More Stable Productivity of Semi Natural Grasslands than Sown Pastures in a Seasonally Dry Climate

Ospina, Sonia; Rusch, Graciela M.; Pezo, Danilo A.; Casanoves, Fernando; Sinclair, F.L.

doi:10.1371/journal.pone.0035555

Cited by 27 publications

(28 citation statements)

References 44 publications

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“…Heterogeneity in semi-arid regions is associated with variability in rainfall patterns (Augustine 2010;Sanchiriro and Wyatt 2002;Hasler et al 2005). The rainfall patterns often coincide with the effects of seasonality which in turn have an effect on the productivity of grassland pastures (Ospina et al 2012). This could explain the consistent negative slope in forage quantity from the wet season to the dry season observed in this study.…”

Section: Discussionsupporting

confidence: 62%

Spatio-temporal dynamics of forage and land cover changes in Karamoja sub-region, Uganda

Egeru

Wasonga

Kyagulanyi

et al. 2014

Pastor Res Policy Pract

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Spatio-temporal dynamics of pastoral grazing resources influences the pastoral production system. Obtaining timely and reliable information on the status of these resources will support planning and early response to climatic variability. This study in Karamoja pastoral sub-region of Uganda identified herbaceous and woody forage species in different grazing land cover types, quantified forage in different grazing land covers, analyzed long-term land use/cover change (from 1986 to 2013) and determined the relationship between Normalized Difference Vegetation Index (NDVI) and herbaceous biomass. Results showed that the sub-region has over 30 grass species that provide forage. During the wet season, woodlands, grasslands and thickets and shrublands recorded a wet weight of 1,342.5 ± 104.5 kg/ha, 857.5 ± 29.4 kg/ha and 501 ± 43.9 kg/ha, respectively. In the dry season, 542.5 ± 57.6 kg/ha, 273 ± 6.4 kg/ha and 140 ± 9.2 kg/ha were realized in the woodlands, grasslands and thickets and shrublands, respectively. However, in the transitionary season, 276, 512.5 and 529.2 kg/ha were obtained in the woodlands, grasslands and thickets and shrublands accordingly. Similar trends were observed in dry matter biomass in the respective land cover type. Seasonality, land cover type and location accounted for the variations in the observed forage quantities. Analysis of land cover and land use change revealed a tenfold increase in croplands in the last 13 years. The expansion of crop cultivation is attributed to interventions by the Government of Uganda and development partners to promote food security in the sub-region. Heightened bushland encroachment was similarly observed in the last 13 years. The study also found a significant positive relationship between NDVI and herbaceous biomass, indicating that remote sensing offers reliable resource assessment and monitoring options for informing planning and interventions in semi-arid areas.

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Section: Discussionsupporting

confidence: 62%

Spatio-temporal dynamics of forage and land cover changes in Karamoja sub-region, Uganda

Egeru

Wasonga

Kyagulanyi

et al. 2014

Pastor Res Policy Pract

View full text Add to dashboard Cite

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“…The temporal changes in grassland ANPP observed in this study follow the pattern found by Ospina et al (2012) in open grasslands in the same area. ANPP is triggered at the onset of the rains, but declines at high levels of monthly rainfall.…”

Section: Discussionsupporting

confidence: 87%

“…The dominant soil type in the studied sites was a grayish to black Vertisol, with high organic matter content in the upper horizons (8 %). The natural vegetation of the region corresponds to a transitional tropical sub-humid forest with semi-deciduous vegetation, and is referred to as a seasonally dry tropical forest (Ospina et al 2012). The land-units in the study were semi-natural grasslands with scattered trees.…”

Section: Methodsmentioning

confidence: 99%

“…The land-units in the study were semi-natural grasslands with scattered trees. These grasslands are spontaneous vegetation that grow after forest clearing, or on fallow land, and which are maintained by grazing and weed control (Ospina et al 2012). The predominant land-use is livestock farming, with relatively homogeneous livestock management.…”

Section: Methodsmentioning

confidence: 99%

“…Hence, understanding the factors that determine grassland productivity is critical for the design and management of silvpastoral systems. In seasonally-dry tropical climates, monthly rainfall is an important determinant of net primary productivity (Ospina et al 2012), but studies that have evaluated this feature in silvopasture grasslands of Central America are few, and it is also not well known how rainfall interacts with the tree canopy in determining levels of grassland productivity in these systems.…”

Section: Introductionmentioning

confidence: 99%

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Determinants of grassland primary production in seasonally-dry silvopastoral systems in Central America

et al. 2014

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Grassland primary productivity is the function that underpins the majority of the fodder production in cattle-rearing silvopastoral farms. Hence, understanding the factors that determine grassland productivity is critical for the design and management of silvpastoral systems. We studied the effect of two factors with documented impact on grassland productivity in seasonally dry silvopastures of Nicaragua, rainfall and trees. We assessed the effects of three species that differed in crown size and phenology, one evergreen, Cassia grandis, and two deciduous species, Guazuma ulmifolia and Tabebuia rosea. Overall, grassland ANPP had a quadratic response to rainfall, with a decline at high rainfall that coincided with peak standing biomass and grassland cover. Trees had a predominately negative effect on grassland productivity, and the effect was concentrated in the rainy season at peak productivity. The effect of the trees corresponded with the tree crown area, but not with crown density. Trees reduced the standing biomass of graminoids and increased forb biomass; thus, the effect of trees on grassland ANPP appears in part to respond to changes in grassland composition. We also found higher levels of soil moisture content below the tree canopy, particularly at the peak of the rainy season when soils tend to become waterlogged. The evergreen species, C. grandis, affected grassland ANPP more strongly than the deciduous species.

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Is Direct Seeding a Biologically Viable Strategy for Restoring Forest Ecosystems? Evidences from a Meta‐analysis

2015

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Ecological restoration has become an important technique for mitigating the human impacts on natural vegetation. Planting seedlings is the most common approach to regain lost forest cover. However, these activities require a large economic investment. Direct seeding is considered a cheaper and easier alternative technique, in which tree seeds are introduced directly on the site rather than transplanting seedlings from nurseries. To evaluate the effectiveness of direct seeding, we conducted a comprehensive search of the literature using 'restoration', 'direct seeding' and 'sowing' as keywords, and we performed a meta-analysis using 30 papers and 89 species. We used two different measures of restoration success: seed germination probability and success probability (the chance that a seed germinates and survives until the end of the experiment). In general, restoration attempts using direct-seeding techniques were relatively unsuccessful. On average, seed germination and success probability were 0·239 and 0·114, respectively, and were not affected by climate, species successional group or the application of pre-germinative treatments. Germination and success probability increased with seed size, and the use of physical protections resulted in a nearly twofold increase in germination probability, but this effect faded by the end of the experiments. Because of the low rate of seedling success, we suggest the use of direct seeding as a complementary technique to reduce restoration costs, particularly for species with large seeds and known high germination rates, but our results do not support direct seeding as a substitute for seedling planting.

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More Stable Productivity of Semi Natural Grasslands than Sown Pastures in a Seasonally Dry Climate

Cited by 27 publications

References 44 publications

Spatio-temporal dynamics of forage and land cover changes in Karamoja sub-region, Uganda

Spatio-temporal dynamics of forage and land cover changes in Karamoja sub-region, Uganda

Determinants of grassland primary production in seasonally-dry silvopastoral systems in Central America

Is Direct Seeding a Biologically Viable Strategy for Restoring Forest Ecosystems? Evidences from a Meta‐analysis

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