Edaphic Arthropods in Fragment of Riparian Forest in the Semi-Arid of Paraíba

Important for soil quality, the edaphic fauna is indicative of an environment in equilibrium. The study aimed to identify the macrofauna and mesofauna organisms of the soil in a fragment of riparian forest. The work was carried out in a fragment of ciliary forest on the farm Tamanduá, municipality of Santa Terezinha, Paraíba. The macrofauna was quantified in soil samples collected at different depths (0-5 cm and 5-10 cm) using the TSBF method. For the mesofauna was collected randomly in the same area, samples of soil + litter in the depths 0-5 cm and 5-10 cm using metal rings. The design was completely randomized in a 4 × 2 factorial scheme (4 seasons, 2 depths), with 5 replicates, the means being compared by the Tukey test. The main orders of the macrofauna were: Hymenoptera, Coleoptera, Isoptera, and Enquitreídeos being the order of greater proportion in the two depths to Hymenoptera. There were a higher population and diversity of soil macrofauna in the superficial layer (0-5 cm). For the mesofauna were found in the samples organisms belonging to the groups Acarina and Collembola, being the order Acarina the most representative in the two depths evaluated. The environment of riparian forest presents greater diversity and density of macrofauna and mesofauna of the soil in the layer of 0.0-5.0 cm of depth, which presents greater food supply and conditions favorable to the survival of these organisms.


Introduction
In the riparian forests, there is a higher number and diversity of plant species, than is generally found in nearby areas.Therefore they play an essential role between the aquatic and terrestrial environments, as they contribute to soil fixation, decrease the exposure of the beds to the wind and consequently the excess evaporation.Riparian zones are considered a refuge for fauna diversity, especially in semi-arid regions that experience long periods of drought (Lima, 2009).These environments are also crucial for edaphic fauna, sheltering them and protecting them from high temperatures, solar radiation, and low soil moisture.
The preferred location of edaphic soil fauna in the superficial layers in the different environments is mainly due to the contribution of litter to the fact that these organisms provide favorable oxygen conditions and greater availability of food, thus favoring a greater proliferation of this community.It acts on the physical and chemical improvements of the soil where they are (Borges et al., 2016).
There are several ways to classify the organisms present in the soil, such as body size, mobility, eating habits, and soil functions.However, the most commonly used classifications involve the separation of organisms according to their diameter or length.
The soil fauna is classified according to its size in different groups: microfauna < 0.2 mm, represented by nematodes and protozoa, mesofauna ranging from 0.2 to 2.0 mm and macrofauna > 2.0 mm (Melo et al., 2009).

Results
In the exp 2012, with significant modificati  Quantifying the macrofauna organisms of the soil in Ciliary Mata area, a total of 210 individuals were observed, distributed in 14 taxonomic groups (Table 3), and 133 were present in the soil collected at depth 0-5 cm and, 77 in the layer of 5-10 cm.Note.*RF = Relative frequency.
The order Hymenoptera presented the highest relative frequency with 21.9%.Of the individuals collected in the 0-5 cm layer (71%) belong to four orders (Larva of Coleoptera, Hymenoptera, Isoptera, and Enquitreídeos), already in the layer of 5-10 cm the orders that predominated were Hymenoptera, Isoptera and Larva of Coleoptera.
Analyzing the Shannon Index (Table 4), it is possible to affirm that there is a greater diversity of macrofauna individuals in the first five centimeters of depth.
Table 4. Shannon (H) and Pielou (e) index at depths of 0-5 cm and 5-10 cm, for macrofauna in Ciliary Mata organisms in the Paraíba semi-arid Depth H E 0.0-5.01.114078175 0.432296 5.0-10.01.958912734 0.450967 The Pielou Equability Index (e), which indicates whether the species are equally abundant, presented similar values for both at depths.The large number of individuals of Coleoptera-larva, Hymenoptera, Isoptera and Enquitreídeos for the first five cm, and of Hymenoptera, Isoptera and Coleoptera-larva for the range of 5.0 to 10.0 cm, reduce the equitability.
In relation to the mesofauna groups, it is observed in Figure 5 that only two groups, Acarina and Collembola, were found in the soil samples + litter, and the order Acarina was the most representative in the two depths evaluated. jas.ccsenet.

Discuss
These con in the crea by 81% of the soil organisms in the forest being concentrated within a taxonomic group, the order Oligochaeta, which reduces the biodiversity index (H') and consequently less equitability (J').
The abundance of the Collembola group is associated with its ability to multiply and grow rapidly (Antoniolli et al., 2013).This group is best developed in environments of native vegetation, where conditions such as plant species varieties and organic soil compounds allow a greater diversity of soil organisms (Rief et al., 2010).

Table 3 .
Abundance and relative frequency of soil macrofauna individuals found in different depths in the Ciliary Mata area in the Paraíba semi-arid region