Hydrological Properties of Litter in Different Vegetation Types: Implications for Ecosystem Functioning

Abstract

This study investigated the hydrological properties of litter in different vegetation cover types, including Eucalyptus sp. plantation, Agroforestry, and Restoration Forest. The research focused on evaluating litter accumulation, composition, water holding capacity, and effective water retention. The results revealed variations in litter accumulation among the stands, and especially Eucalyptus sp., which had a higher proportion of branches compared to leaves. The water holding capacity of the litter differed among the stands. Agroforest and Restoration Forest showed higher litter water capacities than Eucalyptus sp. The composition and decomposition stage of the litter fractions influenced their water retention capabilities, with leaves exhibiting superior water retention. In contrast, branches had lower water absorption due to their hydrophobic nature. Despite these differences, the effective water retention, which indicates the ability of litter to intercept precipitation, was similar among the stands. The findings highlight the importance of considering litter composition and species-specific characteristics in understanding the hydrological functions of litter. This knowledge contributes to effective conservation and management strategies for sustainable land use practices and water resource management. Further research is recommended to expand the study’s scope to include a wider range of forest types and natural field conditions, providing a more comprehensive understanding of litter hydrological functions and their implications for ecosystem processes.

1. Introduction

Litter plays a vital role in nutrient cycling and organic matter decomposition, with notable relevance for global biogeochemical cycles. It refers to the layer of organic or decomposing material present on the forest floor, consisting of a diverse range of components such as leaves, branches, flowers, fruit, seeds, and animal residue. The composition and characteristics of litter are influenced by various factors. For instance, in different types of ecosystems, such as tropical rainforests [1,2,3,4,5] or temperate forests [6,7,8,9], the dominant tree species and their specific leaf traits can significantly affect litter composition and decomposition rates [2,10]. Additionally, forest disturbances, such as logging or fire events, can alter litter dynamics and nutrient cycling processes [11,12,13]. As litter decomposes, it releases nutrients into the soil, which are then taken up by plants, contributing to their growth and overall ecosystem productivity [14,15,16,17,18]. Furthermore, litter provides habitat and food sources for a wide range of organisms [19,20], playing a crucial role in supporting biodiversity within the ecosystem.

From a hydrological perspective, the litter acts as sponge layer, separating precipitation from mineral soil, mediating rainfall splash impact, and reducing or often eliminating overland flow and soil erosion from the forest floor [21,22]. This has implications for infiltration during and after rainfall [2,23]. Understanding the interactions between rainfall, vegetation, and litter on the soil surface is of great importance to forest hydrologists and researchers interested in the partitioning and disposition of rainfall [6,24,25]. The water balance of an ecosystem involves many processes, including the interception of rainfall by vegetation, the portion of rainfall that passes through gaps in the canopy (throughfall), and the water that flows down the trunks or stems of trees (stemflow) [26,27,28,29]. The latter two represent the portion of rainfall that reaches the soil and interacts with a boundary layer between the soil surface and its interior [4,5], known as litter [2,23]. Additionally, the presence of a litter layer serves to minimize water evaporation from the soil, aiding the preservation of moisture within the topsoil [30]. However, it is important to note that water retention in the litter layer is an essential hydrological indicator in forest hydrology, and a significant portion of the precipitation may be retained by the litter layer, influencing both evaporation and soil–moisture dynamics [31,32,33,34].

Soil water conservation capacity involves various natural processes, land management practices, and the characteristics of the landscape that influence water infiltration, retention, and storage in the soil. This conservation capacity is crucial for sustaining ecological balance, agricultural productivity, and mitigating the negative impacts of water-related issues such as erosion, flooding, and drought. Conserving water and soil resources is essential for sustainable land management, agriculture, and overall environmental health. Implementing practices that enhance water and soil conservation capacity helps protect ecosystems, support biodiversity, and secure the availability of clean water for human and ecological needs. However, it is not possible to generalize the hydrological properties of litter independently of vegetation type (e.g., forest or agriculture crop) or structure. The dynamics of litter water interception vary depending on factors such as stand species composition, thickness, storage, water holding capacity, and degree of decomposition, which contribute to different levels of rainfall interception [4,6,35]. As litter has close contact with soil, the water and soil conservation capacity of a forest is also influenced by factors such as forest type, management practices, soil bulk density, and porosity [4,5,36]. Therefore, in the practice of forestry production on agricultural land, in addition to the state of litter coverage, we should also consider the differences in litter caused by the presence of different tree species. While numerous studies have investigated the impact of litter on hydrological processes, insufficient attention has been paid to the hydrological properties of litter under natural conditions, and especially different vegetation types or management.

