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Managed landscapes in which non-native ornamental plants are favored over native vegetation now dominate the United States, particularly east of the Mississippi River. We measured how landscaping with native plants affects the avian and lepidopteran communities on 6 pairs of suburban properties in southeastern Pennsylvania. One property in each pair was landscaped entirely with native plants and the other exhibited a more conventional suburban mixture of plants--a native canopy with non-native groundcover and shrubs. Vegetation sampling confirmed that total plant cover and plant diversity did not differ between treatments, but non-native plant cover was greater on the conventional sites and native plant cover was greater on the native sites. Several avian (abundance, species richness, biomass, and breeding-bird abundance) and larval lepidopteran (abundance and species richness) community parameters were measured from June 2006 to August 2006. Native properties supported significantly more caterpillars and caterpillar species and significantly greater bird abundance, diversity, species richness, biomass, and breeding pairs of native species. Of particular importance is that bird species of regional conservation concern were 8 times more abundant and significantly more diverse on native properties. In our study area, native landscaping positively influenced the avian and lepidopteran carrying capacity of suburbia and provided a mechanism for reducing biodiversity losses in human-dominated landscapes.
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Research Note
Impact of Native Plants on Bird and Butterfly
Biodiversity in Suburban Landscapes
KARIN T. BURGHARDT, DOUGLAS W. TALLAMY,AND W. GREGORY SHRIVER
Department of Entomology and Wildlife Ecology, University of Delaware, Newark, DE 19716-2103, U.S.A
Abstract: Managed landscapes in which non-native ornamental plants are favored over native vegetation
now dominate the United States, particularly east of the Mississippi River. We measured how landscaping
with native plants affects the avian and lepidopteran communities on 6 pairs of suburban properties in
southeastern Pennsylvania. One property in each pair was landscaped entirely with native plants and the other
exhibited a more conventional suburban mixture of plants—a native canopy with non-native groundcover
and shrubs. Vegetation sampling confirmed that total plant cover and plant diversity did not differ between
treatments, but non-native plant cover was greater on the conventional sites and native plant cover was greater
on the native sites. Several avian (abundance, species richness, biomass, and breeding-bird abundance) and
larval lepidopteran (abundance and species richness) community parameters were measured from June
2006 to August 2006. Native properties supported significantly more caterpillars and caterpillar species and
significantly greater bird abundance, diversity, species richness, biomass, and breeding pairs of native species.
Of particular importance is that bird species of regional conservation concern were 8 times more abundant
and significantly more diverse on native properties. In our study area, native landscaping positively influenced
the avian and lepidopteran carrying capacity of suburbia and provided a mechanism for reducing biodiversity
losses in human-dominated landscapes.
Keywords: biodiversity, birds, Lepidoptera, managed ecosystems, native plants, non-native plants, suburban
landscape
Impacto de Plantas Nativas sobre la Biodiversidad de Aves y Mariposas en Paisajes Suburbanos
Resumen: Los paisajes bajo manejo en los que las plantas ornamentales no nativas son favorecidas en lugar
de la vegetaci´
on nativa son dominantes en los Estados Unidos, particularmente al este del R´
ıo Mississippi.
Medimos el efecto del ajardinado con plantas nativas sobre las comunidades de aves y lepid´
opteros en seis
pares de propiedades suburbanas en el sureste de Pennsylvania. Una propiedad en cada par estaba ajardinada
con plantas nativas completamente y la otra presentaba una mezcla suburbana de plantas m´
as convencional
– un dosel nativo con hierbas y arbustos no nativos. El muestreo de la vegetaci´
on confirm´
o que la cobertura
total de plantas era mayor en los sitios convencionales y que la cobertura de plantas nativas era mayor en
los sitios nativos. Medimos varios par´
ametros de la comunidad de aves (abundancia, riqueza de especies,
biomasa y abundancia de aves reproductoras) y de lepid´
opteros larvales (abundancia y riqueza de especies)
de junio 2006 a agosto 2006. Las propiedades nativas sustentaron un n´
umero significativamente mayor de
orugasydeespeciesdeorugas,as
´
ı como una abundancia, diversidad, riqueza de especies, biomasa de aves
y parejas reproductoras de especies nativas significativamente mayores. Es de particular importancia que las
especies de aves de inter´
es de conservaci´
on regional fueron 8 veces m´
as abundantes y significativamente m´
as
diversas en las propiedades nativas. En nuestra ´
area de estudio, el ajardinado nativo influy´
o positivamente
sobre la capacidad de carga de aves y de lepid´
opteros de los suburbios y proporcion´
ounmecanismopara
reducir las p´
erdidas de biodiversidad en paisajes dominados por humanos.
Address correspondence to Douglas W. Tallamy, email dtallamy@udel.edu
Paper submitted October 1, 2007; revised manuscript accepted June 16, 2008.
219
Conservation Biology, Volume 23, No. 1, 219–224
C
2008 Society for Conservation Biology
DOI: 10.1111/j.1523-1739.2008.01076.x
220 Biodiversity in Suburban Landscapes
Palabras Clave: aves, biodiversidad, ecosistemas bajo manejo, Lepid´
optera, plantas nativas, paisaje suburbano,
plantas no nativas
Introduction
Invasive plant species with origins in Asia, Europe, or
South America have received considerable attention in
recent years because of their ecological impact on North
American plant and animal communities (Pimentel et al.
