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Effect of livestock on soil structure and chemistry in the coastal marshes of the central Gulf Coast of Mexico.

Introduction

The central coast of the Gulf of Mexico, in the state of Veracruz, has a large number of ecosystems, among them wetlands, which Olmsted (1993) has said arc far more abundant along the coast than inland. Veracruz has 302 102 ha of wetlands, and the Papaloapan Basin in the south is the largest, covering 169 621 ha (Landgrave and Moreno-Casasola 2012). These ecosystems include shallow coastal lagoons with seagrass beds, salt marshes, mangroves, palm groves, freshwater marshes, forested wetlands, and floating vegetation. Coastal marshes have been described by Moreno-Casasola et al. (2010) and freshwater forested wetlands by Infante et al. (2011).

Different types of wetlands vary in their floristic composition, structure, and hydroperiod. The last is a vital feature for the survival, development, regeneration, succession, and ecological processes of wetlands (Mitsch et al. 2009). These ecosystems also vary depending on the physicoehemical environment of the soil. This component plays a key role at wetland sites, since it is where there is a shortage of oxygen, producing stress, and where organic matter breaks down at varying rates. The characteristics and processes mentioned determine the different types of wetlands (organic and mineral) (Shiflct 1963; Neubauer 2008). In addition, soils play a key role in the legal delineation of wetlands; they maintain the history of the wetland and remain even after it has been drained and wetland vegetation has disappeared. All the physical and chemical changes that take place in the soil serve as indicators of hydric and environmental conditions (Richardson and Vepraskas 2001; Rcddy and DeLaune 2008).

In recent decades, the herbaceous wetlands of the central Gulf of Mexico have been affected by human activities, most notably livestock (Skerritt 1992; Moreno-Casasola 2004). Globally, there are few studies that have documented the impact of this activity in tropical herbaceous wetlands (Jansen and Robertson 2001; Jansen and Healey 2003; Travieso-Bcllo et al. 2005; Coles-Ritchie et al. 2007; Junk and Nunes Da Cunha 2012), but in grasslands and in both tropical and temperate forests, this activity has a negative impact on the vegetation and the soils. In these ecosystems, it has been shown to affect biodiversity, reducing species richness (Collins et al. 1998; Harrison et al. 2003) or increasing it by reducing the dominance of one or two species (Coffin and Lauenroth 1988; Blanch and Brock 1994). Livestock also alter the nutrient balance due to the incorporation of nutrients from manure (Archer and Smeins 1991; Trcttin et al. 1995; Baron et al. 2002), increase compaction by trampling (Martinez and Zinck 2004; Drewry et al. 2008), and have a negative impact on other soil physical properties (Willatt and Pullar 1984; Fassbender and Bornemisza 1987; Chanasyk and Naeth 1995; Greenwood et al. 1997; Rokosch et al. 2009; Fernandez et al. 2011).

The magnitude and duration of soil compaction depend on multiple factors including livestock treading intensity, stocking density, grazing management, and the animal species (Chanasyk and Nacth 1995; Mapfumo et al. 1999). Also, there are intrinsic characteristics of the sites (such as soil texture, vegetation status, soil moisture, and organic matter content) that affect soil compaction (Chanasyk and Naeth 1995; Smith et al. 1997).

In Mexico, and in general in the tropics, there is little research on the physicoehemical characteristics of wetland soils, and less on the effect of farming practices on the soils of these sites (Infante et al. 2011). Travieso-Bello et al. (2005) assessed the effect of different management practices (number of cattle head, years the field had been grazed, wetland drainage) on wetland soils converted to pastures. Their results indicated that factors associated with raising livestock (modification of hydrology, introduction of non-native species, and grazing) affect the physicoehemical properties of the soil, nutrient availability, biomass allocation, plant species richness, and turnover, leading to a loss of the attributes of a freshwater wetland.

In the context of the limited knowledge available on the subject, and the widespread use of wetlands for livestock grazing, this study evaluated, in space and time, the effect of cattle on some of the organic and mineral soil chemical properties of herbaceous wetlands of the central coast of the Gulf of Mexico, in the Papaloapan wetlands. In this paper, we test whether livestock negatively affect the structure and physicoehemical properties of organic and mineral soils, and we hypothesise that the degree of impact will depend on the livestock management carried in the wetland, the soil type, and the properties of the wetland, such as hydroperiod. The results of this study will generate information on the effects of this activity on the different types of wetland soils and provide insight into possible management measures for farmers and local governments. This could serve to mitigate the impact of livestock on the soils of herbaceous wetlands, which provide extremely important environmental services to coastal populations of the Gulf of Mexico, and help to preserve an economic income for local populations and the wetlands.

Materials and methods

Study area

The study area is close to the town of Alvarado, Veracruz, in the Gulf of Mexico, between 95[degrees]34'W, 18[degrees]46'N and 95[degrees]58'W, 18[degrees]42'N, at an altitude of 10m a.s.l. (Fig. 1). The climate is hot with abundant rains in summer. The temperature is 22--26[degrees]C and annual average rainfall 1748.3 mm (INEGI 2005).