In this study, our objective was to assess the water holding characteristics of litter and the physical properties of soil in three vegetation types: Eucalyptus sp. plantation, Agroforestry, and Restoration Forest. We aimed to investigate the impact of vegetation cover on litter water conservation. Our hypotheses were as follows: (1) litter hydrological properties exhibit variations among different vegetation types and (2) soil water content, bulk density, and resistance to penetration are influenced by litter hydrological properties. To the best of the authors’ knowledge, this is the first study to compare different vegetation types, incorporating various management techniques. A comprehensive understanding of the role of litter in ecosystem water balance and nutrient cycling is crucial for evaluating ecosystem functioning, carbon sequestration, and sustainable land management practices. Further research in this field can offer valuable insights into the intricate relationships between precipitation, vegetation, and ecosystem processes, thereby contributing to the development of effective conservation and management strategies.

2. Materials and Methods

2.1. Study Sites

The experimental site is located at the Federal University of São Carlos—Sorocaba, Brazil (23°35′07″ S, 47°31′03″ W, Figure 1), representing three different soil coverings or vegetation types: EU: a stand of Eucalyptus sp. (6 years old); AF: a biodiverse successional agroforestry system including trees from the Atlantic Forest, Musa spp. (Banana), and some leguminous species such as Cajanus cajan (Feijão guandú), with exotic species (Brachiaria sp.) controlled through weeding (established 6 years ago); and RF: Restoration Forest including tree species from the Atlantic Forest and Cerrado (10 years old).

Table 1. Basic information on the sample sites.

Information	Eucalyptus sp. (EU)	Agroforest (AF)	Restoration Forest (RF)
Density [trees ha−1]	1667	1250	1667
Management	3 × 2 m planting system. Established in 2014.	Trees on 4 × 2 m, with Musa spp. (Banana) and leguminous species between rows. Exotic species controlled through weeding. Established in 2014.	3 × 2 m planting system. Established in 2010.
Diameter at breast height [m]	13.5 ± 0.1	14.6 ± 1.5	13.8 ± 2.6
Height [m]	21.5 ± 0.3	8.2 ± 0.2	10.3 ± 0.1
Litter thickness [cm]	1.3 ± 0.1	2.0 ± 0.1	1.5 ± 0.1
Slope aspect	N-NW	N-NW	N-NW
Slope (°)	10.0%	10.3%	10.2%

presents information on the stands. The plots were located 100 m from each other. The mean altitude is 580 m AMSL, and the climate is classified as Cwa or temperate, with dry and hot summers [37,38]. Mean annual temperature is 22 °C and mean annual rainfall is 1311 mm [39]. This site is in a transition region between the Atlantic Plateau and the Paulista Peripheral Depression. It comprises the following soil types: Red Yellow Dystrophic Argisol and Red Dystrophic Latosol [40]. Biotic and abiotic variables were collected simultaneously, allowing a reliable comparison between stands. Three 10 × 10 m plots were established in each stand, and data on throughfall, litter production, hydrological properties, soil bulk density, resistance penetration, and water content were monitored for 8 months, from December 2020 to July 2021.

2.2. Rainfall and Throughfall

The total rainfall data [R, mm] during the experiment were collected from the weather station located at the experimental site. Throughfall data were obtained using 6 rain gauge collectors positioned 1.20 m above the forest floor in each plot. The collectors were placed under the trees, along the center of the planted row, with a 3 m distance between each other. Throughfall values were obtained following [4,27,41]. Each sampling consisted of one or more consecutive rainfall events. An event is defined as rainfall of at least 1 mm in depth preceded by a dry period of a minimum of 12 h. Sample collections were performed as soon as possible after the end of rainfall.