2005). In contrast, non-native plants popular in suburban
landscapes have not been considered a threat to biodi-
versity because most of them are ornamental and lack
invasive traits. Regardless of their dispersal abilities, non-
native ornamentals, favored by landscapers and home-
owners, now dominate the first trophic level in millions
of hectares of North America. How the large-scale re-
placement of native vegetation with non-native plants in
managed ecosystems affects members of higher trophic
levels has yet to be determined.
Of particular concern are insect herbivores and the
many species of invertebrate and vertebrate insectivores
that eat them (Tallamy 2004). Theory (Ehrlich & Raven
1964) backed by decades of empirical evidence (Rosen-
thal & Janzen 1979; Weiss & Berenbaum 1988) predicts
that up to 90% (Bernays & Graham 1988) of all species
of insect herbivores can successfully reproduce only on
plant lineages with which they have shared an evolution-
ary history. With rare exceptions, insects cannot adapt
rapidly to evolutionarily novel plants (Southwood et al.
1982) because developing specialized physiological adap-
tations to detoxify, sequester, and excrete the noxious
phytochemical defenses of one host typically does not
predispose an insect lineage to breaking down the de-
fenses of other plants. Thus, landscapes dominated by
non-native plants, whether unwanted invasives or desir-
able ornamentals, are unlikely to support the same diver-
sity and biomass of insect herbivores as landscapes dom-
inated by native host plants. Moreover, if the presence
of non-native plants compromises insect biomass, it fol-
lows that populations of insectivores such as birds will
also be compromised. Given that 96% of all terrestrial
birds in North America rear their young in part or en-
tirely on insects (Dickinson 1999), large-scale reductions
in available insect biomass may have serious conserva-
tion implications that could be mitigated with changes in
landscape practices.
We quantified how simple changes in the paradigm
that has dominated suburban landscaping for over a cen-
tury affect biodiversity in the Piedmont region of the east-
ern deciduous forest (U.S.A.). Controlling for total plant
structure and cover, we compared biodiversity between
suburban properties landscaped primarily with native or-
namental plants with nearby properties landscaped with
a conventional mix of native and non-native ornamentals.
We used lepidopteran larvae as a surrogate for the insect
herbivores that support much of the terrestrial food web
and breeding birds as a surrogate for insectivore diver-
sity. We predicted that lepidopteran larval abundance
would correlate positively with the extent of native vege-
tation on each property. Given greater insect abundance
on native versus non-native plant species, we also pre-
dicted that bird species abundance and richness would
be greater on suburban properties landscaped with
native plants.
Methods
We conducted this study in a landscape that is typi-
cal of suburban areas in the southeastern Pennsylvania
Piedmont. We selected 6 pairs of properties within this
region that ranged in size from 0.13 to 5.26 ha. One
site-pair member was landscaped conventionally, with
large mowed lawns of cool-season Eurasian grasses, Asian
shrubs and understory trees, and a native canopy. The
other was landscaped entirely with native ornamentals
at all vegetative levels (canopy, understory, shrubs, and
grasses). For each pair of sites, the conventional site was
within 1.6 km of the native site, but the 2 sites were not
adjacent to avoid confusion from bird-use overlap dur-
ing data collection. During site selection, we attempted
to match pairs so they would not differ in area, vegeta-
tive structure and cover, or surrounding landscape fea-
tures such as bordering woodlands and streams, building
cover, bird nest boxes, and bird feeders.
We used line-intercept sampling to estimate vegeta-
tion cover (native vs. non-native), biomass, and structure
as a measure of the overall composition of vegetation
cover (Krebs 1999). We compared vegetation structure
between site pairs by measuring the total percentage of
plant cover at 4 height strata (5 cm, 1 m, 4 m, >15 m).
We estimated percent cover of each plant species along 4
transects originating from, and equally spaced along, the
longest side of each property by recording the length of
each transect intercepted by each species at the 4 height
strata. Areas of the transect with a heterogeneous cover of
multiple species (e.g., a meadow or mowed lawn) were
divided into “communities” in which the cover and plant
species composition remained relatively consistent. We
categorized each species in these communities as a dom-
inant, average, or rare member of that community and
then assigned that species a value for percent cover of
Conservation Biology
Volume 23, No. 1, 2009
Burghardtetal. 221
the transect line based on its dominance category and
number of species present in that community. We classi-
fied plants as native or non-native on the basis of range
and status maps from the PLANTS database (USDA 2007).
We defined non-native as not having shared an evolution-
ary history with the plants and animals of the mid-Atlantic
Piedmont.
From 11 August until 8 September 2006, we used a total
search approach (Wagner 2005) to quantify Lepidoptera
larvae at 3 evenly spaced intervals along each of the 4
vegetation transects on a property. At each sample point
along the transect, on days with no rain, we recorded
all lepidopteran larvae on all twigs and vegetation within
reach and inside a circle defining a vertical cylinder with
a 0.5-m radius between 09:00 and 14:00. We sampled
lepidopteran larvae at one site pair per day, alternating
whether we searched the native or conventional property
first and identified each individual to species or morphos-
pecies. Because Lepidoptera abundance is a function of
the abundance and quality of available host plants, we
sampled larvae in a way that captured the abundance
and dispersion of plants supporting larvae on each pair
of properties. Thus, rather than attempting to record all
the species occurring on each property, we created a rel-
ative index of Lepidoptera abundance and diversity that
we could use to compare the Lepidoptera productivity
of each member of a property pair.
