14 research outputs found
Effect of invader removal: pollinators stay but some native plants miss their new friend
Removal of invasive species often benefits
biological diversity allowing ecosystemsâ recovery.
However, it is important to assess the functional roles
that invaders may have established in their new areas
to avoid unexpected results from species elimination.
Invasive animal-pollinated plants may affect the
plantâpollination interactions by changing pollinator
availability and/or behaviour in the community. Thus,
removal of an invasive plant may have important
effects on pollinator community that may then be
reflected positive or negatively on the reproductive
success of native plants. The objective of this study
was to assess the effect of removing Oxalis pescaprae,
an invasive weed widely spread in the
Mediterranean basin, on plantâpollinator interactions
and on the reproductive success of co-flowering native
plants. For this, a disturbed area in central Portugal,
where this species is highly abundant, was selected.
Visitation rates, natural pollen loads, pollen tube
growth and natural fruit set of native plants were
compared in the presence of O. pes-caprae and after
manual removal of their flowers. Our results showed a
highly resilient pollination network but also revealed
some facilitative effects of O. pes-caprae on the
reproductive success of co-flowering native plants.
Reproductive success of the native plants seems to
depend not only on the number and diversity of floral
visitors, but also on their efficiency as pollinators. The
information provided on the effects of invasive species
on the sexual reproductive success of natives is
essential for adequate management of invaded areas.This work is financed by FEDER funds through the
COMPETE Program and by Portuguese Foundation for Science
and Technology (FCT) funds in the ambit of the project PTDC/
BIA-BIC/110824/2009, by CRUP AccžoËes Integradas Luso-
Espanholas 2010 with the project E10/10, by MCI-Programa de
InternacionalizacioÂŽn de la I ? D (PT2009-0068) and by the
Spanish DGICYT (CGL2009-10466), FEDER funds from the
European Union, and the Xunta de Galicia (INCITE09-
3103009PR). FCT also supported the work of S. Castro (FCT/
BPD/41200/2007) and J. Costa (CB/C05/2009/209; PTDC/
BIA-BIC/110824/2009). The work of V. Ferrero was supported
by the FundacioÂŽn RamoÂŽn Areces
Indirect interactions between invasive and native plants via pollinators
In generalised pollination systems, the presence of alien plant species may change the foraging behaviour of pollinators on native plant species, which could result in
reduced reproductive success of native plant species. We
tested this idea of indirect interactions on a small spatial
and temporal scale in a field study in Mauritius, where the
invasive strawberry guava, Psidium cattleianum, provides
additional floral resources for insect pollinators. We predicted that the presence of flowering guava would
indirectly and negatively affect the reproductive success
of the endemic plant Bertiera zaluzania, which has similar
flowers, by diverting shared pollinators. We removed P.
cattleianum flowers within a 5-m radius from around half
the B. zaluzania target plants (treatment) and left P.
cattleianum flowers intact around the other half (control).
By far, the most abundant and shared pollinator was the
introduced honey bee, Apis mellifera, but its visitation rates to treatment and control plants were similar. Likewise, fruit and seed set and fruit size and weight of B. zaluzania were not influenced by the presence of P. cattleianum flowers. Although other studies have shown small-scale effects of alien plant species on neighbouring natives, we found no evidence for such negative indirect interactions in our system. The dominance of introduced, established A. mellifera indicates their replacement of native insect flower visitors and their function as pollinators of native plant species. However, the pollination effectiveness of A. mellifera in comparison to native pollinators is unknown
Biological Invasions and Ecological Restoration in South Africa
This chapter provides an overview of the researchers and research initiatives relevant to invasion science in South Africa over the past 130 years, profiling some of the more recent personalities, particularly those who are today regarded as international leaders in the field. A number of key points arise from this review. Since 1913, South Africa has been one of a few countries that have investigated and implemented alien plant biological control on a large scale, and is regarded as a leader in this field. South Africa was also prominent in the conceptualisation and execution of the international SCOPE project on the ecology of biological invasions in the 1980s, during which South African scientists established themselves as valuable contributors to the field. The development of invasion science benefitted from a deliberate strategy to promote multi-organisational, interdisciplinary research in the 1980s. Since 1995, the Working for Water programme has provided funding for research and a host of practical questions that required research solutions. Finally, the establishment of a national centre of excellence with a focus on biological invasions has made a considerable contribution to building human capacity in the field, resulting in advances in all aspects of invasion scienceâprimarily in terms of biology and ecology, but also in history, sociology, economics and management. South Africa has punched well above its weight in developing the field of invasion science, possibly because of the remarkable biodiversity that provided a rich template on which to carry out research, and a small, well-connected research community that was encouraged to operate in a collaborative manner