当前位置: X-MOL 学术Plant Soil › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Cushion shrubs encroach subhumid rangelands and form fertility islands along a grazing gradient in Patagonia
Plant and Soil ( IF 3.9 ) Pub Date : 2022-04-09 , DOI: 10.1007/s11104-022-05398-1
Braian Vogel 1, 2 , Marcos Antilef 1 , Ludmila La Manna 1, 2 , César Mario Rostagno 2, 3 , Lucía Molina 2, 4
Affiliation  

Purpose

We assessed changes in soils and vegetation associated with different plant life forms and increasing grazing intensity (GI) in a subhumid grassland of Patagonia (Argentina), with vast portions of these grass steppes in degraded states.

Methods

We reconstructed the historic GI gradient of the study sites and characterised the vegetation cover. We sampled the soil beneath patches of grass and shrub and their bare interspaces, as well as the height of the hummocks and the thickness of superficial horizons. We used multivariate analysis, inferential tests, simple regressions and the relative interaction index to measure the effect of historical grazing in these rangelands.

Results

The soil in interspaces between shrubs was the most degraded, with particle and fertility losses. While the soil of vegetation patches did not differ in any fraction, the soil beneath shrub patches was far more fertile. The soil of the sites with cushion shrubs developed the typical spatial heterogeneity of the fertility island effect, and their fertility decreased with increasing GI. With increasing GI, the relative cover of cushion shrubs grew and the total grass cover decreased, while the percentage of bare soil increased.

Conclusions

The increasing grazing intensity favoured the transition of this subhumid grassland to shrubland. Grazing as an exogenous factor triggers processes of vegetation change and soil degradation, which lead to the encroachment by the cushion shrub Mulinum spinosum and fertility island development. This self-reinforced degradation process, well documented in arid and semiarid environments, also occurs in subhumid rangelands of the forest-steppe ecotone.



中文翻译:

垫状灌木侵占半湿润牧场,在巴塔哥尼亚沿放牧梯度形成肥力岛

目的

我们评估了巴塔哥尼亚(阿根廷)半湿润草原中与不同植物生命形式和放牧强度(GI)增加相关的土壤和植被变化,这些草草原的大部分处于退化状态。

方法

我们重建了研究地点的历史 GI 梯度并描述了植被覆盖。我们采样了草丛和灌木斑块下的土壤及其裸露的空隙,以及小丘的高度和浅层的厚度。我们使用多变量分析、推理检验、简单回归和相对相互作用指数来衡量这些牧场历史放牧的影响。

结果

灌木间的土壤退化最严重,颗粒和肥力损失。虽然植被斑块的土壤没有任何差异,但灌木斑块下面的土壤要肥沃得多。垫层灌木场地土壤呈现典型的肥力岛效应空间异质性,肥力随着GI的增加而降低。随着GI的增加,垫层灌木的相对盖度增加,总草盖度减少,而裸土百分比增加。

结论

放牧强度的增加有利于这片半湿润草原向灌丛过渡。放牧作为外源性因素引发植被变化和土壤退化过程,导致垫层灌木Mulinum spinosum的侵占和肥力岛的发展。这种自我强化的退化过程,在干旱和半干旱环境中有充分的记录,也发生在森林草原交错带的半湿润牧场。

更新日期:2022-04-09
down
wechat
bug