We estimated breeding-bird species richness and
diversity with 25-m fixed-radius point counts (Donnelly
& Marzluff 2004). Sampling points were selected with
orthophotos to maximize the number of points on each
property while maintaining a 25-m buffer between adja-
cent circles to minimize double counting. The number
of avian sampling points was consistent within site pairs.
Avian data were collected between 05:00 and 07:00 from
7 June through 20 July 2006. We recorded all birds seen
or heard within the 25-m radius plot for a 5-minute inter-
val. Birds flying above the canopy within the radius were
not included because we could not determine whether
they were using the habitat. Weather permitting, we sam-
pled a pair of properties per morning and alternated the
treatment that was sampled first for 3 total sample dates
for each pair of sites. We also noted birds actively breed-
ing on a site by locating a nest, observing transport of
nesting material or food, or observing fledglings.
We estimated avian abundance at each site by summing
the maximum number of individuals detected across the
3 point counts for each species and dividing it by the
number of points sampled on a property. All estimates
and comparisons were made with the site as the sam-
pling unit (n=6). We compared avian species richness
between pairs for all native species of breeding birds and
for species of high conservation priority. We removed 2
non-native species from the breeding-bird analysis. These
were nesting House Sparrows (Passer domesticus)and
House Finches (Carpodacus mexicanus) with origins in
England and California, respectively (Ehrlich et al. 1988;
Hill 1993). We based conservation priority on Rich et al.
(2004). For the study area (physiographic area 10), the
birds of conservation concern (BCC) were the Great Blue
Heron (Ardea herodias), Veery (Catharus fucescens),
Wood Thrush (Hylocichla mustelina), Scarlet Tanager
(Piranga olivacea), and Eastern Towhee (Pipilo ery-
throphthalmus). Avian biomass was estimated by mul-
tiplying abundance by average species weight (Sibley
2000). Birds were assigned to either insectivorous or
omnivorous breeding-season trophic guilds so we could
compare guild species richness and abundance between
native and conventionally landscaped properties (Ehrlich
et al. 1988).
We used Simpson’s (1949) diversity index to estimate
plant and avian diversity. We used Spearman’s correlation
to determine the relationships between native and non-
native plant cover and lepidopteran and avian abundance.
We used paired ttests (α=0.05) to compare native
and conventional properties for all variables. We report
all results as mean with standard error. Supplementary
appendices of avian, botanic, and lepidopteran data are
available from D.W.T.
Results
Site size did not differ between native (2.32 ha [0.73])
and conventionally (2.27 ha [0.71]) landscaped sites (t=
0.139, p=0.895). Site pairs were also matched in at least
5 of the other 6 characteristics controlled for in the selec-
tion process (birdseed provisioning, bird boxes, number
of wooded borders, presence of a stream border, build-
ing cover, and encompassed wood). One site matched all
characteristics, 2 sites had a mismatched character that
would seem to enhance bird populations on the conven-
tional site (1 bird box, 1 birdseed provisioning), and 3
sites had such a character on the native site (2 bird box,
1 stream border).
Percent total vegetation cover did not differ between
native (49.3% [3.7]) and conventionally (44.9% [3.3])
landscaped sites (t=1.730, p=0.144). Native plant cover
was 2.4 times greater on the native properties (43.7%
[3.3]) than on conventional properties (17.9% [4.1],
t=7.956, p<0.001), whereas non-native plant cover
was 4.3 times greater on conventional properties (26.2%
[3.3]) than on native properties (6.1% [2.5], t=21.235,
p<0.001). These differences occurred exclusively in the
5-cm and 1-m height strata; properties did not differ in
native and non-native plant cover in the 4-m or >15-m
strata (Table 1). In the 5-cm stratum, native properties had
6 times more native plant cover than conventional prop-
erties, and conventional sites had 3.5 times more cover
of non-native plants than native sites (Table 1). In the
1-m stratum, native sites had 4 times more native cover
Conservation Biology
Volume 23, No. 1, 2009
222 Biodiversity in Suburban Landscapes
Table 1. Comparison of mean percent cover of vegetation at 4 height strata on study sites landscaped with predominantly native plants and sites
landscaped with a combination of non-native ornamentals and natives (conventional).
Height of
vegetation Category
transect of cover Native (SE) Conventional (SE) tp
5 cm total 80.2 (8.8) 78.4 (8.0) 0.328 0.756
native 59.2 (11.5) 10.3 (4.7) 5.419 0.003
non-native 19.9 (8.9) 66.6 (8.3) 4.484 0.006
1.0 m total 33.4 (3.8) 21.3 (8.9) 1.641 0.162
native 31.4 (3.8) 7.5 (4.6) 5.498 0.003
non-native 2.0 (1.5) 12.6 (6.4) 2.276 0.072
4.0 m total 35.0 (6.5) 43.3 (10.0) 0.974 0.375
native 32.6 (5.5) 23.4 (8.4) 1.338 0.239
non-native 9.6 (8.1) 25.7 (9.6) 1.795 0.133
>15 m total 48.3 (10.6) 36.5 (9.8) 0.971 0.376
native 48.0 (10.5) 30.5 (10.8) 1.261 0.263
non-native 0.3 (0.3) 5.8 (3.8) 1.543 0.184
than conventional sites (Table 1). Plant species richness
was higher on native sites (58.0 [13.3] species/site) than
conventional sites (31.2 [6.9] species/site, t=3.806,
p=0.013), but Simpson’s diversity index did not differ
between native (0.91 [0.03]) and conventionally land-
scaped sites (0.82 [0.06], t=2.364, p=0.064). Na-
tive plant diversity was positively correlated with lepi-
dopteran abundance (r=0.836, p<0.001) and avian
abundance (r=0.589, p=0.044). Non-native plant di-
versity was negatively correlated with lepidopteran abun-
dance (r=–0.838, p<0.001) and avian abundance (r=
–0.602, p=0.038).