At the sampling sites, natural herbaceous wetland vegetation dominates, with very few exotics (Echinochloa colona, Cucumis anguria, Momordica charantia) and some native non-wetland species, but these have a low degree of cover. Popal is a local term given by the botanist Faustino Miranda (Miranda and Hernandcz-X 1963) to this type of tropical freshwater marsh. This ecosystem is distributed in areas with tropical climates, on surfaces with almost permanent stagnant water covering the surface on floodplains with virtually no slopes and crossed by rivers (Rzedowski 1983). The vegetation is characterised by emergent herbaceous plants, l-3m tall, with broad leaves. The species reported for this type of wetland on the coastal central Gulf of Mexico, specifically in the state of Veracruz, arc Thalia geniculata, Pontederia sagittata, Sagittaria lancifolia, S. latifolia, Cyperus articulatus, Eleocharis cellulosa, Hymenachne amplexicaulis, and Heliconia latispatha, among others (Moreno-Casasola et al. 2010). Many of these species are still found in the area but in lower abundance, as there are species of introduced grasses and forbs that are gaining ground, mainly in the dry season.

The economy of the municipality of Alvarado is based mainly on cattle. The 19 ejidos (communally owned land) arc dedicated mainly to cattle ranching (INEGI 2007). Extensive cattle grazing is therefore common, although there is some rotation with the animals taken out of the wetland when the flooding is highest. The municipality allows one head of cattle per ha, but frequently numbers arc higher.

We selected four sites for this study (two with organic soils and two with mineral soils), all impacted by livestock because even after extensive surveying, despite the difficult access to the study area, and talking to local people, we were not able to find any areas where cattle were not being grazed; therefore, we did not have a cattle-free control. The two sites with organic soils were located by the Rio Blanco (called RBI and RB2), and the two with mineral soils by the Rio Limon (named RL1 and RL2). On RBI, livestock are generally in the wetland for 8 months, brought in during February and taken out in September. On the RB2 site, cattle are brought in during late January and taken out between September and November, so they are there for 8-10 months (Table 1). In RLI and RL2, the cattle arc there for 7-9 months, brought in during February and taken out between September and November (Table 1).

Experimental design

The two sites at Rio Blanco are separated by 2.5 km, and the two sites at Rio Limon are separated by 2 km. Rio Blanco sites are separated from those of Rio Limon by 14 km (Fig. 1).

At each site, the soil chemical properties were sampled; samples were taken twice in the dry season (January and April 2009) and twice in the rainy season (September and November 2009). Each time, 12 soil samples, were obtained from cores 15 cm deep and 10 cm in diameter. The samples were placed in sterile plastic bags until analysis.

Bulk density and total porosity

Soil samples were oven-dried at 105[degrees]C at 24 h, and small lumps were taken to determine bulk density (BD) by the clod method of waxing. This parameter is calculated using the formula: BD = mass/volume, where the mass is determined by weighing the lump of soil, and the volume is estimated indirectly by covering the lump with a layer of paraffin, weighing, and dipping it in a test tube with water (Moreno-Casasola and Warner 2009). Total porosity was obtained using the formula: 1 - (actual density/BD).

Chemical properties

Soil samples were dried outdoors and sieved (with a mesh aperture of 2 mm). The pH was measured in a 1:2 soil-water using a potentiometer. Carbon (C), total nitrogen (N), and organic matter (OM) contents were determined by dry combustion using a CN TruSpec analyzer (LECO Corp., St. Joseph, MI). Extractable phosphorus (P) was determined using the technique of Bray and Kurtz (Pierzynski 2000), and results were read using a spectrophotometer. Potassium (K) was determined by flame photometry according to Chapman's method (Sparks et al. 1996).

Statistical analyses

To determine whether the physicoehemical parameters (C, N, extractable P, K, OM, pH, BD, porosity index) varied between study sites, we applied a one-way ANOVA and a Tukey test for multiple comparisons. A factorial ANOVA was used to define whether there were differences between the seasons or among treatments (with and without livestock). To normalise the data, variables were transformed [log and log(.v + 1)]. The variables of the locations that could not be processed were compared using ANOVA by ranks in a one-way Kruskal-Wallis test and Dunn's multiple comparisons. For sampling period and treatments, we used the Kolmogorov-Smirnov test (Zar 1999). Pearson's correlation was used to determine the degree of association between parameters. To identify patterns present in the physicoehemical parameters with respect to the sampling sites we used a principal component analysis (PCA). The significance level used in all tests was 0.05. The statistical software used was R 2.5.1 (Dclgaard 2002; Crawley 2007) and MVSP 3.1 (Kovach 1999).

There was an initial analysis of all samples, since it was found that there were significant differences between the sites of Rio Blanco and Rio Limon. A second analysis was performed to detect differences between seasons, and a third analysis to understand the effect of livestock exclusion.

Results

Physicochemical parameters per site

The data presented arc an average of the four sampling periods during the year (two during the dry season and two during the rainy season). Site RBI had the highest percentage of C, followed by RB2; RLI and RL2 had the lowest values (Table 2). Concentrations of N at RBI and RB2 were high (>1%), whereas the values for RLI and RL2 were intermediate. The ratio C : N was significantly higher at RBI than at the other sites. Organic matter values showed a trend similar to those of C and N, since RBI was a highly organic site, followed by RB2, whereas RLI and RL2 had little OM. Sites RBI and RB2 had the greatest amounts of C, N, and OM, and they arc flooded most of the year.

Extractable P concentration was intermediate in RLI, and relatively high at the other three sites, particularly at RBI. The highest K concentration was recorded at RB2, followed by RBI. The two Rio Limon sites had low amounts of K. The pH was moderately acid at RBI, RB2, and RL2, and slightly acid at RLI. Site RBI had the lowest value for BD and thus the highest total porosity, followed by site RB2. Sites RLI and RL2 had the highest values of BD and therefore the lowest values of total porosity.