2.3. Determination of Litter Hydrological Properties

Litter samples were collected from a 100 × 100 cm litter square divided into 4 quadrants. The collection process followed a random sampling method [4,5], where one quadrant measuring 50 × 50 cm was randomly chosen for material collection on the forest floor. The collected samples were then immediately placed in plastic bags and transported to the laboratory. Each stand yielded a total of 240 litter bags (3 plots × 10 random quadrants × 8 months). In the laboratory, the litter samples were sieved to remove soil (mesh 6—3 mm, approximately) and then sorted into four fractions: branches, leaves, seeds, and unstructured material. The monthly and annual litter yield was estimated by summing the fractions. The fresh mass [FM, g] of each fraction was determined using an accurate scale [0.01 g] and rehydrated through immersion in water for 90 min. Subsequently, the litter fractions were placed on sieves and drained for 30 min to determine the humid litter mass [HM, g]. The dried mass [DM, g] of the litter was then determined by oven-drying the samples at 70 °C until a constant mass was achieved. Finally, the litter hydrological properties were calculated as shown in

Table 2. Litter hydrological properties studied.

Indicator	Description	Equation
Water holding capacity [WHC, %]	is the amount of water that can be preserved in litter	$\mathrm{W}\mathrm{H}\mathrm{C}=\left[\frac{\mathrm{H}\mathrm{M}-\mathrm{D}\mathrm{M}}{\mathrm{D}\mathrm{M}}\right]\times 100$
Effective water holding capacity [EWC, %]	is the water holding capacity of litter under ambient conditions [5,9]	$\mathrm{E}\mathrm{W}\mathrm{C}=\left[\frac{\mathrm{F}\mathrm{M}-\mathrm{D}\mathrm{M}}{\mathrm{F}\mathrm{M}}\right]\times 100$
Effective water retention capacity [Weff, t ha−1]	is the maximum amount of rainwater that can be retained by the litter layer in the forest in the natural field environment. Is numerically smaller than water retention capacity [42]	${\mathrm{W}}_{\mathrm{e}\mathrm{f}\mathrm{f}}=\frac{\left(0.85\times \mathrm{W}\mathrm{H}\mathrm{C}-\mathrm{E}\mathrm{W}\mathrm{C}\right)\times \mathrm{M}}{100}$ M = is the unit litter mass, t ha−1
Maximum water retention capacity [Wmax, t ha−1]	is the maximum amount of water that can be retained after removing the amount of water contained in the litter under normal conditions [42]	${\mathrm{W}}_{\mathrm{m}\mathrm{a}\mathrm{x}}=\frac{\mathrm{W}\mathrm{H}\mathrm{C}\times \mathrm{M}}{100}$ M = is the unit litter mass, t ha−1

.

2.4. Soil Physical Properties

Soil bulk density and soil water content were determined by collecting three random samples from the 0 to 20 cm soil profiles in each plot (three plots per stand). Undisturbed samples were obtained using 100 cm³ metallic volumetric rings. The weight of the samples was measured using a precision scale. The determination of these attributes was carried out using the thermogravimetric method, which involves weighing the freshly collected samples and then drying them in a forced circulation oven at 105 °C for 24 h. Soil bulk density (BD, g cm⁻³) was calculated as the ratio of the dry soil mass (Ms, g) to the ring volume (V, m³). Soil water content (SWC, %) was measured gravimetrically and expressed as a percentage of the weight of soil water to the weight of dry soil (g). Soil resistance to penetration (SRP, MPa) was assessed using Digital Falker PLG1020 Penetrograph, with three repetitions per plot, resulting in a total of nine measurements per stand. BD, SWC, and SRP were measured monthly, simultaneously with the collection of litter samples.