Lepidoptera abundance was 4 times greater on native
sites (12.7 [2.1] larvae/site) than on conventional sites
(3.0 [1.4] larvae/site, t=8.665, p<0.001), and lepi-
dopteran species richness was 3 times greater on native
sites (6.8 [1.1] species/site) than on conventional sites
(1.8 [0.8] species/site, t=7.906, p<0.001).
We noted 46 bird species among all the sites. Avian
metrics (abundance, species richness, biomass, diversity,
and native nesting pairs) were all significantly greater on
Table 2. Comparison of bird-community metrics recorded on properties landscaped primarily with native plants versus properties landscaped with
a combination of non-native ornamentals and natives (conventional).
Metric Native (SE) Conventional (SE) tp
Abundance (individuals/point) 16.86 (1.81) 10.96 (1.02) 7.201 <0.001
Richness (species/site) 18.83 (3.09) 11.33 (2.38) 8.859 <0.001
Biomass (g/point) 956.28 (94.97) 636.94 (70.12) 3.238 0.023
Simpson’s diversity index (0–1) 0.92 (0.01) 0.840 (0.03) 3.053 0.028
All breeding birds (pairs/point) 1.63 (0.17) 0.96 (0.26) 2.457 0.057
Breeding birds w/o non-native 1.63 (0.17) 0.75 (0.14) 3.656 0.015
species (pairs/point)
BCCabundance (/point) 1.13 (0.34) 0.13 (0.14) 3.098 0.027
BCCrichness (/site) 1.67 (0.54) 0.17 (0.18) 3.503 0.017
Insectivore abundance (/point) 13.79 (1.76) 7.13 (0.88) 4.434 0.007
Omnivore abundance (/point) 3.07 (0.47) 3.83 (1.06) 0.868 0.425
Insectivore richness (/site) 14.67 (2.67) 7.83 (1.906) 5.590 0.003
Omnivore richness (/site) 4.167 (0.44) 3.50 (0.84) 1.348 0.235
Birds of conservation concern for study region as determined on the basis of Rich et al. (2004).
properties landscaped with native species than on those
with conventional landscaping (Table 2). Abundance and
richness of avian species of conservation concern were
also significantly greater on native properties. The abun-
dance and richness of avian insectivores (n=33 species),
but not omnivores (n=13 species), were significantly
greater on native sites (Table 2).
Discussion
Diversity indices of both lepidopteran larvae and breed-
ing birds responded positively to a greater percentage of
native grasses, forbs, and shrubs in residential landscapes.
Avian abundance, diversity, richness, and biomass (par-
ticularly bird species of conservation concern) were all
greater on native properties. Native nesting birds that
are mostly dependent on insect populations to feed their
young (Dickinson 1999) were more abundant on native
properties. Lepidoptera abundance and diversity were
also higher on native properties, suggesting that food
Conservation Biology
Volume 23, No. 1, 2009
Burghardtetal. 223
availability might account for the differences detected in
the bird communities between native and conventionally
landscaped sites. Beissinger and Osborne (1982) demon-
strated a similar pattern in bird community response to
urbanization in Ohio and alluded to the effect of vegeta-
tion type (non-native vs. native) as a potential explanatory
factor. In addition, the effect of food limitation on fitness
might be even more pronounced when adults of a species
also depend for their own nutrition on insect abundance.
This was the pattern we observed in our study; trophic
guild analyses revealed that the bird species driving the
differences between sites were those that specialize on
insects during the breeding season.
Plant species richness was higher on native proper-
ties but Simpson’s Index, a diversity index that incor-
porates relative abundance, did not reveal a difference
between native and conventionally landscaped sites. Al-
though these results suggest that the evolutionary ori-
gins of the plants is the source of differences in avian
and lepidopteran abundance and diversity in our study,
a field experiment rigidly controlling for plant richness
and diversity would more clearly isolate these variables.
Nevertheless, conventional landscaping typically creates
relatively homogenous habitats. Because we attempted to
control for plant diversity, our 6 conventional sites were
more diverse than typical suburban landscapes. Thus, we
consider our results conservative because of the similar-
ities in native canopy and understory trees between our
native and conventional properties. Our paired proper-
ties differed only in the proportion of shrub and ground-
cover that consisted of native plants. Greater differences
in biodiversity are expected in comparisons between
properties landscaped with natives and more typical sub-
urban landscapes in which non-native trees such as Nor-
way maple (Acer platanoides), Norway spruce (Picea
abies), Bradford pear (Pyrus calleryana), and golden-
raintree (Koelreuteria paniculata) have replaced native
canopy trees.
Our results followed our prediction that enhancing the
biomass and diversity of native plants would increase the
diversity and abundance of insect herbivores and thus
create a greater resource base for important insectivores
such as birds (Tallamy 2004). It is well documented that
most bird species are food limited (Marra et al. 1998;
Nagy & Holmes 2005; Granbom & Smith 2006). What
is becoming more apparent is that by reducing insect
food availability, non-native plants are indirectly reduc-
ing bird abundance in natural systems (Wilson & Belcher
1989; Lloyd & Martin 2005; Flanders et al. 2006) and,
counter to recent claims (Burdick 2005), are not “seam-
lessly” entering North American ecosystems without ill
effects. Our results suggest that the negative relationship
between non-native plant abundance and bird commu-
nity integrity is apparent in managed ecosystems as well,
regardless of whether the non-native species are inva-
sive. By demonstrating the connection between native
plants and suburban biodiversity, we provide evidence
that the landscaping choices of homeowners affect pop-
ulations of both birds and the insect food they require,
thus empowering homeowners, landscapers, and policy
makers to raise (or lower) local carrying capacities by
plant choice alone.