Analysis of physicochemical parameters by season

The data presented are the average of two samples per season (Table 3). The C, N, and OM did not change with the season at any of the sites. Extractable P and K levels were lower in the rainy season at most sites; however, only the RBI data showed significant differences. The pH increased at all sites during the rainy season; however, this increase was significant only at RBI and RB2. Bulk density decreased at RBI and RLI during the rainy season, when the cattle were taken out, but was significantly lower only in the latter. At RB2 and RL2, there was no apparent change in BD throughout the year. Total porosity was only significantly different at RLI, where it was higher in the rainy season (Table 3).

The results of PCA indicate that the first two components explained 79% of the variance. The analysis indicated that the variables with greatest weight in the first component were OM, C, N, C: N ratio (positively associated) and BD (negatively associated). In the second component, the greater weight was associated with K (positively) and with pH (negatively associated) (Table 4). Plots at the RBI site were pooled and separated from plots at RB2, RLI, and RL2. The variables that most influenced the soil structure of RBI were C, N, C N, OM, and total porosity. The BD was negatively associated with respect to the three remaining sites (Fig. 2).

In a second PCA, which excluded data from RBI (not shown), the first two axes explained 67.14% of the variance. The variables with the greatest weight in the first component were OM, C, N, and K (positively associated), and in the second component were pH (positively associated) and C: N (negatively associated) (Table 5). In this PCA, site RB2 separated from RLI and RL2. At RL sites, there was a clear association with high values of bulk density (and negatively associated with the second component).

Relationship between soil parameters

The correlation analysis identified significant relationships between physicoehemical parameters (Table 6). Nitrogen and C were positively correlated with each other, and both had the same positive correlation with OM, K., and P. Physicoehemical parameters were negatively correlated with the BD, except for pH and K. The pH was negatively correlated with all parameters; however, this was only significant for C, OM, and P.

Discussion

Physicoehemical parameters per site and season

Rio Blanco sites differ from those of Rio Limon (Table 2 and 3), primarily because of soil type, since the former have organic soils and the latter have mineral soils, despite their proximity and the fact that they form part of the same wetland complex. There were significant differences between the two sites at Rio Blanco, primarily because of livestock management. RBI can be considered as one end of a gradient of wetland conversion, the site with more freshwater wetland characteristics (layer of organic matter, macronutrient content, low BD). The two Rio Limon sites resemble each other and are found at the other end of the gradient (high BD, low OM, low concentrations of C, N, K, and P), whereas RB2 lies in the middle of this gradient. Therefore, site RBI was significantly different from the others with respect to C, N, C : N, OM, P, and BD. The percentage of C and OM is a little higher than the amounts described by Mitsch and Gossclink (2007), but the other values coincide with values reported by those authors for freshwater herbaceous wetlands. High concentrations of these parameters can be explained in several ways. One is the hydroperiod, since RB1 proved to be a site with a particularly prolonged period of flooding (~9 months). This leads to anaerobic conditions for longer periods, and therefore mineralisation and the decomposition of organic matter are slower (Trettin et al. 1995; Zhang et al. 2002).

Bulk density values for RB 1 are a little higher than the values reported by Collins et al. (1998) for this type of organic wetland. This site was significantly different from the others and had the lowest BD. This is probably due to a series of factors such as cattle spending less time on the site due to the long periods of flooding; in addition, it is the only site where the stocking rate is just one head per ha, and the human influence is low. Moreover, the fact that this site has a high OM percentage allows for greater soil porosity (Richardson and Vepraskas 2001), which favours the flow and retention of water.

The values of C, N, C: N, P, and OM for RB2 were slightly lower than for RBI, but arc consistent with those reported for freshwater herbaceous wetlands (Mitsch and Gosselink 2007; Bantilan-Smith et al. 2009). Hydroperiod was also important at this site, which remained flooded for ~8 months of the year. The fact that the BD values were higher at RB2 than at RBI may be due to the higher stocking density at the former, as trampling by more livestock exerts greater pressure and reduces soil air spaces. This results in greater flooding during the rainy season because water retention is lower, and in the dry season the water level decreases more (compared with that of RBI), allowing livestock to graze longer.

It has been reported that the K. ion is directly associated with the presence of the sodium (Na) ion (Travieso-Bello et al. 2005). In our work, Na was not recorded, but it is likely that this ion is present in RB2, due to the presence of K. Soils at RBI had salic characteristics, so it is likely that both sites are under greater influence of the salt wedge, eventually receiving input from saltwater, in contrast with the RL sites. As shown in Fig. 1 the RB sites arc closer to the estuary.

OM storage results in the accumulation of long-term P in wetlands (Reddy and DeLaune 2008). This explains the high values of P in RBI and RB2, as these sites have a higher OM content.

The values of the physicochemical parameters of RL 1 were very similar to those of RL2 because both sites have soils of mineral origin, materials deposited by the river or lake, and even of marine origin (IUSS Working Group WRB 2006). These sites are dry for ~6 months of the year, and flooding begins in July; the foremen take the animals out between September and November. Therefore, the cattle spend 7-9 months at the RLI and RL2 sites. The BD of the soil at these sites was higher than of those at Rio Blanco, due to the intrinsic properties of mineral soils, since they have lower porosity. However, the BD values of RLI and RL2 were still higher than documented for mineral soils of the Fluvisol and Gleysol types (Thompson and Troeh 1988; Tebrugge and During 1999; Walczak et al. 2002) and higher than reported for freshwater herbaceous wetlands (Collins et al. 1998). The fact that livestock spend more time at these sites and stocking density is greater may be causing the high degree of compaction. At RL2, BD was slightly lower than at RLI, probably because of the higher stocking density at the latter site. Mineral soils have a low organic matter content, and this should be considered before using the land for livestock management, because if the stocking density is high, the low quantities of OM found in the soil may decrease even further, putting the soil structure at risk (Soracco 2005). The low amounts of OM may also be limiting many physicoehemical and biological processes that arc involved in the processes of soil formation.