2.5. Statistical Analysis

To assess the homoscedasticity of variance in litter stocks and hydrological properties, the Bartlett test was employed. Additionally, the normality of the data was evaluated using the Lilliefors (Kolmogorov–Smirnov) test for statistical analysis. For normally distributed data, analysis of variance (ANOVA) with a significance level of 5% (Student’s t-test) was conducted. The non-parametric Mann–Whitney test was used for data that did not meet the assumptions of ANOVA. The statistical analyses were performed using BioEstat 5.3 [43] and @Minitab 17.

3. Results

3.1. Weather Conditions

Accumulated rainfall throughout the research period was 667 mm; that is, approximately 55% of the annual precipitation. Mean temperature was 21.6 ± 3.5 °C, 5% higher than the normal recorded temperature (20.6 °C). The highest mean temperature was recorded in January (24.1 °C) and the lowest in July (15.1 °C) (Figure 2). The mean air humidity was 80.3 ± 1.4%. Throughfall (TF) in the Eucalyptus sp. (EU), Agroforestry (AF), and Restoration Forest (RF) areas was 395, 412, and 471 mm, respectively.

3.2. Litter Accumulation and Composition

The mean litter accumulation ranged from 5.4 to 8.3 t ha⁻¹ in the EU, 4.2 to 11 t ha⁻¹ in the Agroforestry (AF) area, and 3.5 to 8.0 t ha⁻¹ in the Restoration Forest (RF) area. Among the different components, branches accounted for 39% of the total litter in the EU, while leaves were the predominant fraction in the AF area (44%) and the RF area (47%). Seeds represented the lowest fraction in all stands, with percentages of 3.4% in the EU, 9.3% in the AF, and 3.2% in the RF. Although the litter accumulation was similar among the stands, there were significant differences in the mass of leaf and branch fractions (Figure 3).

3.3. Hydrological Properties of Litter

The total litter water holding capacity (WHC) differed between the Eucalyptus (EU) area and the Agroforestry (AF) and Restoration Forest (RF) areas (

Table 3. Water holding capacity [WHC, %], effective water holding capacity [EWC, %], effective water retention [W_eff, t ha⁻¹], and maximum retention capacity [W_max, t ha⁻¹].

Stand	Total	Unstructured	Leaves	Branches	Seeds
	Water holding capacity [WHC, %]
Eucalyptus sp.	164 ± 6.8 a	228 ±16 a	193 ± 28 a	94 ± 3.8 a	141 ± 8 a
Agroforest	218 ± 12 b	222 ± 20 a	272 ± 32 b	200 ± 19 b	179 ± 15 b
Restoration	212 ±14 b	220 ± 18 a	265 ± 15 b	160 ± 24 c	204 ± 39 b
	Effective water holding capacity [EWC, %]
Eucalyptus sp.	23 ± 3 a	25 ± 4 a	26 ± 2 a	17 ± 2 a	24 ± 2 a
Agroforest	25 ± 3 ab	25 ± 3 a	28 ± 3 a	28 ± 2 b	27 ± 2 a
Restoration	34 ± 4 b	34 ± 5 a	33 ± 3 a	35 ± 3 b	36 ± 3 a

Different lowercase letters in the same column mean significant differences (p < 0.05).

). The order of WHC was EU < RF < AF, with AF and RF having 1.33 and 1.30 times the water holding capacity of EU, respectively. The WHC for the unstructured fraction was similar among the stands, and it increased in the following order: RF < AF < EU. EU had the lowest values for leaves, branches, and seeds. The water holding capacity of leaves and seeds was similar between AF and RF, while branches showed significant variation among the three stands (p < 0.05). Although the mean effective water holding capacity (EWC, %) was similar among the stands (p > 0.05), the EWC was consistently higher for RF, followed by AF > EU, for total litter as well as for the unstructured fraction, leaves, branches, and seeds.

The maximum water holding capacity (W_max) was significantly different only between EU and AF, ranging from 10.3 t ha⁻¹ (AF) to 31.7 t ha⁻¹ (RF) (Figure 4). In EU and RF, the W_max was 1.6 and 1.4 times that of AF, respectively. The W_max of the unstructured layer varied among the stand types, with AF (4.3 ± 0.7 t ha⁻¹) < RF (12.1 ± 1.5 t ha⁻¹) < EU (16.3 ± 1.2 t ha⁻¹). There was a significant difference in the W_max of leaves between EU and AF (p < 0.05), with the order being EU (4.1 ± 0.36 t ha⁻¹) < RF (5.5 ± 1.0 t ha⁻¹) < AF (8.2 ± 1.3 t ha⁻¹). RF had the highest W_max for branches, followed by AF and EU. Seeds showed the order of W_max as AF < RF < EU, with significant differences between AF and RF for branches and seeds.