Acknowledgments
We thank Larry Weaner Landscapes for providing access
to willing property owners; cooperating landowners who
allowed us to invade their yards and privacy during the
course of the study; T. D. Pizzolato and J. J. Frett for
help with plant taxonomy; and the Undergraduate Re-
search Program at the University of Delaware for financial
support. This manuscript benefited from the thoughtful
comments of 4 anonymous reviewers.
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Volume 23, No. 1, 2009
... Native plants also support non-insect biodiversity. In a recent literature review, Berthon et al. [24] found that three-quarters of studies assessing the biodiversity impacts of native and non-native plants showed positive effects of native plants on animal biodiversity, including native insectivorous birds [25] and caterpillars [26]. Furthermore, native plants may be better adapted to regional climates than non-native species [27,28]. ...
... However, little is known about the competitive market for native plants, notably which types of nurseries are producing native plants and the types of production and business practices they implement. To date, research on native plants have focused on their benefits (e.g., environmental, ecosystem services, biodiversity) [10,12,18,19,21,26], production challenges [37][38][39][40], and market potential [4,5,35,53,54]. The production literature highlights challenges related to producing native plants; however, to date, a comprehensive assessment of current production methods used by native plant firms and how those differ from non-native plant growers has not been conducted. ...
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Native plant use in United States (U.S.) ornamental landscapes is expected to increase in upcoming years. Various market, production, and economic factors may influence a nursery firm’s likelihood of growing and selling native plants. The objective of this study was to investigate production-related factors (e.g., integrated pest management (IPM) strategies, firm characteristics, and plant types sold) that impact commercial native plant sales in the U.S. The research questions included the following: (a) What production factors drive growers to produce native plants? (b) What production factors increase native plant sales? Insights on production-related factors that influence native plant production can be used to understand the decision-making process of native plant growers and encourage additional production of native plants to meet expected increases in demand. Data from the 2014 and 2019 Green Industry Research Consortium’s National Green Industry Survey were used to address this research objective. Green industry firms were categorized by their annual native plant sales, and an ordered probit model was used to assess differences in IPM strategies, firm characteristics, number of plant types grown, sales attributed to different plant types, and actions to address labor issues. In general, firms selling native plants participated in more IPM strategies, sold a more diverse array of plants, and used more sales avenues than non-native plant firms. IPM strategies varied by native plant sales, with firms generating higher native plant sales exhibiting a higher likelihood of removing infested plants, circulating air, managing irrigation, using beneficial insects, and planting pest resistant varieties as part of their IPM strategy than non-native plant firms. Annual native sales and paying higher wages were impacted by plant types sold. Understanding current production and business practices can help identify practices resulting in market success for native plants, the use of which can enhance sustainable landscapes by increasing biodiversity and ecosystem services.
... Figure 4 summarizes the horticultural scores and pollinator data for the Echinacea trials published in 2021. ; pale pink flowers (26); coral and orange/pink flowers (27)(28)(29)(30)(31)(32); orange flowers (33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47); red flowers (48-51); red/pink and orange/red flowers (52-53); yellow flowers (54-61); white flowers (62-72); mixed flowers (73); and green-pink or green flowers (74-75). The pink-flowered taxa are (1) Engaging in plant-based solutions to combat biodiversity loss [1], Mt. ...
... Botanical gardens can contribute to improving environmental quality in urbanized areas, through greening projects [32] or popularizing new plants [33]. In fact, researchers studying the mid-Atlantic region show that the use of native plants in landscaping supports larger and more diverse animal communities [34]. ...
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Mt. Cuba Center is a botanical garden created with a conservation purpose: to work with native plants and inspire people to become conservators of native habitats. Adherence to this founding mission aligns Mt. Cuba’s activities with 4 of the 17 United Nations Sustainable Development Goals. This article shares aspects of the center’s founding, interpretative plan and content, horticultural research, and conservation programs. We hope that it will inspire the development and implementation of more botanical garden conservation programs that catalyze members, guests, and community partners to participate in and amplify conservation efforts through collective actions. By highlighting the region and its beautiful native flora, Mt. Cuba teaches conservation of native habitats and how to incorporate native plants into home gardens. The garden’s conservation messages are brought to life through interpretive plans, horticultural research, and public engagement. The garden itself acts as a tool to promote conservation by influencing guest attitudes and experiences. The renewal of Mt. Cuba from a fallow cornfield to a thriving ecosystem illustrates that individuals can make a difference. By telling its story and demonstrating accessible conservation actions through its work with native plants, Mt. Cuba aims to transform garden guests into conservators.
... Recently, the incorporation of exotic plants and intensive management of urban green areas (including increased use of insecticides and herbicides) has led to a reduction in insect abundance (Burghardt et al. 2009) and reduced the attractiveness of these green areas for House Sparrows (Wilkinson 2006, Burghardt et al. 2009). Additionally, Vangestel et al. (2010) found that due to increased fragmentation of suitable habitats, urban House Sparrows used only a limited number of food patches. ...
