the fact that higher values of plant richness and diversity result in a greater habitat heterogeneity in the soil, current knowledge on the topic is mixed and very incomplete and, then, one must be extremely cautious when interpreting such correlations.     

重庆市茶园蚂蚁物种多样性及空间分布格局

为筛选茶园害虫的蚂蚁类天敌,采用样地调查法研究了重庆主要产茶区(海拔371~1 068 m)茶园蚂蚁物种多样性特征与空间分布格局。在重庆主要产茶区茶园,设置3条垂直带,每条垂直带划分为低海拔(300~500 m)、中海拔(500~700 m)和高海拔(700 m以上)3个水平带,每个水平带设置3~4块样地,调查茶园的蚂蚁物种组成、群落多样性及空间分布特点。在物种多样性方面:共采集到蚁科昆虫4亚科,39种。各水平带物种丰富度为7~13种,Shannon-Wiener多样性指数0.55~1.25,Pielou均匀度指数0.08~0.16,Simpson优势度指数为0.26~0.65;各水平带蚂蚁群落多样性指数差异不显著,表明其多样性水平比较一致。群落相似性指数为0.22~0.48,多数处于中等不相似水平。在群落优势种方面:不同海拔茶园蚂蚁优势种数目1~3种,常见种最多达6种,最少仅1种;稀有种最多17种,最少5种;从重庆范围来看,重庆主要产茶区茶园蚂蚁群落共有7种优势种。在蚂蚁空间分布方面:有17种蚂蚁具有较宽的垂直空间分布,活动范围涵盖土壤、地表和树冠,有作为天敌昆虫资源的可能。仅有9种蚂蚁在不同水平带的茶园中均有分布。结合群落相似性与多样性分析结果,重庆茶园生境破碎,蚂蚁群落间物种交流受阻,不利于茶园生物多样性水平的稳定与提高。     

Plant type differently promote the arbuscular mycorrhizal fungi biodiversity in the rhizosphere after revegetation of a degraded, semiarid land

It is suggested that the diversity of arbuscular mycorrhizal fungi (AMF) and their association with distinct plants species are crucial in the early stages of revegetation procedures since the AMF roots colonisation plays an important role improving plant establishment and growth. We carried out a study where we analyse the AMF community composition in the roots of Ephedra fragilis, Rhamnus lycioides, Pistacia lentiscus and Retama sphaerocarpa fourteen months after revegetation in a Mediterranean semiarid degraded area of southeast Spain in order to verify whether different plant species can variably promote the diversity of AM fungi in their rhizospheres after planted. We analysed a portion of approximately 795 bases pairs of the small-subunit ribosomal DNA by means of nested PCR, cloning, sequencing and phylogenetic analyses. Eight fungal sequence types belonging to Glomus group A and B and to the genus Paraglomus were identified. The different plant species had different AM fungal community composition. Thus, R. lycioides harboured the highest number of four fungal sequence types while from E. fragilis only two types could be characterized that were specific for this plant species. P. lentiscus and R. sphaerocarpa harboured each one three sequence types and two of them were shared. All AMF sequence types were found in the natural soil. These results show that one effective way of restoring degraded lands is to increase the number of plant species used, which would increase the AMF diversity in the soil and thus the below-ground, positive interactions.     

Neglected landraces of collard (Brassica oleracea L. var. viridis) from the Carolinas (USA)

A common garden crop grown in the coastal plain region of North and South Carolina (United States) is the non-heading, leafy green type of Brassica oleracea L. known as collard (B. oleracea L. subsp. oleracea convar. acephala (DC.) Alef. var. viridis L.). Predominantly a fall and winter vegetable in this region, collard is often the only green planting to be found in the yard or garden of a rural home during these cool seasons. Historically, the traditional collard patch and even commercial fields were planted with unique varieties perpetuated by individual seed savers, and collectively, the regional diversity for this crop was probably very significant for well over a century. Genetic erosion of this collard germplasm pool has been severe in recent decades as commercial hybrids have been adopted by both large-scale producers and home gardeners. Although a significant number of collard landraces are being perpetuated to this day, existing diversity among landraces still grown in the region is now in the hands of an aging population of seed savers who maintain germplasm through on-farm preservation. From 2003 to 2006, we explored the coastal plain region of North and South Carolina in search of collard gardens containing traditional landraces. Exploration trips were conducted mid-winter to early spring. About 90 samples of collard were obtained from seed savers during the course of this exploration. Observations of morphological differences of these landraces indicate that significant diversity exists in this group. Obtained landraces are being deposited into the U.S. plant introduction collection and will be available for future use. This preserved collection could prove to be an important new source of genes for B. oleracea improvement.     

Wild pollinator communities are negatively affected by invasion of alien goldenrods in grassland landscapes

The increasing spread of invasive alien plants has changed biodiversity throughout the world. To date research in this area has focused on how invasive plant species affect pollinator behaviour, but there is a lack of data on the impact that alien plant species have on wild pollinator populations. Since their introduction in the 19th century, and rapid spread after the 1950s, alien goldenrods (Solidago canadensis, Solidago gigantea) have been among the most successful invasive plant species in Europe. We studied the effects of goldenrods on wild pollinator communities in SE Poland. The abundance, species richness and diversity of wild bees, hoverflies and butterflies were compared between wet meadows invaded by goldenrod (10 transects) and non-invaded controls (10 transects). Furthermore, we compared the plant diversity and average cover between the two groups of sites. Invasion of goldenrods had a very strong negative effect on wild pollinator diversity as well as abundance. Plant diversity and average cover were also negatively affected by goldenrod invasion. Wild pollinators were grouped according to their nesting and food specialization, but none were resistant to the invasion, indicating that introduced goldenrod may affect the entire wild pollinator community. Our study emphasises the urgent need to develop specific protection plans for wild pollinators in habitats threatened by foreign plants and we call for the introduction of programs to stop the invasion of goldenrod not only in Poland, but also on a continental scale.