The effective water retention capacity (W_eff) of litter did not differ among stands and ranged from 5.6 t ha⁻¹ for EU to 18.3 t ha⁻¹ for AF (Figure 3). The mean W_eff followed the order: EU (8.3 ± 0.5 t ha⁻¹) < RF (8.7 ± 1.0 t ha⁻¹) < AF (11.6 ± 1.7 t ha⁻¹). For all stands, leaves had the highest W_eff, followed by the unstructured fraction, branches, and seeds. The W_eff for litter was similar among stands. The W_eff for the unstructured fraction ranged from 2.0 t ha⁻¹ to 5.3 t ha⁻¹ for EU, from 1.7 t ha⁻¹ to 6.6 t ha⁻¹ for AF, and from 1.6 t ha⁻¹ to 4.6 t ha⁻¹ for RF. The mean W_eff for the unstructured fraction was similar among stands, following the order: RF < AF < EU. Significant differences were observed between leaves for EU × AF and RF. The mean W_eff for leaves followed the order: EU (2.8 ± 0.4 t ha⁻¹) < RF (4.8 ± 0.8 t ha⁻¹) < AF (5.7 ± 1.2 t ha⁻¹). For branches, W_eff was similar between EU and AF, and followed the order: RF (0.7 ± 0.1 t ha⁻¹) < EU (1.7 ± 0.1 t ha⁻¹) < AF (2.0 ± 0.3 t ha⁻¹). W_eff for seeds was similar among stands, increasing in the order of: EU (0.2 ± 0.02 t ha⁻¹) < RF (0.3 ± 0.07 t ha⁻¹) < AF (0.6 ± 0.3 t ha⁻¹).

3.4. Soil Physical Properties

There were no significant differences in the mean values of soil bulk density (BD), soil retention potential (SRP), and soil water content (SWC) among the stands (Figure 5). The BD was 1.0 ± 0.05 g cm⁻³ for all three stands. EU had the highest SRP (5.1 ± 1.5 MPa), followed by RF (4.9 ± 1.3 MPa) and AF (4.6 ± 1.2 MPa). The mean SWC was highest in RF (19.0 ± 3.7%), followed by AF (16.9 ± 3.5%) and EU (15.1 ± 3.1%). Soil water content ranged from 2.4% to 34.0% in EU, from 1.6% to 36.6% in AF, and from 2.5% to 40.3% in RF.

4. Discussion

4.1. Hydrological Properties and Water Retention Capacity of Litter

Litter serves as a crucial component in the hydrological cycle within ecosystems [8,44,45] and it also plays a significant role in various soil management practices and vegetation covers [45]. In our study, the litter mass of Eucalyptus sp. was above the average of other studies, although it varied within the range reported in the literature. For example, it exceeded the average deposition of 6.33 Mg ha⁻¹ at 14 years of age [46] but was lower than the 16.6 t ha⁻¹ at 7 years of age [47]. Compared with other forest types, the average litter mass of Eucalyptus sp. and Agroforest was higher than that of approximately 46-year-old Cerrado (5.5 t ha⁻¹) [4], while the latter was similar to the litter mass of Restoration Forest. It is worth noting that the composition and dynamics of litter formation can vary depending on the species present in the study area. In this case, the Eucalyptus sp. planting consisted of trees of the same species, while the Agroforest and Restoration Forest were composed of a diversity of plants species. This difference in species composition likely contributed to the higher proportion of branches in the litter of Eucalyptus sp. compared with other studies where the leaf fraction was more dominant [10,48].