The pH values for the four sites correspond to the values reported for mineral and organic soils of herbaceous wetlands. These sites show slight acidification, which is common in freshwater wetlands, as they are flooded for at least 6 months a year, and this causes anaerobic conditions that cause soil acidification (Kozlowski 1984; Richardson and Vepraskas 2001; Mitsch and Gosselink 2007). In the rainy season, the pH was significantly higher in RBI and RB2. Richardson and Vepraskas (2001) mentioned that the reduction process in acidic soils usually increases pH, whereas in alkaline soils it can be decreased. The change in pH can be as much as three units after several weeks of flooding, although changes of less than two units are the most typical.

Phosphorus values were lower in the rainy season in RBI, RLI, and RL2, but the differences were significant only at RBI. This is probably due to water exerting a stronger 'pull' or 'laundering' of soil nutrients, which is why the P content can be reduced (Reddy and DeLaune 2008).

Therefore, the impact of cattle ranching on wetlands is strongly dependent on soil type and stocking density. Land with organic soils is flooded over longer periods, decreasing the time the cattle remain in the wetland and reducing the number of cattle that can be kept. Indirectly, this allows for the conservation of the wetland, as the soils are able to recover during the time they are not under grazing. Mineral soils remain flooded for less time and cattle arc kept for longer and in higher numbers. This causes soil degradation from loss of organic matter.

In general, few significant differences were found between seasons, which may be due to the short time period of sampling (one year), which, for logistic reasons, could not be extended. In order to have 'ungrazed' areas in the present study we conducted a pilot experiment during one year (2009) where plots of 1 [m.sup.2] (this size was used because landowners did not allow more space) were fenced with enough barbed wire to exclude livestock and ensure they could not reach the plants. We also had plots without fencing (grazed). In all plots, soil samples were collected, and the data obtained in those samples were analysed. The results showed few significant differences between the two treatments (grazed v. ungrazed); however, we observed trends such as lower BD and more OM in the plots without cattle.

Based on our study and the small pilot experiment, we recommend that it is necessary to validate our findings and develop similar work for 3 years or more, but with larger plot sizes, 10 m by 10 m optimally.

Relationship between parameters

The negative correlation between pH and each of C, OM, and P suggests that high pH limits soil microbial activity, and thus decomposition processes are slower (Kozlowski 1984). This same type of correlation was found between BD and the other parameters except pH and K. This relationship could indicate that the low levels of OM, C, N, and K favour soil compaction at the sites studied.

The PCA clearly shows that RBI and RB2 are determined by the amount of OM, C, and N and total porosity, which are characteristic of organic soils. This relationship is due to the presence of Histosols characterised by a high concentration of OM at the RB sites along the river bank (Micheli et al. 2006). Rio Limon sites had soils of mineral origin, characterised by high BD values, also resulting from management activities.

Conclusions

* A set of factors associated with management practices (livestock and flooding) in the extensive wetlands of Alvarado, Veracruz, affects the soil chemical properties of fresh water herbaceous wetlands.

* Wetland soil type and, thus, its characteristics define the response to cattle ranching activities. Sites with mineral soils (RL 1 and RL2) are more susceptible to cattle ranching practices than sites with organic soils (RBI, RB2), owing to the low quantity of OM that characterises the former.

* Livestock, mainly at higher stocking density, have a negative impact on soil chemical properties, including reducing the quantity of OM, and therefore macronutrients such as C, N, P, and K, and increasing BD. It also affects soil compaction.

* The results of this study should be taken into account when developing strategies for the management and conservation of these ecosystems, aspects such as the duration and intensity of cattle stocking on organic and in mineral wetland soils. In extensive wetlands where hydroperiod is not easily modified, wetlands on organic soils are able to recover many of their characteristics when stocking is low and cattle are taken out for 3-5 months each year.

http://dx.doi.org/10.1071/SR13037

Received 30 January 2013, accepted 17 June 2013, published online 2 September 2013

Acknowledgements

We thank Joaquin Cano and Gildardo Palacios, owners of the land where we installed the experiments, Tiolino, Alberto Azua and Carlos Yanez Arenas collaborated with the fieldwork, Roberto Monroy helped with the map, Daniela Cella and Sandra Rocha analysed samples. This study was funded with resources from CONACYT-CONAGUA NO 48247, CONACYTSEMARNAT NO 107754, and the Instituto de Ecologia A.C. We are also grateful to CONACYT for providing a PhD scholarship #224618 to the first author.

References

Archer S, Smeins EE (1991) Ecosystem-level processes. In 'Grazing management: An ecological perspective'. (Eds RK Heitschmidt, JW Stuth) pp. 109 140. (Timber Press: Portland, OR)

Bantilan-Smith M, Bruland GL, MacKenzie RA, Henry AR, Ryder CR (2009) A comparison of the vegetation and soils of natural, restored, and created coastal lowland wetlands in Hawaii. Wetlands 29, 1023-1035. doi: 10.1672/08-127.1

Baron VS, Mapfumo E, Dick AC, Naeth MA, Okine EK, Chanasyk DS (2002) Grazing intensity impacts on pasture carbon and nitrogen flow. Journal of Range Management 55, 535 -541. doi: 10.2307/ 4003996

Blanch S, Brock MA (1994) Effects of grazing and depth on two wetland plant species. Australian Journal of Marine and Freshwater Research 45, 1387-1394. doi:10.1071/MF9941387