... Recently, the incorporation of exotic plants and intensive management of urban green areas (including increased use of insecticides and herbicides) has led to a reduction in insect abundance (Burghardt et al. 2009) and reduced the attractiveness of these green areas for House Sparrows (Wilkinson 2006, Burghardt et al. 2009). Additionally, Vangestel et al. (2010) found that due to increased fragmentation of suitable habitats, urban House Sparrows used only a limited number of food patches. ...
Article
Lack of food for nestlings is a crucial factor influencing population size and dynamics in birds. It is one of the most cited reasons for recent House Sparrow Passer domesticus population declines in cities and rural settlements. However, a detailed comparative study of habitat use by parents delivering food to offspring in different environments is still missing. To obtain the most detailed information on fine‐scale foraging habitat selection, foraging‐range size, flight distance, and foraging duration in typical Central European urban and rural environments, we conducted systematic observations of colour‐ringed focal individuals feeding their offspring. We found that urban House Sparrows had larger foraging‐range sizes and longer foraging distances than rural birds. Additionally, some preferred habitats, such as ruderal and woody vegetation occurred less frequently in the urban area and consequently increased flight distance to key sources of invertebrate prey. In both environments, the most selected habitats – bin storage areas and poultry holdings – offered a stable and rich, but probably lower quality “fast food” source. Birds were willing to fly a longer distance to forage at bin storage areas, tall ruderal vegetation and poultry holdings. Our findings imply that natural food sources in the urban environment are scarce and scattered. Due to the improvement of socio‐economic status associated with better handling of waste products in both urban and rural environments, sprawl of highly urbanized areas, and intensification of farming, important foraging habitats have thus decreased. We highlight the importance of maintaining suitable small and medium‐scale farms in rural areas and suggest improvements in the management of green spaces in all types of human settlements that may support House Sparrow populations.
... We had not hypothesized, however, that floral resources would be higher in old-field than in prairie corridors. The differences in patterns that we detected between the entire insect pollinator community and the lepidopteran subset may result from lepidopterans needing host plants to support their larval caterpillar life stage in addition to floral resources for adults [54,55]. For instance, we detected seven species of lepidopterans in prairies that were absent from old-field sites, and several of those require native grasses or forbs as larval hosts. ...
Article
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Electric powerline corridors are informal green spaces that encompass large areas of land and have the potential to support biodiversity in urban and suburban landscapes. However, the extent to which these corridors provide novel habitats compared to the surrounding landscape is unclear. Biodiversity in corridors is often compared to that of “natural” habitats despite the fact that the corridors are subject to frequent vegetation management. In urban and suburban landscapes, residential yards may provide a more appropriate comparison because they are a dominant type of green space and are also characterized by frequent vegetation management. We conducted a study of the biodiversity in suburban powerline corridors in northern Illinois, USA, and compared it to the biodiversity found in nearby residential yards. Our goal was to determine whether powerline corridors added ecological value to these suburban landscapes. We included three different management styles of powerline corridors: (1) frequently mowed and kept as lawn, (2) brush mowed on a five-year cycle (“old-field”), and (3) restored and/or maintained as native prairie. We measured the species richness and composition of plants, birds, and insect pollinators in corridors and yards. The corridor management types and comparison yards differed significantly in the richness of all three taxa, with old-field and/or prairie sites having greater species richness than mown corridors and/or comparison yards. Community composition also differed by management category. While the species richness of old-field sites tended to be high, prairie sites generally had more species of conservation interest. Our study shows that both old-field- and prairie-managed powerline corridors add habitat value to Midwestern U.S. suburban landscapes by providing alternative habitat types that support many species. Nonetheless, we suggest that managers looking to specifically support native and/or grassland specialist species in this region should manage sites as prairies when possible.
... These ornamental plant stocks are commercially available at garden centers (Garbuzov and Ratnieks 2014), have a 'tidy' growth habit, long bloom duration, and are aesthetically appealing to a wide range of consumers (Todorova et al. 2004). However, many of these varieties are nonnative (and likely nonmutualists) (Burghardt et al. 2009, Lowenstein et al. 2019) and have been subject to an extended history of breeding by hybridization and artificial selection (Horn 2002). Moreover, pollinator visitation to ornamental plant varieties can depend on particular cultivar characteristics Ratnieks 2015, Rollings andGoulson 2019), native status (Corbet et al. 2001, Chrobock et al. 2013 see Wenzel et al. 2020 for an alternative result), and environmental context such as site, year, and season (Bosch et al. 1997, Lázaro et al. 2010, Matteson and Langellotto 2010, Baldock et al. 2019, Erickson et al. 2020. ...
Article
Global pollinator declines have fostered increased public interest in creating pollinator-friendly gardens in human-managed landscapes. Indeed, studies on urban pollinator communities suggest that flower-rich greenspaces can serve as promising sites for conservation. Ornamental flowers, which are readily available at most commercial garden centers, are ubiquitous in these landscapes. These varieties are often non-native and highly bred, and their utility to pollinators is complex. In this study, we used observational data and citizen science to develop a methods framework that will assist stakeholders in the floriculture industry to incorporate metrics of pollinator health into existing breeding and evaluation protocols. The results of this study support how plant attractiveness to pollinators is often dependent on variables such as climate and plant phenology, which should be considered when developing an assessment tool. Furthermore, we found that some cultivars were consistently attractive across all observations while for other cultivars, pollinator visitation was apparently conditional. We determine using multiple statistical tests that 10 min is a sufficient length of time for observation of most plant types to broadly estimate three measures of plant attractiveness: visitor abundance, primary visitors attracted, and cultivar rank attractiveness, without sacrificing efficiency or accuracy. Additionally, we demonstrate that properly trained non-expert observers can collect accurate observational data, and our results suggest that protocols may be designed to maximize consistency across diverse data collectors.
