Flowering and fruiting synchronization, pollen number, floral visitors and reproductive success of Paubrasilia echinata (brazilwood; Leguminosae) in tropical urban ecosystem in comparison to Atlantic forest remnant: A dataset description

In this article, we supply raw data on the reproductive biology and frequency of pollinators of Paubrasilia echinata, a threatened tree, endemic to the Brazilian Atlantic forest, which is largely used in Brazilian urban areas (e.g. avenues, parks and squares) due to its ornamental potential. Specifically, we share data on the reproductive phenology, pollen/flower, floral visitors and seed set of P. echinata in urban and natural ecosystems. This dataset article is related to the original research article "Reduced reproductive success of the endangered tree brazilwood (Paubrasilia echinata, Leguminosae) in urban ecosystem compared to Atlantic forest remnant: lessons for tropical urban ecology" (Oliveira et al., 2019). As urbanization is thought to negatively impact the maintenance of plant communities by affecting ecological key interactions, such as pollination, we believe that data as the supplied here are relevant and could support the planning of urban green spaces to maintain viable communities of plants and animals. This is especially valid for tropical urban ecosystems since most of the studies on plant ecology have been developed in temperate regions and there are still several gaps on the knowledge of ecological functions and ecosystems services (e.g. pollination) in urban green areas in the tropics.


Urbanization
Tropical green spaces et al., 2019). As urbanization is thought to negatively impact the maintenance of plant communities by affecting ecological key interactions, such as pollination, we believe that data as the supplied here are relevant and could support the planning of urban green spaces to maintain viable communities of plants and animals. This is especially valid for tropical urban ecosystems since most of the studies on plant ecology have been developed in temperate regions and there are still several gaps on the knowledge of ecological functions and ecosystems services (e.g. pollination) in urban green areas in the tropics.
© 2019 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons. org/licenses/by/4.0/).

Data
Data on the reproductive success of P. echinata in urban green spaces and natural forest remnant in the Brazilian northeastern Atlantic forest are shared in this article. Specifically, data on geographical location (Table 1), flowering and fruiting synchrony (Fig. 1), pollen number/flower (Table 2), floral visitors ( Fig. 2) and seed set are described. Differences on the number of pollen grains from large and smaller anthers, counted with the use of a manual counter, are explored in urban and natural ecosystems ( Table 2). Data on the frequency of floral visitors and their behaviour in both studied ecosystems are also provided ( Table 3, Fig. 3). In addition, the description and incidence of intact and malformed seeds and ovule abortion in developed fruits in urban and natural areas are documented in Table 4  Data presented in this brief is related to the study "Reduced reproductive success of the endangered tree brazilwood (Paubrasilia echinata, Leguminosae) in urban ecosystem compared to Atlantic forest remnant: lessons for tropical urban ecology'' [1].

Value of the data
Synchrony level in flowering and fruiting provide strong evidence about how planted trees in urban green spaces may supply food resource for populations of pollinators and seed dispersers of urban areas and surrounding forest remnants.
Comparisons of the number of pollen grains per flower of a plant species occurring in urban and natural ecosystems may be useful to indirectly access the reproductive potential of the species in novel ecosystems such as the urban green spaces. Data on the frequency of floral visitors and reproductive success, assessed from seed set, is a reliable measure and may be relevant to understand the effectiveness of pollination of P. echinata in urban and natural ecosystems. These data are important for the planning of tropical urban ecosystems (e.g. parks and squares) and to support strategies for ex-situ conservation of native species such as brazilwood (Paubrasilia echinata) in urban green spaces.

Flowering and fruiting synchrony
The level of synchronization of an individual in relation to all other sampled individuals (20 in urban and 15 in natural; Table 1) (di) was calculated to observe changes in flowering and fruiting synchrony  between urban green spaces and natural area. We calculated the (di), which is based on the number of censuses and the intensity in which the analysed phenophase was exhibited for P. echinata populations in urban green spaces (Fig. 1). The (di) represents a more accurate measure of the synchrony of a phenophase in relation to other widely used indices, since it considers the intensity [2] and the overlap of the phenophase at the individual or population levels [3]. Trees of each ecosystem were pooled together in all the statistical analyses (i.e. phenological, pollen number, frequency of floral visitors, and reproductive success).

Pollen number
The male component of the reproductive system of brazilwood (P. echinata) has two whorls of five stamens each, with large (L) and small (S) anthers. Differences in the amount of pollen grains per anther between trees from urban and natural populations and between L-anther and S-anther were tested. For this, anthers were longitudinally opened under optical microscope, and had all pollen grains removed for counting using a manual counter. The average number of pollen grains per L-and S-anther were obtained from 30 intact flower buds in pre-anthesis, collected from both ecosystems ( Table 2).

Frequency of floral visitors
The frequency of floral visitors was observed for about 30 hours in three individuals of P. echinata in each ecosystem (urban and natural). We registered the visitors and their approaching behaviours to the flowers. According to the visiting behaviour, floral visitors were classified as: a) effective pollinators, when the visitor contacted both reproductive structures of the flower in a same visit while collecting nectar, in all observed visits; b) occasional pollinator, when the visitor acted as a pollinator but did not contact the flower structures in all visits; c) thief, when the visitor collected nectar without contacting the reproductive structures of the flower (Figs. 2 and 3). To check for differences on the frequency of floral visitors between urban and natural ecosystems we used general linear models (GLM) with Gaussian distribution and "identity" link function (Table 3) [4].

Reproductive success
The female reproductive success was accessed through the average number of seeds per fruit under natural conditions (seed/fruit). To check for differences in seed set per fruit between urban and natural ecosystems, a total of 100 fruits from 10 individuals in both ecosystems were collected and their seeds were counted and classified in (1) fully developed, (2) malformed and (3) aborted/unfertilized ovule      (Table 4 and Fig. 4). The number of seeds in each category was compared by using generalized linear models (GLM) with binomial distribution and "logit" link function (Table 4) [4].