Chanasyk D, Naeth A (1995) Grazing impacts on bulk density and soil strength in the foothills fescue grasslands of Alberta, Canada. Canadian Journal of Soil Science 75, 551-557. doi: 10.4141 /cjss95-078

Coffin DP, Lauenroth WK (1988) The effects of disturbance size and frequency on a shortgrass plant community. Ecology 69, 1609-1617. doi: 10.2307/1941658

Coles-Ritchie MC, Roberts DW, Kershner JL. Henderson RC (2007) A wetland index for evaluating riparian vegetation. Journal of the American Water Resources Association 43, 731 743. doi: 10.1111/ j. 1752-1688.2007.00058.x

Collins SL, Knapp AK. Briggs JM, Blair JM, Steinaucr EM (1998) Modulation of diversity by grazing and mowing in native tallgrass prairie. Science 280, 745 747. doi: 10.1126/science.280.5364.745

Crawley MJ (2007) 'The R Book.' (John Wiley & Sons Ltd: Chichester, UK)

Delgaard P (2002) 'Introductory statistics with R.' (Springer-Verlag: New York)

Drewry JJ, Cameron KC, Buchan GD (2008) Pasture yield and soil physical property responses to soil compaction from trading and grazing--a review. Australian Journal of Soil Research 46, 237-256. doi:10.1071/SR07125

Fassbender HW, Bornemisza E (1987) Soil chemistry: with emphasis on Latin American soils. Quimica de suelos con entasis en suelos de America Latina. IICA, Libros y Materiales Educativos, No. 81.

Fernandez PL, Alvarez CR, Taboada MA (2011) Assessment of topsoil properties in integrated crop livestock and continuous cropping systems under zero tillage. Australian Journal of Soil Research 49, 143-151. doi:10.1071/SR10086

Greenwood KL. MacLeod DA, Scott JM. Hutchinson KJ (1997) Longterm stocking rate effects on soil physical properties. Australian Journal of Experimental Agriculture 37, 413 419. doi: 10.1071 / EA96131

Harrison SB, Inouye D, Safford HD (2003) Ecological heterogeneity in the effects of grazing and fire on grassland diversity. Conservation Biology 17, 837-845. doi:10.1046/j.1523-1739.2003.01633.x

INEGI (2005) 'Principales resultados por localidad 2005 (ITER).' (Instituto Nacional de Estadistica y Geografia: Mexico, DE)

INEGI (2007) 'Censo ejidal Veracruz. Total de ejidos y comunidades segun tipo de actividad agropecuaria o forestal.' (Instituto Nacional de Estadistica y Geografia: Mexico, DF)

Infante MD, Moreno-Casasola P, Madero Vega C, Castillo-Campos G, Warner BG (2011) Floristic composition and soil characteristics of tropical freshwater forested wetlands of Veracruz on the coastal plain of the Gulf of Mexico. Forest Ecology and Management 262, 1514 1531. doi: 10.1016/j.foreco.2011.06.053

IUSS Working Group WRB (2006) 'World Reference Base for Soil Resources 2006: a framework for international classification, correlation and communication.' 2nd edn. World Soil Resources Report No. 103. (Food and Agriculture Organization of the United Nations (FAO): Rome)

Jansen A, Healey M (2003) Frog communities and wetland condition: relationships with grazing by domestic livestock along an Australian floodplain river. Biological Conservation 109. 207 219. doi: 10.1016/ S0006-3207(02)00148-9

Jansen A, Robertson Al (2001) Relationships between livestock management and the ecological condition of riparian habitats along an Australian floodplain river. Journal of Applied Ecology 38, 63-75. doi: 10.1046/j. 1365-2664.2001.00557.x

Junk WJ, Nunes Da Cunha C (2012) Pasture clearing from invasive woody plants in the Pantanal: a tool for sustainable management or environmental destruction? Wetlands Ecology and Management 20, 111-122. doi:10.1007/S11273-011-9246-y

Kovach WL (1999) 'MVSP A multivariate statistical package for Windows, ver. 3.1.' (Kovach Computing Services: Pentraeth, Wales)

Kozlowski TT (1984) Plant responses to flooding of soil. Bioscience 34, 162-167. doi:10.2307/1309751

Landgrave R. Moreno-Casasola P (2012) Cuantificacion de la perdida de humedales en Mexico. Investigation Ambiental 4, 35 51.

Mapfumo E, Chanasyk DS, Naeth MA, Baron VS (1999) Soil compaction under grazing of annual and perennial forages. Canadian Journal of Soil Science 79, 191-199. doi: 10.4141/S97-100

Martinez LJ, Zinck JA (2004) Temporal variation of soil compaction and deterioration of soil quality in pasture areas of Colombian Amazonia. Soil & Tillage Research 75, 3 18. doi: 10.1016/j.still.2002.12.001

Micheli E, Schad P. Spaargaren O, Dent D. Nachtergale F (2006) 'World Reference Base for Soil Resources 2006'. World Soil Resources Report No. 103. pp. 82-83. (FAO: Rome)

Miranda F, Hernandez-X E (1963) Los tipos de vegetacion de Mexico y su clasificacion. Boletin de la Sociedad Botanica de Mexico 28, 29-72. Mitsch WJ, Gosselink JG (2007) 'Wetlands.' (John Wiley & Sons Inc.: New York)

Mitsch WJ. Gosselink JG, Zhang L, Anderson CJ (2009) 'Wetland ecosystems.' (John Wiley & Sons Inc.: New York)

Moreno-Casasola P (2004) Mangroves, an area of conflict between cattle ranchers and fishermen. In 'Mangrove management and conservation: Present and future'. (Ed. M Vannucci)pp. 181-191. (Renouf: San Diego, CA)

Moreno-Casasola P, Warner B (2009) 'Brcvario para describir, observar y manejar humedales.' Serie Costa Sustentable No. 1. (RAMSAR, Instituto de Ecologia A.C.. CONANP, US Fish and Wildlife Service, US State Department: Xalapa, Mexico)

Moreno-Casasola P, Cejudo E, Capistran A, Infante D, Lopez H, Castillo G, Pale-Pale J, Campos A (2010) Composicion floristica. divcrsidad y ecologia de humedales herbaceos emergentes en la planicie costcra central de Veracruz, Mexico. Boletin de la Sociedad Botanica de Mexico 87, 29 50.

