陕北黄土高原丘陵区撂荒演替及其过程中主要乡土牧草的确定与评价

Vegetation succession of arable old land after being abandoned in Loess Plateau hilly region & ascertaining dominant native herbages in the process, analyzing their chemical nutrient composition

用系统聚类、撂荒年限两种方法对陕北黄土高原丘陵区撂荒演替序列进行分析,结果基本一致:1～6a,1年生杂草类群落→1年生杂草类+丛生禾草群落→1年生杂草类+根茎禾草群落或多年生草本群落→7～16a,多年生草本群落→多年生草本+小灌木群落→17～42a:根茎丛生型禾草+小灌木群落或小灌木+多年生草本群落→小灌木群落或多年生草本+丛生禾草群落,代表性群落依次为猪毛蒿(ArtemisiascopariaWaldstet.etkit)群落或猪毛蒿+长芒草(StipabungeanaTrin.)群落→猪毛蒿+铁杆蒿(ArtemisiasacrorumLeded.)群落或冰草(Agropyroncristatum(L.)Gaertn)群落→铁杆蒿群落→铁杆蒿+达乌里胡枝子(Lespedezavar.dahurica(Laxm.)Schindl)群落→白羊草(Bothriochloaischaemum(L.)Keng)+达乌里胡枝子群落或达乌里胡枝子+铁杆蒿群落或铁杆蒿+硬质早熟禾(PoasphondylodesTrin.etBge)群落。在此基础之上,提出将各物种在演替过程中重要值之和按大小排序,对前35位草种经适口性试验初步筛选后进行以粗蛋白、粗纤维等为指标的化学成分及以有效植被盖度为指标的生态效益的分析、评价,并依据两种评价结果对陕北黄土高原主要乡土牧草进行了综合评定,得出黄土高原23种乡土牧草具备较高的改良潜质,分为4类,主要归属于豆科(Leguminosae)、禾本科(Gramineae)、菊科(Compositae)等,并进一步探讨了黄土高原人工草场改良过程中不同荒地上草种的合理搭配。

A 2-year experiment was carried out in the Loess Plateau to better understand vegetation succession of arable old land after being abandoned in Loess hilly region. Based on 2 kinds of ways, one was quantitative classification using system clustering, the other was abandoned year. Again with the overall understood of 25 sample plots research, the result showed that： from 1 to 6 years, annual weeds community → annual weeds ＋ tuft grass community → annual weeds ＋ perennial herbage community or rhizome grass → from 7 to 16 years, perennial herbage community → perennial grass ＋ undershrub community → from 17 to 42 years, rhizome tuft grass ＋ undershrub community or undershrub ＋ perennial grass community → undershrub community or perennial grass ＋ tuft grass community. The representative communities were： Artemisia scoparia Waldstet. et kit community or A. scoparia Waldstet. et kit ＋ Stipa bungeana Trin. community → A. scoparia Waldstet. et kit ＋ Artemisia sacrorum Leded. community （or Agropyron cristatum （L.） Gaertn community） → Artemisia sacrorum Leded. community → A. scarorum Ledeb. ＋ Lespedeza var. dahurica （ Laxm. ） Schindl community → Bothriochloa ischaemum （ L. ） Keng ＋ Artemisia sacrorum Leded. community Or Lespedeza var. dahurica （ Laxm. ） Schindl ＋ Artemisia sacrorum Leded. community or Artemisia sacrorum Leded. ＋ Poa sphondylodes Trin. et Bge community. In order to restore the degraded environment in the arid zone, it was important to know how to collocate kinds of pastures with wild grasses. There is a new way： first, based on the result of the investigation into succession, all kinds of wild grasses were arranged in order of their important values, 1 ～ 35th herbage was warranted that being able to yield more quantity production than from 36 to the last grass according with the model of important value, this character was the most important not only for the ecological benefit but also for the economic effectiveness; second, according as the result of palatability experiment, 23 kinds of pastures were selected from the 1 ～ 35th grasses to be analyzed their chemical nutrient composition, then, they were graded excellent, fine, good and inferior by the score that gained appraisal by chemical nutrient composition in accordance with the pasture＇s quality standard; third, these kinds of pasture community＇s ecological benefit was analyzed, then, they were graded excellent, fine, good and inferior too ; ultimately, over efficacy of 23 kinds of herbage community was ascertained. To summarize ： 23 kinds of pastures were classified into 3 groups according to their site quality of locality in the community in the succession process. One was constructive or dominant species in the period of succession process, but in the other times there were not these herbages, such as Sophora vicifolia Hance, Phragmitas communis Trin; Two was subdominant or companion species in the whole period of succession process, such as Gueldenstaedtia multiflora Bunge, Potentilla bifurca L. ; Three was those grasses that transform their site quality of locality in the community in the succession process from constructive or dominant species into subdominant or companion species, or reverse, for example Lespedeza var. dahurica （ Laxm. ） Schindl, Bothriochloa ischaemum（L. ）Keng. Besides, chemical nutrient compositions of these pastures have shown much variation, so, we should be attach importance to this phenomenon. When these conclusions being have applied, it appears important to repair vegetation based on the community structure in the succession process of different abandoned lands, the different pastures that should have overwhelming chemical nutrient composition will be selected from the grasses in the corresponding nature communities.