... While the idea of native plant gardening is not novel (otherwise known as, for example, wildlife-friendly, native/indigenous, wildscape and pollinator-friendly plant gardening [18][19][20][21][22], the potential for urban green spaces to contribute actively to the conservation of declining and threatened native species is rarely reported in the scientific literature. Demonstrated justifications for native plant gardening include enhancing biodiversity, particularly insect and bird conservation, and associated social, cultural and psychological benefits 14,21,23 . We argue that native plant species can and should be protected in their own right through conservation gardening and that this may advance the science and practice of sustainable landscaping in multiple useful ways. ...
Article
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Global commitments and policy interventions for conservation have failed to halt widespread declines in plant biodiversity, highlighting an urgent need to engage novel approaches and actors. Here we propose that urban conservation gardening, namely the cultivation of declining native plant species in public and private green spaces, can be one such approach. We identify policy and complementary social mechanisms to promote conservation gardening and reform the existing horticultural market into an innovative nature-protection instrument. Conservation gardening can be an economically viable and participatory measure that complements traditional approaches to plant conservation.
... For instance, a certified Texas Wildscapes neighborhood had higher bird diversity and species richness than an adjacent, non-certified neighborhood (Aurora et al. 2009). Although not specific to sustainable landscaping programs, gardening with native plant species has been shown to increase the local richness and abundance of birds and pollinators (Burghardt et al. 2009;Pardee and Philpott 2014;Narango et al. 2018). Regarding habitat quality, NWF certified yards in the Orlando, Florida metropolitan area had significantly more edge habitat and food sources for birds, insects, and squirrels than the other yard types. ...
Article
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Sustainable landscaping programs are voluntary initiatives that recommend a set of practices to improve the environmental quality of urban ecosystems by providing landscaping materials, guidelines, and educational resources. Our goal was to examine the recommendations and outcomes of these programs in the United States and their value for encouraging conservation practices in residential ecosystems. We conducted a comprehensive web search and identified 193 sustainable landscaping programs in the United States. Programs aim to increase native species richness, affordably manage stormwater runoff, and offer residents meaningful experiences with nature. Sustainable landscaping programs present many opportunities to engage people with local ecological knowledge and conservation practices, provide accessible spaces for environmental education, cultivate interdisciplinary research collaborations, and advance inclusion in conservation. However, assessments of their ecological value are rare, leaving many questions surrounding the benefits to biodiversity and water quality afforded by participation. Many programs also require investments in landscaping materials and certification fees that might limit participation by some households. Future work should examine how recommended practices influence urban biodiversity, identify and address barriers to participation, and generate social-ecological knowledge that can inform future programs.
... Changes in biodiversity in small patches of remnant vegetation, such as isolated trees, have been associated with time elapsed since they became isolated, as well as with their connectivity to large, forested areas [38]. However, the role of isolated trees for biodiversity conservation has received less attention in urban contexts, where most studies have addressed interactions of native plants and birds [39][40][41], and to a lesser degree, arthropods [13,42]. ...
Article
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As urbanization proceeds, natural ecosystems surrounding cities are transformed, but usually some elements persist, notably trees from forest ecosystems. However, it is still unknown the extent to which isolated trees, immersed in an urban matrix, maintain their interactions with insects that feed on their seeds. In this work we analyzed pre-dispersal seed predation by the two main groups of insects, weevils (Coleoptera; Curculionidae) and moths (Lepidoptera: Tortricidae), whose larvae feed on the acorns of two oak species (Quercus rugosa and Q. castanea). We compared these interactions between trees located in a protected forested area and trees isolated in an urban matrix. Our hypothesis was that, since pre-dispersal seed predation depends on insect dispersal, acorns from isolated trees would have lower predation levels than acorns from trees in the forest. A second hypothesis, based on reports that moths exhibit larger dispersal distances than weevils, was that isolated trees would have higher predation levels from moths than from weevils compared to their respective proportions in forest trees. Finally, we expected that moth predation would increase with seed size, as it does in weevils. We collected 1200 acorns of the two oak species (ten trees per species) in a protected oak forest and a nearby highway in southern Mexico City. From the whole sample, 17.3% of the acorns were predated by weevils and 3.8% by moths. The probability of predation was larger in acorns from trees in the forest (0.30) than in those from isolated trees (0.07), which confirmed the first hypothesis; tree species identity did not have a significant effect on the proportion of predated acorns. When only predated acorns were analyzed, predation by weevil larvae was larger than predation by moths in both oak species, although the probability of predation by weevils was higher in the oak species having large acorns (Q. rugosa, 0.93), than in the species with small acorns (Q. castanea, 0.63). Inversely, predation by moths was higher in Q. castanea (0.37) than in Q. rugosa (0.07). Seed predation decreased similarly for weevils and moths in isolated trees, so we failed to find support for our second hypothesis. A positive relationship between seed predation by weevils and seed size was found in Q. rugosa but not in Q. castanea; seed size did not affect predation by moth larvae. Therefore, although isolated trees in the urban matrix harbor smaller populations of pre-dispersal seed predators than forest trees, their interactions with the two main groups of insects feeding on acorns are maintained, which points to their importance for the conservation of urban biodiversity.
