DOI: 10.5061/dryad.qv9s4mwcc
title: Investigation results of 66 mangrove plant plots in Dongzhai port, Hainan Province

description: The distribution of mangroves is influenced by the environment. We aimed
 to understand the ecological adaptability of various mangrove species
 within the range of the exotic species, Sonneratia apetala Buch.-Ham., in
 Dongzhai Harbor, Hainan Island, China. We used three niche breadth indexes
 (Simpson, Levins, and Shannon-Weiner) and two niche overlap indexes
 (Pianka and Levins) to quantitatively determine the niche characteristics
 of nine mangrove species. The results showed that the order of the niche
 breadth values of mangrove species was as follows: Aegiceras corniculatum
 (Linn.) Blanco &gt; Kandelia obovata Sheue et al. &gt; Bruguiera
 gymnorrhiza (L.) Poir. &gt; Avicennia marina (Forsk.) Vierh. Hailanci
 &gt; S. apetala &gt; S. caseolaris (L.) Engl. &gt; Rhizophora
 stylosa Griff &gt; Ceriops tagal (Perr.) C. B. Rob. &gt; B.
 sexangula (Lour.) Poir. Pearson correlation analysis revealed that the
 niche breadth of each population was significantly correlated with the
 importance value of the population in the whole sample (R1 = R2 = 0.771,
 R3 = 0.644, P &lt; 0.05). The nine mangrove species were divided into
 three groups by Bray–Curtis cluster analysis; the groups were similar to
 the distribution of mangrove species in the natural state as determined by
 tide level. Niche similarity analysis showed that the niche similarity of
 most mangroves ranged between 0.5 and 0.8 and that the species pairs A.
 corniculatum–B. gymnorrhiza, A. corniculatum–Avicennia marina and K.
 obovata–S. caseolaris were characterized by large niche similarity ratios.
 Although it had a moderate niche breadth, S. apetala had a relatively
 broad niche overlap with mangroves in the mid- and low-tide zones (S.
 caseolaris, A. corniculatum, K. obovata, and Avicennia marina), a moderate
 overlap with B. gymnorrhiza and R. stylosa, only a slight overlap with C.
 tagal, and no overlap with B. sexangular. There was no obvious linear
 relationship between niche width and niche overlap of mangroves. Due to
 its inefficiency in utilizing certain resources and relatively high degree
 of resource selection, it seems likely that S. apetala will not pose a
 threat to the survival of native plants, let alone completely replace
 native species.
description: The experimental plots used in this study were located in the
 Sanjiang Mangrove Area of Dongzhai Harbor Nature Reserve (the area of
 mangroves here is approximately 1000 ha). In 1989, approximately 1 ha of
 <i>S. apetala</i> plantation was located in this forest area
 and by 1996, the area of <i>S. apetala</i> plantation had
 increased to approximately 10 ha. <i>S. apetala</i> dispersed
 primarily upstream and downstream along both sides of the Yanzhou and
 Meipo rivers. The range of <i>S. apetala</i> dispersal and
 colonization has occurred within an area characterized by a successional
 series of <i>Kandelia obovata </i>Sheue et al. +
 <i>Aegiceras corniculatum </i>(Linn.) Blanco<i>
 </i>communities. The successional community types in this area and
 their substitution order are as follows: <i>K. obovata</i> +
 <i>A. corniculatum</i> (Community I) → <i>A.
 corniculatum</i> + <i>K. obovata</i> (Community II) →
 <i>A. corniculatum</i> + <i>K. obovata</i> +
 <i>Bruguiera gymnorrhiza </i>(L.) Poir. (community III) →
 <i>A. corniculatum</i> + <i>B. gymnorrhiza </i>+
 <i>K. obovata</i> (community IV). The
 experimental plots (measuring 10 m × 10 m) were all located within these
 communities, among which 32, 10, 10, and 14 plots were established in
 communities I, II, III, and IV, respectively. Mangroves in the quadrat
 that were over 2 cm of ground diameter were measured and the name of
 species, number of individuals per species, coverage, diameter at ground,
 and tree height were recorded. Although small numbers of <i>Acanthus
 illicifolius </i>L. and <i>A. illicifolius </i>var.
 <i>ebracteatus</i> (Vahl) Williams<i> </i>were
 also distributed in each community, these were not included in data
 collection owing to their small size and low numbers.