Neubauer SC (2008) Contributions of mineral and organic components to tidal freshwater marsh accretion. Estuarine, Coastal and Shelf Science 78. 78-88. doi:10.1016/j.ecss.2007.11.011

Olmsted I (1993) Wetlands of Mexico. In 'Wetlands of the world'. (Eds DF Whigham et al.) (Kluwer Academic Publishers: New York)

Pierzynski GM (2000) Methods of phosphorus analysis for soils, sediments. residuals, and waters. Southern Cooperative Series Bulletin No. 396: SF.RA-IEG 2000. Available at: https://secure.hosting.vt.edu/www. sera17.ext.vt.edu/Documents/Methods_of_P_Analysis_2000.pdf.

Reddy KR, DeLaune RD (2008) 'Biogeochemistry of wetlands: science and applications.' (CRC Press: Boca Raton. FL)

Richardson JL, Vepraskas MJ (2001) 'Wetland soils. Genesis, hydrology, landscapes and classification.' (Lewis Publisher: Boca Raton, FL)

Rokosch AE, Bouchard V, Fennessy S, Dick R (2009) The use of soil parameters as indicators of quality in forested depressional wetlands. Wetlands 29, 666 677. doi: 10.1672/08-150.1

Rzedowski J (1983) 'Vegetacion de Mexico.' (Limusa: Mexico, DF)

Shiflet TN (1963) Major ecological factors controlling plant communities in Louisiana marshes. Journal of Range Management 16, 231 235. doi: 10.2307/3895331

Skerritt D (1992) La ganaderia en el centro del estado de Veracruz. In 'Desarrollo y Medio Ambiente en Veracruz'. (Eds E Boege, H Rodriguez) pp. 125 130. (CIESAS-Golfo, Instituto de Ecologia, A.C., Fundacion Friedrich Ebert: Xalapa, Mexico)

Smith CW, Johnston MA, Lorentz S (1997) Assessing the compaction susceptibility of South African forestry soils. II. Soil properties affecting comparability and pressibility. Soil ce Tillage Research 43, 335-354. doi: 10.1016/S0167-1987(97)00023-8

Soracco CG (2005) Relacion entre la conductividad hidraulica saturada y la densidad aparente en tres situaciones de manejo contrastantes. In 'Evaluation de Parametros y Procesos Hidrologicos en el Suelo'. (Eds D Lobo Lujan, D Gabriels, G Soto) pp. 35-38. (UNESCO: Paris)

Sparks DL, Page AL, Helmke PA, Loeppert RH, Soltanpour PN, Tabatabai MA, Sumner Mi; (1996) "Methods of soil analysis. Part 3-Chemical methods.' (Soil Science Society of America Inc.: Madison, WI)

Tebrugge F, During RA (1999) Reducing tillage intensity: a review of results from a long-term study in Germany. Soil and Tillage Research 53, 15 28. doi: 10.1016/SO167-1987(99)00073-2

Thompson LM, Troeh FR (1988) 'Los suelos y su fertilidad.' (Editorial Reverte: Barcelona, Spain)

Travieso-Bello A, Moreno-Casasola P, Campos A (2005) Efecto de diferentes manejos pecuarios sobre el suelo y Ia vegetacion en humedales transformados a pastizales. Interciencia 30, 12-18.

Trettin CC, Jurgensen MF, Gale MR, McLaughlin JW, McFee WW, Kelly JM (1995) Soil carbon in northern forested wetlands: impacts of silvicultural practices. In 'Carbon forms and functions in forest soils', pp. 437 461. (Soil Science Society of America Inc.: Madison, WI)

Walczak R, Witkowska-Walczak B, Slawinski C (2002) Comparison of correlation models for the estimation of the water retention characteristics of soil. International Agrophysics 16, 79 82.

Willatt ST, Pullar DM (1984) Changes in soil physical properties under grazed pastures. Australian Journal of Soil Research 22, 343-348. doi:10.l071/SR9840343

Zar JH (1999) 'Biostatistical analysis.' (Prentice Hall: Upper Saddle River, NJ)

Zhang Y, Li C, Trettin CC, Li H, Sun G (2002) An integrated model of soil, hydrology, and vegetation for carbon dynamics in wetland ecosystems. Global Biogeochemical Cycles 16, 1061. doi: 10.1029/ 2001GB001838

Karla Rodriguez-Medina (A) and Patricia Moreno-Casasola (A,B)

(A) Red de Ecologia Funcional, Instituto de Ecologia, A.C., Carretera antigua a Coatepec No. 351 El Haya, Xalapa 91070, Veracruz, Mexico.

