1. Introduction
The interaction between
frugivorous and
fleshy-fruited plants is an
important ecological process that links successive generations of plants
and influences vegetation dynamics (García et al., 2018; Rumeu et al.,
2020). Many fleshy-fruited plants
rely on birds for seed dispersal because of their high diversity,
mobility, diversified habitat selection (Carlo & Morales, 2016; Camargo
et al., 2020), and differences in body characteristics that can
concurrently remove a variety of fruit species (Wang et al., 2019). The
relationship between
fleshy-fruited plants and
frugivorous birds can form a complex
interaction network. Therefore,
unraveling the structure and dynamics of the interaction network can
provide novel insights into co-evolution theory (Schleuning et al.,
2015), and can be used to describe the diversity of interactions, reveal
ecological patterns, and plan conservation efforts (Ramos-Robles et al.,
2016; Beal-Neves et al., 2020).
Rapid urbanization has had significant effects on ecosystem structure,
leading to habitat loss, degradation, and homogenization (Kiers et al.,
2010). Changes in landscape configuration and composition affect the
movement and community diversity of bird (Pena et al., 2017), and
ultimately reduce the stability of the interaction network structure and
ecosystem service function, leading to serious consequences in
ecological and evolutionary processes (Harrison & Winfree, 2015; Guenat
et al., 2019). For instance, urbanization can negatively affect
plant-bird interactions by decreasing bird richness and increasing
interaction evenness (Schneiberg et al., 2020). Urban
green spaces are a multitude of
different open spaces in cities, such as patched native vegetation and
artificially managed parks, which play a crucial role in maintaining
species diversity and act as ecological corridors by connecting natural
vegetation remnants (Daniels et al., 2020; Zhang et al., 2022). Urban
green spaces comprise a range of garden plants, which not only provide
sufficient food resources and suitable alternative habitats for birds
but also influence the dispersal behavior of birds that can connect
different patches (Silva et al., 2016; He et al., 2022). For instance,
19 bird species foraged on 21 fleshy-fruited plants in the Nanjing
Botanical Garden Mem. Sun Yat-Sen during autumn and winter and then
dispersed these seeds to different types of habitats (Li et al., 2001).
With the decline in urban bird diversity and the continuous enrichment
of urban green space vegetation types, the characteristics of
plant-frugivore networks in urban green spaces have aroused great
interest. Previous studies have further shown that the richness and
diversity of bird-plant
interaction networks are affected
by different factors, as suggested by changes across phenology, fruit
size, color, and crop of plants that directly affect the foraging choice
of frugivore birds (Plein et al., 2013; Zhang et al., 2022), while the
body size, mouth-beak length, and tail length of frugivore birds are
associated with feeding amount, mode, and flight ability, and this
variability in functional characteristics might increase the functional
complementarity within networks (Dehling et al., 2016;
Sebastián‐González, 2017).
The Guilin Botanical Garden, located in the Guilin city, Guangxi Zhuang
Autonomous Region, Southwest China, serves as a typical ex-situ plant
protection base in an urban green space (Tang et al., 2009). It has more
than 300 endangered plants, and these plants produce large amounts of
fruit every year, providing an adequate source of food for birds.
However, very little information is available regarding the interaction
network structure and characteristics between birds and fruit plants. In
this study, we report the structure of the plant-frugivore network and
the trophic relationships between the network roles and functional
traits of two trophic species in the Guilin Botanical Garden. We aimed
to answer the following questions: (1) whether seasonal variation
affects interactions between frugivorous birds and plant species and (2)
whether species traits influence the functional roles of plants and
animals in interaction networks. We predicted that (i ) the
network is more complex in autumn and winter because of sufficient fruit
resources and (ii ) the role of species in interaction networks is
affected by their traits.