The results demonstrate variations in litter hydrological properties among the different vegetation types. Understanding the hydrological properties of litter fractions is essential, as it influences the overall water holding capacity of the litter layer. The water holding capacity of litter depends not only on the quantity of organic material deposited but also on the composition and degree of decomposition of its fractions. Litter layers with higher decomposition levels have a larger specific surface area, enhancing their water retention potential [5,49,50]. It is important to note that water holding capacity reflects the ideal water holding condition and may not fully represent litter interception under field conditions [4,5,7]. The water holding capacity of the litter was found to differ significantly between the stands, with Agroforestry and Restoration Forest showing higher capacity compared with Eucalyptus sp. This variation can be attributed to differences in litter composition, particularly the proportion of leaves and branches. The water holding capacity of the unstructured fraction of Eucalyptus sp. was relatively high due to its lower surface adhesion [51,52], resulting in greater water retention rates. In contrast, in Agroforest and Restoration Forest, the leaf fraction exhibited the highest water holding capacity due to its higher surface adhesion. The composition and decomposition stage of the litter fractions, particularly the higher proportion of branches in Eucalyptus sp., influenced the water holding capacity. The hydrophobic nature of branches limited their water absorption capacity, while leaves showed higher surface adhesion and superior water retention. Stems or branches, mainly composed of xylem with thick fibers and a relatively stable structure between cells, have limited water absorption capacity despite the presence of an internal tubular structure [24]. Additionally, the hydrophobic nature of branches is a well-known characteristic that can also be attributed to the presence of lignin in their composition [53,54]. Lignin, being a complex aromatic polymer, contributes to the structural integrity of plant cell walls and imparts rigidity to woody tissues. As a hydrophobic substance, lignin naturally repels water [53,54,55,56,57]. It is important to note that the lignin content can vary not only between different tree species [53] but also between different parts of the same tree, such as leaves, stems, and branches. Moreover, the proportion of branches in the litter layer can vary depending on the tree species composition and forest management practices. This variability can influence the overall water holding capacity of the litter and its hydrological functions in different ecosystems. Overall, for all stands, the water holding capacity was lower than that observed for Amazon Forest [5] and Cerrado under various stages of regeneration [4]. Notably, the water retention rates of Eucalyptus sp. in this study were lower than those reported in other Eucalyptus sites [48].

Despite differences in water holding capacity, the effective water retention capacity (W_eff) of the litter was found to be similar among the stands. The similarity in W_eff indicates that Eucalyptus sp., Agroforest, and Restoration Forest have the ability to effectively retain water, contributing to enhanced rainwater storage within the ecosystem. This fact may explain the similarity in soil bulk density, soil resistance to penetration, and soil water content among the studied sites, although the water retention capacity was higher for Agroforest. This suggests that the hydrological properties of litter did not have a direct impact on soil physical properties in the studied stands. However, it is important to note that in this study, the soil physical properties were investigated at the topsoil level (0–20 cm for soil bulk and water content and 0–60 cm for resistance of penetration), and these properties can vary according to the soil profile [58,59,60]. Nevertheless, as reported by [36,61], W_eff defines the effective interception of precipitation by litter, which is an important hydrological property that can be used to consistently evaluate the potential to absorb rainfall and reduce surface runoff [9,42,61]. Effective water retention is influenced by factors such as litter water content, storage capacity, and rainfall characteristics [5]. Our study shows that the mean annual capacity of litter for both stands to retain water was higher for both sites than that observed for acacia–grass forest, eucalyptus–grass forest, and bamboo–grass forest [61]. However, Eucalyptus sp., Agroforest, and Restoration Forest were lower than Acacia mangium and higher than Hevea brasiliensis [9]. Moreover, Agroforest was W_eff slightly higher than Amazon Forest [5]. However, the W_max, which measures the rainfall absorption capacity, was higher in Eucalyptus sp., Agroforest, and Restoration Forest compared with previous studies on acacia–grass forest, eucalyptus–grass forest, and bamboo–grass forest [61]. It was also higher than Eucalyptus robusta [9] but lower than Acacia mangium [9]. Moreover, W_max for Eucalyptus sp. and Restoration Forest was higher than Amazon Forest [5]. Considering that 1 mm of rainfall is equivalent to 1 t ha⁻¹ [9,61], the litter in Eucalyptus sp., Agroforest, and Restoration Forest could intercept an average of 26 mm, 16 mm, and 23 mm of rainfall, respectively, during the studied period. Considering the effective water retention for the studied period, Eucalyptus sp., Agroforest, and Restoration Forest intercepted a mean of 8.3, 11.6, and 8.7 mm of rainfall, respectively.

