Invasive plants and plant diversity as affected by groundwater depth and microtopography in the Great Basin

Abstract

We evaluated invasive exotic weeds and plant species diversity in relation to depth to groundwater (DTW) and microtopography in areas with DTW from 0·3–4 m in Owens Valley, California. Transects dominated by common plant species of the area were read at 1‐cm intervals, and species cover was obtained at different scales: 1‐m transect portions (microsites), whole transects (68 m average length), and the whole study area. Species richness and the Shannon–Wiener diversity index were obtained in microsites. DTW and microtopographical variation (soil‐surface relative elevations) were jointly measured along the vegetation transects. Found in 34% of the sampled transects, the annual Bassia hyssopifolia was the most common exotic weed of the area. Its cover in the whole study area was only 0·9%, but it was the second most dominant species (19% cover) in microsites. B. hyssopifolia coexisted mainly with herbaceous species, typically in places with shallow groundwater (average <1·5 m) and microtopographical depressions. However, B. hyssopifolia cover was not affected by variations in DTW or relative elevation. In contrast, B. hyssopifolia cover was negatively associated with perennial cover and species richness. Species diversity (Shannon–Wiener) slightly decreased with the increase in DTW but not with changes in microtopography. In contrast, species richness clearly varied with the identity of the dominant species in microsites. Our study suggests that the variation in community‐intrinsic factors such as competition and diversity may play a greater role in the growth of invasive plants than the variation in physical factors such as groundwater and microtopography. Copyright © 2011 John Wiley & Sons, Ltd.

Flood regime alters the abiotic correlates of riparian vegetation

“…Here, we documented substantial divergence in plant community composition between sites that had the capacity to flood and those that no longer flood, including more than 60% greater plant species richness in flooding sites. These results align with findings in other arid rivers (e.g., Mata‐Gonzalez, Martin, et al, 2012; Hingee et al, 2017; Palmquist et al, 2018), but were larger in magnitude than in prior reports. We also uncovered correlations between plant diversity and intra‐annual variability in groundwater.…”

“…In contrast, average groundwater depth was the strongest predictor of total and native plant diversity at flooding sites. This result helps to explain the generally low explanatory power of depth to groundwater in prior studies of riparian vegetation from heavily regulated ecosystems, where flooding is infrequent (Mata‐Gonzalez, Martin, et al, 2012; Mata‐Gonzalez, McLendon, et al, 2012). Finally, plant diversity and composition were more divergent among non‐flooding sites than at flooding sites.…”

Growth, water productivity, and biomass allocation of Great Basin plants as affected by summer watering

“…Ten of the most common plant species in the Owens Valley (Mata‐González et al ., ) were used for this study (Table ). Individuals of each species were grown in the field in 2·4 m × 2·4 m plots as a garden study.…”

Evaluation of structure from motion for soil microtopography measurement

“…Laser scanners and digital photogrammetry have been the most commonly used technologies in the non‐contact category although Mata‐González et al. () have used a reflectorless total station to remotely measure soil microtopography.…”