(B) Corresponding author. Email: patricia.moreno@inecol.edu.mx

Table 1. Characterisation of the different types of management at
the four sampling sites located near the town of Alvarado,
Veracruz, Gulf of Mexico Soil type characterisation for at each of
the sampling sites based on IUSS Working Group WRB (2006), and
topographical profiles were made for Project No. 48247 'Inventory,
delineation, characterisation and sustainable use of wetlands
Papaloapan River Basin, Mexico.' Other data were derived from
interviews with landowners, field observations, and measurements

RB1                          RB2

                       Coordinates

18[degrees]44'49.66"N        18[degrees]45'23.51"N
  95[degrees]52'42.24"W        93[degrees]53'36.38"W

                       Physiognomy

Marsh (popal) with           Marsh (popal) with av.
  av. height 1 m. Most         height 0.75 m. Wetland
  species specific to a        dominated year-round by
  herbaceous wetland           the grass Echinochloa
  preserved. Dominant          cotona. Highly seasonal
  species natives:             site, wetland native
  Sagittaria                   species disappear during
  lancifolia,                  dry season. Behind the
  Hydrocotyle                  site is a Typha
  verticillata; and the        domingensis marsh
  exotic grass
  Echinochloa colons.
  Forested wetland on
  the same floodplain,
  behind study site

                       Management

1 head [ha.sup.-1]           2 or 3 head [ha.sup.-1]

                    Human influence

Very little; on the          Very little; of the five
  five sampling dates          sampling times, a foreman
  no-one was working in        seen only twice looking
  the field                    after the cattle, just
                               going in and out

                       Hydrology

Unchanged                    Unchanged

                             Flood and soil moisture

Remains flooded 9            Remains flooded 8 months,
  months and is                2 months saturated with
  saturated the rest of        water, dry the rest of
  the year                     the year

                Permanence of livestock
                     in the site

8-10 months                  8-10 months

                                          Soil type

Sapric-salic Histosol        Fibric Histosol

RL1                          RL2

                      Coordinates

18[degrees]37'25.49"N        18[degrees]37'39.39"N
  95[degrees]53'24.95"W        95[degrees]52'30.87"W

                      Physiognomy

Marsh (popal) with av.       Marsh (popal) with av. height
  height I m, dominated by     0.75m. Dominant species
  native wetland grasses       throughout the year: Hymenachne
  (Leersia hexandra,           amplexicaulis, Eleocharis
  Hymenachne                   cellulosa. Site highly seasonal,
  amplexicaulis). Behind       most wetlands species disappear
  the site is a T.             in dry season. Behind the site
  domingensis marsh            is a T. domingensis marsh.

                       Management

2 or 3 head [ha.sup.-1]      2 head [ha.sup.-1]

Owner's home 123 m west      Owners home right in the
  of the sampling site;        wetland; he went out at
  owner went on horseback      least once a day on
  twice per day to herd        horseback to herd the
  cows                         cows

                       Hydrology

Unchanged                    Unchanged

Remains flooded 6 months,    Remains flooded 6 months,
  dry the rest of the year.    dry the rest of the year

               Permanence of livestock
                   in the site

8-10 months                  8-10 months

                     Soil type

Haplic Gleysol               Gleyic-salic Fluvisol

Table 2. Physicochemical soil parameters for each of the sampling
sites in Alvarado, Veracruz
Mean [+ or -] s.e. shown in those cases where we applied a one-way
ANOVA and Tukey test; median and percentiles (25-75%) shown where we
applied ANOVA followed by one-way Kruskal-Wallis test and Dunn's
multiple comparison. Within rows, values followed by the same letter
are not significantly different at P = 0.05

Parameter              RBI                    RB2

C (%)                  36.55 (32.4-39.05)a    13.95 (12.9-14.65)b
N (%)                  2.765 [+ or -] 0.06a   1.35 [+ or -] 0.04b
C: N                   13 (13-12.5)a          10 (11-10)b
Org. matter (%)        62.98 (55.85-67.35)a   24.02 (22.23-25.31)b
Extractable P
  (mg [kg.sup.-1])     39.02 (6.06)a          16.12 (1.4)a
K (cmol [kg.sup.-1])   1.31 (1.77-0.84)a      2.09 (2.53-1.62)b
pH                     5.68 [+ or -] 0.17a    5.88 [+ or -] 0.108a
Bulk density
  (g [cm.sup.-3])      1.07 (0.93- 1.23)a     1.65 (1.51-1.78)b
Total porosity         57.42 [+ or -] 2.34a   36.25 [+ or -] 1.77b

Parameter              RL1                    RL2

C (%)                  9.0 (7.4-10.75)c       8.2 (7.15-10.05)c
N (%)                  0.91 [+ or -] 0.04c    0.86 [+ or -] 0.04c
C: N                   10 (10-10)b            10 (111-9)b
Org. matter (%)        15.47 (12.7-18.53)c    14.14 (12.37-17.27)c
Extractable P
  (mg [kg.sup.-1])     9.26 (0.63)c           12.82 (1.31)6
K (cmol [kg.sup.-1])   0.74 (0.81-0.64)ad     0.63 (0.77-0.6)cd
pH                     6.28 [+ or -] 0.096    5.59 [+ or -] 0.12ac
Bulk density
  (g [cm.sup.-3])      1.84 (1.71-1.94)b      1.74 (1.66-1.84)6
Total porosity         29.44 [+ or -] 1.37c   33 [+ or -] 1.566c

Table 3. Mean [+ or -] s.e. soil physicochemical parameters per season
for each of the sampling sites in Alvarado, Veracruz
* P <0.05 for significant differences among seasons