4.2. Implications for Ecosystem Functioning

It is important to highlight that a previous study conducted on Pinus tabulaeformis plantations revealed that around half of the throughfall was retained in the soil without any litter mass. In the litter-covered treatments, this proportion ranged from 77.0% to 87.9% [44], indicating that the presence of litter significantly enhanced rainwater storage [62]. These findings highlight the importance of considering litter composition and species-specific characteristics when assessing the hydrological functions of litter. The variations in litter hydrological properties observed in this study have important ecological implications for ecosystem functioning and water resource management. The higher water holding capacity of Agroforestry and Restoration Forest litter implies that these stands can retain more water, which has implications for water availability within the ecosystem. Increased water retention can lead to enhanced soil moisture, providing a vital water resource for plants and microorganisms, especially during dry periods. Restoration Forest, which exhibited higher effective water retention capacity, can serve as a valuable model for ecosystem restoration efforts. Restoring degraded areas with diverse native tree species can improve litter hydrological properties, leading to enhanced ecosystem services and ecological functionality. Agroforestry systems, with their capacity for higher water retention, can be integrated into water-sensitive agricultural practices to improve water availability for crops and reduce water-related risks, such as soil erosion and flooding. This improved water availability can contribute to the overall productivity and resilience of the ecosystem. Furthermore, litter acts as a natural barrier against soil erosion by reducing the impact of rainfall and slowing down or preventing surface runoff. The ability of Agroforestry and Restoration Forest to retain more water in their litter layers can be particularly beneficial in mitigating soil erosion and preserving soil health. Regarding biodiversity support, litter provides a habitat and food source for various organisms, supporting biodiversity within the ecosystem. The differences in litter composition and hydrological properties among the stands can influence the diversity and abundance of soil-dwelling organisms, contributing to overall ecosystem biodiversity.

Finally, the results obtained in this study provide valuable insights into the hydrological properties of litter in the specific stands investigated. However, further research is needed to expand the scope of the study and examine a wider range of forest types and species to obtain a more comprehensive understanding of litter hydrological functions. Additionally, field conditions and natural variability should be considered to better assess the actual litter interception and water retention capacities of different ecosystems. Such knowledge can contribute to improved water resource management and the development of sustainable land use practices that consider the hydrological role of litter in ecosystem functioning.

5. Conclusions

This study provides valuable insights into the hydrological properties of litter in different vegetation cover types, highlighting variations in water holding capacity and effective water retention among Eucalyptus sp., Agroforestry, and Restoration Forest. The results revealed variations in litter accumulation, composition, water holding capacity, and effective water retention among the stands. The litter accumulation in Eucalyptus sp. had a higher proportion of branches compared to leaves. The water holding capacity of the litter varied among the stands, with Agroforest and Restoration Forest exhibiting higher capacities than Eucalyptus sp. Leaves showed higher surface adhesion and superior water retention, while branches exhibited lower water absorption due to their hydrophobic nature. Despite differences in water holding capacity, the effective water retention, which defines the effective interception of precipitation by litter, was similar among the stands. Moreover, litter hydrological properties did not affect soil bulk density, soil retention potential, and soil water content. These findings emphasize the importance of considering litter composition and species-specific characteristics when assessing the hydrological functions of litter. The results contribute to our understanding of the intricate relationship between vegetation cover, litter properties, and water balance in ecosystems. This knowledge can aid in the development of effective conservation and management strategies for sustainable land use practices, carbon sequestration, and water resource management. Further research is recommended to broaden the scope of the study, encompassing a wider range of forest types and species, as well as considering field conditions and natural variability. This would provide a more comprehensive understanding of litter hydrological functions and their implications for ecosystem processes.