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Worldwide, the percentage of people living in urban areas will increase from 50% in 2010 to nearly 70% by 2050. While in many parts of the world, human development is expanding rapidly on the urban fringe and at the expense of rural hinterlands, some cities decided to focus on densifying the built environment. Since densification leads to a quantitative reduction of open spaces, the pressure on the remaining ones is significantly increasing. On the one hand, open spaces should meet the requirements of its users, on the other hand, they have to fulfil expectations regarding climate adaptation and operating efficiency. Thus, to satisfy these claims, urban open spaces have to be endowed with multi-functionality. Urban agriculture, in turn, offers indispensable opportunities to solve - or at least deal with - urban challenges regarding sustainability, health, economy, society, urban design and local food supply. Due to its cross-cutting and multi-dimensional nature, it has the potential to meet a good many of requirements on open spaces. Nonetheless, it still inherits a rather low visibility on the agenda of urban planners. This situation could stem from various reasons, whereby a gap in the understanding of urban agriculture’s capability seems to be a major cause. To this day, there exists no comprehensive literature on the subject - neither a holistic view on urban agriculture’s multifaceted benefits nor its impacts on urban open spaces. Thus, the purpose of this study is to tap urban agriculture’s potential and to emphasise its raison d’être in sustainable urban planning.
Article
Residential gardens can provide essential opportunities for native wildlife and represent a valuable way of creating new habitats. Bandicoots (marsupial family Peramelidae) are medium-sized digging mammals that play a valuable role in maintaining ecosystem health; retaining these important ecosystem engineers across urban landscapes, including in private gardens, can have enormous conservation benefits. Urbanisation is a significant threat for some bandicoot species, and therefore understanding the factors associated with their activity can help guide urban landscape and garden design. To identify key features associated with the activity of a local endemic bandicoot species, the quenda (Isoodon fusciventer), we carried out a camera trap survey of front and back yards for 65 residential properties in the City of Mandurah, Western Australia. We compared quenda activity with biotic and abiotic factors that could indicate potential predation risk (activity of domestic dogs Canis familiaris and cats Felis catus, and the presence of artificial or natural protective cover), food availability (including deliberate or inadvertent supplementary feeding, provision of water, and diggable surfaces) and garden accessibility (distance to bushland, permeability of boundary fencing, and garden position). Supplementary feeding was strongly associated with quenda activity. Quenda were also more active in back yards, and in gardens where there was greater vegetation cover. Of concern, quenda activity was positively associated with cat activity, which could reflect that straying pet cats are attracted to gardens that harbour wildlife populations, including quenda. Furthermore, almost half of the gardens showed cat activity despite only a small sample of the surveyed residents owning a pet cat. Results of this study can help guide the design of residential gardens to increase useful habitat for these important digging mammals. Vegetation, wood mulch and semi-permeable fencing can provide valuable resources needed to support the persistence of quendas across the rapidly changing urban landscape mosaic, where natural and managed (e.g., gardens and parks) green spaces are becoming less common and more isolated.
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Compared with an undisturbed climax beech-maple forest, urbanization was presumed to be responsible for decreasing bird species richness and diversity, increasing biomass and density, and favoring dominance by a few species. Foraging guilds shifted from forest insectivores that were canopy foliage gleaners or bark drillers to urban ground gleaners. Although urban foliage height diversity was like that of the forest, the urban area contained only one-third of the total percent vegetative cover. Compared to the forest, urban vegetative cover was: 1) significantly less in all but the middle layer; 2) replaced by man-made structures, ground cover and ornamental vegetation in the low and middle layers but dominated the high layer; and 3) highly discontinuous, existing as isolated strata. -from Authors
Article
(1) The invertebrate fauna of six tree species in both Britain and South Africa was sampled using pyrethrum knockdown. Two of the tree species in Britain and three in South Africa were introduced; the rest were native. (2) Average faunal diversities were similar in South Africa and in Britain. (3) The South African arthropod community consisted of fewer, heavier individuals than the British ones and tended to have a more uniform, larger biomass overall. (4) Faunal diversity was similar for native and introduced trees for all guilds except the phytophages, which showed a lower diversity on introduced trees. (5) On every native tree, the most abundant species was an hemipteran; on four of the five introduced trees other orders provided the most abundant species. (6) Total species richness was correlated with tree abundance for both native and introduced trees in Britain. (7) Arthropod abundance increased with species richness--as communities became richer in species, they became more tightly packed. (8) The biomass and numbers of individual arthropods, classified by guild, was not clearly related to structural and other features of the individual trees sampled. (9) There was a positive correlation between the biomass of chewing phytophages and a measure of defoliation.
Article
In short-lived species, fecundity strongly influences population size. For those species with multiple breeding attempts per breeding season, variance in fecundity is best explained by the number of breeding attempts. For birds, multiple brooding may be influenced by food availability. Here, we report results of a food supplementation experiment that tests the role of food as a mechanism driving variation among individuals in the frequency of multiple brooding in a Neotropical migrant songbird, the Black-throated Blue Warbler (Dendroica caerulescens). Supplementally fed females produced more second broods, spent less time foraging and more time loafing, and stayed closer to their nests than did control females. Fed and control females did not differ in the number or mass of young fledged from the first nesting attempt. Supplemental food increased the probability that females would initiate second broods in both a low and an average food year, suggesting that this population is food limited during the breeding season in most years. Our results thus demonstrate that food availability can strongly influence annual fecundity in migratory bird species breeding in temperate forests, which, in turn, affects annual recruitment rates and population size.