Parameter                                   RBI

                            Dry season             Rainy season

C (%)                  35.65 [+ or -] 1.38     35.78 [+ or -] 1.31
N (%)                   2.79 [+ or -] 0.07      2.73 [+ or -] 0.11
Org. matter (%)        61.62 [+ or -] 2.37     61.52 [+ or -] 2.27
Extractable P
  (mg [kg.sup.-1])     53.34 [+ or -] 8.89 *   24.70 [+ or -] 4.49 *
K (cmol [kg.sup.-1])    1.52 [+ or -] 0.15 *    1.02 [+ or -] 0.15 *
pH                      5.31 [+ or -] 0.22 *    6.05 [+ or -] 0.19 *
Bulk density
  (g [cm.sup.-3])       1.18 [+ or -] 0.09      1.03 [+ or -] 0.07
Total porosity         54.55 [+ or -] 3.65     60.28 [+ or -] 2.78

Parameter                                   RB2

                            Dry season             Rainy season

C (%)                  14.61 [+ or -] 0.87     13.55 [+ or -] 0.39
N (%)                   1.39 [+ or -] 0.08      1.31 [+ or -] 0.03
Org. matter (%)        25.20 [+ or -] 1.49     23.34 [+ or -] 0.68
Extractable P
  (mg [kg.sup.-1])     15.21 [+ or -] 1.27        17 [+ or -] 2.56
K (cmol [kg.sup.-1])    2.33 [+ or -] 0.26      1.88 [+ or -] 0.19
pH                       5.5 [+ or -] 0.07 *    6.26 [+ or -] 0.06 *
Bulk density
  (g [cm.sup.-3])       1.64 [+ or -] 0.08      1.66 [+ or -] 0.05
Total porosity         36.68 [+ or -] 3.11     35.81 [+ or -] 1.93

Parameter                                    RLl

                             Dry season             Rainy season

C (%)                   9.12 [+ or -] 0.64       9.05 [+ or -] 0.74
N (%)                   0.89 [+ or -] 0.06       0.92 [+ or -] 0.06
Org. matter (%)        15.69 [+ or -] 1.14      15.58 [+ or -] 1.28
Extractable P
  (mg [kg.sup.-1])     10.22 [+ or -] 0.59        8.3 [+ or -] 1.04
K (cmol [kg.sup.-1])    0.79 [+ or -] 0.11       0.88 [+ or -] 0.16
pH                       6.1 [+ or -] 0.12       6.46 [+ or -] 0.13
Bulk density
  (g [cm.sup.-3])       1.93 [+ or -] 0.03 *     1.73 [+ or -] 0.03 *
Total porosity         25.62 [+ or -] 01.38 *   33.25 [+ or -] 1.4 *

Parameter                                  RL2

                            Dry season            Rainy season

C (%)                   8.62 [+ or -] 0.73     8.26 [+ or -] 0.6
N (%)                   0.84 [+ or -] 0.06     0.88 [+ or -] 0.07
Org. matter (%)        14.86 [+ or -] 1.28    14.23 [+ or -] 1.03
Extractable P
  (mg [kg.sup.-1])     15.10 [+ or -] 2.13    10.53 [+ or -] 1.15
K (cmol [kg.sup.-1])    0.81 [+ or -] 0.15     0.62 [+ or -] 0.04
pH                      5.55 [+ or -] 0.2      5.62 [+ or -] 0.16
Bulk density
  (g [cm.sup.-3])       1.71 [+ or -] 0.07     1.75 [+ or -] 0.03
Total porosity         34.08 [+ or -] 2.87    31.97 [+ or -] 1.37

Table 4. Results of the principal components analysis, with the first
two components explaining a cumulative variance of 79%
Values indicate the weight of each component

Variable                          PC1       PC2

N (%)                             0.393    -0.049
C (%)                             0.398    -0.084
C : N                             0.348    -0.147
Organic matter (%)                0.398    -0.084
K (cmol [kg.sup.-1])              0.085     0.622
P (mg [kg.sup.-1])                0.313     0.329
pH                               -0.144    -0.649
Bulk density (g [cm.sup.-3])     -0.375     0.149
Total porosity                    0.375    -0.149

Table 5. Results of the principal components analysis, using only data
from RB2, RLI, and RL2
Contributing weight of each variable for the first two axes is given

Variable                          PC1       PC2

N (%)                             0.454     0.141
C (%)                             0.465     0.035
C : N                             0.210    -0.580
Organic matter (%)                0.465     0.035
K (cmol [kg.sup.-1])              0.373     0.099
P (mg [kg.sup.-1])                0.259     0.052
pH                               -0.127     0.759
Bulk density (g [cm.sup.-3])     -0.307    -0.231

Table 6. Pearson correlation values for soil physicochemical
parameters
* P [less than or equal to] 0.05 for significant correlations

                         C      C : N    Org. matter     K        P

N (%)                  0.98 *   0.75 *     0.98 *      0.35 *   0.65 *
C (%)                           0.83 *     0.99 *      0.35 *   0.63 *
C : N                                      0.86 *      0.16     0.55
Org matter (%)                                         0.27 *   0.72 *
K (cmol [kg.sup.-1])                                            0.29
P (mg [kg.sup.-1])
pH

                         pH      Bulk density

N (%)                  -0.24     -0.84 *
C (%)                  -0.25 *   -0.85 *
C : N                  -0.24     -0.71 *
Org matter (%)         -0.27 *   -0.85 *
K (cmol [kg.sup.-1])   -0.06     -0.19
P (mg [kg.sup.-1])     -0.40 *   -0.64 *
pH                                0.23
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Author:Rodriguez-Medina, Karla; Moreno-Casasola, Patricia
Publication:Soil Research
Article Type:Report
Geographic Code:1MEX
Date:Jul 1, 2013
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