Tree Canopy Management Affects Dynamics of Herbaceous Vegetation and Soil Moisture in Silvopasture Systems Using Arboreal Legumes

Izabela A Gomes Da Silva,Mércia Virginia Ferreira Santos,Márcio Vieira Cunha,Valéria X O Apolinário,Erinaldo Viana De Freitas,Alexandre Carneiro Leão De Mello,José C B Dubeux

doi:10.3390/agronomy11081509

Abstract

Understanding ecological interactions between the arboreal and the herbaceous components is key to get the full benefits from silvopastoral systems. The objective of this 2-yr research was to evaluate productivity and nutritive value of signalgrass (Urochloa decumbens (Stapf.) R. Webster) subjected to shading from the tree legumes Gliricidia (Gliricidia sepium (Jacq.) Steud) or Mimosa (Mimosa caesalpiniifolia Benth.) under different tree canopy management. Trees were planted in double rows and were either unharvested or harvested only one row, leaving the other row unharvested. Response variables for the herbaceous vegetation included canopy height, herbage mass (green leaf blade, green stem, senescent leaves, and senescent stem), herbage accumulation rate, canopy bulk density, and soil moisture. Total herbage mass, green herbage mass, and green leaf mass were affected by treatment × month and harvest management × month interactions. Herbage accumulation rate in Gliricidia was greater (55 kg DM ha−1d−1) than Mimosa (32 kg DM ha−1d−1). Soil moisture was lesser at the Mimosa sites (16.2%) compared with the Gliricidia ones (17.2%), and it was greater between tree rows (21.9%) compared with full sun (11.5%), varying across the season. Harvesting management had a short-term transient effect on herbage responses. Tree canopy management can affect forage quantity and quality; however, these effects are transient and vary with tree spacing. Signalgrass grew faster and had better nutritive value when growing with Gliricidia.

Highlights

Shade affects the productive, nutritional, and morphological traits of tropical forages [1]
Tree spacing and canopy management affect the dynamics of the herbaceous vegetation, and it varies with species, environment, and management practices
Interaction occurred between harvest management × month, and one-row area had greater total herbage mass only in December (Figure 2B)

Summary

Introduction

Nutritional, and morphological traits of tropical forages [1]. Shade might increase chlorophyll [3] and crude protein (CP) concentrations [4] of herbaceous vegetation in silvopastoral systems. Silvopastoral systems with tree legumes have added benefits such as the potential biological N2 fixation and nutrient cycling [5]. There have been reports that Gliricidia and Mimosa root systems are able to take advantage of the association with rhizobia symbionts, affecting soil Nitrogen (N) cycling [6]. Selecting the appropriate arboreal species for a silvopastoral system is key to enhance sustainability. Multi-purpose tree species with economic potential that provides shading, soil protection, fire resistance, without toxic effect to animals, and forage potential must be selected [7]. Tree spacing and canopy management affect the dynamics of the herbaceous vegetation, and it varies with species, environment, and management practices

Methods

Results

Discussion

Conclusion