Roots of forbs sense climate fluctuations in the semi-arid Loess Plateau: Herb-chronology based analysis

A Comparative Analysis of the Hydraulic Strategies of Non-Native and Native Perennial Forbs in Arid and Semiarid Areas of China

(1) Background: Water transport systems play an important role in maintaining plant growth and development. The plasticity responses of the xylem anatomical traits of different species to the environment are different. Studies have shown that there are annual growth rings in the secondary root xylem of perennial herbaceous species. Studies on xylem anatomical traits, however, have mainly focused on woody species, with little attention given to herbaceous species. (2) Methods: We set 14 sampling sites along a rainfall gradient in arid and semiarid regions, and collected the main roots of native (Potentilla) and non-native (Medicago) perennial forbs. The xylem anatomical traits of the plant roots were obtained by paraffin section, and the relationships between the xylem traits of forbs were analyzed by a Pearson correlation. (3) Results: In the fixed measurement area (850 μm × 850 μm), the vessel number (NV) of Potentilla species was higher than that of Medicago species, while the hydraulic diameter (Dh) and mean vessel area (MVA) of Potentilla species were lower than those of Medicago species. With the increase in precipitation along the rainfall gradient, the Dh (R2 = 0.403, p = 0.03) and MVA (R2 = 0.489, p = 0.01) of Medicago species increased significantly, and NV (R2 = 0.252, p = 0.09) decreased, while the hydraulic traits of Potentilla species showed no significant trend with regard to the rainfall gradient. (4) Conclusions: The hydraulic efficiency of non-native Medicago forbs was higher than that of native Potentilla forbs, and the hydraulic safety of native Potentilla forbs was higher than that of non-native Medicago forbs. With the decrease in precipitation, the hydraulic strategies of non-native Medicago forbs changed from efficiency to safety, while native Potentilla forbs were not sensitive to variations in precipitation.

Alpine plant growth and reproduction dynamics in a warmer world

Climate warming may stimulate growth and reproduction in cold-adapted plants, but also reduce their performance due to warming-induced drought limitation. We tested this theory using a unique experiment with the alpine forb Rumex alpinus. We examined how climate warming over the past four decades affected its annual rhizome growth, leaf production and flowering, and whether responses varied between alpine, subalpine and montane populations. Before the period of accelerated warming in the 1970s and 1980s, the primary limitation on growth had been cold temperatures and short growing seasons. Increased summer temperatures in the 1990s and 2000s enhanced rhizome growth and leaf production, but not flowering. Alpine and subalpine plants profit more than montane plants, currently producing three times longer annual rhizome increments and twice as many leaves as 40 yr ago, and achieving nearly the same values as montane plants. During the warmest 2005-2015 period, growth became contingent on summer precipitation and began to decrease across all populations, likely due to an increasing water shortage in dense monospecific stands. Warming releases plants from cold limitations but induces water shortage. Rumex alpinus exceeds its thermal optimum and becomes water-limited as the climate warms. Our results suggest that warming-induced responses in alpine plants will not be one-sided shifts to higher growth and reproduction, but rather multidimensional and spatiotemporally variable.

Capturing the Geoherbalism Differentiation in Wild Paris polyphylla var. yunnanensis Raw Materials through the Application of Multispectral Information Fusion Combined with Chemometrics

Paris polyphylla var. yunnanensis is a famous medicinal plant distributed in some Asian countries. This species has attracted a great deal of attention and is often used as raw materials in traditional medicine practices. With the purpose of gaining insight into the geoherbalism of wild P. polyphylla var. yunnanensis, a total of 183 dried rhizome samples from eight different regions including 16 typical or nontypical natural habitats have been analyzed by multispectral information fusion based on ultraviolet and Fourier transform infrared spectroscopies combined with partial least squares discriminant analysis (PLS-DA) and hierarchical cluster analysis. From the results, the use of multispectral information fusion strategy could improve the correct classification of samples, and good classification performances have been shown according to PLS-DA models. The discrimination of samples was obtained successfully with respect to the typical and nontypical natural habitats, different collection areas of typical natural habitats, and various sampling sites in nontypical natural habitats. Additionally, the similarities among samples were presented as well. Overall, the rhizome of wild P. polyphylla var. yunnanensis exhibited various regional dependence and individual differences according to the geographical origins, and the relatively appropriate growth region with better quality consistency of samples was preliminarily selected. This study also revealed that the developed multispectral information fusion method has the potential to be a reliable analytical methodology for capturing the geoherbalism differentiation in wild P. polyphylla var. yunnanensis. Furthermore, it could provide more chemical evidence for the critical supplement of quality evaluation on P. polyphylla var. yunnanensis.